Re: [CAD_CAM_EDM_DRO] deep pocket milling

Victor,

If you want chatter free walls on deep pockets, try a cutter with a
smaller radii than the corner and interpolate it. When you come into a
straight 90 degree axis change, the cutter goes from essentially line
contact with the wall to contact that exceeds 90 degrees. I never did
figure this out on my own, read it somewhere.

If you're going to try this, check out this web site:
http://www.schmarje.com/index.htm
They make thread mills, look to the thread milling technical page,
especially on figuring feeds. In linear machining, the feed rate, is the
same at the cutter's edge as at the cutter's center. However, if you
interpolate a radius, suddenly the effective travel speed increases, as
the center of the tool is passing through a much shorter arc than the
cutting edge. (in linear distance, not angular distance)
You need to slow the feedrate to maintain the effective cutting rate at
the cutting edge. At the above site, there are simple calcs to figure
the equivalent circular feed rate for both internal and external
interpolating. I couldn't get the info to print directly, but was able
to save the pics and calcs as GIF's and print.
I've seen this referred to elsewhere as radial chip thinning. I've also
learned this shade tree fashion interpolating say, a .265 wide slot with
a .250 end mill and watching it just rip around the end radii.
I just guesstimate an appropriate feedrate to get around the radii, but
when I recently found this web site, I realized the math applied to
other aspects of machining. It's also an excellent reference site for
anyone interested in thread milling!

Jon