RE: [CAD_CAM_EDM_DRO] Re: Z axis

Jon, I have a relatively new machines and the dovetail ways on the
machine are perfect after 8 years of use. In my case I use my cnc mill
about once a week so the wear, if any, on the knee non existent the last
time I checked. I also have a friend that owns a machine shop and he
runs one of his vertical mills 2 shifts a day 5-6 days a week moving
the knee without wear.

I share your experience with a bad knee. When I was an apprentice I was
periodically forced to use an old vertical mill that the knee was so
loose in spots I could only take light cuts. You had to lock the knee
before every cut or else you would get chatter. So in your case
automating the quill was the better solution.
I would estimate that my table, knee and 6" mill vice weigh about 650
lbs. I am using a servo motor with a 10/1 ratio gearhead ( boy do I wish
I could find more of them)and then a 5/1 reduction using a timing pulley
it works out to 100000 counts to the inch in quadrature. The servo motor
barely gets warm running it all day. I don't have great speed on the
knee but it is respectable. I agree that if one was only drilling pcb's
then motorizing the knee may not make much sense. Again it my case is
was much simpler to raise and lower the knee than to make all the parts
for driving the quill.
Dan

-----Original Message-----
From: mjf462001 [mailto:mjf462001@...]
Sent: Saturday, January 12, 2002 8:21 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: Z axis

--- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
> mjf462001 wrote:
>
> > Hugh,
> >
> > Thank you for the link. I am still not sure weather
> > I should drive the quill or the knee. When I get around to making
up
> > my mind I will at least have some pics to reference to.
>
> If you use the machine to drill holes, or if you have some slack
> in the vertical ways for the knee, like mine, then I think you
should
> go with the quill. My knee sags out, toward the operator, when you
> lower it. I can't tighten the gib because there is a worn spot on
the
> ways.
>
> Jon