On 11/01/2010 09:45 AM, Gunner Asch wrote:
On Mon, 01 Nov 2010 09:32:40 -0700, Tim
wrote:
On 11/01/2010 08:31 AM, Wild_Bill wrote:
Tim, if you haven't had the mill head column off of your machine to
improve the metal-metal contact area to the headstock top surface, you
might consider doing this procedure to gain some rigidity when milling.
The one I worked on was a 12x20 made in 1999 maybe.
While you're milling something fairly aggressively, put your left hand
fingertips at the seam of the contact surfaces at te base of the column.
If you feel movement, this procedure may increase milling rigidity
considerably.
The mating surface of the column flange is likely fairly accurately
flat, as it was probably turned (faced) on a lathe.
The top surface of the headstock may be one of those areas where a
factory worker ran a power scraper on it, just to smooth it somewhat,
followed by filling the seam gap with filler putty.
I managed to get the headstock surface flat, by rough filing, and
checking for contact area with plain printer paper laying on the
headstock surface, and rubbing a (machined flat with a large shell mill
on a large machine) flat thick slab of aluminum on the paper to make a
carbon copy (although aluminum oxide) of the contact area.
I put cardboard and shop rags in the opening to catch the filing swarf.
When I started, there was probably only about 15% contact between the
two surfaces.. when I had finally had enough exercise, the contact area
was probably closer to about 75%, and the rigidity of the mill was
increased greatly as a result.
My biggest complaint about rigidity on that thing is the quill, which I
can somewhat deal with by adjusting the quill lock.
My biggest complaint about the use of the thing as a mill at all is that
the quill drive (which is the only adjustment in the z plane) is much
coarser than the x and y feeds and an odd number in both english and
metric, being something like 0.43 inches. To top off the pain, it's got
an itty bitty knob. So even when I've got the rigidity issues dealt
with, it's very difficult to get the height difference between features
accurate.
So even if the thing were made out of tungsten and worked as smooth as
silk, I'd still be wishing for a mill that had a decent vertical feed
mechanism.
Can I interest you in a Gorton MasterMill?
http://picasaweb.google.com/gunnerasch/NewGorton#
Needs a bit of work, but nothing major and would be a fun winter project
for folks
If you were closer, maybe -- if you factor in lost time I think I can
get a decent mill locally for as much as the trip down & back would
cost. But if I'm ever going to be in your area with a trailer I'll
probably contact you.
Ideally I'd get a smaller mill -- the biggest things that I seem to end
up making are model airplane parts, and those just don't get big.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at
http://www.wescottdesign.com/actfes/actfes.html