Re: [CAD_CAM_EDM_DRO] Re: Linear motion design Q

> What I have been working on is a way to use roller bearing (from
> Roller blades), they cost $15 for 16 bearing. I am thinking of running
> them on a piece of colled rolled steel. It's cheap and will not
> deflect as a round shaft would. I priced a piece at onlinemetals.com
> and it runs about $10 for a 4 ft section. I will post a picture of my
> idea later. Mind you, it's only a ruff draft.

What makes you think CRS will not deflect? All steel has nearly the
same modulus of elasticity, and simply being square in cross section
will actually hurt compared to being round, for a given mass of metal.

Is the CRS perhaps a tube or channel with better geometry? That would help.

But CRS has some problems for high precision applications - it's not
made to nearly the accuracy of shafting, being simply rolled instead
of ground. Yes, you can buy precision ground flat and square steel
stock, but that is neither CRS nor cheap. Also, I belive it may warp
from internal stresses if machined (or is that HRS? I can never
remember)

You may come up with a quite nice machine based on it neverless - just
want to point out what seems to be a flawed assumption.

Chris Stratton

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Christopher C. Stratton
Engineer, Instrument Maker, and Horn Player
ccs@... 617 628 1062
http://web.mit.edu/~stratton/www/brassbuild.html