Subject: milling Everdur

From: [email-masked] (Bathsheba Grossman)
Date: 21 Dec 1993 11:31:46 -0500

I find myself milling a lot of Everdur bronze lately, and am wondering
if there are any tricks to the stuff.  I know large shops keep separate
sets of cutters for brass, but don't know exactly what the difference is
or if I should be using them for this.  I'm using a 3/8" 2-flute end mill at
about 2000 rpm, and while it cuts fine, the tool seems to dull awfully
quickly.

-Sheba  	(100 lbs scrap and a Sherline.  B) )

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From: Doug White <[email-masked]>
Date: Tue, 21 Dec 93 15:59:18 -0500

> -Sheba  	(100 lbs scrap and a Sherline.  B) )

I'm not sure about your tools dulling quickly, although I think I have
heard somewhere that some bronzes can be a bit abrasive.  I have recently
run into a problem with drilling brass that might help.  I was boring a
1/4" hole in some 5/8" brass rod on my lathe.  The first drill I tried
was brand new, and VERY sharp.  It would dig in, and cut off center.
I tried varying the feed rate, but I ended up with a hole that was at
least 30 thousandths oversize!  Attempt No. 2 was done with a drill that
I had just about completely removed the rake angle on, using an Arkansas
stone.  This worked fine.  The idea is that brass (and other soft materials,
like plastic) is best cut almost with a scraping action, rather than with
a sharp edge that can dig in.  This can be a lifesaver (literally) on
plastic.  Many plastics will expand into a hole you are drilling, and grab
the drill bit.  This can be agravated by having a sharp angle on your
drill.  Before I learned to regrind my drills and clamp things securely,
I had a big piece of PVC ripped out of my hands when it froze on a 1/2"
bit.  Although I haven't seen them in any of my catalogs, a friend of
mine had a set of special drills for brass and plastic that were basically
half round, no twist, and no rake.  I've seen similar bits for sale, but
never an indexed set specifically marked for soft materials.

Milling presents its own problems, because its going to be tough to find
an end mill with a shallow rake angle, and I'd hate to try to touch one
up with a stone.  There are a lot of funny specialty mills available, and
it might be worth looking for one.

Doug White
MIT Lincoln Laboratory

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From: Doug White <[email-masked]>
Date: Tue, 21 Dec 93 15:59:18 -0500

Doug White
MIT Lincoln Laboratory

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From: [email-masked]
Date: Sat, 1 Jan 94 13:43:20 EST

hi! my name is Chris fuhr you can reach me thru walkermm's.
What arre you making wtih everdur and a sherline?
I'm slightly fimular with both, and to myknolege their is no shortcuts other
than sub contracting the stuff out.
you pass the cost of the cutters on to the customers.
The big shops use different cutters possibly because their accounting people
want to track each job to eachwear down and of tool costs.
As for the Sherline you may be doing something it wasn't designed to take.
Or you are making passes so small that it's not worth your time.
Signed Chris fuhr
Po. box 6143
lynnwood Wa. 98036