Re: NEMA 34 to NEMA 42

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:

> Michael Larson wrote:
>
> >I just got a Wells-Index CNC 700 and I'm looking into converting it to
> >servos.
>
>http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7511611969&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1
> >That's the ebay listing of some NEMA-34 frame servos that would be

just

> >about perfect. I know I could go cheaper by modifying surplus

treadmill

> >motors or by keeping a watchful eye on ebay, but these look like

they're

> >more or less turn-key (a huge plus). Anything I should know about

them?

> >
> >The problem is that the Wells machine is coming with NEMA-42

steppers in

> >place. What's involved in adapting the 34 frame motors to the 42
> >mount? I looked up the spec sheets on the two, there are different

hole

> >patterns (2.875" square, 34; 3.5" square, 42) and the shaft diameters
> >are different (.5" vs .625").
> >
> >
> If you have a lathe, making adaptor plates for the motors should be

easy.

> Is the Wells-Index a direct drive or belt drive? If belt, then just

get

> a new
> motor pulley with the right bore. If direct drive, the best way is to
> buy a new
> coupling that can be bored out to fit the two shafts. You might

also be

> able to
> turn a sleeve for the motor shaft.
>
> >
> >
> Jon

My concern would be that the new plate would reduce the distance the
shaft extended into the old hole. Will there be enough shaft left to
hold the pulley in the proper place ? or will the shaft need to be
extended ?

Dave