Skate Bearing Design

[coolman]

I used SolidWorks to create this bearing design. It uses skate bearings that are Abec-7, 22mm OD x 8mm ID x 7mm wide which I purchased for cheap at ebay. The top plate of the bearing measures 8" x 4.75" x 0.50 and is made of aluminum. The bolts are 8mm dia. The aluminum plates are held together using bolts screwed into tapped holes. See the pics.

Before I pay to get this machined, does anyone have any comments or suggestions for improvement? Any suggestions on where I should get the parts (aluminum plates) machined?

[abasir]

I see no adjustment mechanism, so precision machining and tight tolerance on the bars are crucial. Should be manageable if it's CNC machined part
BTW, have you seen the setup below. Very close resemblance...

[iregan]

I think the center piece would have to be hardened steel at least, I doubt if aluminum would last long.
Also, why stop at one bearing per bolt, why not 2 or three with leaving just enough room for the mounting setup. The more area covered, the stronger the setup is.
Just a few things that popped out at me, I think its a great idea though.
Regan

[ger21]

I'd definately try to add adjustment.

[georgebarr]

Hello,

As far as adjustments, some of the holes that hold the bolts are actually slots that have an oval shape which allows a 2mm adjustment in two directions (total of 4mm adjustment). Is the 2mm adjustment in two directions enough?

I posted a Request For Quote (RFQ) and someone wanted to know how precise should their CNC machine be in terms of +/- tolerances. Any ideas on the tolerances needed to make this all work?

The middle part is a 2.5" wide by 0.5" think aluminum which is the slides. It will be attached to a vertical support via bolts. Someone said that this 0.5" aluminum slide may not be strong enough. Maybe I should copy Abasir's design where 3 rails are attached to a square tube. His design looks very sturdy.

Abasir, Your design looks very rigid. Can you please provide any guidance on how I can change my design to incorporate some of your design? For example, how do you make sure the rails are attached to the square tube such that they are parallel and straight? What material and how thick are the rails and flate plates for your design?

[iregan]

Hi,
I was the guy who posted about the center piece or aluminum. I think the bearings would wear into it pretty quick, thats why I was suggesting hardened steel. I was reading the other day that people using normal steel have even seen wear over a few monthes from bearings rubbing.
I wonder how much it would cost for that bar out of stainless steel?
Regan

[DareBee]

And if you go with stainless you will need 400 series so as it is hardenable.

[jcc3inc]

I'll try again. This morning I sent a response with 4 pix but I see it did not appear yet. These show a system I made wherein I have used bearings similar to your proposed approach. For the Z axis there are Bishop Wisecarver Vee wheels and ways. Note that they make eccentric bushings which I used with each opposing set of bearings.

Regards,
Jack C

[abasir]

Originally Posted by georgebarr Abasir, Your design looks very rigid. Can you please provide any guidance on how I can change my design to incorporate some of your design? For example, how do you make sure the rails are attached to the square tube such that they are parallel and straight? What material and how thick are the rails and flate plates for your design?

The CNC shown is not mine (I really wish it was ) It's from this site http://home.versatel.nl/smits146/ where you can see more photos and the versatility of the machine.

[2muchstuff]

I would definitly stay away from bearings that ride on aluminum. At work we have equipment that does just that and what a major pain. Debris gets on the rails and gets pressed into the aluminum by the bearing causing bumps and stiff spots. Then when you remove the stuck debris you now have a divit. Bump, bump, bump all the way down. Get some A-2 or O-2 tool steel for your rails, you won't regret it.

[WP1]

Another skate bearing varient, with some adjustability. Rides on 1" square steel tubing.

Pete

[miljnor]

17/4ph is also a stainless that is hardenable and a whole lot easier to come by than 410 stainless