Broken bolt/bit/tap removal from aluminum or stainless steel.

[RBrodnax]

I wanted to share with you all something that I recently experimented with and got great results.
As I was doing some upgrades on a stock Briggs flathead I pulled the head and one of the bolts snapped off. I started drilling a pilot hole in the bolt to try and remove it and the bit broke off in the bolt. I then tried welding a nut on the bolt and unscrewing it. I got it a couple of threads out and the nut broke off the bolt. I took it to a machine shop and they wouldn't touch it. They told me to scrap it.
Later that night I started thinking and came up with an idea. I did some research and found an acid that would eat the steel bolt but not the aluminum block. I also found some recipes online for some chemical mixtures to use for this purpose. I mixed and matched some things from the different methods and came up with my own formula.

I would like to share that with you now because I know that someone could use this.

DISCAIMER: I am in no way responsible for how you use the chemicals discussed here. Do not wear latex or nitrile gloves for this as they won't help. These are VERY CORROSIVE!! USE WITH CARE!


First mix 50ml of water with 1 tablespoon of ammonium persulfate.

Second dissolve a small piece of copper (about 1/16" diameter by 1/8" long) into 10ml of 70% lab grade nitric acid.

Next pour the solution of nitric acid into the ammonium persulfate and water.

Use a pipette to drip this solution into the hole with the broken steel object filling it about halfway (count the drops). If the bolt/bit/tap is broken off flush with the hole, you can build a dam around it with modeling clay to hold the solution.

Then add exactly the same amount of nitric acid to the bolt hole.

The mixture should be bubbling a little by this point.

Next use a piece of stiff copper wire (I used a stripped wire out of romex) to scratch the surface of the broken piece until it starts to bubble vigorously.

Adding heat to the equation (~190*F) will multiply the speed of the reaction. I used a propane torch for this but any heat source should work.

Change the fluid out when it becomes full of oxides and gets "muddy".

The chemicals needed can be bought off of eBay.

Again this will NOT work if the part you are trying to save is iron or steel.

Thanks for reading.

 

[Russ2251]

I will certainly try this method.
I have 2 seized/broken exhaust port bolts in a Honda GC160...(4 cycle, arghh!)..one with a snapped so called "easy-out".

 

[Doc Sprocket]

Wow- neat tip, thanks! It's pretty infuriating when you break a drill or extractor in a bolt, in an aluminum part. I'll be saving this page!

 

[itsid]

Okay nitric acid (HNO3) dissolves most metals.
except Gold, Platinum, Aluminium, Titan, Zirconium, Hafnium, Niob, Tantal and Tungsten
some of the above will still oxidize but not dissolve.

Ammonium persulfate ((NH4)2S2O8 ) will not dissolve any metal, it's just a great oxygen source.. bleach basically.

dissolving copper in nitric acid does NOTHING but reduce the oxygen level of the nitric acid (lowering it's capacity to dissolve metals)

So why reduce the oxygen level of an acid just to add another oxygen source afterwards?
Having a strong bleach and a strong acid you'll create bubbles as soon as you add a catalyst (a metal in our case)
but not from the catalyst! that's from the sulfur I guess (smell it )

Plus.. having a mixture 5:1 of dissolved ammonium persulfate and niric acid (and dissolved copper.)
and then mixing that solution 1:1 with nitric acid again ... really?
why not just make a 5:6 solution?

I'm not a chemist I must admit, and some reactions are counterintuitive indeed,
but without a very good and sound explanation of why the above recipe makes sense;
I'd go for nitric acid and heat (below 120°C / 250F)..

and for sure I wouldn't reduce the power by dissolving other metals...
But that's just me perhaps.

Playing with pointless hazardous materials with an LD50 of 0.5grams/kg makes one tablespoon enough to kill 3 average people
(or 1.5 american fata55es )

So whatever you do.. take care, lock away wife, kids, pets, grandma and the annoying kid from across the street...
and whatever you do do NOT INHALE the crystals!

