Best way to tap thick Cast iron.

Armor said:
Not me doing the tapping but a few guys on different teams............by the looks of it a lot of ' Lead folks' some serious explaining as they are the ones who broke the Tap.:lmao:
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Sounds like a serious lack of skill and/or training .

In the past I've broken taps when threading by hand, but every time it happened it didn't 'just break'; I broke it, and I always knew why, whether it wasn't backing up enough to clear the chips, or getting out of true, or just pushing too hard.
When you buy your own tools and have to put your hand in your own pocket to replace them, it's amazing how quickly your skills increase as you learn from your mistakes! :))



M
 
llarson said:
Tony's two stage thought works great, I've done it too. I prefer dry tapping and the vacuum on it.
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All done now well at least our gear box and no broke tap.

What it really came down to was the wrong size tap drill.

Now corrected , but the chips on the inside well they tried to use a magnet to fish out as many as they could.

I guess only time will tell on that one.:nono:


Thanks all.

Me I have broke taps doing small sizes,to much lean is what that comes down too, hate to say it but they don't buy us Tap Handles , so crescent wrenches or a self locking nut hammered on the end of the tap and turned with a wrench.:thinking:

Jeff
 
Armor said:
Me I have broke taps doing small sizes,to much lean is what that comes down too, hate to say it but they don't buy us Tap Handles , so crescent wrenches or a self locking nut hammered on the end of the tap and turned with a wrench.:thinking:

Jeff
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What kind of a place do you work for? "jawdrop:

That's like being expected to torque down a cylinder head with Vise Grips! :nuts:



M
 
Find a tap drill chart (like this one http://www.physics.ncsu.edu/pearl/Tap_Drill_Chart.html) and drill for a 50% thread rather than 75%. It much harder to break a tap with a 50% thread....

You're tapping dry, right? Using a sharp tap? Also, use a high speed steel tap not one of those carbon steel crap taps that come in the tap/die sets. Those things break if you just look at them cross-eyed.

Oh. And it's IMPERATIVE that your guys start the tap dead straight. No matter what you do a tap will break if you start it cockeyed in CI.

john
 
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