Re: Van Norman #12 Milling Machine

PTENGIN@... wrote:

> From: PTENGIN@...
>
> In a message dated 01/21/2000 5:12:19 PM Hawaiian Standard Time,
> ronhenderson@... writes:
>
> << From: ronhenderson@...
>
> I have a Van Norman #12 milling machine that I use as a hobby for making
> scale live steam engines. I would like to add CNC to this machine.
> Has anyone done this? Were the original type screws/nuts used or were
> zero-backlash ones installed?
> >>
>
> Ron,
> Was this not a horizontal / vertical mill? It has no quill if I remember
> right. This would mean the knee has to be raised and lowered for the Z axis.
> I would say on at least Z, you must replace the existing acme with a
> ballscrew if not all axis because of the friction. Esp if you are running
> steppers. Sure is easier to set up the software and the cut will have a
> superior finish.

If you put a ballscrew on the Z (knee) axis, you will almost certainly need
a power-off brake to keet the knee from crashing to the bottom of
travel when the power is off, or the system is in e-stop. This may even
be true with steppers, depending on how much they drag with power
off. The will also be true on machines where the entire vertical head is
raised and lowered on a dovetail slide.

Jon