Re: My ballscrew / bearing block design.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "leslie watts"
<leswatts@a...> wrote:

>
> 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
> Carved signs:
> http://www.lmwatts.com/signwp.html

That's good to know Les,

The ones I've made where measured with a digital caliper, of course
it could be off by 0.001 or so.
So far what I can tell you is that I've made a mistake on the first
try, got the sleve half way only (was not quick enough to fit it),
and the only way I could get it off was by turning it on the lathe.
trying to press it out did'nt work.
It still holding without pins, drilling and milling steel.It is a
16mm ballscrew on z axis.
I'm just wondering if this heat expansion enginnering theory really
works if so, It's just nice to know.
I know there is those shirink fit endmill holders, it comes with a
induction heater, heat it up put the end mill on it and start making
chips.They say one can get a better finish.
By not having enough money I've being using regular deep grove
ballbearings on one axis instead of the angular contact ones ( it
goes for about 100 Us$ per pair down here), I 've used shims in
between the bearings to get it preloaded just enough toget ride of
the end play on a back to back arrangement.It works ok but I'll
replace as soon as I can.
Btw: got the bearings block drawings from a THK catalog.

Fogassa