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[machinist] workholding

From: Lawrence London <lfljvenaura@gmail.com>
To: machinist@lists.ibiblio.org
Subject: [machinist] workholding
Date: Tue, 28 Jan 2014 19:15:20 -0500

http://www.practicalmachinist.com/vb/general/workholding-237882/

Thread: workholding

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12-23-2011, 03:31 PM #1

dian
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workholding

i have seen this somewhere on the net.

anybody seriously do this?
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12-23-2011, 03:55 PM #2

oldbikerdude37
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I was taught to use round bar on the movable jaw.
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12-23-2011, 06:00 PM #3

David Utidjian
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Dian,

Starrett (and probably others) make a very nice accessory that uses a similar idea. They are the Starrett No. 54 "hold downs" and are very good for thin work in the mill or drilling vise.

Then there is the trick for uneven (bumpy or angular) work pieces of using a ball bearing with a flat ground on the ball. The flat side of the ball goes against the movable vise jaw. Gives you enough grip to even up the top side of the workpiece. Once that is done, rotate the work 90 deg, just machined flat side against the fixed jaw, use the ball again, now machine the next top side. You should now have two flat sides that are square to each other. Proceed as the print requires.

For forcing work down in the vise there are vices with that feature built in such as the Kurt "Anglock" vises (and clones.) The movable jaw is ramped where it engages with the pressure screw so that as the jaw clamps on the work it also moves downward forcing the work against the base of the vise.

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12-23-2011, 06:18 PM #4

cmailco
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A lot of your high end vises; Hilma, Schunk, Spreitzer, Erowa, etc., offer a "pull down" jaw set that functions similarly.
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12-24-2011, 03:55 AM #5

dian
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o.k., but still, does anybody use this method? it sure is a simple solution to the problem, but i dont trust it.
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12-24-2011, 07:46 AM #6

David Utidjian
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Dian,

I don't use that method and I have never seen it until now. I agree that it appears risky. Much safer would be to use some stock that is almost square in cross section. Like this:

Which is essentially what the Starrett No. 54 does.

I also prefer to have concave clamping features (notches and grooves) to be located on the fixed jaw and convex clamping features on the movable jaw of a vise. Much more consistent from piece to piece.

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