Failed Project: Machining Brake Drum Castings for an Antique American Underslung Automobile

[@607perkins]

Kieth, back in the '80s i cut hundreds (700 or more? 150 drum batches.) of CI brake drums for ford model A's. First, we took roughing cuts all over the outside, completely cleaning the surface. Flip drum, same for the inside. The early castings would not always clean at finished dimension. Late castings had at least .200" of extra material almost everywhere, (If not more.) and we found it necessary to cut the OD's/ID's to .060 of finish dimension as the casting would move from stress relief. We would not need to go back and recut the first od of the drum, as if it sprung .010" , who cares. This was the OD where on some drums you find finning. The wheel bolt face was always finish cut for the same reason you found, and this , I think was the final cut of the whole process. The last or next to last operation was to finish the last .020" on the wear surface, finish cut the mounting dia ID and face, in the same chucking. We encountered porosity. Mostly close to the outside diameter surface near the rolled lip, and where the drum turned 90 deg to the mounting face. Spec'd another 1/4" od on the raw casting to be able to cut through it. We did run into "dishing" same as you, just not nearly as bad. That is why we roughed the entire drum first. Then finished the wear and mounting surfaces. The drum really moved as you cut the outside .150" or so of highly stressed "skin" off the drum. All this was done on a 20" Takasawa 20hp cnc, running a Fanuc 5t(?) using a hyd three jaw for all the roughing. We may have made a set of soft jaws cut to radius for the finish ID cuts and then turned down the jaw psi way down to keep from having tri lobed drums! We may have made a special set of cut to radius soft jaws that had side wings welded on to grip more of the od of the drum to eliminate as much distortion as possible. That way we wouldn't have to chuck on a mandrel and then have to worry about harmonic chatter as we did the finish ID cuts. We had just one lathe at first, and I learned my trade on it, at first was just a button pusher. Eventually I was responsible for program, setup and running a pair of them. They eventually gave me my own button pusher to increase productivity. The trick was to set feeds and speeds so as to optimize tool wear so it failed predictably, and then change the inserts a few parts before that. The regular CNMG (?) tungsten inserts were reliable. (Kennametal K68??) This was about 1984, and Kennametal sent us some new , experimental inserts that were SUPER LIGHT. A new, ceramic insert. We had never heard or seen of such. But boy did it cut. The ceramic inserts were highly wear resistant and reliable right up till you hit a porous spot, whereupon they 100% broke off the entire edge, costing you the other 3 cutting edge rotations. I was spinning that 12 inch drum at somewhere about700 to 1000 rpm,(about 3400 sfpm) cutting dry and throwing red hot CI chips for 15 feet out of the machine where the shields didn't cover, and pulling a lot of cast iron dust out of my nose at night. Probably did me no good. So, my experience tells me you need much thicker castings, fully machine ALL SURFACES, PULLING OF AT LEAST .150", rough, then finish. It would also help if the casting foundry cooled the castings down as slowly as possible to minimize internal stresses. I remember reading a very old book put out by RR, and they said they started with a drum casting of about 170lbs to get a finished brake drum of 20-30lbs(not sure i have the finished weight correct, but I remember being startled at the rough casting weight, and so remember it ) Book was very old. Published in the 30's. I was in engineering school at time, so 1977 or so. Long time ago. So if I got anything wildly wrong, my young friends, (like K68 being an insert for anything BUT CI) go easy. I got most of it right, and I haven't thought about that job in several hundred years! 🙂 Last thought. Brembo makes drums and rotors in the USA now. The engineers there might be very willing to help with process, alloys , (Mehanite? mallable? I would not think nodular, but I've not researched it. ) and if your very lucky, they might have a drawing close to it that they may be willing to send you a rough casting to help. But with lawyers, I doubt it these days. Back when I was in engineering school. I could get almost anything from most firms just by going through the engineering dept and doing as much research myself first, the respectfully asking questions . Lots and lots of questions. Most engineers love to share. Which,.....I guess is what I've done here. I sure hope it helps someone in their project.

[@maxwebster7572]

We machined Chevy 1/2 ton drums to fit a Silver Cloud. They were $2k from RR at the time. I could see the drums weighing 20-30 lbs. Bleeding the brakes on Shadows was an experience I'll never forget.

