Thread: Bugga. Broke a tap

Originally Posted by Pete F

Michael the freeze spray normally sells with a nozzle, you basically just poke it in the hole and let her rip. I'm personally doubtful a HSS tap will shatter like the carbon steel ones do, but always worth a go.

... The second reason is I've found once you can get the little suckers to move a little bit, they'll often keep moving .... if you can get a grip.

I tried with and without the nozzle/ tube but with a tap that small the flutes are mainly full of thread.

As for your second thought, I tried to plant a piece of filler wire on the end of the tap when I was mucking around with the TIG but the filler at 1.6mm just about fills the minor diameter by itself. I know what you mean though and if I could get something attached on there it would probably come out easily enough. I did think about using the spot welder but as it works on resistance there would be greater resistance tap to CI, so I'm just as likely to weld the tap in.

Tomorrow is another day (and attempt...)

Michael

Originally Posted by Michael G

I tried with and without the nozzle/ tube but with a tap that small the flutes are mainly full of thread.

As for your second thought, I tried to plant a piece of filler wire on the end of the tap when I was mucking around with the TIG but the filler at 1.6mm just about fills the minor diameter by itself. I know what you mean though and if I could get something attached on there it would probably come out easily enough. I did think about using the spot welder but as it works on resistance there would be greater resistance tap to CI, so I'm just as likely to weld the tap in.

Tomorrow is another day (and attempt...)

Michael

Keeping in mind the full disclosure mentioned earlier regarding having never tried it, nor can I recall it ever being mentioned as a legitimate way to remove a tap, but what I'd do is switch from TIG to Stick on the welder and put it in the rod clamp. Then just jam the (insulated) fastener down the hole and on to the end of the tap. While I think I can honestly say I'm a pretty handy AC/DC TIG welder, I'm truly crap at stick. Abysmal in fact and I truly hate stick welding. One of the reasons is having to unstick rods, and at times I've had those suckers really well planted into my "weld" (to use the expression generously). I figured if I can do that without trying with a welding rod, it should be possible to do the same thing when I AM trying with a fastener!!! What the weld current would do to the threads in the hole I don't know, maybe they'd weld up ... or be disintegrated a little by the current? I genuinely don't know, but if it came down to having to grind/edm/etc the tap out, this is what I would try first and if it buggers it up more, well that's just the price of trying I guess.

Hi Michael, Great thread, If you continue with the hole saw, I would turn up a plug of cast iron to a press fit in the hole, drill & tap 3.0 mm & screw in a SHCS so that the underside of the head was tight up against the plug face & drive it in with a hammer, remove SHCS, cut, file & polish level with table, remove screw & the job is done.
Ian.
P.S. I have made several hole saws over the years, fine for a one off.

Originally Posted by Michael G

There is nothing postive to report.

• Tried TIG but the arc tended to flip to the side of the hole as the tap is in deep. Like the freeze spray there is a lot of thermal mass so I don't think I'll be getting the tap up to red hot very easily.

You may try wrapping the TIG electrode with Teflon tape to cut down misdirected arcing to the sides of the hole.

Originally Posted by Pete F

Keeping in mind the full disclosure mentioned earlier regarding having never tried it, nor can I recall it ever being mentioned as a legitimate way to remove a tap...

Understood, and worth trying as a potential solution

Originally Posted by rob streeper

You may try wrapping the TIG electrode with Teflon tape to cut down misdirected arcing to the sides of the hole.

The arc comes off the point so unless the point is closer to the tap than the sides it will arc there. The tap end is currently around 1mm below the surface, so to establish an arc on the tap the electrode will need to be less than 1.25mm from the tap. Not much room. Having thought about it more I also wonder whether I'm making things worse - I was tapping dry so the hole will be clean as was the tap. Have I zapped the tap to the table?

Michael

How deep is the hole?

Originally Posted by Michael G

• I don't have an oxy, so can't comment on that one.

you could if I lent you a set

Not sure if this is a really stupid idea but could you try a dremmel and a carbide cutter to cut away the cast iron round the tap to lower the level of the CI wide enough to get a narrow pair of pliers onto the tap. Maybe if cutting the CI near the tap, you could swap to just a grinding stone so the carbide doesn't snap on the tap. I like the hole saw idea and this is jsut cowboy version of the same really but I think it could be realtively fast and easy if it was me, because i'm not sure i could make a hole saw. It would need to be drilled and plugged afterwards of course, with a bigger plug than making a nice neat hole saw, so not as good really.

Originally Posted by rob streeper

How deep is the hole?

Roughly 10mm

Originally Posted by eskimo

you could if I lent you a set

Thanks, but I'd need to borrow an operator too - I last lit up an oxy in around 1986.


Anyway, the prize today goes to Andre - His comment about a carbide drill twigged my memory. I was going to go for the holesaw thing but realised a guide would be needed to hold it one place, so before doing that I had another idea. I got a 4mm masonry bit, sharpened it up and managed to drill/ pick the tap out that way. If I'd had a third hand to apply coolant it would have been useful as at the end of it the bit was not in great shape.
P1020652 (Medium).JPG
I then got a real drill and took the holes out to 5.5mm in the hope of neatening them up. I found a piece of scrap CI, turned up a plug the right size*, applied a liberal amount of bearing glue, pounded it home with a big hammer and dressed with a file. (The marks around the hole are from the TIG torch experiment)
P1020655 (Medium).JPG P1020658 (Medium).JPG P1020660 (Medium).JPG

Anyway, I then refitted the cover strip, spotted through and have now retapped the holes**. That was a little nerve racking too.

*I bought a set of pin gauges around a year ago. It seemed like a good idea at the time and this is another use for them. In this case the pin was just fitting a hole at 0.216", so the plug was made a smidge larger.

**You know when you break a tap you think that you could grind it off and use it as a bottoming tap? Not always the best idea...

Michael

Nicely done. Looks pretty neat and tidy.

Now that it's done, someone should unravel this thread and weave it into a set of ideas for broken tap removal, for future reference.

Ray

Talk about snatching victory from the jaws of defeat. Congratulations - I bet you feel better now.

Am Glad I could offer some inspiration Michael and really happy you got r done. I think a lot of people are overthinking the problem. Good job.

Originally Posted by welder

I think a lot of people are overthinking the problem.

Yes, well I'd be one of them (or not thinking enough)

Michael

I hadn't heard about using the Tig till this thread. Considering the tap was below flush with the surface I would be to scared of welding the tap in the hole did you use a 1 mm tungsten?
But I will remember that for rusted bolts. One thing I have learnt working in a machine shop is that simple solutions are better.