Mark Wrathall wrote:

Paul Wrote> >

Yes on the knee mills. I  don't know whether they handle the

ball

screws

but McMaster Carr sells them at reasonable prices.

Mark wrote:
The cheap ballscrews in the Mcmaster-Carr catalog are rolled, and

thus

not

of machine quality (I think the error spec is 0.003" per inch. For

a

machine

you really need precision (ground ball screws). Price is bad.

Mark.

Well then it is cheaper to buy a used Kasuga or Shizouka. Harrison

found

a used Kasuga in Tucson AZ for $3000 that was built later than  mine

and

was

in better physical shape with Fadal tool changer. He had to do some

electronic

work to get it running however.

Paul Lamar

Yep. If you have a space, a good industrial CNC with a blown

controller is

the cheapest way.
Mark

I checked the catalog Mark. Not quite that bad +/- .003" per foot... not

per inch.

Lots of stuff we do is less than a foot square and does not require a lot

of

precision. For casting pattern work it is fine.

However the Bridgeport mill ball screw upgrade kit is $750 making a used

Kasuga look

all that much more of a bargain.

Paul Lamar

Mark wrote:
Sorry about that. The real issue is that that lead error requires back lash
to prevent the nut binding so you end up having to use two nuts in a spring
loaded anti backlash configuration, where a Precision ground ball screw is
so accurate they can use ball size for preloading out the back lash.

Mark.

 
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