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Hit & Miss Gas Engine Discussion

Broke off tap. Need help!


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  #1  
Old 05-10-2014, 10:32:43 PM
Kevin Weis Kevin Weis is offline
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Default Broke off tap. Need help!

All, broke off a tap in threaded hole on my 1 hp Famous. What's the best drill bit to use to attempt to drill it out? Thinking a diamond tip bit would be best. Any thoughts appreciated. Size is about 3/64" - 1/8".
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Old 05-10-2014, 10:40:15 PM
TekNik TekNik is offline
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Default Re: Broke off tap. Need help!

A few Questions:
What size tap is it?
How deep in the hole is it broken off?
Is there part of the tap above the surface?
Is the fracture parallel to the surface?
TekNik
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Old 05-10-2014, 10:51:25 PM
Ryan McClenahan Ryan McClenahan is offline
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Default Re: Broke off tap. Need help!

If your going to drill it out you need a carbide drill. Diamond is for masonry.
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Old 05-10-2014, 10:56:28 PM
Black Eagle Black Eagle is offline
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Default Re: Broke off tap. Need help!

I've had success with one of these tools before. http://www.waltontools.com/products/remvtap.htm remember to use plenty of oil.
I've also used nitrogen to cool the tap then shatter it with a center punch.
Alternatively if you have a micro torch you can heat the tap to anneal it then drill it out when cool.
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Old 05-10-2014, 11:37:26 PM
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Tom Cwach Tom Cwach is offline
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Default Re: Broke off tap. Need help!

find a machine shop with a wire edm would be best.

I have had some success with breaking them up with a punch but you're working in a small hole.

Most taps will evaporate if a cutting torch is used on the larger ones.
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Old 05-11-2014, 12:00:20 AM
Ed Radtke Ed Radtke is offline
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Default Re: Broke off tap. Need help!

go to the enco website and get a tapout
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Old 05-11-2014, 12:20:16 AM
pegasuspinto pegasuspinto is offline
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Default Re: Broke off tap. Need help!

Years ago my boss took one out of a delicate spot with a handfull of carbide burrs in a dremel tool, with a steady hand. they had already busted a tap extractor. In the end of a crankshaft. Cleaned it up, put in a new bolt, and worked fine.
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Old 05-10-2014, 11:04:06 PM
Paul Richardson Paul Richardson is offline
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Default Re: Broke off tap. Need help!

Quote:
Originally Posted by Kevin Weis View Post
All, broke off a tap in threaded hole on my 1 hp Famous. What's the best drill bit to use to attempt to drill it out? Thinking a diamond tip bit would be best. Any thoughts appreciated. Size is about 3/64" - 1/8".
Not really sure why you would need a special type drill Kevin? Am I right to think the material will be either brass or mild steel?
My favourite method with bolts and studs is to make them look like a broken off tap spigot in the hole by drilling the center out as near to the thread as I can get.
After that I insert a small hand held hacksaw blade saw.Sometimes I need to reduce the height of the blade on the bench grinder to allow it to fit the hole.
I section the remains of the bolt or tap,in two three or sometimes four sections,taking best possible care to saw TO the thread and not through it.
I then use a small hammer and punch perhaps like a broken then resharpened scriber and very gently punch from the edge inwards to break out the first willing section.Minor damage to the host thread can usually be renovated ok with a tap.
Don't rush,be gentle,and sometimes a plumbers torch is a great help.I get great results when the job allows that method.
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Old 05-10-2014, 11:15:28 PM
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ssimntih ssimntih is offline
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Default Re: Broke off tap. Need help!

I usually use carbide end mill, if you have the luxury of owning a mill. You definitely need something harder than the tap.
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Old 05-11-2014, 08:33:31 AM
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Default Re: Broke off tap. Need help!

Forget all that stuff about drilling and tap extractors. With a tap that small you have 2 choices. First would be to find a shop with a tap burner. Second is to find someone with a milling machine who knows what they are doing. A good machinist and a carbide end mill will get that tap out. May need a thread insert installed if breaking the tap damaged the hole but at this point your part is salvageable.
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