How to Fail Miserably while single point threading on the Lathe

[@jllaine]

That was heartbreaking, but I have to tell you how much respect I have for you sharing when "life happens", this is why I love your channel.

[@papasfixitshop7982]

Thanks! I’m in this to learn as well as to teach. Failure is the best teaching moment so its important to own it and share.

[@MitchEllis-e4y]

I’m a wanna be machinist don’t have lathe yet. I notice a lot of machinist just stop their machine, back off in their cuter, reverse their machine back to starting point, reposition their cut depth and re-engage the machine in forward without messing with their half nut. Keeps you from having to hit your thread timing mark perfectly to have good thread. Joe pie, advanced innovations shows you how to thread away from the Chuck and jaws removing the worry of crashing your cross slide into the Chuck and it’s jaws

[@vandegriftmichael]

The 4 column on the right of the chart are the feed per revolution for turning and cross feeding. Your machine has a separate power feed shaft as well as the leadscrew. Judging by the gear ratios the lead screw is metric. When doing imperial threads the half nuts will likely have to stay locked. Imperial leadscrews are easier to use with thread dials. Metric machines cutting metric threads are still a pain to use the thread dial as you need different thread gears for different pitches. Many machines mislabel the compound. Your angle looks like 60 vs 30. If you are cutting threads less than 10 tpi I would just use the cross slide and ignore the compound. You have plenty of rigidity for the that cut. In larger pitches where there is higher tool engagement, then the compound can greatly reduce tool load. Always thread on work that has just been cut to gain concentricity. You will see your thread cut has varying width(actually depth) due to the work not being concentric.

[@MegaLostOne]

I'm betting you rammed the tail stock into the piece before the last pass, it drove the piece into the chuck and moved the threads. Watch your video at 3:25 , I knew what would happen when you set the tail stock before the last pass. Ease the tail stock in and lock it down then turn your wheel until you just get contact, you don't have to put a bunch of pressure it's just to hold the piece aligned.

[@papasfixitshop7982]

As a Noob to threading am learning how to make mistakes! Fortunately good folk like yourself are willing to mentor me. Thanks!

[@MegaLostOne]

@@papasfixitshop7982 Are you constantly going in the same amount with your compound on each pass? After my scratch pass I start with about a .005 max on my first pass (depending on how hard the material is) then drop to .003 with my compound and start dropping more on each pass, I'm seeing chatter in the threads being cut which leads me to believe you either have to much tail stock pressure bowing the piece or you are to deep on the compound, your cutting more surface area each time you go in on the leading edge so you have to back it off some if you are going in the same depth each time. If not then again only put enough pressure on the tail stock to hold the piece since to much pressure will push the piece into the head stock or bow the work piece causing issue's as well. Oil on every pass, I use dark threading oil that plumbers use for pipe threaders, it's cheap and works great because it has sulfur added to it to help threading.

[@papasfixitshop7982]

@@MegaLostOne I just finished the video of my success with it. Definitely operator error. I’m using the Cross Slide at this phase but fully understand that method. I also figured out that I needed to take smaller cuts. Plus, the metal I’m using is very soft galvanized rod for reinforcement of metal walls and it’s really gummy. Thanks so much for your advice, every bit is valuable.

[@MegaLostOne]

@@papasfixitshop7982 1144 is an excellent metal to learn on, not much more than 1018 but a MUCH better metal and a fantastic finish. Congrats on the success, I definitely recommend going to the compound for threading.

[@MichaelMurray-w6f]

,Papa, I am sure you know to keep those change gears greased before you start it will quiet your m/c a bit , DO NOT run with dry gears. 2 make sure that the spindle bearings are properly torqued many of these asian m/c's have been shipped with untightened bolts and will give a rough thread, also poor thread pickup can be caused a small amount of end float on the lead screw this the apron to move slightly left and right. I like that you are not afraid to show how things went bad.

[@workbenchz]

That hurt to watch, so much good work go south, I just had to go find the manual for ANMEC lathe, hoping I could be of some help to you. On page 12 it says when cutting threads to NOT disengage the half nut at the end of a pass. Stop the motor and back the cutter out of the thread (at the same time!?!?), then reverse the motor to move the cutter back for the next pass, stop the motor, move the cutter head inward, start the motor forward to cut the next pass. To answer your other questions: Best guess is that Imperial Measurements got lower case n from the elementary school math "8 - n = 4, what is n?" which was around before the metric system, leaving lower case m conveniently available for 'metric' and 'millimeter'. Thread cutting chart: first column is M/N gears for coarse threads per unit, second column is M/N gears for fine threads per unit, third column is the ABCD gear selections for threads per unit. Columns 4,5,6,7 make no mathematical sense in relation to the advancement ratios, but those values are really really really really really close to 1/2 the thread depth value for each thread pitch, so perhaps they are the maximum recommended depth of cut per pass. 6 and 7 would then be for cutting a spiral thread like you are facing a piece, (looking like a vinyl LP record) but why would anyone ever do that?

[@papasfixitshop7982]

Fantastic Comment, Thanks! I did figure out the data plate. Being a Noob to this operation means I lack muscle memory. Also, I’ve watched literally dozens of videos and never encountered the method of reversing the motor and never releasing the half-nut. Everything I’ve studied warns about the backlash causing errors. Have faith, I’m disinclined to give up! Thanks!

[@yifanjiang292]

The cutter appears to enter the thread at slightly different places each time. Judging from the video, when a cutting pass reaches its end, you appear to have backed off the tool holder manually. If it's possible to reverse the axis, you can probably try to back off the tool holder using the power feed as well, which will ensure that the cutter enters the thread at the same place each time. The travel of the tool holder should ideally always be proportional to the number of main spindle rotations, in both directions.

