RE: [CAD_CAM_EDM_DRO] CNCing the knee axis...

I have my enco 8X36 mill with a 600 oz in servo motor driving a 3/1
ratio timing pulley which in turn runs the knee acme leadscrew. With
this arrangement the weight of the knee keeps the slop out of the Z
axis. Using a 3/8" end mill I can bore a 1.000 hole usually within
.0005. (I have zero backlash ballscrews on the XY axis)
While it is true that I cannot cut as heavily using the knee as I could
by locking the knee and using the quill, I can still take respectable
cuts. The reason that adding a servo to the knee, is that in my opinion,
it is much easier that building all the stuff for the quill. I did not
use any air springs on my knee but I am happy with the speed that I get
on the Z axis. I could probably double the speed if it the knee was
counter balanced.
I guess it depends on how much work you want. Putting a ballscrew and a
servo on the quill would be the best solution but in my case putting the
servo on the kneee was the best compromise.
Dan


-----Original Message-----
From: Kim Lux [mailto:lux@...]
Sent: Wednesday, September 24, 2003 7:40 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] CNCing the knee axis...



Does this mean that CNCing the knee is not a good thing to do ? Should
I just CNC the quill and leave the knee alone ?

Kim

On Wed, 2003-09-24 at 08:19, Weyland wrote:
> Hey Kim~!
>
> On Wednesday 24 September 2003 09:17 am, Kim Lux spake:
>
> > I've got two concerns with controlling the knee:
> >
> > a) does the knee remain square to the machine when not locked ? Ie
> > is the knee designed to be an axis feed, ie moved up and down
> > without being locked ? (my friend tells me no...)
>
> Your friend is absolutely correct.
> A knee *will* move without it being locked.
> You can verify this by setting up an indicator on the
> table, against the quill, and locking and unlocking the knee.
> On some machines, you will see it move as much as .010".
> On my Bridget, it moves just under .001".
> (and I probably need to adjust the gib...)
>
> > Our mill does not have a gib
> > adjustment on the knee.
>
> Are you sure?
> Just about every one I've ever seen has a gib...
>
> Check under the way wiper.
>
> Best,
>
> Weyland
>
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If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it
if you have trouble.
http://www.metalworking.com/news_servers.html

http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
sister site to the CCED group, as many of the same members are there,
for OT subjects, that are not allowed on the CCED list.

NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........ bill
List Mom List Owner



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