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Newbe hobbiest broken tap advice.
I have a broket 1/4-20 tap in some 1/2 in steel plate.
(Last hole of 8, of course) I can access both sides of the tap, the tap is a 4 flute tap and has a dimple in the end (Looks like it was setup to drill it out.) My HSS drill bit does not even touch it. So my thought is to go to the local machinist supply store on monday and buy a carbide drill of the apropriate size and drill out the tap on the drill press. Should I drill undersize and work my way up to the proper size? Or should I drill at the apropriate size all at once. The part is simple and not worth taking to to an EDM shop etc.. I'll just make another one if I have to. I can rotate the tap back and forth abut 10 degrees with some small needle nose. In general I've never had any luck with tap extractors, alas if one was ever going to work at all now is the time. Paul |
I have a broket 1/4-20 tap in some 1/2 in steel plate.
(Last hole of 8, of course) I can access both sides of the tap, the tap is a 4 flute tap and has a dimple in the end (Looks like it was setup to drill it out.) My HSS drill bit does not even touch it. So my thought is to go to the local machinist supply store on monday and buy a carbide drill of the apropriate size and drill out the tap on the drill press. Should I drill undersize and work my way up to the proper size? Or should I drill at the apropriate size all at once. The part is simple and not worth taking to to an EDM shop etc.. I'll just make another one if I have to. I can rotate the tap back and forth abut 10 degrees with some small needle nose. In general I've never had any luck with tap extractors, alas if one was ever going to work at all now is the time. Paul I would think, that since you can rotate the tap back and forth a bit, that the tap extractors made with the little metal pins just may work for you in this situation. You may even be able to slip a couple of little pins down into the flutes of the tap yourself, and unscrew it with a pair of needle nose pliers. HTH. Ken. |
You may be able to back the tap out by reaching down into one of the flutes
with a small punch, screwdriver, whatever and rap on it with a little hammer, turning it backwards in small increments. Barring that, I'd try a tap extractror - the fact that you can move it back and forth 10 degrees suggests a tap extractor might work. If you go for it with a solid carbide drill, position the drill in a drill press or milling machine exactly over the center of hole. Bob Swinney wrote in message ... I have a broket 1/4-20 tap in some 1/2 in steel plate. (Last hole of 8, of course) I can access both sides of the tap, the tap is a 4 flute tap and has a dimple in the end (Looks like it was setup to drill it out.) My HSS drill bit does not even touch it. So my thought is to go to the local machinist supply store on monday and buy a carbide drill of the apropriate size and drill out the tap on the drill press. Should I drill undersize and work my way up to the proper size? Or should I drill at the apropriate size all at once. The part is simple and not worth taking to to an EDM shop etc.. I'll just make another one if I have to. I can rotate the tap back and forth abut 10 degrees with some small needle nose. In general I've never had any luck with tap extractors, alas if one was ever going to work at all now is the time. Paul |
I had a business removing broken taps and bolts for 18 years. And I think
you might be able to use a Dremel slitting wheel to put a slot like a screw slot in the end of the tap and then use a screw driver. If you use a carbide drill I would try a .125 dia. Carbide does not like interrupted cuts and if you go bigger the cut will be breaking into the flutes. Then break tap out with a punch. If you use carbide be sure the broken tap is not moving around in the hole .Because if it moves under load it can break the drill. And drill from the bottom and the drilling may unscrew the tap. So leave room for the tap to go if it does unscrew. Jim wrote in message ... I have a broket 1/4-20 tap in some 1/2 in steel plate. (Last hole of 8, of course) I can access both sides of the tap, the tap is a 4 flute tap and has a dimple in the end (Looks like it was setup to drill it out.) My HSS drill bit does not even touch it. So my thought is to go to the local machinist supply store on monday and buy a carbide drill of the apropriate size and drill out the tap on the drill press. Should I drill undersize and work my way up to the proper size? Or should I drill at the apropriate size all at once. The part is simple and not worth taking to to an EDM shop etc.. I'll just make another one if I have to. I can rotate the tap back and forth abut 10 degrees with some small needle nose. In general I've never had any luck with tap extractors, alas if one was ever going to work at all now is the time. Paul |
with larger taps, like 1/4 inch, I've had good luck using a diamond point (I
suppose that's what you call it) in a high speed drill like dremel or an air drill - the diamond dust on the point will cut the tap easily, just cut the flutes off - since it's loose, cutting just one flute off ought to do the trick. I get the "points" - whcih look like toothpics with diamond dust on them - from a jewelry/lapidary store - they are pretty cheap (around a dollar or so each) - lube with water if you wish wrote in message ... I have a broket 1/4-20 tap in some 1/2 in steel plate. (Last hole of 8, of course) I can access both sides of the tap, the tap is a 4 flute tap and has a dimple in the end (Looks like it was setup to drill it out.) My HSS drill bit does not even touch it. So my thought is to go to the local machinist supply store on monday and buy a carbide drill of the apropriate size and drill out the tap on the drill press. Should I drill undersize and work my way up to the proper size? Or should I drill at the apropriate size all at once. The part is simple and not worth taking to to an EDM shop etc.. I'll just make another one if I have to. I can rotate the tap back and forth abut 10 degrees with some small needle nose. In general I've never had any luck with tap extractors, alas if one was ever going to work at all now is the time. Paul |
