# Sometimes A Little Bigger Lathe Would Be Nice.



## Chipper5783 (Dec 11, 2016)

This is the biggest lump of iron I have ever worked over (about 100#).  Buddy asked me if I could trim / clean up the front idlers on a small Case crawler he is resurrecting.  The idea is to remove the one flange that is nearly worn away, and prep it for welding a steel ring on.  The lathe manual says I can take 22" diameter in the gap.  The wheels are 21.5" (so about a 1/4" clearance).

Fortunately the actual wheel is not much out of round.  Because of the saddle wings, and the limited cross slide travel I had to hang way out.  My slowest speed gives a surface speed of 250 fpm.  The cutting goes pretty slow - things were complaining if I went with a DoC > 15 thou and a feed of .003 per rev.  Needed to take about .6" off the radius.

The set up took most of the effort, I made steel plugs that fit the bearing bores very snug and piloted to my face plate.  I then pulled the whole works in hard with a length of 1" threaded rod right through the headstock.  I planned to put the tailstock center into the threaded rod, but I couldn't get it to reach or clear the compound (which is swung round backwards).  I'll probably spend most of 30 hours (which seems just crazy long).

I'm guessing the typical approach would be to use a lathe over about 26", with about a >24" 4-jaw, grab it on the rim, dial it both ways and go.  Then with the tooling in close enough, one could take a decent cut.  I'm guessing a "real" shop would do this in just a few hours?


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## 4GSR (Dec 12, 2016)

Dad had a 22" Springfield lathe in his shop that had about 8" of the tailstock bed ways cut out right in front of the chuck to swing 26".  You do just about anything to get a job that you hated to pass up for good money.  When he passed, my brother and I had to finish up some work he had sitting there for one of his good paying customers.  One was a chuck adapter that was at 26" OD with a 12" hole in it by 2" thick.  Had to chuck it up very carefully to get it to swing over the cutout in the bed of that old lathe.  Had to cut a "makeshift" A-28 nose on one side and the other had a counterbore register to fit the spindle of the machine it was going on to.  Was able to hold less than .002" T.I.R. concentricity all over!  Ken


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## Reeltor (Dec 14, 2016)

When I saw the title I thought you had a mini table top lathe; not how to mount a 22" diameter wheel!
Good job getting your friend's machine up and running.

Mike


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## Martin W (Dec 25, 2016)

Its a little intimidating standing by that when you first start it I bet.
Martin


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## Charles Spencer (Dec 26, 2016)

Chipper5783 said:


> The set up took most of the effort,



Doesn't it always?


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## john.oliver35 (Dec 26, 2016)

It's probably too late now that the wheel is mounted, but could you take a die or surface grinding to the ring and remove material more quickly than @ .015"?  

Also curious, how much out of round can you tolerate on the outer diameter vs. axle?


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## Downunder Bob (Dec 27, 2016)

Chipper5783 said:


> This is the biggest lump of iron I have ever worked over (about 100#).  Buddy asked me if I could trim / clean up the front idlers on a small Case crawler he is resurrecting.  The idea is to remove the one flange that is nearly worn away, and prep it for welding a steel ring on.  The lathe manual says I can take 22" diameter in the gap.  The wheels are 21.5" (so about a 1/4" clearance).
> 
> Fortunately the actual wheel is not much out of round.  Because of the saddle wings, and the limited cross slide travel I had to hang way out.  My slowest speed gives a surface speed of 250 fpm.  The cutting goes pretty slow - things were complaining if I went with a DoC > 15 thou and a feed of .003 per rev.  Needed to take about .6" off the radius.
> 
> ...




Nice setup, sometimes you just do what you have to do. I like the heavy duty boring bar holder, is that an off the shelf or home made, just curious, I have  a job coming up where I have to bore a 3.000" hole about a foot long, so I'm going to need a serious boring bar and holder, just looking for ideas at the moment.


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## Chipper5783 (Dec 27, 2016)

John.  I don't know what the tolerance is.  The flange which locates on the inside of the track rail was pretty well gone in places.  The runout on what was left of the flange was about 3/4".  The runout on the normal bearing surface was about 0.02".  I piloted of the bearing bores with a pressed in stub pilot - the result was pretty well right on.  Whatever the tolerance is, my result was far better than the application required.

Bob.  Yes, the boring bar holder is a nice piece of kit.  It is repurposed from an old lathe (1900s) I got years ago.  I don't have that lathe, but I kept the 14" 4 jaw, and this boring bar holder.  I'll post some pictures of it.  It will only hold bars up to 1-3/8.  It is quite a simple design, and you could easily copy it to suit your machine.  The center column has a wide flange that sits down on the compound and the boring bar holder clamps to that cylinder - no keys or pins are involved (just bolt it up and everything stays put).


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