Extracting broken bolt

[Kez]

All,

I am trying to extract a broken bolt from a P-80 case. Don't know the history or how the bolt was snapped (ie while tightening or unscrewing). It is almost impossible to drill into the bolt. Any suggestions? Should I just forget it?

Thanks,

kez

 

[Brian Blazer]

Can you use a dremel tool and cut a small slit in the top of the screw to use a screw driver?

 

[Joe Warren]

All,
I am trying to extract a broken bolt from a P-80 case. Don't know the history or how the bolt was snapped (ie while tightening or unscrewing). It is almost impossible to drill into the bolt. Any suggestions? Should I just forget it?

Thanks,

kez

small Kobalt type bit, is the only chance of saving it

 

[Kez]

Thanks for your replies:

The bolt is too small to cut a slit with a Dremel. The kerf will be as wide as the bolt.

A cobalt bit will probably drill into the bolt. The challange here is to find a bit small enough and to keep it centered. The smallest I can find is 1/16". And past experience told me it will tend to walk and drill into the aluminum.

kez

 

[Mike Byer]

The best way that I have found to remove something like this is to use a heliarc welder to build enough weld on top of the broken piece that you are able to grip it with a small vice grip. This welding does 2 things, it will cause the bolt to expand when heated by the welding and crush the rust that has grown on the bolt, and it gives you something to grip to turn it out. When you grip the bolt to turn it out the vice grip pulls the heat out of the broken part causing it to shrink and turn loose of the threads in the hole. Stop and think about drilling, the bolt was held tight enough by the threads that it broke the full diameter, now you want to drill a small hole in the center and use something half the diameter to remove it, probably not. Extractors will work on a bolt that has been streched to its beaking point or over tightened, but not when there is failure due to corosion. Find a good welder in your area, a fab shop or a bike or hot rod builder, or send it to me and I'll take it out.

Mike B

 

[Terry Keeley]

Rudy Formanek who is on this board was going to try some sort of acid to dissolve a bolt, wonder if that worked?

 

[Kez]

Mike,

Welding a piece on top of the broken bolt is a new idea I never thought of. I agree it should work although the challenge is to weld on top of the broken bolt. I do not have welding equipment but I wonder if I can silver braze a piece of piano wire to the bolt. It would be difficult because the aluminum case is a good heatsink and if I get it hot enough to braze, I would be annealing the aluminum.

Terry,

I think it would be difficult to find an acid that would selectively etch steel and not harm the aluminum. I can certainly etch the steel bolt but the same acid would eat the aluminum.

Thanks,

Kez

 

[Terry Keeley]

Mike,
Welding a piece on top of the broken bolt is a new idea I never thought of. I agree it should work although the challenge is to weld on top of the broken bolt. I do not have welding equipment but I wonder if I can silver braze a piece of piano wire to the bolt. It would be difficult because the aluminum case is a good heatsink and if I get it hot enough to braze, I would be annealing the aluminum.

Terry,

I think it would be difficult to find an acid that would selectively etch steel and not harm the aluminum. I can certainly etch the steel bolt but the same acid would eat the aluminum.

Thanks,

Kez

Actually there is, do a search for "broken tap" at he newsgroup "rec.crafts.metalworking" and all kinds of info will come up...

http://groups.google.ca/advanced_search?hl=en

 

[jimv]

Mike,
Welding a piece on top of the broken bolt is a new idea I never thought of. I agree it should work although the challenge is to weld on top of the broken bolt. I do not have welding equipment but I wonder if I can silver braze a piece of piano wire to the bolt. It would be difficult because the aluminum case is a good heatsink and if I get it hot enough to braze, I would be annealing the aluminum.

Terry,

I think it would be difficult to find an acid that would selectively etch steel and not harm the aluminum. I can certainly etch the steel bolt but the same acid would eat the aluminum.

Thanks,

Kez

Actually there is, do a search for "broken tap" at he newsgroup "rec.crafts.metalworking" and all kinds of info will come up...

http://groups.google.ca/advanced_search?hl=en

A solution of nitric acid will do it. I don't remember the details. Should be somewhere on the web. A solution of Alum will do it too - takes a long time. Won't hurt the aluminum but will oxidize the steel.

Jim V

 

[steve wood]

or you can send it to me and i can take it out for you. i just did two like this for big chuck.