[@607perkins]

One last thing I just remembered. The casting firm, in Salem OR., would throw the raw casting out in the weather for three months(?) for stress relief. I doubt they used any other stress relief, because I remember the boss saying the raw castings cost $12. There would have been no $$ for normalizing. At the time, that firm I worked for was the worlds only supplier for CI model A brake drums. They advertised in Hemmings! 🙂

[@TomokosEnterprize]

We can all learn a bit more info betwee then and now I have been at itsice the 50"s and still picking up bits of this and that.I surenhope I am not unable to learn more. It is what we are as Machinests. WE MAKE THINGS THAT MAKE THINGS EH, Yup, I am a Canuckian LOL.

[@bcbloc02]

Always good when there is a lot of extra material to come off so you can find the piece you want when you are done. Sometimes like here there just isn't enough for that.

[@stephenc.120]

As soon as he said 'metal insert' - (light bulb moment) - I used to make those (part of) on Rolls Royces in the UK. I do remember the process of taking the cast iron disc and inserting a metal disc and pressing them together, they were then turned and milled to spec.

[@windrk_6754]

Wonder if the rims of the castings could still be used, by brazing a large steel disk on to replace the cast iron face? Or, to more closely replicate the original pressed steel drums, carefully weld a large steel hoop to a round steel plate.. with such a large diameter, did the geometry of the shoe mountings and actuation cylinder mechanism reduce the effect of runout in the drum? Great video!

[@Quilbily]

I am restoring a 1920 Stanley Steamer and it needed new brake drums. I investigated having them cast as in this project. However the cast iron foundry talked me out of it telling me that machining them out of Dura-bar, which is cast iron bar stock, would result in a better end product. It worked out fine, there was no warpage in them though it made for a lot of machining to hog them out of solid stock.

[@royreynolds108]

For only 2 or 4, this might be the most economical solution.

[@TomokosEnterprize]

That is a serious chunk of cast Iron.

[@607perkins]

But which dura bar? Grey CI (G2) or nodular?

[@Quilbily]

@@607perkins I don't remember, if I can find the receipt I could check.

[@edsmachine93]

Unfortunately the brake drum did not work out. But the brite side of this project is, the chuck is re-machined and rebuilt. And thats a Win for sure! Thanks for sharing Keith. 👍 🇺🇸👍

[@jimmurphy6095]

It's a learning experience for all involved. And you found the problem with your chuck and got it fixed in the process. No failure.

[@wdhewson]

Failures are our greatest learning opportunities !!

[@dirtapple1716]

Love your failed projects, I'm sure you hate them, but they're great teaching moments and I appreciate you including them in your content.

[@shadowcard6923]

A neat trick I sometimes like to use is do like 2 wraps of auto body painters tape around a rough diameter. Saves the indicator, and averages the surface. Just make sure the tape splits line up between the jaws so that the little bump isn’t going to affect readings

[@DoktorBayerischeMotorenWerke]

Interesting video, we all keep learning.

[@garychaplin9861]

Keith, I have read a lot of the comments and there are some good suggestions there . A couple of points I would like to contribute. There is nothing wrong with all cast brake drums, most trucks today still use all cast drums but the hub and support disc are massively heavier than your example, the disc is usually of comparable or greater thickness than the rim and often incorporates webs for added strength. Also, when turning brake drums, they are always mounted on an arbor which centered the drum and clamped by flat faced discs either side of the center hole to avoid any distortion of the rim by jaw pressure. When machining the brake drum working face chatter was always a problem and various methods were used to counter this, a thick rubber strap tightly wound around the outside of the drum being the most common. A steel hub for the drum would be my choice in this situation, attached to the rim with a lot of small screws. Welding or brazing would not be appropriate in such a critical part and a press fit with the thermal expansion of the rim under braking would be hard to manage. I look forward to seeing how or if you overcome the problem. Cheers

[@RRINTHESHOP]

Better to find out now. Job still well done Keith. Thanks for sharing.

[@petebouchard1777]

Never a failure when you’re trying to solve a problem in a new way. Edison was once asked if it was a failure that he needed 1000 tries to create the electric light bulb. He said that it was not a failure because he learned of a 1000 ways to not make a light bulb.

[@GameBacardi]

...was Edison the one who invent that light bulb :) ?

