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Tapping drill sizes?

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the artfull-codger19/02/2020 15:40:39
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249 forum posts

Some of the more modern zeus books don't give the diameter of ba threads just the tapping drill sizes, if your threading whit/bsf & bsp threads in the lathe use the constant 640, ie divide your tpi into 640 & you get the thread depth within a thou but on ba it's within a few thou.

Graham.

Russell Eberhardt19/02/2020 15:54:09
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Posted by the artfull-codger on 19/02/2020 15:40:39:

if your threading whit/bsf & bsp threads in the lathe use the constant 640, ie divide your tpi into 640 & you get the thread depth within a thou but on ba it's within a few thou.

Graham.

For BA threads use 600/tpi to get the thread depth in thou.

Russell

Edited By Russell Eberhardt on 19/02/2020 15:55:46

the artfull-codger19/02/2020 18:05:08
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249 forum posts

Thanks Russell I'll put that on the workshop wall along with 640

Graham.

Mick B119/02/2020 19:14:07
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Posted by the artfull-codger on 19/02/2020 15:40:39:

Some of the more modern zeus books don't give the diameter of ba threads just the tapping drill sizes, if your threading whit/bsf & bsp threads in the lathe use the constant 640, ie divide your tpi into 640 & you get the thread depth within a thou but on ba it's within a few thou.

Graham.

Yeah, I've noticed that.

'S a bu99er, innit?

face 5

the artfull-codger19/02/2020 19:43:14
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249 forum posts

Haha yes it is Mick,as my old one gets more worn I keep my eyes open at autojumbnles for older ones in good condition.

Graham.

Mick B119/02/2020 20:08:43
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Posted by the artfull-codger on 19/02/2020 19:43:14:

Haha yes it is Mick,as my old one gets more worn I keep my eyes open at autojumbnles for older ones in good condition.

Graham.

 

I've got a dogeared old Dormer Tap & Die handbook I've had since 1977. Won't last much longer, though.

Edited By Mick B1 on 19/02/2020 20:09:16

Howard Lewis19/02/2020 20:15:14
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When I was at work, I laminated the Zeus charts that i bought as an Apprentice. Grubby but still regularly used.

The neat clean Metric copy sits beside the computer for reference, but it lacks some of the info compared to the old one.

Howard.

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