I am going to do some weld build up on the idlers and rollers of my D47U.  I will follow the weld build up procedure from Cat but I have a few questions regarding turning them back down.  The small rollers I can turn back down on the lathe although that hard facing might be extremely tough even with ceramic inserts.  My thought was to build a jig on a die plate and use an old surface grinder arbor to grind them back into round.  My front idler would not fit in my lathe anyway.  I would need a gap bed lathe with a pretty good swing to get it in there.  Has anyone ever done anything like this?  Seems like once the jig was built it would be pretty easy.  

no need to turn them down.

especially if using abrasicord 600 or 650 it will wear in on its own.

the cat roller machine rotates the roller so the bead is concentric to the roller.

I used 60-13 rod and just ground down any real high spots with my angle grinder

Not an apples to apples comparison but I did the track chains and one bottom roller on my d2 and am amazed at how fast the welds find their own level. I've only run up and down the driveway a few times and I can already see the difference. A friend who has done undercarriage work before also says that the weld doesn't just wear off but also gets peened into the low spots. I did grind some of the high spots but unless they are very excessive I probably wouldn't bother with the grinder again.

I have thought about having a strap of steel rolled into a circle the right size to fit the idler then welding it to the idler where the chain runs ,but haven't yet tried it.

JackD6-5R wrote:

I have thought about having a strap of steel rolled into a circle the right size to fit the idler then welding it to the idler where the chain runs ,but haven't yet tried it.

I think the problem with this idea is the steel ring has nothing holding it to the idler in the center section of the added on ring. If you plug welded it every couple inches your success rate would be higher.
The weld build up is a tried an true method  although a little labor intensive. 
This is literally not rocket science  and not that hard to do. We are for the most part hobbyists and don't really need this stuff to go back into production,  very different scenarios. 
 

If I can get photos to load here is a front idler from L Twenty that has had some serious repair. All gas brazed together. Some has cracked after who knows how many hours of work. This tractor came from the South Australian mallee area and has had a lot of care with extra shielding made to try and keep sand out of the tracks also other gas weld repairs. Almost no rust on this tractor even on surfaces that were not painted from the factory. Looked at a 2 ton that is coming up for sale front idler tyres on the outside completly gone and inners paper thin worn to death. cheers WF