'sid

 

[Doc Sprocket]

kill 3 average people
(or 1.5 american fata55es

You just made my night.

 

[RBrodnax]

Okay nitric acid (HNO3) dissolves most metals.
except Gold, Platinum, Aluminium, Titan, Zirconium, Hafnium, Niob, Tantal and Tungsten
some of the above will still oxidize but not dissolve.

Ammonium persulfate ((NH4)2S2O8 ) will not dissolve any metal, it's just a great oxygen source.. bleach basically.

dissolving copper in nitric acid does NOTHING but reduce the oxygen level of the nitric acid (lowering it's capacity to dissolve metals)

So why reduce the oxygen level of an acid just to add another oxygen source afterwards?
Having a strong bleach and a strong acid you'll create bubbles as soon as you add a catalyst (a metal in our case)
but not from the catalyst! that's from the sulfur I guess (smell it )

Plus.. having a mixture 5:1 of dissolved ammonium persulfate and niric acid (and dissolved copper.)
and then mixing that solution 1:1 with nitric acid again ... really?
why not just make a 5:6 solution?

I'm not a chemist I must admit, and some reactions are counterintuitive indeed,
but without a very good and sound explanation of why the above recipe makes sense;
I'd go for nitric acid and heat (below 120°C / 250F)..

and for sure I wouldn't reduce the power by dissolving other metals...
But that's just me perhaps.

Playing with pointless hazardous materials with an LD50 of 0.5grams/kg makes one tablespoon enough to kill 3 average people
(or 1.5 american fata55es )

So whatever you do.. take care, lock away wife, kids, pets, grandma and the annoying kid from across the street...
and whatever you do do NOT INHALE the crystals!

'sid

I am not a chemist nor did I do the math or get technical with the formula. I just shared my final results and what worked for me. This worked the best. It worked better than pure nitric with heat although that did work pretty well. The ammonium persulfate is an oxidizer and will help to dissolve the bolt. http://en.m.wikipedia.org/wiki/Ammonium_persulfate

This method takes time but definitely works when nothing else does. It also perfectly preserved the threads.

 

[fowler]

Do t think I'd trust this
Drilling it out isn't that hard

As a General rule of thumb
If the bolt snaps due to seizure in the part then u have to drill it out

If it snaps during install or due to too much load then an easy out may work

Basically if the bolt isn't spinning then an easy out won't work

Of the 5 or 6 times a week I remove broken bolts only 1 would've easy out able

 

[RBrodnax]

This is mainly for when the easy out, tap, or drill bit is broken off in the hole. Ever tried to drill one of those?? I've removed plenty of broken bolts in my day. Trust it or not... It works.

 

[machinist@large]

This is mainly for when the easy out, tap, or drill bit is broken off in the hole. Ever tried to drill one of those?? I've removed plenty of broken bolts in my day. Trust it or not... It works.

I'm not saying it doesn't work, just that it's dangerous as bloody . And as a machinist/CNC machinist with almost 30 years experience, I've removed my share of hacked out junk.

The reason 'Sid & I both flagged it as dangerous is because it is. You have to remember, this forum has members from the highly qualified expert down to the newest beginner. We can't be there to hold their hands; all we can try to do is showcase best practices, especially when it comes to safety.

That it worked was never a question......

 

[AceEngineer]

RBrodnax,

If you had gone to a proper machine shop, they could have removed the broken stud easily. Most machine shops worth their salt will have what is called a tap burner. It is a small specialized Electro Discharge Machine (EDM) that can easily burn right down the broken stud, tap or drill regardless how hard it is. With this device it is normal to be able to remove a broken tap from any material even soft stuff like aluminum and save the threads.

AceEngineer

 

[machinist@large]

RBrodnax,

If you had gone to a proper machine shop, they could have removed the broken stud easily. Most machine shops worth their salt will have what is called a tap burner. It is a small specialized Electro Discharge Machine (EDM) that can easily burn right down the broken stud, tap or drill regardless how hard it is. With this device it is normal to be able to remove a broken tap from any material even soft stuff like aluminum and save the threads.

