10/2009

My father needed to cut 34 tpi threads so his custom CCD camera adaptors could be mated to his telescope.  Neither his South Bend 9" nor my ATW cuts 34 threads, so we worked out a replacement gear to be mounted on the quick change box of his lathe which would "speed up" the 32 tpi setting and in fact cut 34 tpi.

We decided a 54 tooth gear would do it, and since it was for a few jobs in aluminum, we also decided to do the gear in aluminum since its easy to work and he already had stock at hand.



I prepared a blank.  As expected, parting this was a big problem but I eventually got it done.






I also prepared a mandrel out of scrap.  The knurled piece is also a bit of scrap, complete with hole off center.






I bought a #3 18dp  cutter from Victor and set it up on the Nichols.  The long overhang isn't the best idea but with the 1-2-3 block & adjustable angle underneath it worked out OK.  If the gear were steel it probably wouldn't have worked out.









Back to the lathe to face off the burr left on the trailing face, and slightly chamfering the teeth.









I broached the keyway using the Bridgeport slotting head and the gear was ready.









Installed on my father's lathe, it was a little noisy for a while but quieted down.   He succeeded in making several 34 tpi threads with it.




;;; eof