Adam Savage Stumped by This Mystery Lathe Problem

While working on a powered hacksaw build, Adam runs into a problem with his lathe's ability to cut bolt threads, with the machine not cutting the desired threads per inch. It's a bit of a head scratcher as Adam attempts to problem-solve and understand this unexpected behavior before making his fix!
Shot by Adam Savage and edited by Joey Fameli
Music by Jinglepunks
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#adamsavage #onedaybuilds #repair

[@tested]

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[@KenFullman]

I think what went wrong was, a red pointer has been taken off your lathe. This red pointer would have been pointing to the number on the bottom of that wheel. So your assuming that the top number is the one selected, whereas, if you had that red pointer, you'd have been looking at the digit on the bottom of the wheel.

[@MichaelBerthelsen]

27:34 Was that Fraggle Rock, by any chance?😅 Sounded kinda like it at the end, there.😁

[@christopherleveck6835]

I would have mounted the Guage pin in the chuck. Dial in the vice. Position the quill so that the pin goes EXACTLY through the hole. Measure the offset. Replace the Guage pin with the drill bit and drill your hole. Done.

[@noelhenderson8095]

Ask Curtis from Cutting Edge Engineering I'm sure it is just something simple he might be able to help you figure out your problem

[@dallasarnold8615]

Adam, now that you have it right, I would suggest you plug the other hole so that if you ever remove the dial, you will not be guessing which way is correct going back on.

[@hectorrenesegovia779]

Imagine... WE ARE NOT THERE WITH HIM! He is alone in his workshop talking to himself... to an inanimate object (the camera) with no feedback nor emotion (not even a crew) - and STILL he is able to maintain - without feeling insane - an actively engaging personality and demeanor as he works his way through this... alone. Adam, you are a national treasure!

[@snorttroll4379]

it helps to see that people in the comment section exsist

[@hectorrenesegovia779]

@@snorttroll4379 Yes, of course. I'm just reminding people that when he does record, it's just him and his thoughts.

[@alabamaflip2053]

Well said.

[@salviguitars]

Explaining something to someone can make it easier for oneself to understand. He's doing himself a favour and helping us in the process. Brilliant!

[@eugenecbell]

Yes, a treasure.

[@gregolson1824]

On the left of the threading chart there is a diagram of the gear mesh for cutting standard threads and another mesh for cutting modified threads (the chart with the yellow screw at the top). Your gears are set to cut the mod chart not the standard chart. Open the door on the left side of the machine, flip the middle gear so the larger diameter gear (56t) is in mesh with the bottom (57t) gear. Then put your dial back on the correct way.

[@nealblackburn8628]

i am thinking the same thing but i don't have the same lathe as he has so i can't replicate the situation and check

[@i-squared]

The 56 tooth setting effects a 1.27:1 (non-integer ratio, common between metric to imperial change gears). His initial error ratio was 1.125:1 (integer divisible steps selection), So, it's not a function of the metric/imperial conversion.

[@richardbastow5605]

The beauty of our position is that we are trained ( I assume) machinists. But this does show the worth of proper training and apprenticeships.

[@alistercarmichael4990]

Just as I'm watching this that's what I'm thinking. Despite the box there are often some change gears, or rather gears common to everything that can be changed. Be it broken/worn or modified. The lead screw could also have been changed (and half nut) for a different set. All the issues with a previously loved machine.

[@dc6233]

Great reply! I guess that could be confusing when the rest of the settings seem to be so foolproof...

[@Evan-e-cent]

Adam, Check the gear train. It should be set up using the diagram at the top left of your gear table. There is a second gear train diagram, but it has the diagram of a yellow thread beside it. That one is used only for the column which also shows a yellow thread ie for modulus and Diametric Pitches for cutting gears. For threads you should use the top gear train diagram. Specifically: stud gear 24T (teeth), idler gear 56T and leadscrew gear 57 T. In this setup the middle gear is an 'idler gear' which does not affect the gear ratio. I suspect your lathe has been set up for gear cutting, using the bottom gear train. In that case it includes a pair of compound gears with a 56 T gear connected to a 44T gear by a keyway. This introduces a ratio of 56/44=1.272727 which approximates 1.27 with 0.21% error. Why would we want a ratio of 1.27? Well, we can easily use gears to multiply by 2, and then 2 x 1.27 = 2.54 and there are exactly 2.54 cm in one inch. So this gives you conversion between metric and imperial threads. I have written a free online computer program called RideTheGearTrain for doing gear train calculations. Just put dot com after the name! This will work for any lathe without a gearbox. But for a lathe with a gearbox (like yours) it needs to know the gear ratios in the gearbox. The program contains gearboxes for many different brands of lathes. I could add your lathe to the list, but need to know the pitch or TPI of the leadscrew. Unfortunately it is not shown on the table.

[@SmokePoppa]

It is clear that you have transcended above us mere geeks venturing towards the dark arts of Nerd Fu, should you ever require a disciple of the arts, many would rally to your banner good sir. I tip the hat with respect.

[@Evan-e-cent]

@@SmokePoppa Thanks for the complements. This week I am making a new KZbin video called Understanding Gear trains in my KZbin channel called evan-e-cent. I made the same video 4 years ago and since it had 21,000 hits and the quality was very poor, I have done it again with some nice PhotoShopped graphics. Comment if you like it. Should be online in the next few days.

[@gotindrachenhart]

Awesome work man, thanks!

[@charleshartlaub3725]

With a little bit of math you can calculate the leadscrew because the same settings use the 2 diffrent input ratios and have a known output, example the m14 and 3.5mod both use settings HO4Z

[@kmDooms]

So has this been resolved lol?

[@coyotestickers]

I just watched 45 minutes of solving a problem on a lathe i'll never known but LEARNED A TON! Grateful.

[@supralapsarian]

Was I the only one screaming “Don’t change all the numbers on the dial; just move the index mark on the panel!” 🤣 Thanks for welcoming us into your shop. We always learn something!

[@HandymanKurt]

Move the index!!🤣🤣🤣

[@stevetaylor996]

My thoughts exactly. I just finished commenting the same thing and deleted it after seeing that you had made the same comment.

[@patrickd9551]

Well no, because then the index mark would be on the bottom. And that is pretty much useless, at least if you want to read your machine correctly and/or easily. Unless you want to make things harder, in that case, yeah go for it ;)

[@jasonsullivan2775]

​@@patrickd9551 Ehh, there's only eight settings. It would be pretty easy to use a mark on the bottom with a dial that large with that few settings

[@supralapsarian]

@@patrickd9551, I meant for testing purposes. The labels for the dial were only meant as a temporary measure for testing purposes. Placing a single temporary index mark on the panel would have achieved the same result (determining it was 180º our of phase) with a single piece of tape (instead of 10). I am dying to know how the thing got to be out of phase like that. Keeping my eyes peeled for that video!

[@positronalpha]

As a software developer, this process is very familiar and I actually find this kind of troubleshooting quite comforting.

[@cem_kaya]

As a systems engineer, i think this kind of debugging is the best kind.

[@mbak7801]

I have seen a lot of software developers who magically add a constant in the middle of some code. When asked they say they have to add 5 to get the right solution later on but have no idea why. Personally I think that was dreadful especially as this was for calculating trajectory for a defensive missile on a ship. If it goes wrong nobody can prove it was them that messed up. Yuck!!!

