Broken bolt extraction - successful methods?

[Oliver S.]

My question is not Corvette-specific and pertains to a general problem: What are your successful methods (and concrete tools/brands since there is a lot crap out there) to remove rusted, broken and now recessed bolts - I have got 2 of them (3/8") in the cylinder head (from the exhaust manifold) of my '68 Firebird 350.
Regarding extractors following type - if applicable - seems to be the one accepting the most torque (most stubborn bolts) compared to other types:
https://www.amazon.com/Head-Multi-Sp...gateway&sr=8-2
Does anybody have experience with TIG welding a 'tower' on top of the bolt (and only the bolt) so that finally a nut can be welded on this?

Oliver

[Gary R.]

Re: Broken bolt extraction - successful methods?

Those can be tough for sure. I never had any luck with those cheap spiral E-Z outs and snapped some of those. Snap On has/had a straight flute design that worked the best for me. I hit the bolt with heat if possible, then use the kit drill and the extractor. I have the socket type extractors too that Sears once sold, when Sears was open and had good tools. They worked good on the #3 body bolt. For a broken tap I used a carbide ball burr in my Bridgeport, which completely burned away to nothing but it did burn out the tap.

If possible you can try center drilling and drilling a hole through the center to help break it free.

[David H.]

Re: Broken bolt extraction - successful methods?

My question ... to remove rusted, broken and now recessed bolts ...

Oliver,

Took offending part to a machine shop that used a "Metal Disintegration Machine" or MDM to remove broken bolt.

Dave

[Frank H.]

Re: Broken bolt extraction - successful methods?

when you drill the hole for the extractor use a reverse drill bit. sometimes that will
remove the offending bolt by itself.

[Oliver S.]

Re: Broken bolt extraction - successful methods?

Anyone tried this successfully

https://m.youtube.com/watch?v=g6w2grAV-oc

[Richard G.]

Re: Broken bolt extraction - successful methods?

Th YouTube video is an effective method of removing a broken off easy-out.
The Tig welder's skill level has a lot to do with the effectiveness of this method.
I wouldn't recommend this method using a Harbor Freight Tig machine and no experience.

That said you don't have the broken out easy-out to deal with so it's much easier.
You will make or break the project when you drill the first hole into the bolt.
It has to be on center! If it's off you lose more than half your options if the easy-out fails to remove the bolt.
Some folks even drill and easy-out them on the vehicles. (Ford trucks mostly)
However, if it a valuable head, I would pull it and drill it on a milling machine.
This allows you to "even the face" of the broken bolt or stud that you are drilling and used a spotting drill to get in the center.

I personally have had little luck with the remover style you linked at Amazon. They may be fine on the larger diameter stuff but you are dealing with something close to 3/8" I suspect.

They make a lot of tools for this task.

https://maniboltdriller.com/

it basically a bolt on drill guide. Catches multiple holes at the same time.

https://www.brokenbolt.com/blog/tag/broken-bolt-tool/

Another jig for centering the drill.

If there are any exposed threads, as in some of the bolt came out and left good threads at the top, you can center drill a bolt and insert it into the hole. This will guide the drill down the center. They make kits for this also but I have access to a lathe so I can make them myself.

A left had drill set is one of the best tools as often the broken bolt will come out as the center is relieved and the heat from drilling has its effect.

The also sell "BombSite" - Precision Optical Hole Locator in several versions each a slightly different design.,
Basically you site the hole with an optical sight, typically with concentric rings in the site to assist in finding center, then the site is removed from the holder and the center punch inserted and hammered on. These can be off set if the top of the bolt is not broken clean or flat. Use with care.

All take a "feel" to how much torque can be applied before breaking something. I have drilled out bolts and pealed the threads out like a helicoil after not having any luck with an easy out. Get the hole in the center to the best of your ability!
Best of luck.
Rick

[Joe L.]

Re: Broken bolt extraction - successful methods?

My question is not Corvette-specific and pertains to a general problem: What are your successful methods (and concrete tools/brands since there is a lot crap out there) to remove rusted, broken and now recessed bolts - I have got 2 of them (3/8") in the cylinder head (from the exhaust manifold) of my '68 Firebird 350.
Regarding extractors following type - if applicable - seems to be the one accepting the most torque (most stubborn bolts) compared to other types:
https://www.amazon.com/Head-Multi-Sp...gateway&sr=8-2
Does anybody have experience with TIG welding a 'tower' on top of the bolt (and only the bolt) so that finally a nut can be welded on this?

Oliver

Oliver------


The big problem is that the reason that a bolt or stud broke off in the first place is that the threads were seized in whatever they were threaded into. So, if the bolt or stud could not be removed when the bolt or stud was intact, it's going to be hugely more difficult when broken off. This is the reason that most "extractors" are useless. In fact, in the often fruitless process of using various extraction methods, the part that one is trying to save may be damaged or, even, ruined.

For pieces worth saving, I think an MDM or EDM removal is the best way to go. Of course, this is not a "do-it-yourself" kind of thing.

[Dan B.]

Re: Broken bolt extraction - successful methods?

Oliver,

Took offending part to a machine shop that used a "Metal Disintegration Machine" or MDM to remove broken bolt.

Dave

This guy has bult a whole business around broken bolt and tap removal using MDM, its pretty amazing to watch:

https://www.youtube.com/watch?v=YbeKxFBZrF8

Dan

[Richard G.]

Re: Broken bolt extraction - successful methods?

I agree that MDM or EDM removal is the foolproof method.
With 40 years in the Mechanical Trades I only once had it used on the equipment I worked on. Some of it equipment cost more than fifty 1967 435HP Corvettes.
Don't get me wrong as I am a proponent of doing it once and doing correctly.
Just never could get them to pony up with the cash to pay for EDM.
Their are even guys with portable EDM units that will come to you.
Plug welding parts and re-drilling it was a common occurrence. Typically not cast iron parts but did that to.
Typically braised up the hole in cast not welded.

Most local machine shops will remove the bolts on a time and material basis.
Experience helps and many of the seasoned fellas can get them out without a EDM.
Rick

[John D.]

Re: Broken bolt extraction - successful methods?

Oliver I didn't read all the posts. I highly suggest you farm this job out at a qualified machine shop. John