Best way to cut driveshafts apart on a lathe?

[Jeep07]

I have a south bend lathe I use primarily to cut drive shafts and do a few other turn down jobs on for tube inserts etc. However I'm not very efficient at it. (I took a machine shop class before I bought a lathe but learned everything on new equipment.) Does anybody have any pointers and what tooling works best for cutting drive shafts apart for a retube and any hints on good techniques etc? Like I said I can get the job done but it takes me at least 15 minutes per side and I think that's due to technique and lack of confidence to take bigger bites..

[jstarnes]

take a guess as to how thick the tube is

cut the weld to tube dia

estimate the tube/yoke interference cl start plunging a V cutter into the tube until its through beat yoke out of tube maybe heat tube then beat yoke out

you do need a steady rest to correctly re assemble the shortened shaft

[dopeassjackson]

the yoke is usualy pressed onto the tube so you need to cut a wide path in the tube to make it think enough for the tube to come off. when you do this make sure the tail stock is in the tube so you dont have a razor sharp tube spinning at 900rpm flying out of the thing.
your useing carbide tooling? if its non indexable are you getting it real sharp? what color are the chips that come off?
15min isnt to bad for a first timer. good machine work takes time so take your time.

[Jeep07]

Chips are hot and blue.

I need to buy some new tooling as I'm using some that came with the lathe and some my Father in law gave me. Normally I take the drive shaft and cut it in two pieces and turn down each piece separate.

I found a V shaped bit last night and it worked better than the other bits I'd been using. Where do you all buy your tooling from?

Thanks for the feed back. It sounds like I've got the basics down but where I'm a newb it just takes time.

[FullsizeYota]

If you have HS bits, you can grind them into any shape you want if you know what your doing.

The carbide bits are pretty sweet. the ones i used were a triangle so you could rotate them around and we used the triangles on a wide variety of cutting operations

[CJeep77]

I will turn the weld down to the tube diameter, and then use a cutoff blade (carbide insert type will help against the weld) to cut off, and at the same time, leave a square shoulder for the tube to seat up against. I keep the tailstock lightly against the end for safety and cut as close as I can to leave the origional shoulder position that was there when it was assembled. If you feed slowly enough (probably will chatter due to the light feed), you will see when the tube is ending, and the forged tube end is starting. At this point, the yoke end will still be engaged about 3/8" into the tube, and it should be easy to tap the end out of the tube. It should need little to no cleanup needed to be reinstalled.

[GubNi]

I do all mine with a grinder. A normal disc is about the right width. When you have it close you will see what looks like a slight crack in the weld area. Once that crack is most of the way around grab a big hammer and beat it loose.

[cdansan]

Trepanning tool (basically a cut off tool) with replaceable carbide inserts. Stiffness in the tooling is always an issue the tool wil howl and sing sometimes. You can make a nice square cut almost all the way through and then break off the yoke.

Dan

[beartj]

It's hard to beat the repeatability and precision of a lathe but I didn't have that kind of patience that day.

Stick it in the chopsaw, center blade on weld, loosen vise just enough that you can rotate the tube, start cut and rotate slowly.

Then do cleanup of the spline stub or tube yoke on the lathe.

As far as reassembly goes, tack it together and bolt it up. Put a dial indicator and indicate in at each joint. Once you have good runout TACK IT SOLID. Pull it out and weld it.

As far as balancing goes: I just made sure to get good runout and ran it with 2.5" pipe. I have unbalanced 40" TSLs, full hydro, etc. but I've had it up to 35-40 mph at harlan going to the trail and it was fine. I read something (think it was a post by chopperman) about adding some ATF or light motor oil inside the tube before you weld it to serve as a dissipation medium to cut down on possible vibrations. Talked to a friend (willycj) who is finishing his PhD in vibrational something or other of nanomolecules and he though it was a good idea.

Sorry for the shit quality of pictures. I have a crappy samsung flip phone and didnt have the camera with me that day.

Hope that helps and isn't too hack for your needs.

[KrebsATM02]

How do ya'll hold yokes in the chuck? I like to turn mine down so I can use heavywall pipe, but I have a hard time holding the yokes.

[Jeep07]

beartj - Thanks for the info on that technique. I've considered that a few times but figured it would be slower. I will try that on my next one. I used to use an air grinder with a narrow cutting disk but that was pretty time consuming as well..

Cleanup on the lathe is pretty easy its just the cutting part that takes me so long. Thx again for the info.

[uglyscout]

It's hard to beat the repeatability and precision of a lathe but I didn't have that kind of patience that day.

Stick it in the chopsaw, center blade on weld, loosen vise just enough that you can rotate the tube, start cut and rotate slowly.


I use the chopsaw method as well. Done tons of them that way -- it is pretty fast and accurate if you rotate it evenly.