Thread: Bugga. Broke a tap

Originally Posted by Pete F

In my experience you will have zero chance of directing a TIG arc down into a small hole like this. The arc will instead get pulled to the bore of the hole.

That's not what the idea was about, the electrode is shorted to the tap when the power is turned on. With the handpiece clamped in place, On my tig it just hums like it does with a stuck electrode. No arcing.

Ray

Nice work Michael. I will remember that idea.

Simon

Michael,
Good to hear that you have solved the problem.About six months ago a mate of mine arrived with a piece of casting that he had broken a 1/8" whitworth tap off in,below the surface just like your problem. I removed the tap by putting a short as possible length of soft steel (piece of soft tie wire around .080" dia) in a hammer drill,held it down firmly and gave it a very short burst,then while maintaining the pressure hit reverse and out it came.It was a HSS tap. The hammer effect had driven the soft steel just a little way into the flute grooves just enough to enable it to turn in reverse.
Bob

Originally Posted by RayG

That's not what the idea was about, the electrode is shorted to the tap when the power is turned on. With the handpiece clamped in place, On my tig it just hums like it does with a stuck electrode. No arcing.

Ray

Oh ok, but now I'm completely lost. So you take your TIG torch stick the electrode on the end of the tap and turn the welder on? What happens then? A genuine question BTW, not trying to be a smart-ass, as I don't follow this at all.

BTW a thousand apologies to BaronJ, I read back through the thread to see what I'd missed in terms of the TIG solution Ray pointed out, and instead found, to my complete horror, that BarronJ had already suggested essentially the same idea as I did, except that I proposed a fastener instead of the welding rod. Sorry 'bout that, there were a lot of potential solutions coming through pretty quickly and I missed that one. At least you know I think it's a great idea though

Originally Posted by Pete F

So you take your TIG torch stick the electrode on the end of the tap and turn the welder on? What happens then?

I must apologise as well, as I misunderstood this idea too. Next time I get the TIG out I may have to try this. My TIG has all sorts of idiot proofing in built (probably just as well considering the user...), so if I started with a dead short it would probably not kick in (this one has an auto OCV reduction thing which effectively stops that when using stick. Not sure whether it is still in the circuit when using TIG)

Michael

Ah ok, I found the post referring to that now, and understand why I couldn't get it. You must have an old School transformer welder Ray, as that won't work on modern semiconductor based TIGs, they have protection in to shut them down with a short. Mine won't do squat if you short the tungsten out. You can still scratch start them, but it's not great, they do however come to life as the short is removed.

Great to hear Michael.

I used the masonry drill trick to drill a hole in an almost new ride on mower blade that I stuffed. It split about a third of the length and came off the bolt. I decided to fix it just to prove I could and for experience. Also it was on the weekend. The mowers get lots of use at this time. I drilled a hole to prevent the crack extending further. I managed to straighten the 2 sides as I mig welded it bit by bit. The blade has done quite a bit of work since.

I will try this trick on my broken tap tomorrow. I can easily tap the next size. It does not matter.

Dean

Originally Posted by Pete F

You must have an old School transformer welder Ray, as that won't work on modern semiconductor based TIGs, .

My TIG is a pretty basic smps model, but doesn't have all the bells and whistles that yours obviously does.

In any event the TIG is only the power supply to provide a current pulse, and also happens to have a convenient holder for a tungsten electrode.

No reason you couldn't try the same trick with just a car battery and a few wires hooked onto the tungsten electrode. The purpose is to apply a current pulse to the tap and heat it up enough to loosen it, not weld or erode it.

Ray

Yeah I think it's a good idea Ray, I just couldn't grasp the concept as I was thinking of my own welder.

If using TC masonry drills, they strike me as something that wouldn't be too difficult to change to LH. The helix serves no useful purpose in this instance and it would likely just require a bit of a touch up of the TC tip on an appropriate wheel to change the clearance from RH to LH so they can cut. I've often found taps come out on their own when I'm trying to do something else with them, hence always try to run a drill etc in reverse if I can. I think masonry drills go down to about 3 mm IIRC, certainly 4 mm as I have some of those, so getting in to the useful territory for this type of thing.

Hi PeteF,

BTW a thousand apologies to BaronJ, I read back through the thread to see what I'd missed in terms of the TIG solution Ray pointed out, and instead found, to my complete horror, that BarronJ had already suggested essentially the same idea as I did, except that I proposed a fastener instead of the welding rod. Sorry 'bout that, there were a lot of potential solutions coming through pretty quickly and I missed that one. At least you know I think it's a great idea though

Thanks, but no need to apologise. Just thowing in a suggestion based on experience, been there, done that, got the T shirt.
Incidentally I've never had a TIG/MIG welder and only had, and still have a transformer based welder, not that it gets much use nowadays.

Originally Posted by Pete F

Yeah I think it's a good idea Ray, I just couldn't grasp the concept as I was thinking of my own welder.

If using TC masonry drills, they strike me as something that wouldn't be too difficult to change to LH. The helix serves no useful purpose in this instance and it would likely just require a bit of a touch up of the TC tip on an appropriate wheel to change the clearance from RH to LH so they can cut. I've often found taps come out on their own when I'm trying to do something else with them, hence always try to run a drill etc in reverse if I can. I think masonry drills go down to about 3 mm IIRC, certainly 4 mm as I have some of those, so getting in to the useful territory for this type of thing.

I thought the same thing myself about left hand grinding of masonry drill tips. I think I have a 3mm one. You would need to take care with chips tho if you manage to drill to any depth and with 3mm diam this would not be much.

Dean

The amount of chips you'd need to deal with would be minimal Dean, besides which, when drilling a tap I'd expect them to come out more like a powder. Just pull the drill, wipe it off, and reapply lube.