Screw thread identification

Screw thread identification

This topic has 4 replies, 3 voices, and was last updated 6 January 2014 at 17:38 by Bev Archer.

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5 January 2014 at 18:05 #139782
Bev Archer
Participant
@bevarcher94647
Hi,

My first posting on this forum. I'm trying to restore some fairly old model aero engines that I inherited from my dad. The first one I've tackled is a K&B Torpedo 15 and I'm puzzled by the threads on the head and cylinder retaining bolts. They appear to be 7/64" and 40 tpi. I suspect this is a Model Engineer Screw Thread but none of the tables I've looked at go below 1/8". Did American manufacturers use the M.E. thread?

Would anybody know what this thread is and is it possible to get taps and die to suit?

Bev
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5 January 2014 at 18:05 #6998
Bev Archer
Participant
@bevarcher94647
5 January 2014 at 18:08 #139783
JasonB
Moderator
@jasonb
Quite likely 4-40 UNC which is 0.112" dia so allowing for the crests being a bit undersize close to your .109" ( 7/64) below 1/4" dia the US system uses numbers much like the old UK wood screws did.

Should be able to get taps OK try here

Edited By JasonB on 05/01/2014 18:27:16
5 January 2014 at 18:42 #139788
Nicholas Farr
Participant
@nicholasfarr14254
Hi Bev, and here **LINK**

Regards Nick.
6 January 2014 at 17:38 #139867
Bev Archer
Participant
@bevarcher94647
Many thanks to JasonB & Nick. I've now ordered taps and a die. When I get these engines finished I'll post some photos (when!!)

Bev
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