AceEngineer

Up here in my part of Michigan, we've got enough EDM shops in the neighborhood that most small machine shops (and many large one's) just farm that type of work out. That's one of the reason's I recommended the phone book.

Other parts of the country, as well as the rest of the world, will probably be a different story though..... As for how I would attack it if it crossed my bench, I'd just carbide the thing out, but that's just because almost all of the job shop's I've worked for over the last 20 or so year's stocked at least a minimum of solid carbide tooling, making it the first wave of attack for a problem like that.

 

[Doc Sprocket]

RBrodnax,

If you had gone to a proper machine shop, they could have removed the broken stud easily. Most machine shops worth their salt will have what is called a tap burner. It is a small specialized Electro Discharge Machine (EDM) that can easily burn right down the broken stud, tap or drill regardless how hard it is. With this device it is normal to be able to remove a broken tap from any material even soft stuff like aluminum and save the threads.

AceEngineer

Perhaps, but... $

I'm sure the proposed chemical method is hazardous. If it's not clear, it should be. So- a disclaimer: Anyone NOT proficient and competent in the use of hazardous chemicals and/or dangerous goods, should NOT attempt it!

That said, there is only so much you can do to hold somebody's hand. Scour the interweebs hard enough, and I'm pretty sure there's enough info to McGyver a dirty bomb, and there's a 13-year-old out there just itching to do it.

Really, I can't see many people actually taking a whack at this. It's interesting, sure- but none too practical for your avergage mechanic.

 

[machinist@large]

Perhaps, but... $

I'm sure the proposed chemical method is hazardous. If it's not clear, it should be. So- a disclaimer: Anyone NOT proficient and competent in the use of hazardous chemicals and/or dangerous goods, should NOT attempt it!

That said, there is only so much you can do to hold somebody's hand. Scour the interweebs hard enough, and I'm pretty sure there's enough info to McGyver a dirty bomb, and there's a 13-year-old out there just itching to do it.

Really, I can't see many people actually taking a whack at this. It's interesting, sure- but none too practical for your avergage mechanic.

Chris, I totally agree with your argument; the reason I said to hit the phone book is because I've worked with some of those chemicals. I personally value my life and health enough to run screaming from them. The other reason I stated is because the most likely way that I would remove the broken part involves tooling and skills that you really can't teach on line.

There it is.... Pat

 

[Poboy kartman]

Broken bolts are hard to remove. ...broken drill bits not so much. .....you can usually back those out or break them into pieces.......

I'll keep this in mind though for the rare occasion I may need it. .....

I start off with a 1/16" drill and try to center it as accurately as possible. ...then I start working up.....it's a little tricky as just going one size is likely to bind....so you have to go just big enough it doesn't seize. ...but small enough that the pilot hole keeps the bit from wandering......I drill up to the largest size I can without hitting threads and then try an ease-out......

I should add that I usually wait overnight. .. (at least)....to let the PB Blaster do it's job. ...I've never broken an ease-out....as Fowler stated....they don't work that often.....but I only apply reasonable pressure and it either works or not. .....if not. ...I will drill down to the threads and peel out what's left of the bolt.....sometimes the threads get a little boogered...but it usually works. ...worse case scenario. ...I either need to tap to a larger size bolt...or use a heli-coil.......

Just my experience. .....

 

[machinist@large]

Broken bolts are hard to remove. ...broken drill bits not so much. .....you can usually back those out or break them into pieces.......

I'll keep this in mind though for the rare occasion I may need it. .....

I start off with a 1/16" drill and try to center it as accurately as possible. ...then I start working up.....it's a little tricky as just going one size is likely to bind....so you have to go just big enough it doesn't seize. ...but small enough that the pilot hole keeps the bit from wandering......I drill up to the largest size I can without hitting threads and then try an ease-out......