[@zyzzy1944]

Many years ago I spent some time at a Ford foundry (fixing computers, not foundry work) where they cast parts such as blocks, heads, crankshaft, steering components, and such. I found out that for every part, a specific "recipe" was used. Things such as the chemical chemical composition of the iron (this was measured and adjusted during the melt), cooling rates, and probably a dozen other things too, were controlled. For something like a break drum where safety is a factor, you probably can't just melt some iron, pour it, and call it done. Jack

[@tomtke7351]

you might consider nitril gloves that are frequently on sale at Harbor Freight. Makes cleaning your hands quicker/easier. Surgeons are adaptive to using them.

[@diggerddawg]

This is one of my favorite videos yet. I can't wait to see the next design for these drums!

[@siggyincr7447]

As you were lifting that drum on the lathe I was already thinking to myself, "Boy, that thing is really light weight for being so big." I'd go with at least .320" thickness of the back plate and/or add some fins on the back side if there's room which would help with strength and cooling. And yeah, stress relieving on something like this is almost a necessity.

[@hankcohen3419]

Thank you for this. As so often we learn more from our failures than from our successes.

[@calevel]

If only politicians could be as transparent as you… great episode!!

[@TomokosEnterprize]

You nailed that one stock on the button bud.

[@brucecliffe6213]

No failure there Keith, just a valuable learning experience. It is just as well this happened as the owner may have taken the car on the highway and the drum flange disintegrated and he could have carreered across the road into the path of an oncoming vehicle doing 50mph. Who knows what the outcome could have been, certainly not good. Chances are that the cast iron would have cracked when tightening the wheel nuts anyway. Hopefully it would be noticed at such time. Interesting project with an interesting outcome. A real learning experience. Thanks for sharing Keith.

[@edpopelas2844]

Kudos to Alen (?) for what he’s working on. A great piece of history preserved and working to solve a difficult problem. Keith you may know this but incase you do not I’d/when you return to this when you go to machine the inside drum surface (brake shoe surface) you may run into some harmonics. We wrap a belt around the drum when machining them to keep the vibration down. I try to use as big of a hub to keep this down but with the method you are using this may not be possible. Just a FYI if you run into it.

[@johnmolnar2957]

I agree , it's not a failure, it's a learning experience for everyone

[@bertjankosters]

I'm a very proud patreon of your channel Keith!

[@MrChevelle83]

i had an equipment trailer that i had to turn the hubs down to match thw wheels i had handy. it was quite a job chucking those things in my lathe because they weighed about 75lbs each! nice work!! keith!

[@thirzapeevey2395]

This is why we hold inventors in high regard. It takes a lot to go through all these iterations, refuse to be discouraged, and keep solving problems. Maybe the good thing that comes out of this is more people understanding why we respect inventors, and what it takes to be an inventor.

[@petergregory5286]

Part of my early life, the education part, was spent in Essex in England and a major local employer was Fords in Dagenham. Not my employer but they were large enough to influence the curriculum of local engineering colleges. My Metallurgy lecturer used to spend periods of time with Ford’s Metallurgy department to keep track of the latest trends as they applied to vehicle production. One of his interests was the design and development of brake drums. He had a collection of drums going way back starting with totally cast iron designs through to the cast iron rims with steel webs. The process was marked by the weight of the finished product i.e. by the design being lighter but stronger than the previous version. So I was not at all surprised by the failure of your customer’s design. If Fords took a long time getting their designs right with all the manpower they had available then one man’s effort is bound to fail unless he was extremely lucky. It’ll be interesting to see how he gets around the problems, might even be worth him buying brakes for a different vehicle and going from there. Regards.

[@scottpecora371]

@petergregory5286 The idea of searching for an existing drum that could be remachined to the desired specifications might be the simplest application?

[@alandaters8547]

Great analysis of a deceptively complicated job.

[@paulwilson2161]

Hello. I am an avid viewer of your channel. I hope I am not being redundant to a previous comment. You mentioned your friend is restoring a 1914 automobile that originally has pressed steel drums. If he ever wants to compete with his car, my understanding is originality is critical, and he might lose significant points for "aftermarket" cast iron drums. Also, I would think this car would never be driven "hard," ergo why would non OEM upgraded drums even be needed? He might want to investigate suppliers or metal workers who could press or spin new steel drums and maintain originality. Just a thought. Thanks for a great channel.