[@Bleats_Sinodai]

​@@mbak7801you'd be surprised how much of the things in the world rely on "if it works, it works!". You'd be driven mad like a character discovering an eldritch being in a cosmic horror novel.

[@piercebros]

@@Bleats_Sinodaitrue!

[@jamestbfraser]

Totally agree

[@Esteb86]

I'm and ISP/Telecom field tech. Troubleshooting is what we do all day. Watching someone troubleshoot, and isolate a problem in itself is interesting. To then watch someone come up with a way to fix the problem is the cherry on top. A terrific way of gaining knowledge is by viewing someone else resolve problems in systems different than yours, because it gives you a different perspective, and allows you to always keep an open mind when encountering issues.

[@jlconway]

Honestly my favorite thing about watching Adam Savage work is that he does all the same weird stuff I do when I'm building/creating/troubleshooting/repairing and I feel so seen. The pauses and the tapping and the random singing and noises and drumming tunes and patterns, staring at the lathe and having it click "the knob is 180 out!" within moments of one another. Then the horror of realizing the knob only goes on one way, pausing, and exclaiming "the handle is on the shaft right, the shaft is in the machine wrong!" how do I fix this without taking the machine apart DRILL ANOTHER HOLE anyway thank you Adam Savage for being yourself unfiltered on camera.

[@kahlesjf]

It gets old. It is so self-conscious, repetitive, and wears poorly. Not that it is all staged. I believe it has a genuine core. But its frequency and intensity come off as a byproduct of so much time behind the camera and his role as the quirky member of the MythBusters team. For example, the pregnant pauses...We can all relate. But not to their frequency, especially in a video that he has to have given much thought to before he turns on the camera. It is not believable that he is having these "aha" moments spontaneously as film is rolling. These melodramatic storytelling devices slow down the narrative and just do not ring honest or true, but seem more like an actor trying too hard to stay in character. But each to his own. It is how I read it after having watched so many episodes of MythBusters.

[@bulwulffcristole3235]

@@kahlesjf So to your comment I would disagree whole heartedly. Adam appears to be a particular type of personality, and he has the additional quirk of exhibiting adhd and savant behaviors which is really common in very intelligent people. I myself am ADHD and I do these sorts of things often randomly as my mind gets distracted by something before going back to what I was doing, or as a side product of thinking out a problem. Some people mutter to themselves. What he's showing us is who he is without being ashamed of that fact. I do NOT believe it has anything to do with the Camera and, if anything he may be trying to reign it in. This is apparent when you watch MythBusters and I'm sure may have been a point of contention between him and Jamie if I were to guess. People with ADHD and this type of personality are hard to work with sometimes, and it's even harder to have a relationship with them, not because they don't care like everyone else but because we're just built differently. That's not a bad thing at all! It just means you need to be around other people who understand and get it so you can continue to be you without being judged by others. That's harder than you think and is evident in how you responded. Also you mentioned MythBusters as your point of reference. Again, that was likely him trying to do exactly what you're accusing him of here, and it probably was really hard and draining on Adam to pull it off. You're also assuming he put thought into anything at all before turning on the camera when, in fact, he likely had an Ah HAH moment and decided to click the camera on to record his thoughts. Was this prescripted? I'm sure it wasn't and did he retake to make the video more clean? Nope. This is about as unrefined as you can get and it's absolutely lovely! If he's anything like I am in the approach, there is often very little planning at all nor should there be because when you start planning what you're going to say, making retakes, etc. its no longer real. It's a fabricated experience sanitized for the internet. Being who you are requires zero planning, and far too many people today live fabricated lives rather than just being who they are. Keep being you Adam! I'm there with you and it's extremely refreshing to see someone who's being who they are instead of trying to be someone others, like @kahlesjf here feel you should be.

[@kahlesjf]

@@bulwulffcristole3235 As I mentioned in my original comment, I do not think it is all put on. But behaviors get shaped up, whether one has ADHD, any other condition that affects behavior, or no diagnosis at all. I believe it is a genuine aspect of his personality. I also believe that years in front of a camera, audience feedback, and enough positive attention for his quirkiness has lent a self-conscious and exaggerated aspect to his on-screen persona. It may even have happened so gradually that it is mostly sub-conscious now. He will affect others differently, people will disagree. Not a big deal in the scheme of things.

[@user-yx5hy2rk9c]

If you open the door on the left side of your lathes headstock you will find a 127 tooth gear and a few other gears with likely a diagram of at least 2 configurations that the gears can be arranged in. This is how lathes are designed to be configured for odd thread sizes and sometimes metric sizes .This is a likely might be the source of the gearing problem. I am a machinist and have seen similar problems on my equipment when someone has rearranged the gear's to cut a special thread. The side of your lathe opens up for this purpose.

[@AmericansWillRise]

If only he'd asked a machinist. 🤦‍♂️

[@jasonaldenhaley1]

Yes, some you need to swap the 2 on the threaded drive for carriage. Also gotta start either odd or even on that dial that spins once threads are engaged EVERYTIME you make a pass. He should try threading up to a shoulder....sucks. rpm soooo slow. Thing was probaby crashed, twisted the carriage driveshaft?? That one ripped my t-shirt off of me before on an old Summit. Good times

[@DJPLAST2]

@@AmericansWillRiseseen this many times over my career as a mold maker. Duffer getting out of his lane and trying to be something he is not! Ask for help from someone that is qualified.

[@jasonmorgan4108]

@@DJPLAST2for me it’s more rewarding to troubleshoot and solve problems myself. I go out of my way to not ask for help on a problem until I’m totally stumped.

[@willthomsen7569]

Other problem with calling a machinist is he’s gonna say sure I’ll fix it $150 bucks an hour plus or no I’m too busy to mess around with that cause I’m already entitled and spoiled by too much money for easy stuff. Machinists can be the worst

[@jvanbelle]

It could probably have been diagnosed much faster by looking at the setting for the thread you actually cut. When you wanted to cut the 18TPI you set it to LB3P, but got 16TPI, which is LB7P, which immediately tells you your number dial is off (by 4) without the trial and error, though you'd obviously still want to confirm with a few more tests.

[@Koushakur]

Yeah he definitely overthought it

[@arkieguy1]

Also, he could have just put an arrow on the machine body that points to the "correct" dial position instead of adding new numbers for each position on the dial. ;)

[@matspatpc]

@@arkieguy1Except that would now be UNDER the dial, which if you are standing in front of the machine trying to see what the setting is: not ideal. The "here's the right setting" is at the top of the dial normally. Half a turn off is the opposite side.

[@wobblysauce]

Bingo

[@smartgorilla]

Adam look at the manual or something. Not this. 😢😢

[@fuzzydrake2716]

It's hilarious how I watched you go through this process, and realized how similar you are to my father and I in certain regards. The pauses and "Oh" moments of realization, the various fiddling and mumbling or humming while working on something. It was a wonderful wind-down watch for the night. Thank you for sharing Adam!

[@teamja1088]

As a builder, I too know the absolute frustration of going to my shop to accomplish an easy job only to find myself 8 hours later trying to solve some complicated problem that I never even knew I had, while not even beginning the original job I set out to accomplish that morning.