[@joecanales2175]

I have a BL330E-1 when engaging for threading you have to keep it on and reverse mortar back to start. Otherwise it doesn’t repeat sometimes it does but that one time it won’t so that’s how you do it. .

[@GWAYGWAY1]

My failings at threading is not having any decent lathe tools. And not being able to see the inside of the external thread. I can really fxxk up loads of metal , whilst trying to make something, but I did learn something today whilst using the lathe, it is to UNDO all the cog nuts BEFORE removing the cogs from mesh. Otherwise you have to put them back together and try again, there is nothing to stop the shafts going freely.😢😊

[@billdoodson4232]

The Imperial is 1/n where small n is the number of threads per inch. You have quite a comprehensive set of threads on there for both Metric and Imperial. The others are feeds for the saddle and cross slide. Bit of a pain having to change the gears that much. Sorry should have listened to the whole video first. The compound slide should be set to 1/2 the thread angle, if this is UNC or metric then that would be 30°. When you put a small feed on the compound it will only cut on the front left hand side of the insert so the back of the thread will be cut in a series of small steps with the flank of the insert polishing off the surface of the thread. Carbide inserts need a bit more speed, but you run the risk of sending the tool into the chuck. Best way would be to cut the thread with the tool upside down and the lathe run in reverse so the tool runs out towards the tailstock. Joe Pie has an excellent video on how to do it. kzbin.info/www/bejne/kF7HooKflN9omM0

[@papasfixitshop7982]

Fantastic Comments Thanks! I’ve watched Joes video several times and this lathe is the first one I’ve owned that can turn in reverse safely.

[@tempisunavailable]

Hi Papas! It is hard to tell exactly what is happening without being there, but to me it appears you simply hit the wrong position on the thread dial. It's easy to do; I've done it quite a few times over the years. My recommendation to you is to start your cutter as far back as possible without touching the tailstock support. I've noticed that you are positioning your cutter directly behind where the thread/cut starts, but it doesn't have to be that way. You can give yourself more time to react to a bad thread dial position (or even cancel your cut before it begins) by starting as far back as possible. The others are right about using the compound to advance your cutter in. It's not absolutely required, but you'll get much better finishes by using the compound, and your chances of a tool crash are lessened. Two problems you may run into while threading (especially using the cross-slide to advance your cutter) is that your stock may appear like it wants to "jump" on top of the cutter, or that your thread cutter tip wants to bury itself in the work. Either of these two problems are more likely when using the cross-slide instead of the compound, and especially so if you are working with stock that is a small diameter, flexible, or unsupported for long distances. So, it's something to watch out for. Some have mentioned other procedures for cutting threads, such as keeping the half nut engaged the entire time and running the lathe in reverse, etc. There are many ways to cut threads, and you can try that method if you wish. It may be the way to go if your thread dial method is continually not working, or there is some other unforeseen issue with the lathe. Choose the method that works for you and your lathe. However, to clarify why some might specifically choose that method: it can be performed on lathes that are not equipped with a thread dial. That's how the operator keeps the lead screw in phase without a thread dial (by simply engaging the half nut and never disengaging it until the thread is completely finished). Oh, and I have the same thread cutter as you for my home lathe. I've found that it has the potential to be finicky in regards to tool height. So, make sure you're right on center. As an absolute last resort/last ditch effort, you can play with +/- height to get better or worse results. Just know that too far +/- and you risk other issues or a tool crash. So, do be careful. Good luck and enjoy your lathe! She's an absolute beauty!

[@papasfixitshop7982]

Fantastic advice! Every bit helps me. I definitely intend to practice with the Compound method next (baby steps). I’m working out how to Mount an indicator to the compound for that purpose. I also tend to be very focused of the tool height and typically use the live center on the tail stock to precisely align the cutter. On this lathe, the manual states to keep the half-nuts engaged during the entire operation. It also has a Metric Lead Screw so that is another consideration. Yes it is a great machine with outstanding capabilities given its price, mine cost $2400.00. Thanks for all the great comments!

[@jerrywallis599]

The threading dial on my lathe doesn't do 13tpi so I don't disengage the the half nut. Kind of like metric threading.

[@MidEngineering]

Were you feeding in using the compound slide.? I can see it's set at an angle but it's the wrong angle!

[@papasfixitshop7982]

I was using the Cross Feed, though my Compound slide is set at 29 1/2 degrees.

[@MidEngineering]

@@papasfixitshop7982 Looks like 29 1/2 degrees from the spindle axis - zero on the compound scale is parallel to the spindle? I think you made the right choice to feed in with the cross slide. Works fine with Carbide threading inserts. I never bother with the 29 1/2 degree thing!

[@madebythevise]

후퇴할때도 자동이송을 해서 후퇴를 했어야하는데, 수동으로 움직여서 맞췄군요...ㅜ.ㅜ

[@tandemcompound2]

you need to use the compound slide.

[@simjett9998]

First pass great next pass no good what is wrong

[@papasfixitshop7982]

Incorrect angle of the compound

[@Doppiovetro]

Hi! I might had the same issue. I'd like to share what i discutere. First thing first I'm a newby. I was cutting a 24TPI on my new lathe using the thread dial indicator. I had issue re entering the lead screw in the same place when re engaging. I did some research and it appears that you cant use the metric TDI on a metric leadscrew to cut imperial thread and viceversa. Now I cut the thread without disengaging the leadscrew to avoids the wrong re entering with the TDI (now it works). Hope it helps someone