Yeah, I know. It was a stupid mistake. I am rebuilding a 350 SBC. I was in the process of cleaning out the bolt holes on the block with the correct tap for the bolt hole. I was working on the oil pan bolts and was on the next to the last bolt when the tap broke off flush with the block :( Can't understand why. I was using the same pressure as all the other holes and was not really binding up. Just pop! and now I have a real problem:eek:

It tried drilling it out, yeah right, like that would work. Tried heating it up and drilling it. No go.

Anyone have a word of experience for this problem.

Anyone heard of a process called "Zap a tap" or something like that? From what I am told, it removes the broken tap by shooting it with an electrical charge that shatters the brittle tap? But it costs about $60 to have it done. Anyone done this before? I would pay that if it works.

Thanks for your help.

snap on sells a tool called a tap extractior. slides down the "empty" parts of the tap and allows you to back it out. when you do so i would highly recommend using a lot of oil and backing out 2 turns, then go back in 1/2 turn. that'll keep the tap from loading up and should let you pull it.
good luck!
;)

You could take the block to a high-dollar machine shop that has
a machine known as an EDM.... (electronic-dsicharge-machine--?)

it uses high-frequency currents to zap the metal-to-be-removed
without damaging the outer metal--(your block)

I find it hard to beleive they would only charge $60 bucks to
do this though.... sounds cheap enough to me.....


--Sherpa

I had the same problem and I asked a buddy who is a Machinist at Lawrence Livermore. He brought me a few drills made By Dormer and it went thru it like butter.

I found them on the net:
http://www.eisonindustrial.com/cobmac.htm

I will be is Sac tomorrow let me know it you want to borrow them.

Don't know if it would work on a tap, but ever since I got a welder, anything that breaks just gets a nut MIG'd to it and then I use a wrench....

Man, you guys are quck to respond. Thanks for the speedy replies

Old Scout, sure I will give them a try. But I don't want you to go out of your way. If your in the neighborhood, I work downtom off 30th street and Q.

Is their anyone in Sacto that sells those??

I did the exact same thing on Friday in out commuter car. I broke it off in the head (exhaust manifold stud hole). Let me know what works cause I need to get it out this week :(

I've gotten broken taps out by drilling through them with a carbide end mill in a milling machine. I know this probably doesn't help in your garage, but if it comes down to it you should be able to find a machine shop that can do the same thing.

use safety glasses, a sharp center punch, and a hammer, taps are brittle enough that you can usually shatter them with the center punch.

I'll meet ya at 20th and Capital Ever heard of Rubicon Brewing co? :beer: :beer:

last time I did that, I started drilling it out with a left-handed drill bit. about a half inch(maybe) into the tap, the drill bit bound up and spun the tap out. I don't know if you'll get that lucky, but it's worth a shot. If you are going to go the drill-route, go with a cobalt bit, low rpms, and oil.

I'm sure you are working with an aluminum block so just pour some (muratic?) acid on it. If you use the right kind of acid, it will eat the ferrous metal and not touch the non-ferrous metal. Any way, sounds like you'll get it!

Originally posted by wejacks
Man, you guys are quck to respond. Thanks for the speedy replies

Old Scout, sure I will give them a try. But I don't want you to go out of your way. If your in the neighborhood, I work downtom off 30th street and Q.

Is their anyone in Sacto that sells those??

If you have a Home Depot or similar in your area. You can probably get a cobalt drill bit with another brand name on it.

Have fun, I just got done drilling out my spring packs for a larger center pin. Even cobalt with cutting oil and low rpms was barely up to the job. It's a b~tch when what your drilling is as hard as the drill bit itself. :D