X2 head dis/re-assembly

[X2cnc]

After separating the two head castings on my X2 I found some randomly-applied grease and a bunch of cast iron grit which really needs to be cleaned out of the front half that holds the spindle and gears.

I'd like to strip this part all the way down, clean it, reassemble, and set the preload on the bearings. Before attacking the head with my hammer and monkey wrench, I thought I'd solicit comments from anyone who has been into one before. Are there any gotchas with getting the spindle out, or does it slide right out?

[Crevice Reamer]

Here's some info:

http://littlemachineshop.com/Instruc...ndle%20Kit.pdf

http://littlemachineshop.com/product...2287&category=

http://littlemachineshop.com/product...2637&category=

http://littlemachineshop.com/product...2537&category=

To do any serious work with the X2, you will also need this:

http://littlemachineshop.com/product...2560&category=

CR.

Triple4

[X2cnc]

Thanks, CR! That's what I was looking for.

[Crevice Reamer]

You are welcome X2CNC! Just a note: If you opt for the belt conversion, which is best because then you needn't fear stripping the plastic gears, it bypasses all of the gears, so it no longer would MATTER whether they were lubed or not. So then you wouldn't NEED to disassemble the head.

BTW: Welcome to the Zone!

CR.

[X2cnc]

Originally Posted by Crevice Reamer BTW: Welcome to the Zone! CR.

Thanks!

I blew $20 at the local hardware store for the bits as described in the LMS instructions. For some reason I didn't realize what the electrical box was used for; I had several feet of 3" .090-wall tubing in the bits-bin already. Well, at $1.29, it was no big deal. I made the stepped washer on the lathe, so now all it takes is some round tuits...

[X2cnc]

Okay, I got the spindle apart, cleaned a bunch of cast iron grit out of it, and put it back together.

The spindle didn't turn all that freely to start with; once it was back together, it's noticeably tighter. I'll press it back apart and see if there's any obvious reason. The top bearing seemed to be tighter going on than when it came off, anyway.

In the meantime, since the LMS directions included setting the preload on the bearings, I assumed the inner races didn't bottom out on the stack of gears and spacers, so I left all the bits out since I was fitting a belt drive. Did I make a mistake here? I tapped the spindle down a bit to eliminate any bearing preload, and it's still stiff to turn.

[Crevice Reamer]

The gears and spacers are only necessary, as are the woodruff keys, if the spindle is to be gear driven internally. The belt drive turns the spindle directly so none of this is needed. Perhaps the bearings have not seated properly. It may take chilling the spindle and heating the bearing inner race (and maybe the headstock) to get a good fit. It is possible that the bearings have been damaged and need to be replaced.

There is an ongoing thread about X2 bearings and preload here:

http://cnczone.com/forums/showthread.php?t=60759

CR.

[sansbury]

I'm the guy responsible for that thread CR linked above. My one suggestion is that if you feel any drag at all in the spindle when turning it then you may have too much preload. From my (painful) experience I think it is most likely that the preload is too high more than anything else. After pressing the bearings in and out about a dozen times they no longer need a large amount of force to seat--they don't slip in but they move in smoothly with moderate pressure.

[X2cnc]

I've read that thread with interest. I took mine apart and reassembled it; it got stiff again. So I took it apart again, did some fine sanding in the bearing counterbores in the headstock casting, and polished the top part of the spindle with abrasive tape in the lathe. The headstock went back together much more easily... but the spindle was still stiff.

I used the puller to move the lower bearing out a bit - just some tension until it went "pop". The spindle then turned freely. So you are correct, it's a preload problem.

I made my puller using the directions on the LMS web site that CR pointed me to. The LMS design uses a washer that sits on the inner race of the top bearing. I'm wondering if I ought to make a bigger washer that will bear on the outer race. The bearings fit tightly to the spindle and housing; it's very difficult to tell when they're seated, and once you get them in there tightly, they stay tight.

My immediate idea was to polish the spindle until the top bearing was a slip fit, then make a metal bearing retainer to hold the bottom bearing to the headstock, which is the "proper" way to hold a shaft - one bearing fixed, one floating. However, I think I'm going to try just pressing on the outer race first and see if that's good enough.

[S_J_H]

Once the whole deal is apart this method works a charm.
First get some new bearings. Mcmaster.com has SKF precision plus 6206 made to a abec3 tolerance for under 20$ each.

Next chuck the bare spindle and with 400 grit sand the rear end of the spindle until you can just slide on the new bearing.polish with fine steel wool.

Clean the heck out of the headstock. I boil mine in a strong tsp solution and water.

Put a new bearing in the oven at 200'F and the spindle in the freezer for about 30 minutes. Then use a little wd40 to remove any frost on the spindle and drop the heated bearing right on the spindle. It will drop right on.

Now heat the entire headstock in the oven at 200'F. and freeze the other bearing. Then remove and drop the rear bearing into the headstock bore.Again a little wd40 will remove any frost on the cold bearing.
Again it will drop right into the headstock. Don't disturb for a few minutes to let the temps equalize.
Put the headstock with the rear bearing now installed back in the oven at 200'F and freeze the spindle that now has the front bearing installed again for 30mins.
Now again, a little wd40 to remove any frost on the spindle and bearing and slide the spindle/front bearing into the headstock and through the rear bearing. It will all slide together easily. Work fast.

This method works without any press, pressure of any kind and no chance of distorting anything.

Just did this procedure 2 days ago. .0001" runout on the OD of the mill spindle. The lousy internal mt3 taper shows .0003" though.
Smooth as can be though.

Steve