[@goblin5030]

At 20:06 I couldn’t stop laughing. The conveyance of complex mechanical work and repair through little sound effects followed by vigorous shaking was pure gold. We all knew what Adam was saying without a word spoken

[@antiverisimilitudify]

I feel like this why we *really* come here to watch Adam.

[@StephenCole1916]

Victor Borge would be proud!

[@MrNikolidas]

@@StephenCole1916 Shouldn't that be "Victor Borge would be proud fssssssss pfick"

[@SweDownhill]

This is one of the best episodes I've seen in years. I loved the fact that Adam speaks through and explain the troubleshooting process.

[@TheAmericanDane]

I’ve never used a lathe in my life, although I know what one is… I think it speaks volumes to Adams character that I just know I will enjoy watching this before it’s even started. Such a relatable man, no ego, no front and down to Earth just a man being himself. Much love from England brother 🇬🇧

[@psuaero100]

One of the best Tested videos I watched in a while. I don't know why I waited a month but it probably has to do with my KZbin Watch Later list being too long). I love to watch the thought process Adam goes through identifying and solving the problem. I figured he was going to make a whole new knob out of some exotic material or lathe off (is that a process) the numbers and re-etch them in the correct locations. Of course, he came up with a new solution. Chapeau Adam, nicely done.

[@RelUnrelated]

About thirty years ago I worked as security in a large factory. Some of the coolest people I knew there were machinists, and this reminds me so much of all of the times they allowed me to watch as they cut custom threads on a project. Thanks for being real with us, Adam, and letting us in on the problem-solving!

[@tommcd5146]

There is nothing more satisfying than troubleshooting and remedying the problem after a solution has been determined. Also, I really like the warning sticker on the lathe. "This machine has no brain, so use your own". That is such a good reminder that in order to do something to be in the moment when making anything in a shop setting.

[@goreobsessed2308]

It's necessary lathe injuries are super common

[@joejoejoejoejoejoe4391]

And nothing more frustrating than failing to diagnose an intermittent fault.

[@frankieromnimon5898]

Just like watching myself debugging a faulty FPGA design. Great teaching and smooth narrative to match. That was 45 minutes very well spent. Thanks Adam, that was awesome!

[@CynicalWilson]

I've watched so many of Adam's videos by now, and oddly enough, this one right here is up there with my favorite ones! Loved it

[@erikpeterson4873]

These episodes are what make me really appreciate Adam, I love the insight into the problem solving rationale. His whole approach is built on probabilities.

[@dog3y3]

he also approaches it as we amateurs would approach the problem. I'm glad he brings it down for us non-machinists to understand. I wish I could get more like this.

[@J.C...]

This is soooo much cooler than Mythbusters, IMO

[@Nyghtprowler]

It's an internal issue. As they grow older, that "rough" engagement you are dealing with can hop out of phase and engage 180 degrees from the intended engagement. They are always whacky and you have to wiggle the spindel to get it to slip into gear. You can probably google that model lathe and get the schematics for the threading mechanism setup and you'll understand what I'm saying when you see the layout of how that scales the feed lengths based on that dial. I don't doubt that you had it working at some point, and later it slipped out while trying to engage it and now you are 180 off. It's also very possible for you to get it slipped back in and you will be back to normal the your dial mod will be wrong :) Those lathes are old and worn, it's probably due for some much needed maintenance or a rebuild.

[@deadfisher0000]

I literally yelled aloud "no!" when he admitted his plan was to mill a second hole in the dial. I'm not a machinist by any measure, but a different point of failure seems so undeniable. I'm glad to hear somebody with an idea on it.

[@YippingFox]

It's one of those "temporary" fixes. I can't imagine it being this old and not having functioned before. It solves a symptom, not the cause.

[@attyschack]

Why would it hop 180 degrees? Wouldn't it more likely skip a tooth or two? Seems more likely that somebody installed it in that position. I'm obviously not a machinist. Just doesn't make intuitive sense that a gear would hop 180 degrees.

[@cattey3306]

only 2 teeth on the gear?@@attyschack

[@dranorter]

Some other commenters have pointed out, it's likely the configurable gears under the left panel, which are accessible because they're meant to be arranged for unusual threadings that aren't on the chart. That seems much more likely than a 180 degree slip.

[@adamtebrugge4937]

I have dealt with non-flippable (its a word) shafts and handles or pulleys myself. It may be that something inside can be flipped, and IT is the problem. Love watching you work through this. Best of luck determining the actual mode of failure.

[@jacobpeterson628]

It's flippable 180° but not infinitely adjustable

[@keithhogg1963]

You’re a fascinating man Adam. I’m 60 years old. With barely a High School degree. Was never a smart boy. But watching your videos. I’m in Awe of you.

[@xKiNx]

Looks like the shaft was installed upside down during the mysterious rebuild you mentioned. All the gears and bearings were done correctly, but the shaft they sit on is what's °180 off.

[@ehsnils]

Well, the index wheel at least could be turned around 180 degrees on the shaft and maybe it will solve the problem. Edit: I have seen that the wheel can't be misinstalled 180 degrees off.

[@nathano2778]

This seems to make sense

[@jacobbrown9978]

I know nothing about lathes but I was going to comment this exact thing.

[@nathano2778]

It makes sense but is probably a manufacturer issue from day 1. I can't imagine designing a shaft that could have 2 mirror image ends where everything else still fits somehow. Would also explain why its been passed around a few times.

[@markbernier8434]

It occurs to me, that the simplest explanation for this problem is that when the dials were being made one was put in the jig upside down thus drilling the registration hole with opposite offset and everything afterwords was done correctly. It would be easy to prove if one could find an owner of the same machine and just have a look and say the offset is towards the #3 or towards the #6@@nathano2778

[@reddcube]

You should try cutting metric threads and see if reclocking the dial is still correct. The dial fixes could be the solution or it could be a bandaid to a different problem

[@charleshettrick2408]

Correct. We outfitted a tool room with cheap-brand, cheap lathes (against my protestations). One brand new lathe, never used, would not properly cut American threads, but cut metric just fine. We immediately realized the builder did not verify Imperial unit threads, only metric. The local supplier could not fix. Corporate told us in no uncertain terms, the lathe was under warranty. Do not repair. The supplier must fix. Supplier's fix was to replace the lathe in 10 months and I had to pay shipping from averseas mfg out of my budget. No way! We looked at actual cut threads per inch, compared to chart, found the correct combinations, and glued laminated labels to the lathe for American Imperial units. As soon as the lathes and other equipment from that manufacturer were out of warranty, we sold them and used pre-planned budget money to purchase new American built machines. 25 years later, the American lathes are daily still running.

[@davemccann7446]

I see the metric numbers are in the same order as the SAE numbers, and they should be reversed as SAE is TPI and metric is pitch.

[@T0phen95]

This is the type of problem solving I absolutely love. One day something was really frustrating me and I just couldn't figure it out. I knew it was something I was doing, not the project I was working on. But I could not understand what I was doing wrong in the moment. It took me into the middle of the week while driving my Semi, that I randomly thought about the process, mentally pictured what I was doing in my head, and it immediately hit me what I was doing wrong. As soon as I was able to get home, I tried out what I thought I was doing wrong, figured out a solution, and solved it within 20 minutes of being home. Such a great feeling.