I should add that I usually wait overnight. .. (at least)....to let the PB Blaster do it's job. ...I've never broken an ease-out....as Fowler stated....they don't work that often.....but I only apply reasonable pressure and it either works or not. .....if not. ...I will drill down to the threads and peel out what's left of the bolt.....sometimes the threads get a little boogered...but it usually works. ...worse case scenario. ...I either need to tap to a larger size bolt...or use a heli-coil.......

Just my experience. .....

Doug, your experience is what you've gained by doing; what started this debate was the "Here's what I did, and it's easy!!!!" using potentially lethal chemicals.

If you have an easy way that you want to share, that doesn't involve Federal time for environmental impact/ damage if you up, please post it up.

 

[fowler]

Unless the shovel goes down in the pit

The down tine is already into 6 numbers by the time u get there
OH&S goes out the window, environmental protection is out the window

Then someone breaks a bolt

And the dirt boss is telling u to just weld the f@#%*n half clamp back on (which won't work)
That's when u hope a drill doesn't snap

No chemicals on hand no time to soak it overnight no time to set up the drills
No time to **** up

Gotta love komatsu and their great engineering skills

 

[RBrodnax]

Lol you guys crack me up. Nowhere did I say this wasn't hazardous. This post was not to say it's the way EVERYONE should do it. I couldn't find anywhere in this crappy town with an EDM but I did try that option first. I guess I should add that immediately after breaking it I soaked it in Kroil for 24 hours which did not help at all. I included a disclaimer in my post for a reason. I merely started this thread to give people the information of an unconventional method that worked for me to save the engine from the scrap pile. So basically I'm saying when all else has failed and chances of saving the piece are looking slim, those of you with the balls and sense to use this method and not F$CK up, it does work. For the rest of you, good luck and I hope you have the same outcome as me.

 

[Metal_Rott]

First let me just LOL at you breaking the bolt I'm not here to Second Guess everything you say like everyone is doing (someone always knows more or at least they think they do). I appreciate you risking w.e. dangers could come from this in order to teach us a sweet way of removing broken bolts. Point is it got the job done and that is more than I could say for anyone else, they would have given up. Grats on the bolt and don't let the smart aleck's get to you

 

[RBrodnax]

Thank you metal! I appreciate you seeing my point.

 

[machinist@large]

I am not a chemist nor did I do the math or get technical with the formula.......

So, just to reiterate, you freely admit that you aren't a trained chemist, yet you deride those of us, who also refuse to claim to be trained chemist's but have worked with some of the same chemicals.....

For the record, you don't list any of the hazards of working with such chemicals, let alone exactly how to do it safely, and then try to get pissy about how some of us call you out on it? Sorry, just posting a link to where ever just looks like the lazy man being just that.

Lol you guys crack me up. Nowhere did I say this wasn't hazardous. This post was not to say it's the way EVERYONE should do it. I couldn't find anywhere in this crappy town with an EDM but I did try that option first. I guess I should add that immediately after breaking it I soaked it in Kroil for 24 hours which did not help at all. I included a disclaimer in my post for a reason. I merely started this thread to give people the information of an unconventional method that worked for me to save the engine from the scrap pile. So basically I'm saying when all else has failed and chances of saving the piece are looking slim, those of you with the balls and sense to use this method and not F$CK up, it does work. For the rest of you, good luck and I hope you have the same outcome as me.

For the record, see all of my post's on this thread; I, as well as several others have thrown out the safety issue, and you continue to have a "HAH HAH" attitude about it.

First let me just LOL at you breaking the bolt I'm not here to Second Guess everything you say like everyone is doing (someone always knows more or at least they think they do). I appreciate you risking w.e. dangers could come from this in order to teach us a sweet way of removing broken bolts. Point is it got the job done and that is more than I could say for anyone else, they would have given up. Grats on the bolt and don't let the smart aleck's get to you

OK, just what part of other posts about safety in this thead did you miss as well?


I hereby flag this thread as dangerous; if anyone wants to try to tell me I'm an idiot or worse for calling a spade a spade, contact me with a PM. I'll give you the city I work in, and when you see what I do for a living, you might begin to understand why I think safety first.

If, after that, you still think I'm wrong, you're on your own.