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best material for making a quill

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  • dian
    replied
    Originally posted by nickel-city-fab View Post

    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?

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  • dian
    replied
    Originally posted by Mcgyver View Post
    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.

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  • darryl
    replied
    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

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  • J Tiers
    replied
    Originally posted by The Metal Butcher View Post

    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.

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  • nickel-city-fab
    replied
    Originally posted by The Metal Butcher View Post

    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.

    Leave a comment:


  • The Metal Butcher
    replied
    Originally posted by J Tiers View Post

    Moglice would likely work well on a tailstock barrel. Those usually have a long contact length inside the barrel, and near-100% contact, other than the key slot area (which would need to be dealt with).

    The "small bench mills", aka "mill-drills" may have drill-press type construction, meaning they have 2 , or in some cases, three, ring contact areas, but nothing remotely approaching 100% coverage. Such design would not be very suitable for Moglice, it would be far better to use some form of sleeve arrangement.

    My 18" Atlas-Clausing drill press has that sort of support, three rings, each of the upper ones maybe a half inch wide at most. It's not a consumer item, but an industrial version with an MT3 spindle. I do not know how moglice would work well on that, it seems to depend on a fairly large area and low force per unit area. If I ever do any work on the quill area, I would sleeve it, but never consider Moglice, at least as I understand that material at the moment..
    Why couldn't the areas in between be filled with moglice as well to make complete contact?

    Leave a comment:


  • J Tiers
    replied
    Originally posted by nickel-city-fab View Post
    So.... whats stopping anyone from using moglice? Of course you have to polish up the mating shaft. Or just use some TGP rod. Or an old hydraulic rod. YES you are supposed to use the release agent -- else you won't get the part out. The release agent also gives a very small clearance, I would imagine sub-micron.
    Moglice would likely work well on a tailstock barrel. Those usually have a long contact length inside the barrel, and near-100% contact, other than the key slot area (which would need to be dealt with).

    The "small bench mills", aka "mill-drills" may have drill-press type construction, meaning they have 2 , or in some cases, three, ring contact areas, but nothing remotely approaching 100% coverage. Such design would not be very suitable for Moglice, it would be far better to use some form of sleeve arrangement.

    My 18" Atlas-Clausing drill press has that sort of support, three rings, each of the upper ones maybe a half inch wide at most. It's not a consumer item, but an industrial version with an MT3 spindle. I do not know how moglice would work well on that, it seems to depend on a fairly large area and low force per unit area. If I ever do any work on the quill area, I would sleeve it, but never consider Moglice, at least as I understand that material at the moment..

    Leave a comment:


  • The Metal Butcher
    replied
    Hydraulic rod is very round, straight (when new) and chromed, yet still soft enough on the inside to be machined. Assuming the diameter was right, that would be the way to go. And since it's sold in standard lengths, the odds of a hydro shop having a short drop they would give you or sell for scrap price is pretty good. I've got to agree with Nickel here.

    Leave a comment:


  • nickel-city-fab
    replied
    So.... whats stopping anyone from using moglice? Of course you have to polish up the mating shaft. Or just use some TGP rod. Or an old hydraulic rod. YES you are supposed to use the release agent -- else you won't get the part out. The release agent also gives a very small clearance, I would imagine sub-micron.

    Leave a comment:


  • Mcgyver
    replied
    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.

    Leave a comment:


  • psomero
    replied
    TACrafted, some German guy, did a quill sleeve on a RF45 clone. NYCCNC had a shop tour that had shown it off. I assume he has more videos on his own channel, but never seen them. https://youtu.be/In6VqiHL7rM?t=1279

    I am mildly interested in doing things to my own G0759 quill because it's a definite weak link on an otherwise decent machine. Haven't bothered to check and adjust the gibs on the column, or actually check the condition/preload on the spindle bearings, so need to do some stuff first. I also just picked up a Biax 7ELM, sooo...

    Leave a comment:


  • psomero
    replied
    Originally posted by nickel-city-fab View Post

    Actually the moglice is a great suggestion from TMB. It is almost certainly the cheapest and easiest way to do the job. Using the proper release agent, you can use your existing quill to mold it. Make the quill very shiny first, and remove the rack if possible.
    Just make sure the quill itself ain't a tapered cone first. Molding off of an angle will get you an angle and not solve the slop problem at extension.



    Don't expect to take more than a couple tenths off with a lap. You should bore the hole over its current maximum diameter and round, then make it really round and true with the lap.

    Either way, you have to map out and true up the geometry on one of the parts first.

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  • old mart
    replied
    If the bore is bellmouthed even 0.003" at the lower end, it would take a huge ammount of lapping.
    If a lathe with enough swing can be found, I would set up a steel bar in a four jaw chuck with about 4" sticking out and turn the end 2 1/2" so the mill head just fits on it from the top half of the quill bore. Then bore the lower part to just clean up the bore. Turn the bar around in the chuck and turn it to just accept the mill head the other way round and bore to match the first end. Holding about 2 1/2" would support about 1/3 of the length assuming the quill moves 3" and would be good enough.

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  • dian
    replied
    to use moglice (or make your own) you have to grind the quill first.

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  • nickel-city-fab
    replied
    Originally posted by Paul Alciatore View Post
    I may be way off here, but wouldn't it be a good idea to bore it first to get it straight and round and then worry about lapping?
    Yep -- that's why I initially suggested making an aluminum lap that is 2x longer than the bore. Also to avoid bell-mouthing issues.

    Leave a comment:

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