[@elasticroentgen8887]

I love this. Just the quiet comfort of watching a brain problem solving. no show, no effects - just plain old graymatter doing graymatter things.

[@ceaselessshadow4060]

i realize problems like this aren’t planned obviously, but seeing this kind of real time problem solving from adam is so fascinating. i love watching the process, seeing him not know the solution and experimenting and troubleshooting to find it. this is just as interesting to me as any one day build. love seeing stuff like this

[@TheYourfaceable]

My favorite thing about watching the process real time through a video is looking back after the solution has been found and implemented and thinking about how obvious it seems with hindsight but how vastly overwhelming it can feel when initially digging into it

[@snorman1951]

He didn't find the problem and maybe not a solution; after all he didn't try all the standard threads let alone metric. What he did was a jerry-rig. If there are change gears at the left end of the lathe, the solution probably lies there. The idea that the factory got it wrong is preposterous.

[@christopherhelvey5371]

Well done Adam! Greetings from New Mexico. I think what you were saying about honesty is so right-on. Being exactly who we are with the issue at hand, and engaging fully with it is what connects us as viewers (and probably you too as the creator.) I started this process about 52 years ago when I was five, taking apart the toaster to see how it made bread into "toast." We get perplexed, frustrated, even angry, and then it feels so good to come out the other side when the problem is solved. Forever, I thought I wasn't very good at this because I thought, if I was good at it, THAT wouldn't happen. WRONG - we're all in the same boat! Thanks for sharing the REAL process of problem solving.

[@Niamhnyx]

Putting it back on, having it be put back the way it was on initially is such an Adam Savage thing. I saw it coming from so far away and it still made me smile.

[@Gillysaurxx]

I love how Adam explains everything like a father would teaching his child something. One of the many reasons why i like watching him. You can tell he loves teaching.

[@jomgelborn]

I hate how he does that. I'm not a child

[@alabamaflip2053]

I too love the way he explains. It really helps me remember important points. I also try to duplicate a similar demeanor that he has in his videos for myself when things are not going so well on a late night project.

[@jd52wtf]

These kind of "informational/learning journey" videos are my favorite. Everyone makes mistakes. Learning from them is paramount. Edit: Only 1/4 way through the video. I'm betting someone rebuilt the gearbox and misplaced one of the gears on the selector trees. Edit2: After watching the entire video I'm betting that the other end of that shaft, that the selector knob " does not" have an offset pin or key and is 180 degrees out of phase. As a field service person I'm good with the "quick" fix just to get it done. I'm also going to think about this issue every time you use this lathe now. I look forward to the day where you completely disassemble this and determine once and for all the "actual" cause. Amazing content as always!

[@glensmith766]

I love the problem solving method Adam went through, I try to help my mentees go through a similar process. When Adam decided to fix the problem the 'easy' way I was shaking me head and thinking, "but that just means there is a chance to assemble it incorrectly!".... Annnnd there it is. Personally, I would have left the tape fix on there until I was ready to go inside the gearbox and make the repair where the real problem is. That second hole in the knob is there forever now and may trip up a future rebuild.

[@ade63dug]

With you on this . whatever is fitted to the other end must be 180 out and did not have an offset connection .

[@beezul]

@@glensmith766I'd be inclined to tap the *incorrect* hole and put in a couple of grubscrews to prevent that splitpin from being installed in the wrong side. Or, if wanting to preserve that dial knob in original condition, make a replacement dial from scratch to use for now, until the gearbox could be corrected, then stick the OEM dial back on.

[@Scott_A]

.

[@ttraband]

Diving into the gearbox opens a risk for creating a whole new set of issues. I"d plug the original hole in the knob so that it couldn't be used. I'd probably use something reversible, so that if I did eventually fix the true root cause inside the gearbox it could be re-used.

[@thejamesnash]

I love watching Adam make stuff, but for some reason, watching him troubleshoot this issue was like a big hug.

[@Furry19931993]

to this day it is absolutely ... stunning to follow along these mini-adventures, get enchanted by this charm... from my childhood till now and probably way into the future.... thank you adam

[@flatulentdragon]

Adam, the honesty you bring to your content is what makes you one of my all time favorite content creators. When you show your pain and frustration, when you're willing to show your humiliation (for want of a better word) - like with the thumb injury video or your story about screwing up your friend's college project - that picture of your humanity is an amazing gift. Beyond priceless. Especially to amateur, ham-fisted makers like myself, to see that the "great Adam Savage" has those moments helps me on my own journeys. To err is human. To make an honest KZbin video about erring reassures us that it's OK to be human.

[@vanrick772]

I did not expect such a thorough guide through lathe basics on this video but I am SO here for it.

[@ebayscopeman]

Adam this was delightful and the reason is you have a natural knack in connecting with real people that have real down to earth problems to solve and you go about it in a very methodical fashion. It's sort of intune with the medical method of differential diagnosis, "It can't be this, because of that so it must be this", very sweet work!

[@David-hm9ic]

What a fantastic episode! My first thought was, "Have you ever cut ANY single point threads successfully on this lathe?" The disturbing thought was seeing someone else think and troubleshoot exactly like I do. I usually lose others in explanations because they can't jump from A to D to G without b, c, e and f explained in detail. It's comforting to see someone else troubleshoot based on the bigger points. Most people are not troubleshooters, or at least not good ones. Your audience is different. For redrilling the hole I would have just chucked it up in my super spacer, lined up the existing hole and rotated the knob 180°. That eliminates any chance of measuring or mathematical error.

[@JeanYvesBouguet]

This must be my favorite episode! I absolutely loved the way Adam walked us through the problem solving process from start to finish. Please please, make more of those!

[@ionstorm66]

If you look next to the numbered knob for the gearbox that is a change gears that are required to get to the correct tpi. The circles with numbers in the middle are the teeth on the gears. Make sure the change gears that are installed are correct.

[@Eluderatnight]

FYI 3dp PLA gears hold up pretty well. Just set the wall thickness to r/2.

[@AnanusBananus]

The answer is here, Adam. I bet it is Set up for metric.

[@TDQ_Gaming]

I'll add because it took me a second to figure out what that diagram was illustrating because the difference is very subtle, it's what gear should be engaged on the center shaft, the 44 or 56 tooth gear.

[@wayneziegelemyer2161]

Yes. Check this^

[@habbidasher6937]

"When it doesn't, cuz it won't, cuz it didn't" is my favorite thing you've said.

[@hemlock40]

Great video. I appreciate and relate to your thought processes, problem isolation and solving. I have nearly identical ADD ways of thinking and your thinking out loud brings me along that journey. Love it. It helps with the application of many other things.

[@alastairmcmurray4873]

Great video Adam. The genuine unscripted chatting whilst fault finding is ‘content’ gold.

[@chaos.corner]

Personally, I wouldn't do a permanent modification for something that's misconfigured and can be fixed. Temporary labelling is fine. Someone suggested moving the target arrow that would also work. 3d printing an overlay for the numbers would also be an option. Your dial can now be put back in two different positions. It probably won't make any difference in the long run but I believe when you fix things, do it right. Shortcuts bite you more often than you'd think.

[@noblsht]

I would bet now that he thinks about it he would have preferred not to alter the dial now it's also been weekend obviously the problem is internal the shaft on the gear needs to be rotated 180° for whatever reason it must've been taken apart at some point and not put back together correctly

[@chaos.corner]

@@noblsht Someone below suggested that there may be a sheared pin internally too.

