Other v wheels

discussion of design changes / improvements / suggestions
galyion
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Joined: Tue Feb 19, 2013 9:00 am

Other v wheels

Post by galyion » Thu Feb 21, 2013 1:57 am

I have seen steel wheels but wear is a concern. Has anyone tried making plastic wheels out of PVC or polycarbonate. There both stiffer than delrin. My shapeoko is sitting in the ups box on my porch. I'm counting down the hours till I get off work to go home and start playing with it.

WillAdams
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Re: Other v wheels

Post by WillAdams » Thu Feb 21, 2013 2:42 am

The only other material I've seen that I recall is steel (paired w/ anodized Openrail).

Can't recall a discussion of reasoning behind material choice for the wheels either. Isn't PVC prone to chipping though?
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets

galyion
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Joined: Tue Feb 19, 2013 9:00 am

Re: Other v wheels

Post by galyion » Thu Feb 21, 2013 2:54 am

I'm not sure about pvc chipping. But polycarbonate would be better all around. Ill prob make some to try them out. I got nothing better to do at work all day

galyion
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Re: Other v wheels

Post by galyion » Thu Feb 21, 2013 6:15 am

More I research looks like peek might be a good material. Little pricey though

microwavesafe
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Re: Other v wheels

Post by microwavesafe » Thu Feb 21, 2013 3:54 pm

I don't think the stiffness / strength of the material used is really the issue. For me the issue is with how the bearings sit inside the wheel. If you could manufacture a delrin wheel with the bearings inside (like the RM1ZZ type http://www.vxb.com/page/bearings/PROD/Kit8351) I think they would work just as well in this application. After all the load isn't that great.

cvoinescu
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Re: Other v wheels

Post by cvoinescu » Thu Feb 21, 2013 4:39 pm

If that's a dual-row bearing, it's good. With our V-wheel, because the Delrin deforms and allows the bearings to move relative to each other, you get performance close to that of a single-row bearing, even though you have two bearings in there. Which leads to the question (this just occurred to me, so I haven't thought it through): what if we assembled our V-wheels with dual-row bearings?
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galyion
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Re: Other v wheels

Post by galyion » Thu Feb 21, 2013 8:26 pm

Another idea would be to use angular contact bearings without the shim. There designed to take radial and axial load.

microwavesafe
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Re: Other v wheels

Post by microwavesafe » Fri Feb 22, 2013 8:28 am

I think the problem lies in mechanically coupling the groove to the bearings. I believe the weakness of the design is having to machine a shim that exactly matches the inner ridge of the delrin v wheel. So how about we get rid of the internal ridge altogether and we use flanged bearings to clamp the delrin v wheel from the outside?

http://en.lily-bearing.com/cp/f625-2rs-bearing.htm

This way the bearing coupling will not rely on two parts matching. This could be tried with existing v wheels. The flange will move the bearings 2mm further apart so just use a couple of standard of washers in between so you can tighten the whole wheel together with good amount of force between the flange and the outside edge of the delrin wheel. Ideally the wheel would be thinner or outside ridges could be added.

This could be worth a try? Main problem is moving away from the readily available bearings currently used, but if they provide significant improvement it could be worth it. It would be interesting to get a price for the flanged bearings. If it works out we can always go for a group order.

galyion
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Re: Other v wheels

Post by galyion » Fri Feb 22, 2013 8:50 am

Problem with flanged bearings is most are regular or deep groove bearings and can only take a minimal axial load. From tightening the wheel. That is why I suggested the angular contact bearings. But after pricing them they are way too much. Around 40$ a piece was the cheapest I could find.

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microwavesafe
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Re: Other v wheels

Post by microwavesafe » Fri Feb 22, 2013 11:08 am

Ah yes! The same issue with the existing bearings. The only really good solution I can see is what I've gone for in the RM1ZZ type bearing with the V groove built into the outer race. The only problem with them is the steel issue. and them being a different diameter. The performance however is very good.

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