Question about size. Since skate bearings seem to be becoming a universal component for all things RepRap rleated...

Are skate bearings standardized to a single size? And are skateboard bearings internchangeable with skate bearings?

I happened to find this, after wondering what sizes of bearings are used on Mendel.
[www.vxb.com]

Mendel I think uses, 608, 625 and 624, at least that is what I can gather from the file names in SVN

I'm looking through that web sites description of different products, and whether its skate or skateboard bearings, the dimensions seem to be coming up as 8x22x7. (inner diameter x outer diameter x "B" which must stand for thickness)

So if there is any real difference between skate and skateboard bearings, it must be a difference in the kind of stresses that they are designed to withstand.

Either type of bearing should be able to withstand a person standing or jumping in it while it rolls for miles in possibly dusty souroundings, which is probably more stress than it's going to get in RepRap related applications. I'll probably just go with what's cheap.

I have bought both skate and skateboard bearings they were identical bearings.

They all have the standard 8x22x7 dimensions.

Skates/ Roler blades use two bearings per wheel.

I have not looked at a skate board I would expect them to be identical as in Two bearings per wheel.

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As a test I just did a google search for "8x22x7". It looks like this size is also being sold as "model car bearings" and "hobby motor bearing". I found an outfit that will sell them for 58 cents each (U.S. funds) which is cheaper than what I've seen on skate supplier web sites. I'm betting that they will generally be cheaper through non-skate related suppliers.

Check around on ebay. I bought a lot of 32 for $10. It was more bearings than I needed, but I couldn't beat that price. And those extra bearings wound up in other projects.