[@lDanielHolm]

This is what I was thinking as well. While it won't be a big deal even in the long run, the indexing that was originally the reason for the off-set pinhole is now lost. You could argue that it was lost regardless, but I would then argue that the incorrect indexing might have been a fixable problem, and permanent solutions to temporary problems aren't ideal.

[@TheAleQc]

Im sure he would happily make another dial when it started to bug him. Or he realized its still wrong...

[@blahorgaslisk7763]

"Doing it right" would this time have involved draining the gearbox of oil. Opening the gearbox, extracting the shaft the dial sits on, turn it 180° and insert it again. And that is providing you don't discover that it engages using something like a half moon, single spline or some other way to index a shaft. But lets say it can be turned over 180° and that you then close the gearbox and refill it with oil before you do a scratch test to see that you really inserted that shaft the right way around and didn't do what Adam did and put it back the same way it was, forcing you to repeat the process yet again. And when you are finally done and everything is correct then you can go to bed knowing you did it right. Would that really be worth it? And what if you discover that the shaft is indexed properly and can't be turned over 180°? And I wouldn't be the least bit surprised if that's the case. What do you do then? Someone above mentioned that the knob doesn't look like it is made in one piece, but that the "skirt" with the numbers is a separate part. It might be possible to separate them and turn it 180°. It would be worth taking a close look to that dial. But Adam is not inexperienced, and I'm sure he looked quite closely at that knob when he had it in his hand. So the next idea would be to relabel it, but doing it so it looks nice and is permanent is quite a bit of work. My favorite idea would be to do as some people in the comments has suggested, move the arrow indicating the selected gear to the bottom below the knob straight across from the original. But that's not "doing it right" either so what do you do then? I have a feeling the factory had these knobs made with the hole for the roll pin in both directions and they installed the correct one after checking each machine. So it's possible it would be possible to get a knob that is correctly indexed for this machine. But after considering all of these things I think Adams solution was perfectly fine. It fixed the problem, and if anyone but Adam tear down the gearbox at any time in the future they will see that the knob can be installed two ways. If they can tear down that gearbox and get it back together again then they are most probably savvy enough to realize they have to check the orientation of the knob. But seriously I doubt this lathe will ever be tore down to have the gearbox renovated. It's a machine built for heavy used in a factory and the way Adam use it it will last for a hundred years more.

[@mfratus2001]

Thanks for sharing your thinking process with us. I don't have a lathe, don't need to cut threads like that, but I do have to solve problems every day. Thanks, and I'm glad you figured it out.

[@djtopherau]

i love the fact you put the pin through the original hole in the end; mainly because like you, I have done similar things in the past, and this shows that even you are human, which as you said, makes for really engaging interactions

[@mousemade1]

Adam, with respect, no matter what other problem may exist, the first check should always be "are the change gears ok". PS You should still do this! Other people have used your lathe.

[@timkohchi2048]

Absolutely! In the “hierarchy of states” troubleshooting, the input to the gearbox FIRST. Input is by usually 3or 4 changeable gears, Most lathes show the change gears to use right on the threading chart. Just went back and looked, yup it’s right there at 6:57 (corrected). It’s also the rule of “wait, before I alter, have I eliminated the easy stuff first?”

[@TDQ_Gaming]

@@timkohchi2048 I'm seeing it at 6:48 And if I'm understanding this correctly, because it took me a bit to figure out what was being talking about, it's the gear diagram next to the knob. It's subtle but what it shows is what gear should be engaged on the middle shaft, the 44 or 56 tooth gear.

[@sunsoar1822]

Someone else commented: Check the change gears. While all threads are able to be cut without changing the gears, it appears as though your lathe has different gears for cutting worm drives. At the 7:00 minute mark I could see on the chart the engagement between gear 44 and 57 is different, right above the dial.

[@sunsoar1822]

i think he might have made a perminent modification to his machine needlessly. The moment i found out that the nob was designed to only be connected in 1 fixed orientation, i would have reassessed possible user error.

[@TDQ_Gaming]

@@sunsoar1822 Kind of what I was thinking. The other moment for me was when first looking at the change gear diagram, all the numbers were the same so at first I was dismissing it. But that was another instance of, well that doesn't make sense, why would it be there. And then a little confirmation bias with a successful work around. We could test this theory if someone that knows Adam could suggest a project that needs a worm gear.

[@SalvageWorkshop]

I appreciate the honesty about getting stumped and wondering how you were ever going to finish a project! I get that way ALL the time, but the more I am in situations like that the better I have become at problem solving, and i'll bet that's true for many people! Thanks for the honest content! I truly enjoy it!

[@jasonstinson1767]

Are you wondering about this type of problem applying your recent acquisitions?

[@ComteSt.Germain]

Adam, I think you hit the proverbial "nail on the head" concerning the content of videos that you like best. The word that I didn't hear you mention is to be, "genuine". Honesty is awesome, but being genuine (or real, in some circles...lol) makes all the difference. I too, love it when content creators are genuine. Thank you, for being you, and sharing your experiences with us.

[@janyoung1633]

I stumbled across this video and was pleasantly. surprised to see you. I'm a big fan of your original show and happy to see you're still at it! I appreciate your thought processes.and am now a subscriber . Keep up the great videos and fun work!!

[@Poyntlesss]

This is wild Adam is living the exact problem I had a week ago before I decided to just use a die and deal with the ridiculous effort required on the large thread size. Only afterwards did I do exactly this, and figure out which setting had to change to get me where I needed to go and found my dial setting 180 degrees out of phase for that specific thread. Can't wait for Adam to unravel the mystery and have it apply to my machine also.

[@Poyntlesss]

So I posted the above early in the video before Adam began to diagnose the issue, and I am so confused how the exact same issue is apparent in both machines, even down to the roller pin scenario across totally different machines on totally different continents. This is just spooky, especially when Adam's solution was exactly what I thought about doing, before deciding my plan was "too jank" for 7:30pm and put on the backburner until I could come up with a better one. At least I know it'll work if I do it right, thanks Adam!

[@AshleyGittins]

@@Poyntlesss Oh that's fascinating! I spent the last 20 minutes of the video shouting something at the screen that maybe you could check... that skirt/flange on the knob that has the numbers on it looks like it's a separate piece, press-fit to the main knob body. If so, I wonder if it can be removed, rotated and re-fitted in the correct orientation? Maybe it's a near-permanent fit, but it seemed like a possibly simpler explanation for the problem if it might have been previously re-assembled in the wrong orientation.

[@dave122288]

​@@AshleyGittinsI had same exact thought!

[@123hurst3]

Great catch @@dave122288

[@seldoon_nemar]

if it's 180*... just use the read the number at the bottom of the dial instead? ?

[@efenili]

I absolutely LOVE that you put it back into the original hole 😭 Knowing I'll never do this I can say with 100% certainty I would have done the exact same thing.

[@mandolinic]

It's like when you have a micro-USB plug. You look at the plug, look at the socket, orient the plug to match the socket.... and it won't plug in. So you turn the plug 180 and try again....and it won't plug in. So you turn the plug back 180 so it's in the original orientation, and it plugs in first time! Happens to me every time.

