RCU Forums - View Single Post - Electronic solutions to modifying glow engines of all sizes to gasoline
Old 08-16-2022 | 07:40 PM
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From: Prince Albert, SK, CANADA
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Originally Posted by Jesse Open
Do you have the ability to single-point cut the threads?
With a little bit of calculation, could make indexing reasonably accurate.

BTW, I can loan you 5/16-32 taps in both plug and bottom forms.
Thanks Jesse,

Yes I can cut single point threads and would only need the tap to create a go/no go gauge to get the outer threads right... I have a trick VFD drive on my old lathe and it makes treading a much easier task as i have the ability to drive very slowly and stop instantly.

Originally Posted by Glowgeek
I have 7/16" C360 H02 brass, 5/16-32 plug tap and die on order. Should be here by week's end. I don't have a way to accurately synchronize/index the threads other than by trial and error, using an index mark on the tap. With a little luck I should be able to get them sync'd In a couple of tries and I do intend on short tapping the threads, a little more at a time, until the Timesert insertion tool swages the last couple of threads without excessive pressure.

The broken piece of insert I removed from the cylinder has a 32 thread pitch and the int/ext threads are not synchronized. My thread pitch gauge is barely visable once inserted into the insert bore but it appears to be 32.
Here is how I would proceed - rough finish the insert and "short tap" it. Then using the tap as as a guide the setup can be made of the carriage to thread the OD . Because of the "flange" the setup would be a bit tricky and would have to be cut "upside down" and "backwards".

This type of repair is better done with all parts on hand to get the fits correct - if you can find a "local" with the right equipment it might be easier - I am willing to give it a try though Lonnie but it might take me a while as I have a pile of work stacked up here..