 

[Rudy Formanek]

I tried the alum method (aluminum sulfate) and it did not work for me. Tried it on a Picco 45 case with a broken head bolt caused by corrrosion welding the threads together inside the case. I got the case in a buyout, but it will cause me to really be sure to use anti-sieze on all head bolts in the future, (especially those that have water directly on the bolt/case joint as does the Picco). Maybe I did something wrong, but it sat for 4 days and discolored the case alot certainly enough to worry me that it was causing a change in bearing seat sizes. I did warm the solution for the four days on a coffee mug warmer. Maybe I need to pack it all up and send it to the Myth Busters. I have not tried the Nitric acid method yet, but can't see why the Nitric acid would not eat the aluminum also. Was hoping I could find some Nitric acid off the web cheaply, but online chemical suppliers will only sell educational institutions. The local chemical supplier wants $70.00 for a pint. Also worried that I might pop-up on some FBI list for purchasing it, though I'm probably already popping up for nitromethane. I had a dirt track racing friend that has removed studs from V-8 blocks using the "welding a nut over the broken bolt" method, but that is far different situation than this. Hard to get the arc inside a 4/40 size nut! Rudy

 

[topfuel443]

Also worried that I might pop-up on some FBI list for purchasing it, though I'm probably already popping up for nitromethane.

I felt the same way when I rolled a 53 gallon drum of pure Nitro into my garage.... My home insurance man woulda shot me had he known it was in there...lol

~James :blink:

 

[troytron1]

Grind the top of the bolt flat. Get a good sharp center punch and keep tapping with that punch untill you get a hole in the center of the bolt. Stick the case in a machinest vise, carefull not to distort by over tightening. Use a mill or good drillpress.A slopy drillpress won't work Start with a center drill. Then get a number drill that is used for what ever thread size you need and drill thru the bolt. Use a new or like new drill bit and drill slow. A dull bit will wander off center. Run a tap thru the hole and you should be good to go. The hardest part is to get the punch hole in the exact center. Once you break a bolt off in the case and have to repair it, you will allways remember to run WD40 or something like it thru the water jacket after a days running. BTDT. Good luck.

 

[Terry Keeley]

I tried the alum method (aluminum sulfate) and it did not work for me. Tried it on a Picco 45 case with a broken head bolt caused by corrrosion welding the threads together inside the case. I got the case in a buyout, but it will cause me to really be sure to use anti-sieze on all head bolts in the future, (especially those that have water directly on the bolt/case joint as does the Picco). Maybe I did something wrong, but it sat for 4 days and discolored the case alot certainly enough to worry me that it was causing a change in bearing seat sizes. I did warm the solution for the four days on a coffee mug warmer. Maybe I need to pack it all up and send it to the Myth Busters. I have not tried the Nitric acid method yet, but can't see why the Nitric acid would not eat the aluminum also. Was hoping I could find some Nitric acid off the web cheaply, but online chemical suppliers will only sell educational institutions. The local chemical supplier wants $70.00 for a pint. Also worried that I might pop-up on some FBI list for purchasing it, though I'm probably already popping up for nitromethane. I had a dirt track racing friend that has removed studs from V-8 blocks using the "welding a nut over the broken bolt" method, but that is far different situation than this. Hard to get the arc inside a 4/40 size nut! Rudy

Hey Rudy, send it to me if you want, I have some nitric acid I used to mark ports on the sleeves. I can tell you that it doesn't touch the case at all. Send me a pm if you want my address...

 

[Roxyflash]

I use to work for a chemical house nitric acid that we used to handle would eat a penny in 2 minutes.Same with aluminum.It would turn green and no more penny.Send it to Steve Woods.

 

[tnrcboatracer]

When drilling, it helps to use a Left Hand twist drill. We use this to remove broken bolts ftom mold components all the time. The heat and vibration help to loosen the bolt.

 

[Brad Christy]

Kez,

I suggest the left handed drill. It will do one of two things. You will either drill out the center of the screw so you can pull the threads out like a spring, or the drill will catch the screw, breaking it loose and it will back out on it's own.

Thanks. Brad.

Titan Racing Components

BlackJack Hydros

 

[Tom Foley]

Kez , if you have a friend with a milling machine you can have him fixture it in the mill vise then plunge cut it with a carbide center cutting end mill . Then carefully pick out the remaining pieces and chase threads with proper tap . If the threads are damaged increase to the next available SAE or Metric size . Teflon thread sealing compound works wonders on those head bolts in our motors .

 

[Kez]

Thanks all for your replies and your offering to help. I learn something new everyday. I did a search on the internet and there are ways to "dissolve" broken tap/bolt electrichemically. This is too elaborate to try at home but it is good to know anyway.

tnrboatracer, Brad, where can I buy a left hand drill? I think a regular HHS will not work. Of course the next challenge is to have a drill press that can turn CCW. Mine is belt driven and will only turn CW.

Mike, if I tried to drill it out and failed, would you be able to weld on the broken bolt?

Steve, I don't know how you took out the broken bolts. If I failed to drill it out, will you be able to save it?

Thanks,

Kez

 

[330T]

tnrboatracer, Brad, where can I buy a left hand drill? I think a regular HHS will not work. Of course the next challenge is to have a drill press that can turn CCW. Mine is belt driven and will only turn CW.

You can get the bit from granger and to make your press run backwards get a longer belt and make it into a figure 8