[@nilsthemis]

If the casting was properly stressrelieved and the dish part left at original thickness it could work. The stress from clamping, brake torque and heat expansion in this application (very antique car) would be pretty light. But for heavy use the dish would need to be redesigned. Especially to handle heat expansion of the drum, like curved spokes instead of solid.

[@mjkaelbling]

Respect.

[@dianelabelle6939]

Looking at the amount of material on the rim, that much material would hold a lot of heat after the pour and if it was removed from the mold before it had cooled, it would shrink inward causing the inside disc portion to be under a lot of pressure and that material would have to go somewhere causing the dish. I think Clark hit the nail on the head. Good luck.

[@Ervan-l9v]

I was having all these thoughts when you said you was going to machine the center disc to .200" which is not acceptable for cast iron. Also concerned about stress relieving. Bad design as you now know. Wish I knew the answer. This is a tough one. Possibly fabricate blanks from steel weldments and sacrifice the superior cast iron for the actual braking surface. Possibly the outer ring could be cut from cast iron pipe. I have sourced some pipe materials from the Texas oil field areas that I didn't know that existed which you will not find in any catalog. For example 42" diameter pipe with 1" wall thickness. You will not find that in Mc Master Carr. Sawbrook Steel Castings in Cincinnati may be a possible solution.

[@stuartschnare152]

Errors, in the trial and error process, create the most valuable lessons. Great explanation .

[@phlodel]

The gentleman who owns this project is an engineer. If you or I do something like this, it's trial and error. When an engineer does it, it's research and development.

[@jodyvanliew2514]

Thanks for the in depth explanation Keith of what went wrong with this casting .

[@davep8462]

thanks for sharing setbacks, its good to see it happens to all of us!

[@scottpecora371]

The simplest of projects can become massive undertakings. Right from the beginning, it caught my attention how thin the back wall was for drums of that size and weight. This project is undoubtedly going to require considerable re-engineering and considerable expenditure of cash. I'd also go searching through the extensive volume of Pakistani videos of casting. There are some brilliant old-time masters still casting the ancient ways. Casting the cap stand for the Tally Ho starts to come to mind!

[@amateurshooter6054]

Thanks Keith

[@Utahdropout]

Keith... Great video. Excellent example of how to learn from our mistakes. Also, new information about the construction of brake drums. I didn't know that the backs are imbedded steel. Now I do. Thanks.

[@rustyshackleford928]

Good news.. you got a great rebuilt chuck out of it. So, success.

[@WoodenBoatBen]

Thanks for sharing, it’s valuable experience to many of us.

[@paulputnam2305]

Great investigative techniques Professor.

[@elcheapo5302]

Not a machinist, but I sure learned a lot in this video. Thanks Keith!

[@alstonofalltrades3142]

As a younger man and kid, Things used to break or wear out and I had no idea how to repair it and no spare parts around, so in the bin with it. These channels show the opposite. One way or another this century old car will be running again.

[@mattthescrapwhisperer]

Thanks for keeping it real Keith. I find the corrective actions as fascinating as the original projects.

[@davidc6510]

A very interesting video Keith. Thanks for sharing!

[@michaellenz9121]

great video Keith

[@mhansl]

First time I’ve ever heard the phrase “reinventing the wheel” in reference to an actual wheel.

[@bin_chicken80]

You're smashing out the videos Keith. I think I've been watching your videos for about 15 years now. Always so interesting to see so many different aspects of the trade. Awesome as always. Thank you!

[@g.l.g.6064]

And the learning curve continues ! 😎

[@frankerceg4349]

Thank you Keith!

[@5stereosteve]

Thanks for this learning experience video. I also appreciate the work and time you are investing in more frequent videos. I often share with others that retirement doesn’t hurt a bit.

[@SettledBatches]

23:06 - Good choice. Accelerating is optional; decelerating, not so much.

[@gerryoneill8881]

Were interesting video Kieth.

[@gregmizell7861]

Keith, there's no such thing as a failed experiment. Regardless of the outcome you learn something.

[@lerkzor]

Yeah, when you mentioned how thin that back wall was going to be, I was instantly concerned about the shear strength of cast iron. I have never considered that brake drums had a steel backplate, but it makes sense once you said it. I wonder what project you are going to upload a vid about next ... guess I will just have to be patient and see!

