RE: [CAD_CAM_EDM_DRO] Re: My ballscrew / bearing block design.

Try #0 tapered hardened pins. They are very strong. You'll have to
spend a penny for a box and a reamer, but it's handy to have in the shop.

As far as shrink fits...

No, you don't heat the part up to red heat. That would cause all sorts of
problems
including the ones mentioned.

Typically a couple hundred degreed F is enough. Light bulbs in a box are
often used to heat
up bearings.

The thermal coefficient of expansion for steel is about 7x10-6 /degreeF.
So a 1/2 hole will grow about .0007 in with a 200 degree rise, and about a
thousandth
with 300 degrees. That's plenty...a strong force fit. Try pushing a 0.5
shaft into
a 0.499 hole and you will see.

Les


Leslie M.Watts
L M Watts Furniture
Tiger Georgia
(706) 212-0242

Main page:
http://www.lmwatts.com
Engineering:
http://www.lmwatts.com/shop.html
Cnc surplus for sale:
http://www.lmwatts.com/forsale.html
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http://www.lmwatts.com/signwp.html


-----Original Message-----
From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com]On Behalf Of fj62@...
Sent: Wednesday, November 09, 2005 10:51 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Re: My ballscrew / bearing block design.

> Also, Les mentioned to pin the shaft. I looked at pins and drills and
> realized that if you have a small shaft, say, 1/2 inch, you cannot put
> in a 1/4" pin. you remove too much of the shaft.
>
> of course a 1/8" pin is small and can shear.
>
> Is there any rule of thumb or formula ?
>
> And, then (mini rant) pins can be really expensive. a couple $$ each
> or you have to buy 50 for $5.00 to $10.00 bux.
>
>
> Dave