[@stevemartin9200]

I like it when you explain what you were doing more fully. For people interested in learning machining building, and that sort of thing it gives them a place to start to expand their education.

[@ianrigby7395]

I love this video, the process is fascinating. He makes me want to learn machining

[@timshurtz6383]

The thing I didn't see him do (but he probably did at some point) was to lookup the settings for the TPI he was getting and see how they differed from the settings he chose. If there is only one way to get each thread pitch, that should tell you wich knob is wrong. For example he got 16 TPI when he wanted 18. 16 TPI is LB7P on the chart where 18 TPI is LB3P (the same off by 180° off on the knob he found)

[@jaysound55]

I love these kinds of episodes. This one really showed the logical steps in troubleshooting for many kinds of problems, not just his lathe. Even though the process can be time consuming, Adam's narrative and tight editing keep the story moving. A really interesting and informative episode. I'm looking forward to the cruise in November to hopefully meet Adam and other fans in person!

[@beardoe6874]

Just wow... The way you figure that out is you look for the pitch you cut vs. what you intended, see what the difference is, see if reversing the difference fixes the error and then see if the fix works for a pitch with different lever settings. After you determine that the knob is 180° out but it only goes on one way, you get out the schematic to see if it looks like there is a way to do that internally. Then to drill the second hole (if you just don't want to mess with the gear box), you just use a pair of calipers to measure how far off center the roll pin hole is and calculate what the center to center distance of the pin holes should be. You don't have to find center of the shaft hole at all. Lastly, it's a roll pin and each division of the knob is 45°, you have lots of wiggle room. You probably don't have to but you can mill a flat spot and center drill to start your new pin hole accurately or else just go for it and oversize your hole if there is any alignment issue. Adam is funny but I thought he was smarter than this.

[@ThePCExpertAmateur]

Congratulations, Adam! I love troubleshooting and problem solving, too, but I can't do what you just did - my skills lie in other areas. I, too, swim in honesty and transparency, so I appreciate you!

[@SaltBayGull]

now that you have two sets of holes for the roll pin, maybe you should thread them, so that when you determine the incorrect set of holes to use, you can block them with grub screws. Then the next time you rebuild the lathe and whatever bit internally that can be clocked 180 degrees out of phase inevitably goes back to the setting that would make the dial correct with the dial in the original position,, you can swap the screws between the holes.

[@bfischerr]

Being authentic is one of the great qualities that is relatable. As a consumer of a great deal of maker content, I sincerely appreciate the troubleshooting steps you went through as well as, and this sounds bad but it's not, seeing the visible frustration you were experiencing. It was gratifying to see that even someone with your institutional knowledge can experience the same trials and tribulations that I go through. Thank you for taking the time to film and present this.

[@jasonk699]

Hi Adam! Quick recommendation. Set your cross slide to somewhere around 30 degrees, 29.5 if you can, and use the cross slide to feed your tool into the part. This should also give you better surface finish. I have not done single point threaded in a few years but this is what I was taught. Shoutout to Yuba College manufacturing and Chico State Advanced Manufacturing.

[@robertpowell7672]

you mean the compound slide.

[@WCGwkf]

He doesn't have a compound slide

[@xXLingunXx]

That is the correct way of doing it, cut with the leading 30 degree edge, not the full 60 degree angle, then your just rubbing the trailing edge and chatter but ya gotta have a compount for that

[@thaostrich]

As a maintenance tech, this was painful. As soon as you measured the thread that was wrong, you should have consulted the chart to find the settings for that thread. At that point you would have noticed the only difference in the setting was the number, and that it was 180 off from the markings. You took the long way around, but you got there. Now don't get me started on how you milled that hole....

[@thechumpsbeendumped.7797]

I was thinking before he put the split pin in “I’d probably stick it in the wrong hole” I'm glad I'm not the only one that does dumb stuff. 😂

[@lomiification]

I wouldn't just put it in the wrong hole, I'd stuff some like paper in the other hole just to make sure I got it right, knowing I'd put it in the wrong hole, and get *that* wrong and still have to redo it. Then I'd put it on wrong a second time because muscle memory remembered the way it was on last time, and that it's historically been on that way

[@thething4763]

I've seen this problem before. What has happened is the tool crashed into the chuck while threading. The roll pin inside the gear box sheared, spun 180 degrees and caught back on the roll pin. You need to pull it apart.....yeah! .

[@noblsht]

That sounds very logical, that or someone had it apart and put it back together incorrectly

[@davidpence4190]

Being a maintenance tech on lathes and mills i enjoyed your adventures in lathe repair. Another example of "What is the most likely solution? as soon as you said the gear selector was troublesome. BINGO ! The operators in our shop called me "The Grand Inquisitor" because of the questions that i would ask upon arrival in their work areas.

[@Vile-Flesh]

This video had me so engaged and interested and is so enlightening that it felt entirely way too short and I felt a little sad that it was over. I learned a bunch in this video.

[@krmould]

Only Adam could get me to watch and enjoy an entire video on troubleshooting a lathe!

[@metalhedatmedotcom]

The whole time you were preparing to mill the second hole, I was saying to my screen "If that were me, I would scribe a mark on that original hole so I could tell which was which afterwards". As always, thanks for showing us that we all make the same kinda mistakes on our roads to success. Love this stuff sir!

[@Kehvarl]

I love your troubleshooting and the overnight epiphany. When you measured your 18 threads per inch as 16 threads per inch, I went back to look at your chart and saw those two are identical except the dial setting. Which had me suspecting (as you did) that the dial was your culprit. Glad to see you have a solution that works to get through the project!

[@picklemat4619]

i love these videos. i spent my younger year in my granddads work shop when he was a maker and after he died I was the goffa mystep dad when he was doing the projects around the house and I would always take a step back and try and work things out when he was stuck on something and we would rift of each other. I could see myself in your workshop helping out and all that. brings me so much joy watching these and hearing your stories like I di when I was just a young kid in my granddads shed

[@SUPERCR0WL]

Just for brevity's sake, I went ahead and created an acronym for your method of solving your problem. You mentioned assessing the problem, naming it (which is different!), and understanding the problem. The final step being to solve the problem. Great engineering Scott I think you've done it! Assess Name Understand Solve I will hang this on the wall in my shop

[@MrSpirit99]

Poetic.

[@Hockleberry]

As a flight controls systems engineer, I love watching people's problem solving methods in action. I definitely understand the fear and frustration and anxiety that can come from certain types of problems, however. So thank you for sharing what you do when it comes to content like this!

[@cembellsteve]

Adam, as a machinist myself. I can't believe you wouldn't mark a line on the chuck and engage the 1\2-nut(threading handle). Zero out the DRO. Rotate the spindle by hand 360deg. Now see how much the carriage moved for your lead. That's what I would have done. I had the same issue with a lathe that was feeding wrong. Turns out that dial was 180 deg. off. So the number 180deg from what you select was the right number 3 should be where 7 was. 7 should be where 3 was. And so on

[@michael-michaelmotorcycle]

I’m not a machinist but logically wouldn’t the diameter of the stock you are cutting the threads into play a key role in the outcome? I mean if you think about it there’s a reason a 1/4-20 thread is on a 1/4” diameter ‘shaft’. Mathematically if you are trying to cut a 1/2 - 18 thread into a shaft that is 3/4 wouldn’t that screw the outcome up? If Adam tests all cuts into the same 1” anodized piece of pipe/tube the outcome would not be correct for any of them until he gets to the 1” threads. This is why the ‘root’ of the thread is a critical dimension when fitting up a thread. Yes/no? Like I mentioned I’m not a machinist. Just been fascinated by machining since I was a kid, I’m 46 now and a industrial maintenance mechanic.