[@peterhobson3262]

I didn't know brake drums had steel plates. Of course it's reasonable considering the problem that Keith showed with the casting and, way back when, the engineers came up with an ingenious solution to a difficult problem.

[@PhilG999]

As a Mechanical Engineer by profession (now retired) I was thinking the same thing! .020" is THIN! Especially in cast iron. I can see where having a steel backplate with a cast rim makes sense. I never knew that modern brake drums had a steel/cast iron combination. I just used them and had them turned as needed (I DO know how as I took Automotive Technology in HS). Just as I "Farm Out" my other Machine Shop work, not having a shop of my own to work in... Be interesting to see what the "fix" is... 🤔

[@larrywalker7759]

@@PhilG999 His target thickness was 200 thousandths of an inch which is expressed as .200", not .020". What you typed as .020" is actually 20 thousandths of an inch, and yes that is "feeler gauge thin". To take this discussion further it might be appropriate to say that 200 thousandths could also be referred to as 20 hundredths, or 2 tenths or even 1 fifth as equal value. 200/1000 = 20/100 = 2/10 = 1/5.

[@TMxl-w5t]

@@larrywalker7759 or quite simply 5mm 🤣👍

[@lerkzor]

@@larrywalker7759 I recon it was a typo on their side ... but if you consider the amount of force from stopping a whole antique car, 0.25" or 1/4 inch (which is thicker than the target) is not a lot of material. Would you use a cast-iron pan as a brake drum?

[@MrBurnzy440]

always informative , thanks for making your videos...

[@RustyInventions-wz6ir]

He he. I get that. I have a few failed projects. Your work is on another level though. I love the size of your lathe. It’s man size.

[@randallparker8477]

Seems like with the loads and speed this vintage rocket will travel with, cast might be okay if that backing was designed as a thicker spoked pattern with a bronze or steel bushing in center. But at least you got that chuck identified with issues and revamped it! It will be interesting to see what your customer comes up with. My Dad used to fly crop dusters and he always said "There's always a bright side to things, as long as you remember that in clouds there's a darks side also."

[@ypaulbrown]

Keith, very very interesting content.....thank you so much.......well worth the time watching.......Cheers, Paul Brown

[@jamesallen712]

Wonder what the fix will be on this? Good to see a 'Punt' video.

[@Satanist-zm2rq]

He mentioned a steel plate back which seems to be the standard solution

[@rlewis1946]

I’m searching the Internet for a further explanation of what steel plate backing is all about - how those types of drum brakes are made. Frankly, I wasn’t aware to that kind of drum brake construction.

[@davidstreeter9426]

AT RMG , we routinely had problems related to hot shakeout of castings.

[@ryanp0342]

Kind of interesting that you ran into some of the same problems the early engineers did and now can see some of their design choices.

[@chadwynia5021]

Would cutting the thin layer off and brazing and bolting on a piece of 1/4 inch steel be a viable option? It would fit with the time the vehicle was made and be stronger.

[@Joemama555]

that's what i would do. if brakes got hot enough to melt the braze.... lol, well there would be larger issues at play~~ a ceramics kiln might fit those rotors for the braze job.

[@rosshimebauch3769]

Ues an indicator tip with a big radius (Starrett 25R Indicator Contact Point Set )

[@eliduttman315]

Resolving this is going to be VERY interesting. I have no expertise, but some thoughts that may be useful. Use nodular ("ductile") iron for any cast parts, to maximize strength. Perhaps a disk of 4140 steel for the thin cross section wall, along with a significant interference fit between steel disk and the casting. Disk in liquid nitrogen and casting heated prior to merging?

[@martingoudreau8249]

hey, you have a new old chuck... still a win after all.

[@forthwithtx5852]

That was interesting

[@generessler6282]

Excellent teaching. You used the perfect word: iteration. In an iteration, something going not as planned isn't failure. It's learning that takes you closer to the goal.

[@johncunnington3914]

Most more modern drums (even 1950's) have some taper and/or features in the face to keep the shape and have a small area in the center where the wheel mounts that is turned flat. Even the "wide 5" Ford drums have an area where the wheel mounts that's turned flat. Most of the drum is left as cast. The inside would be similar. If it mounts to a surface only an area the size of the mounting surface is machined.

