urbanrifleman
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How do you fix this?
Same here.How crooked are they? I have yet to find any that won't straighten out when punched out to 8-40. Cut the new holes with an endmill so they don't try to follow the crooked holes.
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I use carbon steel taps in receivers for the simple reason that carbide will cut it out if you break one off. Still a bad day but not as bad as it could be. Speaking of this, I need to order some more taps. I try to keep several of the plug, taper and bottoming taps in 6-48, 8-40 and 3-56. A fresh, sharp tap is often the difference in a bad day and an effortless job. They pay for themselves in tap handles alone...by not throwing them across the shop and losing them. Lol!You have to have a mill. Then you have to have patience, and you have to have good taps. Break a tap off in one of these holes and you'll have a bad day. I've never seen any so crooked that you couldn't fix it by just redrilling for 8-40. You have to drill with an endmill so as not to follow the old hole. Not a big fan of welding in general--too much heat and residual stress.
That's all I use when power tapping any thru hole. Chip evacuation is often the problem in small holes.Mill & convert to 8-40, then open up the standard bases with a .161 drill. If it's a through hole, I use a gun tap. They can be driven under power. The three & four flute taps made in Guangdong province that are being peddled today are prone to breakage, even sharp ones.
For those not familiar with what's commonly called a gun tap:
https://www.mcmaster.com/gun-taps
Shouldn't need carbide but it won't hurt...unless it breaks off in the hole.I talked to my smith he has never done one, but he is willing to try. I might have to buy the end mill bit. I am not sure he has one. He said he needs carbide?
Shouldn't need carbide but it won't hurt...unless it breaks off in the hole.
I use a 9/64 end mill. You should be able to find it in carbide without issue.