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Thread: Tapping Problem
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30th Jan 2012, 04:21 PM #1Member
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Tapping Problem
Hi All
I'm trying to re tap an existing thread in a 12mm square lathe toolholder. The existing thread is imperial and because I cant locate the correct screw to hold the carbide insert I want tap it to 3.5 metric. So far I've had no success and have broken two 3.5M HSS taps. Is tool holder steel generally very hard? Would I be better of with a tungsten tap?
TIA
Scott
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30th Jan 2012, 04:28 PM #2Most Valued Member
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Hi Scott
What size did you drill it out to and was it easy to drill
Phil
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30th Jan 2012, 04:37 PM #3Member
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30th Jan 2012, 05:06 PM #4Most Valued Member
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Have you thought that the Tap you are using is catching in the existing threads and causing it to break.
Is the Tap your using Fine or Coarse pitch?Last edited by pipeclay; 30th Jan 2012 at 05:10 PM. Reason: more
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30th Jan 2012, 05:23 PM #5Member
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No. I was hoping the tap would recut the existing threads.
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30th Jan 2012, 05:28 PM #6Dave J Guest
You will probably find it's at least case hardened, are you using some sort of lube with it?
Dave
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30th Jan 2012, 05:36 PM #7Member
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30th Jan 2012, 05:45 PM #8Dave J Guest
Unless you anneal it, you are probably going to keep on having problems.
Not sure if you know how, but you heat it up and cool it slowly, the slower the better. You will then have to re harden it again when your finished, or could just leave it.
Don't forget the tool holders are only cheap from CTC so don't go spending to much on taps.
Dave
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30th Jan 2012, 06:04 PM #9Philomath in training
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What's the imperial screw size? As the US economy is still largely imperial, I'm having problems with the idea of an imperial screw not being obtainable. (Large degree of difficulty yes, but we are machinists (or wanabees) - problems are made to be solved!)
Michael
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30th Jan 2012, 06:09 PM #10Most Valued Member
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Tool holder shouldnt be that Hard will be Tough.
Is it a fine or coarse thread.
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31st Jan 2012, 09:59 AM #11Member
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Yep that's were I heading.
What's the imperial screw size? As the US economy is still largely imperial, I'm having problems with the idea of an imperial screw not being obtainable. (Large degree of difficulty yes, but we are machinists (or wanabees) - problems are made to be solved!)
Is it a fine or coarse thread
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