Tramming a mini mill. Shims vs epoxy?

[Mach_Zero]

Hello everyone!

I just got a Littlemachineshop 3990 mini mill and it's awesome. I haven't actually checked the tram of the column yet, but I figure I'm going to have to tram it with shims.

I know these little mills suffer from less rigidity than larger machines, so I'm wondering if I should tram the mill with a solid steel filled epoxy at the base of the column to provide a more solid connection (like what Stefan Gotteswinter did on his mill:

).

The question I have is, is it worth it? I'm not sure how bad shims would be for rigidity, but on these little mills how much would I be gaining by using epoxy? Is it overkill on such a small machine?

 

[mickri]

There was a thread awhile back about using epoxy to tram a mill/drill. If you go the epoxy route be sure to use plenty of mold release wax on the column and the base. You don't want the column and base to be glued together. Pure epoxy is rather brittle. You will definitely need a filler of some kind. Coradical silica commonly called cabosil is used extensively in boat repair as a filler. Epoxy/cabosil is quite hard when fully cured and even dulls cutting tools. True full cure takes a while.

Epoxy is messy to deal with and some people have allergic reactions to it.

When I was doing lots of boat repair stuff I used to buy it by the gallon. My favorites were West System and the epoxy sold by US Composites in Florida.

You might be able to achieve the same result with JB Weld.

 

[tghsmith]

shims are fast and easy,, the rigidity issues has more to due with the column than the bolted up base.. as long as you don't expect more than it can do, it will do nice work.. spend more time on adjusting the handwheels and other motions.. (ps better handwheels make a big difference) the spindle lock block helps, a better precision drill chuck, add a tach.. https://macpod.net/misc/sx2_tachometer/sx2_tachometer_kit_v2.php

 

[Mach_Zero]

There was a thread awhile back about using epoxy to tram a mill/drill. If you go the epoxy route be sure to use plenty of mold release wax on the column and the base. You don't want the column and base to be glued together. Pure epoxy is rather brittle. You will definitely need a filler of some kind. Coradical silica commonly called cabosil is used extensively in boat repair as a filler. Epoxy/cabosil is quite hard when fully cured and even dulls cutting tools. True full cure takes a while.

Epoxy is messy to deal with and some people have allergic reactions to it.

When I was doing lots of boat repair stuff I used to buy it by the gallon. My favorites were West System and the epoxy sold by US Composites in Florida.

You might be able to achieve the same result with JB Weld.

Yeah I didn't really want to go the epoxy route. I was thinking of using some steel filled epoxy but I know it's messy. I used to do a lot of work with carbon fiber. It's a pain. I just wanted to know if it would make a significant improvement over shims. Thanks for the informative reply.

shims are fast and easy,, the rigidity issues has more to due with the column than the bolted up base.. as long as you don't expect more than it can do, it will do nice work.. spend more time on adjusting the handwheels and other motions.. (ps better handwheels make a big difference) the spindle lock block helps, a better precision drill chuck, add a tach..

Those are some awesome upgrades. I agree with you that shims are fast and easy. I've seen/read a lot of people say that shims are less rigid and, while I'm sure that's true, it can't be that crazy of a difference. The only concern I have is that there isn't much bearing surface area where the column meets the base. So I figured the epoxy would really lock everything in place. But I'm sure you're right that the column itself is the weakest link.

I think I'll use shims for now and see how it goes. I'll probably never get around to changing it if it works, but I could always change my mind and do the epoxy later on.

 

[tghsmith]

I had some shim stock of several sizes on hand,, used small pieces to establish tram.. then cut U shaped shims to fit the bolt diameter of the proper thickness and replaced the the small pieces.. then rechecked all to make sure nothing changed...

 

[Mach_Zero]

I had some shim stock of several sizes on hand,, used small pieces to establish tram.. then cut U shaped shims to fit the bolt diameter of the proper thickness and replaced the the small pieces.. then rechecked all to make sure nothing changed...

I don't have any shim stock. Any particular type of shim stock I should buy? I was going to buy some 0.003" steel shim stock.

 

[tghsmith]

I can't say offhand,, don't remember the thickness.. ask LMS

 

[matthewsx]

I don't have any shim stock. Any particular type of shim stock I should buy? I was going to buy some 0.003" steel shim stock.

I buy my shim stock by the 6-pack...

John

 

[Mach_Zero]

I buy my shim stock by the 6-pack...

John

I tried that but the glass kept shattering

 

[tghsmith]

don't use the drill chuck that comes with the mill for tramming..