Homebrew stud extractor

You know when you want to extract a short, unbroken stud from a casting without damaging it, but it's stuck tight? Well I never found a good
way. But I had an idea this afternoon. I took a hex nut, cut a radial slit through the nut, screwed it onto the stud, and squeezed it tight in a mole wrench (i.e., vise grips). So it worked a bit like a collet. It turned the stud out easily. Here's a picture:
http://www.mythic-beasts.com/~cdt22/stud_extractor.jpg
No doubt some dude in Detroit had the same idea about 80 years ago, but I was pleased with it :-).
Chris
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Christopher Tidy wrote:

That looks like it should work nicely. The more traditional approach is to use two nuts jambed together
-jim

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jim wrote:

I tried that a good few times. Often, it didn't grip tightly enough. In this case, there's only enough thread protruding for one full nut.
Chris
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Christopher Tidy wrote:

Reminds me of a couple of years ago when I wanted to extract the shanks of the spinning tools I had made from the ash handles. When I made them information was not that readily available it seemed so I sank the steel tools too far into the handles for the size of work I was doing and wanted to extract them about a further 6", luckily I had made them longer than really required. I had set the shanks in with fibreglass resin. I made a U plate to fit over the tool shank and that had 2 bolts that bore against the vice jaws that I clamped the shank into, the U plate pushing on the handle end. Tightening the vice as much as I dared, a Record 4" vice, it always slipped. When I sat back and thought about it I realised that vices aren't really intended for high clamping loads so I made a new clamp for the shank out of 2 pieces of 2" x 1/2" CRS and used 2 1/2" UNF bolts to provide the clamping load, when tightened that didn't slip at all and when the bolts on the U plate were tightened it almost immediately creaked as the bond was broken and the shanks came free.
I think like vices Mole wrenches don't clamp that hard but good to here a nice easy solution worked for you.
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David Billington wrote:

A nice little 6 inch Ridged pipe wrench works great for pulling out studs. It also works well on those corroded brake line fittings that a regular tubing wrench slips on.
John
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They make a V-jawed Vise-grip model in several sizes for just such tubing fittings. Would also work for the slit nut on the stud thing, too. I tend to use the 3" model a whole lot, works great on brake fittings. Haven't run across one yet that it couldn't get out. Even works on the rounded-off jobs that the flare-nut wrenches sprung over the flats on.
Stan
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Clap, clap clap! That idea is a keeper in case I ever need it.
----- Regards, Carl Ijames

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wrote in message

I've used this same trick to make thread repair inserts for stripped aluminum using steel setscrews. I'll anneal them first then mount them in the chuck with this trick to cut the internal threads of the insert. These work much better than heli-coils. On the larger screws I'll cut a groove down the outside threads of the insert and after it's turned in to depth I'll drive a stiff wire down the groove to lock it all in place. phil
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Christopher Tidy wrote:

Positioning the vise-grip jaws one facet to the left would let the "leading edge" of the nut (that follows the cut) dig in for a better bite.
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Beryl wrote:

The vise grip slipping on the flats of the nut are going to be the limiting factor in the amount of torque you can deliver to the stud.
-jim
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jim wrote:

Looks like the nut is clamped between the tips of the jaws so that the nut won't be damaged. Who cares? Get the nut down in the toothy area, closer to the fulcrum, and it's less prone to slip.
I think the cotter pin on that other nut is installed incorrectly. Should be turned 90*, so that one leg bends up over the nut, and the other points down. I never figured out why it makes a difference, but that's what I learned somewhere.
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"Beryl" <

That cotter pin is in correctly. In this postion it is more resistant to shearing if the nut is turned somehow in service. And with the eye protruding it is easier to pull for maintainence. phil k.
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Phil Kangas wrote:

I've seen them installed both ways. But more commonly in the way shown in my picture.
Chris
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Christopher Tidy wrote:

An Airframe & Powerplant Mechanics textbook, and FAA Advisory Circular, agree that both methods of securing cotter pins are acceptable.
The textbook refers to the up/down bend as the "preferred" method, implying that the other way is somehow less-than-preferred. There's no explanation why. The AC refers to the sideways bend as an "alternate" method.
I think I'll return to the sideways method on my bike, which leaves the cotter pins in much better condition to reuse, which you aren't supposed to do.
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Beryl wrote:

The most important thing on installing cotter pins is that they are tight and don't wiggle in the hole or twist because it could eventually causse them to wear.
John
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Beryl wrote:

And maybe damage the stud, which I badly needed to avoid!
Chris
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Christopher Tidy wrote:

I did a crummy job, describing the edge literally digging into the stud!
The way the pliers are positioned in the pic, clamping pressures are as close to the trailing edge, and far from the leading edge, as they can be. The split nut is pushed around from behind, tangential force wanting to lift the rear of the nut off the stud, "unwrapping" it. Move the clamping pressure close to the leading edge and the nut will wrap as it's pulled, closing more tightly around the stud.
A situation where a split "stud" grabs the nut around it...
Think of drum brake shoes. When forced outward, the leading edge of a shoe wedges tightly against the turning drum. A trailing edge forced outward isn't very effective.
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It's hard for me to imagine this making a significant difference.

That isn't how self-energizing brakes generate extra friction -- friction against the drum rotates the shoe assembly forward, and the front shoe works to push the rear shoe harder against the lining.
Ideally, the whole lining will be pressed against the drum.
--
It's time to try defying gravity

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Joe Pfeiffer wrote:

Yes, it is the trailing shoe that applies the most force against the brake drum.
In this case, I think the grip on the nut slipping or the stud snapping will happen before the nut turns on the threads.
-jim

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Right -- but it isn't because the leading edge is wedged against the drum.

Agreed.
--
It's time to try defying gravity

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