Subject: milling the whole surface

From: "Steven O. Smith" <[email-masked]>
Date: Mon, 9 Dec 1996 18:32:03 GMT

I have several projects in mind which involve milling the entire surface
of a piece of steel. I can shift clamps around ok, but I'm wondering if
there is a better approach.

I don't know enough about clamping from the sides (mechanically). This
sounds like an easy solution, but how do you keep the work flat to the
table, and not riding up on the clamps? Does tapping it down as you
tighten work well, particularly with larger areas?

A magnetic chuck is another possibilty, but it seems like all the chips
piling up on the chuck would get in the way of the mill cutter. Is a
magnetic chuck useful for milling?

-- 
Steven O. Smith
[email-masked]

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From: Jay Hayes <[email-masked]>
Date: Mon, 09 Dec 1996 23:15:55 -0800

> magnetic chuck useful for milling?

If you can attach the part to a sub-plate from the back side, you can
then clamp the sub-plate down to the table outboard of the part. You can
also use edge clamps, depending on the thickness of your work.

I've also used two Kert vises in tandom with their jaws relocated
outboard to clamp large parts. A few wacks with a dead blow hammer does
help to insure that the part is seated correctly.

Jay

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From: [email-masked]
Date: 11 Dec 1996 06:24:22 GMT

MSC sells toe type clamps that pull Downward as you tighten them leaving
the 
whole top free.
I prefer this method over gluing or magnets because the tension is
predictable.
This is critical if you are going to be close by.
If you want more pressure you add more clamps.
Have a great day!
Paul D. Nordhaugen

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From: "Steven O. Smith" <[email-masked]>
Date: Wed, 11 Dec 1996 16:40:00 GMT

Thanks for all the replies. I got some replies email only, so I figured
I figured I should summarize.

Methods for holding work to the milling table allowing cutting the
entire top surface:

-Special toe clamps (clamping force sideways and down) on edge of work.

-Attach a base plate, giving you ears to clamp on. Attachment methods
mentioned included welding (heat distortion?), glue, wax, solder and
screws.

A couple of tricks were also mentioned using vises.

Thanks!

-- 
Steven O. Smith
[email-masked]

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From: Steve Wellcome <[email-masked]>
Date: 11 Dec 1996 13:27:20 GMT

I'm no expert on magnetic chucks, but after having had an end mill
walk a steel bar out from under some clamps that were tight, but
not quite tight enough, I seriously doubt that a magnetic chuck 
could hold a part against the forces of milling.  

There are special side-biting clamps available; look in the
MSC or Travers catalog.  The suggestion in the previous response,
of attaching the work to a baseplate with screws from the back, 
then clamping down the baseplate, is also good.

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From: "Henry P. Szostek" <[email-masked]>
Date: 13 Dec 1996 01:08:49 GMT

Steve;  
Just how big a piece are we talking about here? what is it made 
of and how thick is it?  

Henry

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From: Mark Winlund <[email-masked]>
Date: 12 Dec 1996 04:05:46 GMT

Some of the jewelry supply houses have a resin material that they sell by the 
pound... heat it up to place it and remove it. Try Swests.

Regards, Mark

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From: Mark Winlund <[email-masked]>
Date: 12 Dec 1996 04:08:32 GMT

Don't forget vacuum. 15lbs per square inch adds up. I've put sandpaper down (glued) 
to a vacuum plate... holds very well.

REgards, Mark

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From: Lee Marshall <[email-masked]>
Date: Tue, 10 Dec 1996 10:48:13 -0800

> there is a better approach.
A method that you might try is to heat a larger piece of material that
can be secured to the table. Melt tooling wax on this piece and place
the warmed part to be machined in the wax puddle. This is a standard
method for grinding ceramics. The nice feature about this method is that
there is no forces applied to the part from the clamping itself. Be
cautious in how big a bite that you take in the machining. It is also
possible to increase the clamping area by placing flat bars against the
sides of the part with these also being held by the wax.
Lee Marshall
Bonny Doon Engineering     http://www.bonnydoonengineering.com

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From: Steve Wellcome <[email-masked]>
Date: 12 Dec 1996 20:49:58 GMT

Another thought on this: Starrett sells some vise inserts
that are shaped like thin triangles in cross-section and
are about 6" long.  The shortest side of the cross-section
is beveled in such a way that when you put these inserts
on either side of a piece of work in a vise, then tighten
the vise, the inserts tend to pivot down and hold the work
in place.  I wish I could remember the name of these things,
but if you look in a Starrett catalog you ought to be able
to find them....

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From: [email-masked] (Fdmorrison)
Date: 12 Dec 1996 15:38:56 GMT

Many of the older holding techniques developed in the last century for
planing and shaping would be useful.  Most general machine-shop texts from
years ago have sections devoted to such.  One I particularly enjoy is
Robert H. Smith's "Text-Book of Advanced Machine Work," available in
reprint through Lindsay Publications, Inc., or peruse used-book shops and
you may find an original that's cheaper.  Smith taught at MIT around
1920-30.