[@LIKEABOSSTOKE]

I saw on Adam Booth's channel that he runs the indicator on a scale that runs on the surface of the casting to average out the rough surface. I thought this could have been a nice trick to use while dialing the drum concentric to the spindle.

[@Joewho99]

Interesting video thanks for posting.Think the right decision made as disk of drum was going to be way to thin .

[@chestertownelectric6290]

Can you find a similar-sized off-the-shelf drum that can be machined to fit?

[@anthonycollin8303]

Really interesting video, thank you. I may be missing something, but would it not be possible to totally machine off the dished bottom of the piece and bolt the remaining cast iron ring to a steel backing plate, it would save the restorer having to have the drum recast?

[@repete2362]

this is what i was thinking .

[@elsdp-4560]

Thank you for sharing.🤔👍

[@dumx4591]

I was thinking to adapt a rig/tractor trailer drum but that drum looks even bigger. The earth mover type drum could work but they are probably 10x more expensive

[@loch1957]

I live machining cast but it has limits. Perfect decision.

[@plainnpretty]

Your video on the 4 jaw chuck was interesting I enjoyed it . I understand up grading the brakes . My question is how much will the car really be driven ? That would determine how it should be repaired. Thanks Keith

[@Letsmakeitgreatagain.]

I always enjoy watching your videos! Especially, when we something in common! My ears perked up when I heard you say the word Underslung! I own a 1913 Scout! The American Underslung “Scout Model “was considered America’s first sports car! The Underslung touring model was a top of the line automobile of the time! Mine is also red in color, with gray fenders! I’ll drop you a snapshot, for your collection! Sincerely, Steven M.

[@VintageMachinery]

Thanks Steven!

[@robertlevine2152]

Keith, As your client moves forward it would be a good idea to look at the chemistry of the cast iron. There may be elements missing from the mix. I am also curious about the diameter of the drum. 17" seems to be very large. In the photo at the start, I would have expected a 17" drum to have stood out. Bob

[@christophertogher7826]

Hi Keith another Bonus is you found the problem with the chuck and you sorted it out

[@trevorkrause7220]

Sometimes the best way to learn is to fail. At least now it would seem that all parties involved will be talking with each other going forward, which did not seem the case previous.

[@tomp538]

Not a failure; but more an education.

[@LennyCzerwonka]

Look into them being poured in ductile iron and leave the back surface.300 (as well as getting stressed relieved) Also look into them being machined from solid Dura Bar for only 2 it might make sense

[@johncloar1692]

Thanks Keith for the video, It always something to learn.

[@RobertFay]

*- Keith, as a non lath person, I think i have seen machinists mill a gripping flang onto a plug {with centering hole for the tail stock) to hold the drum from the start* *- Then do whatever truing-up miling you want to do next.* *- With that done, you could true up the outside, and then mill the axel shaft hole to round and then face off the excess.* *- I am curious, there must be a good reason why did you not start that way, right?* *- Additionally, why chuck the drum by the most crushable outside part of the drum? *~ ~ ~ ~ ~* *- Now that I have gotten to the end of the video, I see my question is moot.* *- Casting disk brake material on top of a steel back-plate would be the way to go, especially given the thickness specs given.* *- Given the time and expense of the casting process, would purchasing round stock steel blanks large enough to mill the whole drums out of be more cost effective and more durable?* *- Or is cast iron for drum brakes more workable for some reason I don't know about?*

[@grntitan1]

Cast iron handles the heat from braking much better than steel. Steel tends to warp from the repeated heat/cool cycles.

[@RobertFay]

@@grntitan1 *- Thank you.* *- I wondered if warping was what happened.* *- Now I know.*

[@AffordBindEquipment]

@@grntitan1considering the car this is going on, I doubt it will get used much and the speed it will be going at won’t generate much heat. If I spent 15 years and probably tens of thousands of dollars on it, it would be on a trailer going to car shows not being driven.

[@ricktotty2283]

Composite casting is the way to go. It will still have issues. It’s a lot harder than people think. They tried composite rotors to save weight years ago. Also a fail. Nobody knows what they’re doing until they do it many times. The real question is how much is this car going to be driven and is it worth the change.

