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View Full Version : Making Left handed taps



ronald44181000
05-18-2012, 05:06 PM
Does anyone know of any video's that I can view in regards to making a 1/4'' x 20 left handed acme tap. I figure it should be easy enough. I was contemplating using the left over portion of a Left Hand 1/4'' Roton Acme Leadscrew that I'm using to CNC my Taig Micro-Lathe.

Bob Fisher
05-18-2012, 08:22 PM
1/4 " seems very small for an acme thread, at least to me.Smallest I could find commercially available was 3/8". 20 tpi also seems a lot for an acme thread of that dia. Bob.

macona
05-18-2012, 11:04 PM
I have seen acme 1/4" and smaller. All the was down to 1/8" or so. Though at that point I am not sure it follows a standard acme profile. The profile is almost involute like a gear. The depth helps because the nuts are usually plastic.

I have made taps for plastic from a piece of the stock. Even then they can be tough to get through plastic. Acme really needs to be done in a set of successive taps, a rougher and a finisher.

elf
05-19-2012, 03:21 PM
The Acetel lead screw nut thread is conveniently on the front page now: http://bbs.homeshopmachinist.net/showthread.php?t=43645. This would probably be a better solution than tapping.

gwilson
05-19-2012, 05:05 PM
I make left hand taps frequently. What I sometimes do is turn down a neck in the metal near the chuck end to thread depth so I have somewhere to hold the threading tool at rest while I engage the half nuts,and also someplace to let the tool set while I adjust the tool to take the next deeper cut. Then,after I am ready to thread,I engage the half nuts and take the next pass,repeating until the thread is finished.

Normally I'm making V thread left hand taps,but would do the operations the same way,except for adjusting the angle of the compound to fit the angle of the acme thread.