screw extraction

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Jan 20, 2008 | 01:25 AM

ford2go

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Cargo Master

Joined: Apr 2003

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From: Frequently frozen MN

screw extraction

The following link should get you to a great discussion of extraction
techniques originally published in a 2003 issue of Autoinc. (autoinc.org)

http://www.asashop.org/autoinc/may2003/techtotech.htm I think that it would be a good starter for discussions on extraction.

( personal opinion:There aren't many things that feel better than when that b**ch moves that first 1/100th of an inch)

This service oriented mag is is available online, and it occasionally has sone really good stuff. It's mainly business oriented, but it does have some tech info. I thank those who make their living as techs for sharing some of their secrets.

ford2go

Jan 20, 2008 | 08:34 PM

fixnair

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From: Sapulpa OK

Thanks ford2go. Good reading. One thing he didn't discuss was the reason for the fastener breaking in the first place can dictate which type of removal preceedure to follow. If the fastener had been over torqued and the head broke off, then I would first try and turn it with a sharp instrument such as a pick or scribe. Failing that I would next try to rotate it with a small cape chisel. If that doesn't move it then I would get out the left handed drill bits.

If the fastener broke because the threads bound up from corrosion or lack of lubrication, then easy outs will not exert enough torque on the bolt to turn it and chances are slim that penetrating oil will help. I usually skip the heating because it is too time consuming. I go straight for the drills and taps. Most of my work is done in the field and while I do have a welder and torches it takes a lot of work to install the regulators and hoses.

And yes! when that bolt moves that first tiny bit it is so encourging.

Jan 21, 2008 | 07:05 AM

cujo8

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From: Williamson, NY

That was a good article, but the author missed one method for removing a broken tap. They make a special tool for removing broken taps and logically it is called a "Tap-Extractor." Each tap extractor is made specifically for the size/type of tap to be removed. These extractors have sliding hardened steel fingers that slide down the flutes of the broken tap and if you're lucky the tap will turn out. I used one of these successfully on a 1/4-20 tap I broke off below the surface of an engine I was rebuilding.

Jan 21, 2008 | 11:21 PM

Super Steve

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From: PHOENIX

I do not miss the days of removing broken taps.
When you get down to 8-32 or 6-32 taps broken in blind holes, in stainless, it can take half the day to get one out. Using a piece of carbide at 5,000 rpm will usually burn the tap out.
If you can put the part on a mill.
Those tap extractors work on the larger taps and on two fluted taps, but when you get to the little four fluters, they will break and make a bad problem worse.

Jan 22, 2008 | 12:20 AM

Ford_Six

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Joined: Oct 2002

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From: The Big, Oregon

I, as much as possible, use a torch to remove broken bolts. Can't really do it in aluminum, but in cast iron and heavy steel I can blow a bolt out without hurting the threads, be it an open or blind hole.

Jan 22, 2008 | 06:15 PM

66fdtrucknut

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From: Eastern Shore, Md.

I tig weld a molten blob on the broken end of a stud, big enough to grab it with a pair of vise grips, works especially well with a broken fastener in alum. I work on power and sailboats for a living and run into this all the time.
Charlie

Jan 22, 2008 | 09:53 PM

frederic

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Joined: Oct 2003

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From: New Jersey

I do the welding thing more often than other methods, and have had good luck with it, even if the stuck bolt is in aluminum. Of course one will damage the the threads at the top of bolt hole but if the hole is long enough one can chase the threads and the new bolt will hold just fine, depending on the application and clamping force required.

One trick someone showed me was to take another, slightly smaller diameter bolt and drill a 3/32" hole down the shaft, head to tip. Then slide down a piece of plastic coffee stirrer and and shoot the flux-core mig wire through the straw so the weld is made at the very bottom of the drilled bolt to the bolt inside the hole.

I know this sound weird, but try it, it actually works!