Broken tap removal

[DPittman]

I was tapping a 6x32 thread in the end of a 3/8" rod and was doing it like I wanted to break the tap...which I did. Damn it, I knew better.

I suspect I will need to start over on this part but wondering what the thoughts are about breaking the rest of the tap out with a punch? I guess I don't have much to loose. All other methods have failed so far including those worthless asian broken tap removal tools.

 

[PaulL]

Have you put the heat to the rod and tried the extraction tool? A thou or two of play might be available.

 

[140mower]

If it was an aluminum part, which it doesn't look to be, I would suggest dissolving it with a solution of allum and water.....
But don't give up too soon, I would probably break a couple carbide drill bits and end mills before starting over......
I have successfully removed a couple with a punch, but the time it took, I probably could have made a new part, and the threads were less than perfect afterwards.

 

[Six O Two]

I broke a tap in a thread over the weekend, but it was a bit bigger at 1/4-20 and it was a thru-hole in 3/8" plate. I also should have known better...

I managed to get it out as you suggest, by breaking apart the tap into small pieces with a punch. I used a lot of force and very little finesse and it did chowder the hole a bit. YMMV...

 

[DPittman]

Have you put the heat to the rod and tried the extraction tool? A thou or two of play might be available.

No I didn't try that, unfortunately I tried the removal tool and broke off the little teeny bit of the tap that was available to grab onto.

I sure it would be much easier (and probably less expensive) to just start over as this isn't a high priced/precision part but I thought I would "practice" my broken tap removal skills, and I hate to give up.

 

[DavidR8]

I've had some luck removing broken taps by using a small pair of needle nose pliers, grabbing onto one of the webs of the flute and gently rocking it back and forth to loosen it. Nothing as small as a 6-32 tap mind you...

 

[Crankit]

Taps are pretty hard so you could try a punch and break it apart into pieces

 

[fixerup]

This is what I do if the broken tap sticks out or just flush with the hole. First I use the air nozzle and blow the hole clean of chips. Put a few drops of light oil, then I use a punch and gently hammer in the counter clockwise direction, then clockwise until I see some movement, be patient and gentle taps. I use a visor to see if it does move. Once it moves, I insert my junk tweezer in the tap flutes has deep has possible and wiggle it and unscrew it out. If I am not successful and break the tap below the hole and can't punch sideways any more, I switches from gentle hammer to firm blows to break it apart.
My favorite punches for this jobs is broken taps which I sharpen to a very fine point on the grinder.

 

[Tom Kitta]

Old carbide EM is usually what I use.

After trying all other methods.

 

[Susquatch]

I have VERY successfully used Walton Tap extractors. No force allowed. Just wiggle back N forth and tap the piece upside down to get the chips out. Lotta time but it usually comes out after some time leaving behind an undamaged part.

Walton Tap Extractor Tools to Remove Broken Taps

Remove broken machine screw and hand taps, pipe taps and STI taps quickly and easily. Available in every tap size, both inch and metric.

www.waltontools.com

They are available all over and even individually. Use NO FORCE as the fingers will bend. Just play with it and tap out the chips until the tap comes out.

 

[Former Member]

if you need the part, heat it the aluminum will expand against the tap compressing the aluminum, cool it and it will contract give some wiggle room. Now with small needle nose vise grips (if possible) grab and remove use the tool you have or use a small punch and tap it to rotate it out.

It is a hit or miss thing.

I've broken enough to know in exactly the same conditions. It was a very expensive learning curve.

To avoid breakage switch to 6-32 forming tap which drill a large hole and produce a stronger thread.

 

[Dusty]

@DPittman Walton tap extractor sets or individually can be had from KBC tools, might save your project.

Results Page 1 :: KBC Tools & Machinery

www.kbctools.ca

 

[DPittman]

Thanks for the tips and links.
I had no carbide bits/endmills that small, so I tried with a Dremel and diamond bit but it was just too small. Tried with punch and could see that was going nowhere good.

So I started over. No big deal. Now I have a broken #6-32 tap I can grind flat for a bottoming tap

2nd go round I used the tap drill size for 60% thread, which of course I should have done to begin with but I read the charts in too much of a hurry and used 75% drill. As it turns out, it was nice to have a "bottoming" tap for this hole anyhow and I didn't have one till I busted the first!

 

[RobinHood]

This might be a tough one as I believe the tap broke when it reached the cross-drilled hole and chips jammed.

Use the methods suggest above by others. Hopefully one will work for you.

If you need to remake the part, I highly recommend to drill the cross-hole after you thread the axial hole. Cross drilling will leave a burr in the threads, but they are easily cleaned up by running the tap one more time in the hole.

 

[DPittman]

This might be a tough one as I believe the tap broke when it reached the cross-drilled hole and chips jammed.

