best material for making a quill

[nickel-city-fab]

Why couldn't the areas in between be filled with moglice as well to make complete contact?

Yes, that is what I'm thinking. The moglice is used by *new* machine builders nowadays so I doubt there's any issues with unit contact pressure -- after all, its basically just powdered molybdenum in epoxy.

[J Tiers]

Why couldn't the areas in between be filled with moglice as well to make complete contact?

Take a squint at the innards of a DP head. You'd have 2 inches of Moglice in there, and you'd need to leave space for the quill pinion, etc. Uneconomical, and probably the thicker areas would be softer/springier, not contributing as much to supporting the quill. Boring and putting in a new quill, or grinding the quill and sleeving are almost surely better as far as effect per $.

Moglice is not as cheap as a mill-drill........ you don't want to be pouring quarts of it into cheap equipment.

[darryl]

I like the idea of getting an engine shop to prepare the bore. The machine they would use would be the right one for the job. As far as the quill, it's most likely that you could set that up in a lathe and true it- that would save you mucking around with the bearings, etc. You could in fact secure the spindle in the tailstock and use its own bearings as a live center. This will help to make sure the spindle is concentric with the quill. At the same time it should allow you to true up the quill while removing the least amount of material. Only after this will you know what diameter the bore needs to be to suit the quill and the sleeve.

In this case the sleeve won't be making a full circle, so it could be rolled from suitable sheet stock.

What are the potential snags of doing this? If the quill is hardened it may be difficult to skim it to roundness. On the other hand, this could mean that the quill doesn't need any reshaping, which would be good. If it's not hardened, it then could likely be out of shape, but more easily true-able. If it's hardened, but out of shape as well, then you risk an inconsistent surface depending on how deep the hardening goes.

Just a few thoughts

[dian]

Has anyone here actually used moglice or heard of it use for a 'trapped' (vs one mating part sitting on another like a lathe carriage) application like this? You have to have some clearance or the parts won't move.....where does the clearance come from?

If there's an easy way out of that issue (there maybe, I hardly know everything about moglice applications), you're also going need to get one part machined with a ground or lapped finish and perfect geometry such that you can have a thick enough layer of moglice to work. Lastly, these resin type fills are suppose have fancy rubber fit seals made and installed as any chips or debris that gets in there will likely embed in the plastic and grind away at the mating part. They are a very cost effective way to recondition a machine tool bearing set up...no doubt....but I'm not convinced they are the best.

i believe s. gotteswinter (also joe pie for the deckel) has a demo on this. besides the wax providing clealance moglice is epoxy and has some shrinkage. (i make the stuff myself and can easyly adjust the shrinkage by adding a bit of solvent.) you are correct on the embedding and thats the whole point, it takes the gritt out of action.

[dian]

Yes, that is what I'm thinking. The moglice is used by *new* machine builders nowadays so I doubt there's any issues with unit contact pressure -- after all, its basically just powdered molybdenum in epoxy.

"powdered molybdenum in epoxy":

you did not really mean to say that, right?