metal stretcher & shrinker

Hello all,
I just bought a set of tools consisting of a metal stretcher and a
shrinker. They work unbelievably well. The problem is they leave marks on
the metal due to serations on the jaws. I was wondering if anyone has a
stretcher/shrinker with smooth jaws, and how well it works. I could grind
off the serations and if I lost 3/4 of the ability to stretch/shrink, it
would still be acceptable since it works so great now. But if they don't
work at all with smooth jaws, I won't bother.
Thanks,
Bill Chernoff
Reply to
Bill Chernoff
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Those marks are what does the work. Without them no shrinking or stretching happen because the steel cannot be held solid enough to be formed.
Reply to
Steve W.
I think it is the way they work. You jsut need to learn how to do bodywork.
Reply to
yourname
Photos would be great. I'll also take some of mine for interest's sake.
Bill
Reply to
Bill Chernoff
I have a set that was made by a company called DFS in the UK, unfortunately not longer in business, but similar units are still available I am told. What differentiates them from the cheaper units which are commonly available is a preload device that allows clamping the metal prior to shrinking so the metal surface is relatively undamaged. I got the set with medium serrations, coarse, fine, and epoxy jaws for minimal marking were an option. I have done a back to back test against some like those supplied by frost, eastwood etc and those are brutal to the metal surface in comparison to the set I have. Let me know if you want some pics in the dropbox I may be able to take some tomorrow.
Bill Chernoff wrote:
Reply to
David Billington
Let me know if you need any more detail. I guess these unit are comparable to the swiss Eckold units shown in Fournier. They were not cheap compared to the ones commonly available.
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From the ideas shown it may be possible to improve the cheaper ones to include this type of preload device. As you have a set you could see what you reckon. I can dig out the rest of the patent if required and post the angles given for the wedge and preload spring force tomorrow.
Bill Chernoff wrote:
Reply to
David Billington
With reference to the dfsshrinkpatentpic.jpg . The faces shown 15 have an included angle of 136 degrees, the wedge 21 has an included angle of 20 degrees, and spring 22 is set to preload the wedge to 12 lbs when the jaws are at rest. That info is from the patent spec.
David Bill> Let me know if you need any more detail. I guess these unit are
Reply to
David Billington
thanks for the info. The serations on your jaws look a lot finer and smoother.
the photos of my test piece are in the drop box:
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Reply to
Bill Chernoff
Nice curves!. Have you considered getting sponsored by the maker. I didn't have any examples about at the time to add but could run some off if you are interested. Most marking I have found is on Al but its not much, its noticeable due to the marring of the surface. I did some SS the other week and I couldn't see any surface marking corresponding to the jaw pattern, only a surface change where the metal was shrunk.
I looked up the details of the jaws I got and the quoted thicknesses for various materials are as follows.
Aluminium 12swg Mild steel 14swg Stainless steel 18swg Nimonic 18swg Titanium 20swg
Those are british gauge sizes and although similar to US are not quite the same.
I look up "metal shrinking" on google and found the following
Probably like yours
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Sit down before you look at the Eckold shrnker price.
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for the info. The serations on your jaws look a lot finer and >smoother.
Reply to
David Billington
David, Can you please post a link to the patent directly? Is there any reference to the face serrations or head material in the patent?
Reply to
jim.dhillon
It can be found at the european patent office site, this link should take you straight to the patent
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The patent doesn't give detail of the serrations that I can find but the makers leaflet I have says the following. "Teeth on the gripping surfaces can be supplied in three grades, Standard, 50 TPI-, Fine teeth 80 TPI-, and very fine 100TPI, the later being used only where the minimum marking of the metal is important", as well as an epoxy based material.
snipped-for-privacy@cibc.com wrote:
Reply to
David Billington
HA! The piece in the photo was my very first try at it. Thats why I was so impressed with the whole shrinking/stretching process.
I
No rush, but I would be interested in how smooth the surface finish is with those smooth(er) jaws of yours.
Bill
ps I take it you are in the UK? gotta love the internet. I'm in western Canada.
Reply to
Bill Chernoff
----- Original Message ----- From: "Bill Chernoff" Newsgroups: rec.crafts.metalworking Sent: Thursday, June 30, 2005 2:07 AM Subject: Re: metal stretcher & shrinker
Hi Gents You may already be aware, Kent White has some new jaws out that are a lot smoother. Have not seen them in the flesh.
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the best.
Peter E. Newcastle - Australia
Reply to
Peter Eedy

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