[@monkeyboy4746]

The small cast iron train wheels revisited.

[@butter262]

Good morning

[@macks2023]

I've learned a lot from your videos! If I were a younger man, I'd probably would've become a machinist myself! My question on this project. How much did the 4-jaw chuck's problem affect the flatness of the brake drum when you did the turning with a run-out of .030 already in the chuck itself? 🤔

[@shuntawolf]

I have to wonder if you'd done the inside first before taking the material off the back would have produced a different result. Would there be a way to salvage that original drum by machining out the center and leaving ears where you could rivet it onto a steel center core? Maybe 6 double hole ears around it with a center of steel and recesses for the ears with hammered in rivets to hold it together? I've got a small castiron griddle that has a bow in it from years of heat cycles. Cast iron sure is a fickle material to work with for sure.... At least now ya know your chuck is in good shape!!!!

[@PurityVendetta]

If I were designing something like this I'd simply machine the drum out of cast and stress relieved steel and sweat in a cast iron insert into the braking contact area. It's similar to the way I have produded hubs for vintage motorcycles in the past but using aluminium rather than steel. The foundry HAS to be competent to carry out the casting and relief processes. Premature turning out of the casting can cause all sorts of problems on it's own.

[@Stefan_Boerjesson]

Strange but I got a feeling for trouble when You first set the drum up in the chuck. Anyway, You got the chuck renovated!

[@boydovens4180]

Hi Keith , every day is a learning day , Remember the person that invented the wheel , did not get it right first time .

[@alstonofalltrades3142]

So true, I heard he was a right square and this showed in everything he tried to do.

[@parsias5381]

Super interesting. Good breakdown of the problem and possible solutions. This was quite a project with refurbishing the chuck too!

[@ronald2811]

very realistic; you are going to make or restore something for sombody and things go wrong and are giving you a hell of a lot more work to do, to fix it. In restauration ther is a rule. If you calculate the time for a yob , you have to dobble it because of wat for example happend with the brake drum. And ther is always something that dos'nt work out the way you thought.

[@LarryWayne-x5v]

The work you have done is a step in the greater process. I'm a piddler at best, but even so with a few failures along the way I usually get by. You have to love the process.

[@HemiRod23]

Just thinking out loud... it should be possible to make a welded steel drum to simulate the original pressed drum. A steel disk for the back, and a steel ring for the drum. Carefully welded together with enough extra to machine straight, it might be easier than casting a drum in a different way. What do you think?

[@bobmazzi7435]

This is one of the ideas that occurred to me as well. A decent steel plate for the disk and something for the drum. Now, what the something is could be interesting. I don't like the idea of bolting the pieces together, so something that can be welded to the disk? Is there a decent way of welding cast iron drums to steel disks? Or, steel drums to steel disks as a second thought. Or, the brute force idea of starting with solid chunks of cast iron and just machining the whole thing? Or, just use steel for the whole thing? It's not like that car is going to be run hard and steel is what it had to start with..... And those drums are 16 inches across.

[@samuraidriver4x4]

You can do that but it is going to warp like crazy due to the stresses. You do need seamless pipe in the right diameter as the weld seam often is a bit harder or softer then the original material. Decent K groove, tig weld the root followed by filling it with mig would give plenty of strength but that's alot of heat and stress. Welding/brazing cast iron to steel is a bad idea for the application. Starting with solid cast iron is going to give the strength issues Keith mentioned with brake drums, they cast the steel plate in place for a reason.

[@curtzimmerman8766]

@@samuraidriver4x4 I thought you might be able to relieve the stresses by heating the whole assembly and cooling slowly before machining. I've never actually done it, so I don't know if that would work or not. Being a 1914, it's a relatively slow moving vehicle, so you don't need to hold tolerances like on a Corvette.

[@jst.hilaire354]

Can it be made from a round steel billet? Learning from failure. Thanks for sharing your shop time.

[@danieljennerman7549]

What about an assembled brake drum using a machined steel "disk" solid riveted to a cast iron brake "rim?" The drum castings might even be able to be salvaged for that design. I'm just thinking out loud as an aircraft mechanic and as an engineer.

[@gregolson1824]

Make it a two piece design, cast outer bolted to a steel center. Could save the current cast pieces in the process.