Re: Who had some .100 pitch ball screws FS??

Jon:
I would recommend using www.schneeberger.com on the West Coast.
The price that I got from Motion Industries, San Diego for NSK
ball screws was very good for the 12mm x 2 mm pitch class 3 screw.
That was $650. The quote I got from THK was twice that! Bearings
for these things seem to be around $200 per end and more for the
fixed end. If you have thicker screws, then you may not have to
support the back end. For class 7 12mm x 2 mm screws (with preload)
was about $360 each for 5 or more. I think that the NSK ball
screws in quantity will be cheaper.
For the Z-axis, I would recommend going with a 16 mm ball screw
so it has more weight capacity. The screw will have to carry the
whole load of the spindle and may have the most travel of all the
axes, except the X-axis.
I'm not sure what torque will be required to drive these screws,
but it may be less than that used for the present screws.
The cheapest retrofit that I can think of would involve the use
of a Teflon-coated stainless steel screw with an acetal pre-loaded
double nut. If it's been discussed on a forum before, I missed it.
Supposedly, there is no backlash with this nut, but
I'm sure it is expensive too and you have to keep the chips away
from it.
If you are making linear ways using THK slides, then you'd have
to make housing of some kind to keep it from getting full of chips.
Really, doing all this is more than a modification of the mill and
now you're building something completely different. What will this
look like in the end and how much will it weigh? Why keep the
Sherline spindle at all if you are building what is essentially a
new machine? What do you think of the mill at www.5bears.com?
This is an interesting topic and it would be interesting to discuss
this off the list. Send me an e-mail and I'll let you know more
about these price quotes, etc. Later, Jim



--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Anderson <janders@n...>
wrote:

> Jim,
>
> The screws were being described as .100 pitch. I see .100 = 2.538mm
> which is close enough they might have been mis-measured.
> I've never looked for screws in that pitch myself, but if I can find
> them, I'll use them. I've seen ads for Steinmeyer, might go with

them

> given qty discounts. My dad's gone far with his Sherline, but it's
> wearing out and we've decided to build up something with linear

ways and

> real ball screws. With the automatic tool changer drawings for the
> Sherline spindle, I'm once again interested in building something
> similar for myself, so maybe he and I can double up and get a good
> price.
> Do you deal with anyone on the west coast for Steinmeyer that you

would

> recommend?
>
> Thanks,
>
> Jon