10-24 broken bolt in expensive injection mold

[metron9]

My neighbor does plastic injection molding. He snapped off a 10-24 bolt in one of the dies that's about 2 x 4 inches by 1/4 thick, it is part of a larger die.

Holes are 1/4 deep. He wanted me to drill a hole in the broken bolt so he could use an extractor. long story short I said I would send it to the die maker as I just snapped a 10-24 spiral tap last night and I am uneasy when it comes to working on this kind of thing.

Anyway , drilled hold and he used a bigger hammer and wrench to snap off the extractor inside the broken bolt.

Just curious, how will the die maker get this piece out? EDM?

Any links to how to do something like this without breaking the extractor? I suggested heating the part but I have no idea how hot or even if heat would warp the die plate.

 

[Dave Storm]

If its flush or protruding, I had had the good luck getting broken bolts out by welding a nut to the end of the bolt. I think getting heat in the bolt doesn't hurt, plus then you have a decent hex to unscrew the broken part with.

 

[aerodark]

It will not help your grief, but why in the world is a 10-24 in an expensive mold (as opposed to a 10-32)?

 

[xdmp22]

I use center cutting carbide endmills in knee mills.....usually old emndmills ones with rounded corners, chips, etc.....

Locate hole, get endmill close to broken part, then drop quill to touch broken part...loack quill. Drop the knee a few thou and start motor......crank the knee slowly up so the part feeds into the broken part.....

Works well with bolts, taps, center drills, etc....

High rpm and very slow feeding....

Some people use the quil stop and pull the handle down, then spin the stop a few thou each turn and pull the handle again....works great for one guy in the shop....everytime I do it though, I snap the endmill, so I just went back to feeding with the knee......

 

[toolmaker35]

I'd probably use an old 5/32" or 1/8" carbide ball nose endmill to peck the extractor out. Higher rpm's and a real light feed on the quill of a mill will do it. As far as broken screws like that, short length LH drills work wonders on them. Once the drill breaks through the screw's bottom, it'll usually unscrew itself out.

 

[Richard King]

It sound like that EDM you only option now. They may have applied Loctite red on the threads and one has to heat up the bolt before turning it. I see your in MN. There are several places that can do it in the Twin City. Good luck Rich, Cottage Grove, MN

 

[toolmaker35]

P.S.

If he did use red loctite on it as Richard suggested, charge him $150 and casually remind him what the difference is between the red and blue...

 

[ToolPost]

EDM is pretty much the only way out now. Good luck if you try to use a carbide endmill.

I've never worked on a mold that had 10-32 instead of 10-24's; I had assumed it was common practise. PITA to tap.

 

[TurboFabSupply]

I have gotten a decent number of SS bolts and HSS broken taps out using a carbide endmill. They're pretty easy to do actually. We used a lot of 6-32 and if the tap was a cut tap before, I could often get away with simply pecking down the hole with a 1/8 carbide endmill and then running a forming tap down it. (Which is actually the correct size)

If it was a broken bolt I'd run the cut tap down again and then run the forming tap.

The carbide EM is usually chipped after that so toss it.

Also I have never ever seen an extractor work for something that small. Stick it in the CNC, peck away for like 10 minutes with flood coolant, junk the endmill after. Works every time....75% of the time.

 

[Kd4ttc]

The AGB Portable EDM by Gordon Engineering has an EDM and can refer you to a local jobber.

 

[Mike C.]

Yeesh, tell this guy to buy a set of left hand drills. Screw extractors almost NEVER work, and if they do, you could have taken it out with a left hand drill to begin with. Trick to left hand drill is to step drill. Soon as the drill grabs it backs out, unless the thread is stretched in the hole, the hole is rusted up, the works is galled, etc... In those cases the extractor isn't going to work, either.

If you have to use extractors, get the Vermont American square shank ones, NOT the spiral types. The spiral ones just expand the upper end of the bolt and bind it up even tighter as you try to loosen. The square shank ones put the force exactly where you need it.

As Dave Storm says, if you have anything hanging out, weld a nut on it, or just build up a knot of weld you can get hold of. I have used MIG, stick, TIG and more commonly Oxy Acetylene to do this. Weld it up and as it cools, lightly tap in all directions, as well as driving straight in, like you are trying to drive in a nail. If it is not galled, it'll usually come right out.

 

[xdmp22]

+1 on the square type extractors......

 

[jamie76x]

I remove broken bolts, bolts with broken easy outs and broken taps all the time. even if its broken off below the surface, I can usually weld onto it and get it out. If not, As the guys above said a carbide endmill, very slow feed, listen, feel and be one with the end mill. Often when the stuck bolt, tap or whatrever breaks loose, it breaks the endmill. Don't use an endmill that you can not live without.

 

[S_W_Bausch]

If time machines were ever created, machine shops would be standing in line.

"I am from the future, you DON'T want to do that! Your boss has authorized my visit, but he won't know he did, until next month. Please sign this invoice."

 

[oldbikerdude37]

The left hand drill trick is the best, Iv made a hell of a lot of money with left hand drill bits on broken bolts. A whole lot.

Easy outs work fine on through holes, bust one on a bottom hole and you messed up.

Iv seen holes with 2 broke drills and a broke easy out, it went to the EDM tap burner. A carbide endmill would just die.

 

[lbhsbz]

I'm always amazed at people who break off bolts and think that for some reason a smaller diameter, more brittle tool will remove it. I'd set a nut on top and shoot a mig wire down through it, may take a few tries, but it's never failed me and doesn't take as much finesse as one might expect.

Then go to his shop and ask to see the extractors he used.....and thrown them the trash.

 

[Ohio_Ford_Farm]

I have removed a lot of broken screws / bolts with left hand drills and left hand end mills. Just the other day I removed a broken 4mm screw out of the end of a 5/16 shaft. I chucked the shaft in the lathe jaws, and a small left hand end mill in the drill chuck, ran the lathe in reverse, put a little force on the end mill and it backed the broken screw right out of the shaft.

 

[Porschefix]

If you run out of possibilities Fed-Ex it to me and I'll remove it for you. I have 3 Swiss Sinker EDM's and will not tear up your mold.

 

[Alford317]

I'm always amazed at people who break off bolts and think that for some reason a smaller diameter, more brittle tool will remove it. I'd set a nut on top and shoot a mig wire down through it, may take a few tries, but it's never failed me and doesn't take as much finesse as one might expect.

Then go to his shop and ask to see the extractors he used.....and thrown them the trash.

This guy probably has the best answer, but if that's not practical get yourself a good dental bur a very high speed pencil grinder (like 20K+ rpm) and some ear plugs and grind that extractor out. Once you have the extractor out grind the hole just a shade bigger and use a #3 easy out. I know a #3 seems too big, but you're just going to put the tip in there If you feel the easy out flex at all, for the love of god STOP.

If that doesn't work, get a small oxy acetaline torch out and heat it up a LITTLE BIT. I'm talking 300 - 400 degrees, not even enough to change color. Then try your easy out again. It helps if the easy out is new and sharp.

Good luck!

 

[metron9]

Thanks for all the suggestions, I just called him and he want's me to contact Porschefix or Gordon Eng. to get it fixed.

We did use a reverse drill ( I happened to have one that came with a right hand cheap Chinese cheesy set) last time I just touched the top of the bolt and it came spinning out. I think he used too long of bolt and bottomed it out this time. I also suggested he use a new bolt every time he sets up this mold. Not sure if there are other suggestions for the type of bolts he should use or a small torque wrench he should buy so this wont happen again.

I am PMing Porschefix his number so he can give him a call to start with.