Square jaws for round collets anyone attempt them?

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jcfx
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Square jaws for round collets anyone attempt them?

Post by jcfx »

I'm looking to make some square jaws for a few of the collets that came with a deckle clone grinder
I recently acquired used. Harold Hall has a write up on how to make them here -
http://www.homews.co.uk/page75.html
One of the problems I'm encountering is how he was able to hold 4 square pieces together in a 4 jaw
chuck with just card stock, which I'm assuming is manila folder type card stock. The chuck jaws land
right on the edges of the the ganged up stock and seems to want to wedge the square stock apart
once you tighten the chuck.
Since he's not really responding to correspondence as per his note on his site, I was wondering
if anyone here has attempted to make them ?
Patio
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Re: Square jaws for round collets anyone attempt them?

Post by Patio »

As long as the card stock is a bit narrower than the metal stock, it should hold together well. While one set of jaws is pushing the pieces together, the other are keeping them contained and vise versa. As each set is tightened they will compress the package.
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Magicniner
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Re: Square jaws for round collets anyone attempt them?

Post by Magicniner »

If I'm not making heavy cuts I hold Octagonal, Hexagonal, square etc. in ER Collets with a tube of shim in the collet if required (but usually it's not) and have never had any problems.
Obviously the above is described as impossible by those who have never tried it and made it work ;-)
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tornitore45
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Re: Square jaws for round collets anyone attempt them?

Post by tornitore45 »

Seems to me a huge complication for nothing.
I have used exactly Mgicniner approach and worked every time.
The only time a split bushing may be required is when the part sides number is incompatible with the collett slits and the part runs off center.
Mauro Gaetano
in Austin TX
John Hasler
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Re: Square jaws for round collets anyone attempt them?

Post by John Hasler »

Wouldn't it be simpler to make four pieces with a truncated pyramid cross-section, clamp them in the four-jaw, and turn them round? You'd mill all four pieces with a single setup and cut them to length. Turning would be the final operation. You could still use the card stock and the piece of square stock in the center but the jaws would grip the centers of the bases of the pyramids.
earlgo
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Re: Square jaws for round collets anyone attempt them?

Post by earlgo »

I am sure you know that there are some collets already with square holes, and unless you have an odd requirement, it might be more cost effective to buy.
5C collets
5C collets
--earlgo
Before you do anything, you must do something else first. - Washington's principle.
John Hasler
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Re: Square jaws for round collets anyone attempt them?

Post by John Hasler »

Why buy something you can make for twice the cost?
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tornitore45
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Re: Square jaws for round collets anyone attempt them?

Post by tornitore45 »

Why buy something you can make for twice the cost?
Isn't that the Home Machinist's credo?
Mauro Gaetano
in Austin TX
earlgo
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Re: Square jaws for round collets anyone attempt them?

Post by earlgo »

Oh, isn't this the same group that can't stand anything that is more than .0000000001 out of tolerance. :roll:
ROI is important especially if it takes a week to make an unusable part, not that any of us would do that. Ever.
--earlgo
Before you do anything, you must do something else first. - Washington's principle.
jcfx
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Re: Square jaws for round collets anyone attempt them?

Post by jcfx »

Thanks for all the replies, I'm wondering if the card stock trick requires the chuck jaws having a wider jaw face,
meaning the part of the jaws that contact the work, the chuck that I'm using now has very narrow jaw faces
and they act as a wedge to separate the four pieces.I may try adding a thick pad on the four sides so that the jaws have
a continuous surface to bear on.
I know about square and hex collets, but the collets I have are Deckle clone style, 20mm dia with buttress threads
square ones sell for $300, that's two hundred shy of what I paid for the grinder.
earlgo
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Re: Square jaws for round collets anyone attempt them?

Post by earlgo »

Can you do all the operations except the gripping feature and then have a wire EDM shop do that part? The shops in this area will hit the detail right on the schmeckel, as the saying goes. Just a thought.
--earlgo
Before you do anything, you must do something else first. - Washington's principle.
jcfx
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Re: Square jaws for round collets anyone attempt them?

Post by jcfx »

I had to look up what wire EDM does and I could probably have them do it out of round stock
and EDM pie slice it lengthwise. It's probably worthwhile if I were making these in quantity
since I think for one or two it may be cost prohibitive.
Besides ever since I read Harold Halls' technique of making square jaws for round collets I wanted to give
it a try, I may try glueing the four pieces of square stock together with a shim pad where the jaws touch the split line.

I had good success doing that on a recent project with aluminum half rounds, up until I had to drill a through hole. :oops:
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