RE: servo mill for possible conversion

>From: "Harrison, Doug" <dharrison@...>
>
>My guess is step motors (X&Y), probably Slo-Syn and coupled directly to the
>ballscrews. Most of these older NC knee mills were factory retrofits of
>manual machines and many of them had substantially less travel on the X axis
>than their manual counterparts. Looking at the pictures I would say the
>machine is early to mid-70's, as step motors and tape drives were common at
>that time. The machine likely cost the school about $40K new.

I wrote the seller and he claims that the motors were DC servos.

Here's his direct quote:

It is servo controlled.
Shipping from Henderson, Arkansas 72544 with loading possible here.
The machine is considered a 2 1/2 axis NC controlled. As the X axis is
controlled for a plunge and retract from set depth. Rate is mechanically
controlled.

I don't have any way to confirm this but I did specifically ask.

>> > From: Jon Elson <jmelson@...>

>> > I couldn't tell how big this machine is. It most likely has DC servo
>> > motors, but may have resolvers instead of shaft encoders. These will
>> > require a converter/interpolator, or need to be changed to encoders.
>> > Servo amps may need to be changed. The CNC control has got to
>> > be one of the oldest I've seen, must be mid 60's.

The description says the table is 9 * 36 which is an ideal size for both my
work and workshop. I wonder about the reduced table travel issue,
though...

Thanks for your feedback

David M. Munro