william_b_noble wrote: with larger taps, like 1/4 inch, I've had good luck using a diamond point (I suppose that's what you call it) in a high speed drill like dremel or an air drill - the diamond dust on the point will cut the tap easily, just cut the flutes off - since it's loose, cutting just one flute off ought to do the trick. I get the "points" - whcih look like toothpics with diamond dust on them - from a jewelry/lapidary store - they are pretty cheap (around a dollar or so each) - lube with water if you wish wrote in message ... I have a broket 1/4-20 tap in some 1/2 in steel plate. (Last hole of 8, of course) I can access both sides of the tap, the tap is a 4 flute tap and has a dimple in the end (Looks like it was setup to drill it out.) My HSS drill bit does not even touch it. Check with your dentist for diamond & carbide burrs that they throw out by the gross. They are usually happy to see them going to good use instead of the dump. I have a lifetime supply. Bugs So my thought is to go to the local machinist supply store on monday and buy a carbide drill of the apropriate size and drill out the tap on the drill press. Should I drill undersize and work my way up to the proper size? Or should I drill at the apropriate size all at once. The part is simple and not worth taking to to an EDM shop etc.. I'll just make another one if I have to. I can rotate the tap back and forth abut 10 degrees with some small needle nose. In general I've never had any luck with tap extractors, alas if one was ever going to work at all now is the time. Paul |
wrote in message ... I have a broket 1/4-20 tap in some 1/2 in steel plate. (Last hole of 8, of course) I can access both sides of the tap, the tap is a 4 flute tap and has a dimple in the end (Looks like it was setup to drill it out.) Assuming that you've tried to gently puch it out by using a small punch on the flutes and failed. Only a diamond drill will work on a typical tap, but that is in itself very chancy. A tap extractor (hah!) might work if you're lucky. Realize that the point of a tap extractor is to save the work, not the tap extractor. They break more than half the time. If you try that, be sure to lubricate well and to work back and forth, very slowly and gently. Maybe 100 times or more. In a big shop with great tooling it would be done with an EDM machine. The simplest way (what I would do) is to punch it out. Do this in three steps. First use a very small cold chisel and attack whatever is sticking out on the broken end. You might be able to chip part of one or more flutes that way and thereby make it easier to remove with a tap extractor. This works about half the time. Next (if that failes) use a punch with a slight hollow so that it can fit exactly over the center of the point of the tap. Then whack it good and hard. Very rarely, you'll be able extract it then. More likely, with a few good whacks you'll drive the tap out, leaving a worthless thread and over-sized hole behind. And that's why Helicoils were invented. I made myself a 12" cast iron lathe face plate with about 120 3/8" x 16 holes tapped in it. Had to use the above procedure with Helicoils for three holes. Boris -- ------------------------------------- Boris Beizer Ph.D. Seminars and Consulting 1232 Glenbrook Road on Software Testing and Huntingdon Valley, PA 19006 Quality Assurance TEL: 215-572-5580 FAX: 215-886-0144 Email bsquare "at" earthlink.net ------------------------------------------ |
--Where are you and how large is the part? I'm thinking
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In article , kens_at_sys_matrix_.net wrote: snip I would think, that since you can rotate the tap back and forth a bit, that the tap extractors made with the little metal pins just may work for you in this situation. You may even be able to slip a couple of little pins down into the flutes of the tap yourself, and unscrew it with a pair of needle nose pliers. HTH. I've made a home brew tap extractor by using two sewing needles. The are hardened & quite stiff, and just about the right size to drop into the flutes of a tap. I've done a couple smaller taps this way, but it should work on a 1/4-20 if you can find some large needles. A pair of pliers up close can be used to twist them. Parallel jaw pliers would work best. Doug White |
Do you have a welder or access to one? MIG, Fluxcore or stick will work.
Weld a nut to the the stub and turn it out with a wrench. I've done this with broken bolts, but I've heard it works with taps. -- Ron DeBlock N2JSO If God had meant for Man to see the sunrise, He would have scheduled it later in the day. |
Ron DeBlock wrote:
Do you have a welder or access to one? MIG, Fluxcore or stick will work. Weld a nut to the the stub and turn it out with a wrench. I've done this with broken bolts, but I've heard it works with taps. I've tried this with broken 3 mm taps and a stick welder. I didn't have any success. The weld always broke before the tap came out, and I had to make a new part :-(. Chris |
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