[@barcodenosebleed5485]

This kind of thing fascinates me because it gets into how our brains actually work. I feel like your approach is, what's the best question that I can ask that will give me the information that either solves the problem or gets me to the next step. So you ask the machine what is it actually doing in this moment vis-à-vis the current setting. I think, because you know that information will be extremely valuable, that that information might, in fact, lead directly to the answer. Whereas Adam has a hunch on where the problem might lie and thus attempts to change some variables close to that locus and see where that leads, perhaps not super confident he's asking the right question, but hopeful the additional information will be at least helpful. Depending on the situation I could see myself going down either path as well as others. So what is it specifically that helps us choose the more direct path? Experience, sure. But more specifically: Is it that something similar has been dealt with before? Is it because of a more detailed understanding and mental model of the machine? The specific process in question? A better general conceptual understanding of single point threading? Is it training? Documentation? Is it some innate abstract troubleshooting talent? Is it the specific abstract troubleshooting skill a person has developed over their lifetime? I'm sure it's a combination and varies person to person, situation to situation. I work in software, but in a training-related domain. We provide technical training for a specific industry, but nearly all of it is concepts and specific how it works examples. I've always wondered, beyond simply experience, if there were more effective ways to train folks to be better troubleshooters, to be better to apply the very useful training knowledge to something in the field that's similar but also way different than anything they've seen before. I'm way outside of my lane here discussing pedagogy, so maybe there's some real obvious crap I'm not aware of. But the best I've got from our field guys is that after a few weeks you can tell if someone "has it" or they don't and that's not particularly satisfying to me.

[@ModdingMonkey]

@@michael-michaelmotorcycle the settings on the lathe just set a specific pitch, the diameter of the workpiece comes only into effect in the imperial system of threads that are linked to specific diameters. In the metric system you just set the pitch of the thread you want (threads of different diameters can have the same pitch), so a machinist used to the metric system is likely to use the method mentioned by @cembellsteve because that corresponds to checking the actual pitch the machine is cutting and therefor to the settings on the lathe the dials/levers/indicators should point to.

[@harvey66616]

@@michael-michaelmotorcycle _"wouldn’t the diameter of the stock you are cutting the threads into play a key role in the outcome? "_ -- no. The tool is moved distance X for every revolution of the lathe. E.g. for 18 threads per inch, the tool is moved 1/18" per revolution. It doesn't matter what diameter the stock is, you always need to move the tool the same amount per revolution. Now, it's true that for larger stock, more cutting is done with each revolution. This means either the linear speed of the stock's surface is higher (when RPM is unchanged) or the RPM has to be reduced (to keep the same linear speed). But either way, you still get the same distance per revolution, which is all that matters for the "threads per inch" application. The distance between threads is the same whether you're talking about a 1/4-20, a 1/2-20, or a 3/4-20. They are all 20 tpi, and the threads are always 0.05" apart (i.e. 1/20"). (I have no idea what that other comment about metric vs imperial is on about...I don't see how that comment addresses your concern at all.)

[@michael-michaelmotorcycle]

@@harvey66616makes sense now that you explained it that way. Thanks for taking the time to respond to my inquiry.

[@christopherjoneswa]

Ok, this is the first of your videos I've watched. It's like you are inside my brain's problem solving center, translating things in to spoken English.... I think all people mechanically minded can probably agree. I was so entertained and thoroughly enjoyed your journey down this particular rabbit-hole of logically connected steps.

[@oldschoolmachinest]

I love watching how you solve problems. In my opinion being able to suss out a problem and solve is the most important skill in any complex endeavor. Everything else is technique. I can teach anyone how to single point threads or change a collet but teaching people how to think through a problem and solve it is harder by an order of magnitude. You are a master cognitition. Thank you for being generous enough to bring everyone along for the journey.

[@patrickdiehl6813]

As a stopgap measure I see the value in your temporary fix and thoroughly enjoyed seeing you ferret out the problem. But I'll be OCD until you drain the oil and dig into the root of the problem. Great video Adam 👍

[@Shocker-6699]

Hey Adam, I have not posted before that I know of. Your problem in this video was so well documented that i wanted to comment. Your thought process is so similar to many other problem solvers out there. Thank you for showing how many of us go through the same logical steps that find that absolute solution. Obstacles in our lives give us the greatest opportunity to learn and apply that new found knowledge to a future dilemma.

[@The_HomeHandyman]

I do love seeing the process of you problem solving, and I can identify the issues that you struggle with. I go many of the same things when I'm trying to figure out how to solve a problem.

[@jeffdickinson9819]

Excellent content. Problem solving gives one such a unique emotion that I find difficult to explain. Thank you.

[@draganignjatovic4812]

Your dial is not out of phase, but rather, its the dial-shaft that is 180° out of phase into whatever it splines into. The extra hole for the roll pin makes the dial mounting equivalent to a single hole through the center. In other words, you can still mount the dial 180° out of phase if you are not careful. (Not to mention that a proper fix requires you to open up the gearbox.) If I may make a suggestion, you may want to plug the old holes on the dial, in which case your fix will be complete.

[@AoDude]

I was thinking the same thing, even if it's just with some rubber plugs. That way if the problem is ever fixed internally, it doesn't have to be re-drilled once again.

[@killingtimeitself]

until the next person goes in and flips it again.

[@m16ty]

The odds of having to ever pull that knob again are very small, I wouldn't worry too much about the extra hole.

[@draganignjatovic4812]

@@AoDude Sound idea.

[@draganignjatovic4812]

@@m16ty Agreed, the odds are negligible. but as @killingtimeitsel says, "until the next person goes in and flips it again.", The video shows a couple of days frustration, diagnosing and fixing. Admittedly, however, it also demonstrates problem solving and the immense satisfaction in succeeding.

[@Lance_Arn]

It has been years since I did any kind of machining, but your joy when resolving the issue is very reminiscent of how I used to feel when I experienced success at problem solving.. Kudos Mr. Savage. 👍

[@bobpurcell5662]

Hi Adam. As a physics teacher with 15 years classroom experience I believe problem solving to be the the most important skill that I could teach my students. And I believed that authentic problem solving (i.e. using my skill set or "tool kit" ) was the epitome of this. So when a student posed a question regarding a concept or theory or mathematical solution or relevance of a physical model, I would began to try to explain by describing my approach: Is the problem;em similar to one I've seen or is it novel? Is there a useful diagram to be had? Can we narrow the parameters? etc. And I would be stating this aloud with feedback from the class, shaping and modifying and parsing as we went. Sometimes it was a relatively quick process but often it led to expanding the question. Truly the most satisfying way to teach and to learn.

