How do I machine this: Bearing Sleeve

[CuttersCov]

These are bearings sleeves I need to make for my cnc router rails. The green lines represent two bearings side to side.

I think the best way would be (on a lathe):

Face one side
Make the groove
Bore it
Face the opposite side

The concern with those steps is that their may not be enough surface area for the jaws of the chuck to grip to give me room to do the facing in the last step. (Don't want the bearing to wobble and definitely don't want to hit the chuck with my tool bit)

The problem with this part for me is I need accuracy on all the dimensions except the boring.

Another issue is I need to make 8 of these with each set of 2 sleeves being as close to identical as I can get.

[Kevin Taylor]

Make several at one time and part of as you go as far as the facing the second side it dosent take much to hold to do a light face cut maybe you could use an expanding mandrel to hold them from the inside the side the id. is straight through it look's like so the sides arent critical just the id to od runout. To get a nice press fit I would hone the id to get an exact fit you might want a lock grove on each side or a step on one and a grove on the other but this makes the part more dificult to make. Good luck Kevin

[CuttersCov]

Kevin,

After reading your post and thinking about it some more. I think this would be the best

Face one side
Make the grooves for two bearings leaving enough space for facing
bore out both
part and then face the last side

I can shim the sides if I have to, to mount them and the bore isn't too critical I made a test one last week with a different groove, and just used a drill bit to do the hole through the center and the bearings pressed in fine. Had to get them in with a hammer and they still turned. Although I believe we have an actual press in the shop at school I'll see if it's possible to use that instead.

Even if the last side to be faced isn't accurate it isn't too important because bearings could be flush with the good side and there isn't anything to contact the "bad" side.

Thanks, you gave me that extra little "thought" push I needed to get this figured out. I'll post a pic of them on Thursday.

-Matt

[Mcgyver]

how many do you have to make? I'd maybe think production rather than one of's.

The two challenges are, how do you get the two faces in parallel planes, and how do i keep the bore concentric with the OD (if I'm doing it production style).

Here are two devices that will help. the spacer is accurately made and basically brings the back of the chuck forward. Face one side, flip it over and make sure the just machined face is registered against the spacer - now you're not relying on the three jaw's grip for accuracy (never a good idea!), There are commercial version of this available, often as extrusions but they are expensive, are easy to make and steel is preferable. Do not do bad things like stuff a parallel in there or you’re flirtin with disaster

second photo is some stub arbors. You make these accurately and either hold them in a collet or indicate true in the 4 jaw. Once you've the bore and faces done , you can swap parts in and out for operations and the turning will be concentric with the bore (to the accuracy of your arbor & setup work, not to hard to get it better than a thou, but the arbor has to fit the bore with minimal slop)

hope that helps

[CuttersCov]

Mcgyver,

I was kinda of wondering if I could do it the way you posted. I would have to make my own but it might be easier in the long run. This way I could get two bearings of equal width, bore them out, mount all of this as you suggested then touch the end with the toolbit, and then do the groove according to the DRO.

This way the grooves won't be on EXACTLY on center but they will match each other.

Looks like I should maybe try it both ways.

There's only 8 total, but each sets of 2 have to be identical.

Thanks,

Matt

PS- Always great suggestions on here.

[One of Many]

Originally Posted by CuttersCov These are bearings sleeves I need to make for my cnc router rails. The green lines represent two bearings side to side. <Snip> The problem with this part for me is I need accuracy on all the dimensions except the boring. Another issue is I need to make 8 of these with each set of 2 sleeves being as close to identical as I can get.

As drawn, I see no provisions for keeping these split rollers from coming off the bearings. There should be a shoulder on the inside faces for the outer race to seat against or a shoulder on the outer race to keep the wheel there. The wedge forces of the rail will try and separate them. I would think they should be one piece press fit on a common bearing. The commercial ones I have worked with also utilize an eccentric sleeve bushing mount to allow adjustments and alignment against the rails.


I would turn them in pairs directly from the stock to get the bearing bores identical, the OD will also be concentric to the ID, and the faces will be turned and parted off perpendicular to the bore. Everthing done in one setup will keep them as matched as they will ever get for the equipment available. As another option, you could match them up in pairs and finish turn the groove after assembly on the bearing to insure minimal runout.

DC

[Rich Carlstedt]

I would bore all the parts first.
leave them oversize in width if you want.
Set them aside
Chuck a 3/8 socket head cap screw (Allen) on the threads and turn the head to a taper of about 10 to 30 degrees, so the head resembles a taper pin .
Flat heads have too blunt a tapper to use here
Now,make an expanding arbor.
Take a 1 1/4 piece of steel or aluminum.
center it and tap drill for a 3/8..tap it like 1 inch deep
Counterbore the hole to the middle of the tapered head diameter.
Remove the arbor and saw cut about 1 inch of of the end into 4 quadrants.
No accuracy is reuired.
Return it to the lathe ...DO NOT remove it till the whole job is finished!
now screw in the Cap Screw and wedge it into the c'bore till it expands the
arbor, and turn the diameter to exactly the size of the bores for about 1 inch.
Now when you loosen, the bores will mount and then tighten and you will have very accurate bushings that you can work on the sides and the OD. you will have no run out here, if you turned the fit with the screw tightened..

For llighter jobs, and out of balance jobs, some guys dispence with the screw and taped hole, and only centerdrill the hole and use the tailstock center for expansion.
You must be vary careful however that the tailstock does not loosen up.
it also does not provide the higher level of grip that a screw gives.
You may want to do a combination of both to get rock steady support.
Rich