Problem- VMC 2216 Thrust Bearings and/or Ball Screw

[Billet Sean]

So here's what I've got: a 1996 VMC2216. I was getting a bad finish on some 6061 aluminum parts. I was getting Vertical lines in the finish. But they were way out of the ordinary. I'm taking .01" as a finish pass. I switched tooling from a 1/2" 3 flute 60degree helix carbide endmill to a 1/2" 2 flute aluminum cutting to a 3/8" 3 flute 60degree helix carbide endmill, with no change. I know it's the X Axis thrust bearing and possibly the ball screw. If I mount a block and put a indicator on it, I can move the table almost .002" BY HAND!! Does anyone know how to replace the thrust bearing? How big of a pain is it going to be?

[philserveng]

put an indicator on the end of the ballscrew and check if there is axial play in the screw itself. If yes, the thrust bearings are shot.........if no, its the ballscrew or both. thrust bearings are not a problem, just preload them correctly, use the original spacers to begin with. A ballscrew is more difficult and expensive.

[Billet Sean]

I did like you said and there's play at the end of the ball screw. I had to go last night and buy a 1 1/8" impact socket to get the nut off the right side of the ball screw. What do you mean by "preload" the bearings? I was told that I just need to take the bearing mount off, press the old bearings out and press the new bearings in (flush with the inside surface) with the spacer provided with the new bearings. Is there more to it then this?

[Billet Sean]

The thrust bearings are bad. I popped them out and there's A LOT of side to side movement. There's no seals left on them to cover up the balls and the shim is a little chewed up. I should have the new bearings and shim in today and hopefully this fixes my problem. All and all, this hasn't been too bad to fix... Knock on wood...
Sean

[philserveng]

Ideally, the thrust bearings will preload correctly with the original spacer, but you need to check there is no axial play in the screw after fitting. Also, dont overtighten them or they will not last too long. After fitting you need to check for axis backlash caused by wear in the nut, this is normal, but any more than 0.002" means the nut is too worn and needs either a re-ball or replacing. Re-balling is the cheaper option, but the screw race needs to be in good condition. Backlash can be compensated for in the parameters, zero this value before you check it so you measure the absolute value, never over comp because this will cause axis reversal problems and mark your workpiece.

[TurtleRacing]

Could someone please tell me where to get directions for changing the thrust bearings? I know mine are bad, but where are they even located?

[Billet Sean]

They are located on the same side of the ball screw as the motor. Take off all necessary way covers, unbolt motor and mounting bracket. Use a impact gun and remove the nut on the same side of the ball screw (1 1/8" socket I believe). Unbolt the bracket from the otherside of the ball screw. Slide the table away from the motor side. Unbolt the bracket with the thrust bearings. Replace. Do all this in reverse to install. It's a piece of cake once you've done it. Be sure to grease the bearings.

[TurtleRacing]

Thanks, that helps a lot.
Would anyone know the actual bearing number? It looks like SKS bearing, I might be able to get it from a local source today instead of waiting for fadal.

[TurtleRacing]

One more question, obviously the ball screw will turn during this process and the motor might turn, will any of this matter? DO i have to worry about any indexing?
I really appreciate your help.
I ordered the bearing from Fadal, I figure if it doesn't show tomorrow, I'm ready for a break anyhow.

[Billet Sean]

You're going to unbolt the motor anyhow. As far as the ballscrew, it doesn't matter. You're going to have to reset your offsets anyway. I always call KMAC in Michigan and ask for Keith (248)528-8572. He knows as much about Fadals as they do in Cali. He also does same day shipping and stocks almost all parts for less then Fadal.
On a different note, what kind of racing are you into?

[TurtleRacing]

Thanks for all your help.
We make hop-up for 1/5 scale Rc. They're huge, they have 2-stroke motors and burn gas instead of nitro. Real kick and it's growing expondetially.
Check out our web-site, www.turtleracingproducts.com

[smittys800]

Hey Turtle,
Sure do miss the R/C action.
My Daughter and I used to race 1/8th scale a few years back, what a blast those were. Good memories!
I just got myself a 95 VMC 15, and looks like I will be doing the thrust bearings as well. Just finished the LCD upgrade, best money spent right there!!
Smitty