[@robertoruiz7069]

HI ADAM> using a pen and tape on round stock to measure TPI was brilliant.I've used a lathe for years and had never thought of that,i always just used a cutter.Your explanation of how a lathe works was really good too.thanks

[@jeremyupton850]

Hi Adam, worthwhile checking this... on many lathes there are gears behind the headstock cover (opposite end of chuck) usually called change gears/wheels, these gears allow you to deviate from the chart on your lathe and make obscure/specialist/bastard threads if required. So these gears under the cover allow you to change the relationship or ratio of spindle rotations to carriage drive spindle. There would be "standard" gears that give you the thread pitches on the chart on your lathe, however the machine is very often supplied with different gears to allow you to go "off the chart" as mentioned above. so you need to check the gears installed at the rear are the "standard" set or not. Hope this helps prior to you messing/modifying the lathe. Edit, just read comments below, others have similar thoughts, switched video off before I could not un-see the carnage about to follow. Edit 2, just looked through the vid again, standard gearset in the rear looks to be (see gear chart to left of thread chart and above rotary knob) 24, 56, 57 for "normal threads" and 24, 56, 44, 57 for the "yellow thread" ACME or Worm? worth checking to see machine is set up to the correct gear set and thread you are trying to cut. Whilst cover is off, gears should also have number of teeth stamped on to them, otherwise just count them to check they are correct or "optional" as mentioned above. Either way this most likely to be the error rather than machine fault.

[@lomiification]

Why would they give gears that let you swap it to other numbers that are already on the dial though? Ship a different chart instead of different gears.

[@jeremyupton850]

Hi, I think you missed the point, it would be for numbers that are not on the dial, or levers or the chart i.e. as Adam said there are numerous thread specifications, the "standard" set up allows you to make/cut common threads. The changing of the rear gears allows you to make custom threads etc. Most manufactures provided information and formulae in the machines manual or handbook so that you could calculate what rear gears would be required to be fitted to produce a specific pitch thread.@@lomiification

[@alwynhumphries391]

If you want to cut metric pitch threads on an imperial lathe you have to change the back gears.

[@jeremyupton850]

Hi, yes sometimes, but many lathes such as Adam's are capable of metric or imperial without changing the back gears. @@alwynhumphries391

[@ProcintUS]

I'm glad this stuff happens to other people too, because this is the exact kind of problem I'm always finding myself dealing with. Thanks for sharing.

[@PickupsAreNotTrucks]

Awesome watching you work through this. I’m pretty mechanically inclined though so, I would’ve went about this differently. I would’ve dug into the gear set inside instead of the knob itself. I would’ve had the entire transmission in bits and pieces laying all over the shop before I modified the handle. Your way is much easier, I dig it!

[@breusin]

45m video to drill one hole. I loved this video. Truthfully I was very entertained and watched it from start to finish. Thumbs up.

[@J.C...]

On an Adam Savage binge! Woohoooo! After Mythbusters, this is EXACTLY what we needed. Talk about insider access! Thank you, Adam! 🙏❤️

[@mikep3226]

My immediate thought when you found the dial out of phase was not relabeling the numbers on the dial, but simply to obscure the original index mark and put a new one in the correct orientation. Requires much less tape and might even be acceptable as a final solution, rather than modifying the dial to make it possible to put back wrong (as you did 🙂 ).

[@munky52]

I’m right there with you!

[@chrisbulmahn3573]

I was thinking the same thing.

[@samfeldston8664]

My exact thought! ...because, the REAL solution is to go inside the gearbox, and see what was rebuild incorrectly! Presumably, when the lathe was built, it was correct. At some point, the gearbox was disassembled and reassembled incorrectly. (in fact, Adam, you did this yourself, and could have introduced the problem at that point). Flipping the dial around is a mask for the solution of putting the gear assembly back together properly.

[@jasonsullivan2775]

@@samfeldston8664 And that would be why he said that one day he's going to go in and fix it properly, but he didn't want to spend the time on that right now....

[@tomnielsen3661]

I love your logic and the way that you think or approach the problem. My friend is a bull in a china shop approach and I like to stop and think about it for a bit. Neither one of can just stand there and watch, so what we have done, is one of takes it apart and the other gets to put it back together. It has worked for us for the last 15+ years.

[@jimw.4812]

I made a living, and had fun, fixing things for industry and universities for many years. Design flaws of all kinds were not all that rare. I loved seeing you work through the process of observing a problem, identifying a possible cause, arriving at a hypothesis, testing the hypothesis, then implementing the solution in hardware. I admire you for including the part where, after all the work you did, you wound up putting the pin in the wrong hole. LOL

[@barmanvarn]

Watch a guy on YT recently that was rebuilding a lathe. It was variable speed so was driven w/ a dial like this one you have. He put everything back together and found the speeds were wrong as you had to index the shaft correctly when reassembling. I agree w/ you that someone rebuilt this lathe at some point and put that shaft back indexed wrong.

[@terryaugsburger857]

I am not a machinist and I do not work with a lath although I understand Adam's analogy to a mechanical computer. In my opinion, Adam could have diagnosed the cause of the thread count problem much sooner and possibly easier. I was almost shouting as I was watching his pondering how to diagnose the cause of the problem. What he ignored was the fact that he was able to produce a known thread count even though it was NOT the one he Programed into the lath. What I would have done was to FIND THE SETTINGS FOR THE PRODUCED THREAD. At 9:30 Adam produced 16 tpi when the lath was set for 18 tpi. At that point, look at the settings chart for 16 tpi and see which of the 8 settings is different from the current setup. Given the eventual finding that it was the dial that was off, that would be the only difference between 16 and 18 tpi. This step would have pointed to the dial as the source of the error. My method would have worked in this case only because the end result was a known good tpi. If the tpi was not found or it was not a standard tpi that had an entry in the chart, this troubleshooting method would not have been possible. It may be that Adam did the step I just described. but due to editing or to make a more interesting video that part was left out or was not filmed? I cannot imagine that he would not have done this especially since he went to the trouble to find out exactly what tpi the lath cut at 9:30 in the video.

[@Smokejumper92]

I really love seeing Adam make little mistakes and miscalculations, it really makes me feel connected with him in the sense that we are all capable of the same things, good of bad.

[@Shutupimslow]

It's why blondihacks and thisoldtony are so popular. Mistakes are more useful to learn from than successes, and we can only learn from creators that include them in the video.

[@Stardusted]

As someone who has for decades been in the presence of these machines (and their masters) but never even turned one on, I have always been leery of their precision and my OCD actually meeting each other and then entering the rabbit hole to master them, (from which I may never return). I never would have guessed that the machine had been built with an error. I would have accepted the blame myself and reworked the set-up down to the Nth degree for days. Well done sir.

[@TheJacklikesvideos]

the machine was not built in error.. he failed his own advice to identify the highest hierarchy 8th adjustment of actually swapping the gearing.

[@frankconnell7481]

My first thought on the first cut, Open the door back of the spindle, shuffle a couple of gears, Voila

[@QuantumVariant]

Creative problem solving is the best content. Thank you Adam, this was entertaining and helpful. We all go through this in our daily lives and it helpful to see others thought processes.

[@Fr0stbite999]

This is easily one of my favorite videos you've ever posted. For some reason my brain immediately links into this type of problem solving from a software development standpoint. Amazingly fun to watch Adam, nice work!

[@johnnyb95678]

Thank you so much for the dose of reality. This is the kind of video I find so enjoyable. It is as though we are in your workroom and just talking through a problem.