Removing a broken tap, or other options

Before i go the a machine shop, i figured i would ask you guys.

Vintage centerline billet aluminum wheels. 

Had a broken center cap bolt i drilled out. When i went to retap the threads, broke the tap off.

Tried drilling the tap and just killed two brand new bits.

Not enough material to weld to for a nut.

My thought was to rotate the holed 90 degrees, and drill and tap new holes, but theres no good way for me to measure and mark the points that the holes need drilled on, and my drill press too small to do it anyway. 

Any ideas? Or is the machine shop my best bet?

Yeah - It's shop time.

What size is the tap?

They make broken tap removal tools, but  home depot or Ace won't have it.

You need to contact a serious industrial tool place. 

That said, it might cost near as much as a machine shop fixing it. 

http://www.omegadrill.com/  or  http://www.waltontools.com/products/extract-machsc-hand.htm

This worked for me but not aluminum.  I was able to pulverize a broken tap (cheapie) with an air chisel. 

Yep, tap extractor.  I've got a few small ones, what size tap?  Have you tried to slip a small hardened pin down each side of the tap and move it in the reverse direction?  Sometimes you can muscle it out once you get it out of the metal it broke off in.  Plan B could be using another small tap (the only thing hard enough) and bust the stuck tap up into pieces and pull them out.

A picture is worth a thousand words.

Dan

Tap is 1/4-20. 

Its actually a piece of a matco rethreading tap if that makes a difference. 

https://www.flickr.com/photos/150940429@N02/shares/8GA6uj

Link to picture of what im dealing with.  

Dont think theres enough room for an air chisel, and i think its too embedded to drive through with a hammer and drift.

Keep the ideas coming!

I've used a solution of alum to dissolve a broken exhaust stud in an aluminum head. It should work for a tap as well. 

Can you give me some more information about the solution ?

Turn the cap 90 degrees, use the holes in the cap as the guide for your drill, no measuring required.

Being a re-threading tap, it should be softer than a regular tap and my set has a relatively flat end on the leading side.

It looks like the holes go through the wheel, correct?

If so, did you drill from the back or the front? Drilling  from the back will keep you centered and at the same time, the force will be trying to spin the tap out instead of in deeper.

A carbide drill bit would most likely drill through with no problems, but they are very brittle. The least bit of bending force, and they will break! 

Worst case, can you use the cap as a drill guide to drill and tap new holes?

Good Luck!

 Michael the cap will cover previous Mess-up but still If you break off another you get to buy a Third Tap. I would do that though along with still attempting to remove the first Tap, Just Not Today.  

JB Weld a wee magnet to the cap and another one to the wheel.  That plus the one good retaining screw will hold the cap.  Then cut the head off another retaining screw and JB it to the cap.  Boom, symmetry.

AngryCorvair said:

JB Weld a wee magnet to the cap and another one to the wheel.  That plus the one good retaining screw will hold the cap.  Then cut the head off another retaining screw and JB it to the cap.  Boom, symmetry.

Really bad idea. What happens when it comes off at speed on the road?

Aluminum wheel? If you can't get the tap out with an extractor (you probably won't be able to) knock the tap out from the back with a punch and use a thread insert to repair the damaged thread if necessary

Hammer and a punch.  Try beating it in an anti-clockwise direction.  Or just put the BFH on it and bust the tap into pieces.  They are very hard, but shatter fairly easily.

Walton tap extractor as mentioned above. This is for a 3-flute, they also have a 4-flute. https://www.amazon.com/Walton-10253-Flute-Extractor-Square/dp/B0006NGFQO.

Dusterbd13 said:

Can you give me some more information about the solution ?

You should be able to find quite a few YouTube videos showing it, but I made a saturated solution of alum and water. My head was still in the car, so I cut a can in half, glued it to the head around the stud and filled it with the solution. It took about two days to dissolve enough of the stud to be able to pull the rest straight out and it did not affect the aluminum at all. It works faster if you keep it warm, so I had a nightlight plugged in right under the can. 

FIXED!!!!!!

decided to try the back it out with a puch as suggested, which quickly became use the BFH and shatter the tap. 

Its out. Hole is helicoiled now. But, center cap screws on!

When finesse and technique fail, it's the BFH FTW!

Glad it worked out!

Those Matco rethreaders are pretty questionable - I have broken a few of them including an M8 in the header flange of my Corvette.  I am generally not a hammer, they just don't work too great.  The thread files in the kit are really nice though.

I have found that most of mechanics is:  What to hit, when to hit it, how hard to hit it.

And I've always said that doctor and mechanic are the same job, the only difference is the equipment you're working on

I have referred to myself (and profession) as "God's Mechanic."  When applying for neurosurgery residencies, I put down "Midas Rex or Dremmel.  What's the difference?"  And drilling thousands of holes through plastic, metal, wood, etc., give you a feel when drilling through skulls that you just can't get anywhere else. 

Actually I was thinking that the value in a doctor and mechanic are in the troubleshooting, but there's the drilling in the head thing too.