I did not know that thanks. I was thinking the cross hole would be helpful as it allowed me to see the tap before it bottomed out on the other side.
Edit....and I thought the cross hole would allow the chips to fall out.

FWIW.Here is the piece I cut out with the busted tap still stuck in it. The cross drilled hole is 1/8".

 

[Dusty]

@DPittman Walton tap extractor sets or individually can be had from KBC tools, might save your project.

Results Page 1 :: KBC Tools & Machinery

www.kbctools.ca

Video by tubalcain-mrpete-Lyle (2016) on Walton Tap Extractors with reasons why taps break, a real eye opener in using Walton tap extractors from a well known shop teacher.

 

[RobinHood]

I was thinking the cross hole would be helpful as it allowed me to see the tap before it bottomed out on the other side.
Edit....and I thought the cross hole would allow the chips to fall out.

Yes, you would see the tap come through and thus have an indication of when you are reaching bottom.
Not all taps push the chips ahead of them. AFAIK only the “machine” taps do and thus are not suitable for blind holes.

Here is an illustration of a cross hole (misalignment greatly exaggerated)



The tap comes down into the cross drilled hole. Side B is in the clear while at A the tap is still cutting. Since taps are very brittle, it will not take much at all to snap it right off where it enters the cross drilled hole because it tries to bend towards side B. If you are lucky, you may be able to back the remaining tap in the vertical hole out. But more often than not, some of the shattered tap bottom jams the flutes just as you are backing it out and then it shears the shaft off flush with the top surface.

From your picture, it looks like you were using something other than a taper tap for the initial threading pass. It takes much more torque to use a plug or bottoming tap right off the bat - especially in steel.

 

[DPittman]

Yes, you would see the tap come through and thus have an indication of when you are reaching bottom.
Not all taps push the chips ahead of them. AFAIK only the “machine” taps do and thus are not suitable for blind holes.

Here is an illustration of a cross hole (misalignment greatly exaggerated)

View attachment 30690

The tap comes down into the cross drilled hole. Side B is in the clear while at A the tap is still cutting. Since taps are very brittle, it will not take much at all to snap it right off where it enters the cross drilled hole because it tries to bend towards side B. If you are lucky, you may be able to back the remaining tap in the vertical hole out. But more often than not, some of the shattered tap bottom jams the flutes just as you are backing it out and then it shears the shaft off flush with the top surface.

From your picture, it looks like you were using something other than a taper tap for the initial threading pass. It takes much more torque to use a plug or bottoming tap right off the bat - especially in steel.

You'd never know by that last picture I posted but the tap never did come down far enough to hit the walls of the cross hole. I actually had the tap hole well aligned with the cross hole. While I wasn't using a bottom tap, I believe it was only a plug tap or it had very minor taper to it. I had 2 taps to choose from: a hss tap and a carbon steel tap that may have had more taper to it. I chose the hss as I find they usually cut better (all things equal). I now have a bottoming tap and some new ones on the way.
The main reason I believe the tap broke was my over aggressive tapping method without backing out to break the chip. I had done one the same previously the same way and decided to push my luck again. Lesson learned (and hopefully retained).

 

[140mower]

Thanks for the tips and links.
I had no carbide bits/endmills that small, so I tried with a Dremel and diamond bit but it was just too small. Tried with punch and could see that was going nowhere good.

So I started over. No big deal. Now I have a broken #6-32 tap I can grind flat for a bottoming tap

2nd go round I used the tap drill size for 60% thread, which of course I should have done to begin with but I read the charts in too much of a hurry and used 75% drill. As it turns out, it was nice to have a "bottoming" tap for this hole anyhow and I didn't have one till I busted the first!

.... well, that's why you broke it..... Because you needed it.

 

[PeterT]

Conventional taps are supposed to push chips forward into the pilot hole, but that is kind of idealized generalization. If chips get packed tight enough into the flute its just not going to dislodge itself & move down the hole. If you have ever picked out sticky swarf stuck on a tap or dill flute, its a good example of what's going on but in a more confined hole. So, the usual guidance. Break the chip often so they don't get long & problematic (in 3 turns, out one turn... something like that). On deeper holes or stickier alloys you should just get the tap right out to inspect & clean until you have a feel for how much to push it. Use cutting fluid to avoid sticking, lubricate cutting, reduce friction heat etc. Axial alignment is very important. Taps are brittle & flutes reduce the section area, so they are kind of weak in any lateral bending. I power feed as well, but only when I'm pretty sure or done a couple test runs. You might also want to try chip ejecting taps like this (Sowa). They don't cost much more. The difference is you don't do the interrupted 1-turn back out thing. Go in (the safe depth) & all the way out again, clear chips if required. I use thee on aluminum & mild steel all the time. They make a bunch of different grades but unless you're doing exotic or hard alloys the blue ring are fine. You can break them too, they are not magic beans LOL