Picked up a freebie lathe off Craigslist. Real antique, guessing around 1910, old lineshaft driven unit converted to an electric motor.



Needed to make a shaft to replace a broken one in the apron. Not real complex, figured I could manange.

Rough cut to length. Face to final length. Center drill the ends. Turn the various diameters. Hit them all within a couple of thou and got a nice finish. Feeling pretty proud of myself.

Drill out the short end and and thread it 5/16ths-18 where it mounts to the boss on the apron. Nice!

Woo-hoo, almost done! Drill out the long end and thread it for the 10-32 screw that retains the gear on the shaft.

Break the tap off in the hole...

Anybody that's been there knows you're boned when that happens, no way in hell you're getting that broken tap out.

I'll crank out another one in the morning.

I broke a tap off in an engine block on which I was doing oil mods.

Yeah, had that "Oh Fuck!" moments.

Kroil, very small needle nose pliers, and the desire to not have to knock it out and then over drill and retap much larger than I really wanted, gave me patience to work it back and forth until it let loose. I also used a 2 inch long finish nail and a neodymium magnet to get the broken pieces of the tap (it sort of shattered).

(and some leftover luck from the time I fell off the ladder while trying to hang a mirror and squashed that black cat...)

Hope that helps.

Any chance you can drill and tap that hole sooner in the process? That way if it happens again you won't have wasted as much time and effort?

quote:

Originally posted by trapper189:
Any chance you can drill and tap that hole sooner in the process? That way if it happens again you won't have wasted as much time and effort?

There's a thought. No real reason I can't drill and tap right after I use the center drill.

Reminds me of a parts Stratocaster I finished a couple of months ago. Someone had broken off the whammy bar in the hole, nothing sticking out.

After much chin scratching, I was finally able to take the smallest grinding die I had for my Dremel and make a slot for a small screwdriver. Managed to work it out eventually.

That, however, wasn’t the hardness of a tap. It wasn’t a carbide bit, and I doubt it would more than polish the trapped tap.

Can you spot weld a piece of metal rod or threaded rod to the tap and simply unscrew it? I've done that with broken bolts several times.

quote:

Originally posted by jimmy123x:
Can you spot weld a piece of metal rod or threaded rod to the tap and simply unscrew it? I've done that with broken bolts several times.

It's a # 10 screw that is 3/16 inch in diameter. A very good and well trained Micro Welder might be able to weld something to the screw but to do so will have to use a Plasma Welder that probably costs 10-20K. Bottom line, welding something to the screw aint gonna happen and even if it did happen the OP will find that the selded extension will snap off at the weld as soon as he applies some torque to it.

For a screw this small the best method for removal is to spend 100 bucks or so to have the tap core "removed" by Carbon EDM. After that the cutting flights will either fall out of the threads or be relatively easy to remove with a pick or magnet.

 
If you can grab it with needle nose pliers or vise grips, or alternatively cutting a slot in it for a screwdriver, what sometimes works is to take a can of canned air, turn it upside down and spray it. Upside down, the canned air freezes what it sprays. I've been able to remove a couple of them that way.

As a toolmaker in the stamping industry, I have broken my share of taps. A carbide ball nose endmill will work at breaking up the tap. You may sacrifice an endmill or two.

I've broken alot of taps!

In some cases, if the tap is broken with the flutes accessable, you can make a broken tap remover out a steel rod. Grind or mill a + or y shape in the face, depending on whether it's a 4 flute or 3 flute tap. Something like this.

https://www.google.com/search?...imgrc=53IS4qwufTMljM

A cheap Chinese probe EDM from ebay works for deep broken taps, or carbide taps.
https://rover.ebay.com/rover/0...2Fitm%2F183231100037

I have had some success with Walton tap extractors if the flutes are not clogged.

I have learned from doing the same thing, that cussing at it doesn't help.

quote:

Originally posted by Tinyman:
I have learned from doing the same thing, that cussing at it doesn't help.

Oh, I dunno. I think it helps my blood pressure return to normal sooner...

Second attempt at the shaft came out okay.

Got the apron reassembled and reinstalled and found a few other minor issues that I fixed. After a half dozen times taking the apron off and putting it back on, I'm now confident that all the functions work as they should.

Other obligations enforce a couple of days of taking a break from overhauling the lathe which is probably just as well.

Next project is to reassemble the head stock. I'm not aware of any issues there, but that doesn't mean there aren't any.

I put ferric chloride (circuit board etchant) on the broken tap and the hole and let it sit a day or so. It will eat at the tap and loosen it. If you can grab the broken tap with needle-nose pliers afterwards it will unscrew and come right out.

(I use ferric chloride to etch damascus knife blades so I always have some around.)