Chainsaw Repair

If you are going to turn new inserts on a lathe  if you cut a slight interference thread they won't back out .Don't get too carried away because what you're actually doing is reforming the hole thread .Too much interference you could make yourself more trouble than you already have .

They also make some factory made inserts which have serrated teeth in the bottom which once set hold pretty good .You'll have to Google it because I can't remember exactly who made them .Mc Master -Carr might carry them for all I know .Keep in mind if you stay with steel there's less chance of screwing up the internal threads than with aluminum .It takes just the bolt diameter for depth of threads on steel to get full holding power .Double on cast iron and about 4 times on aluminum .Trivia 101 .

The trouble with the pre made inserts is I need to go from 7/16-14 to 1/4-20 in one step.  The ones I will eventually make will be about .0015 interferance fit with the 1/4-20 pre dilled and tapped in the end of the bar.  I will use the bar to seat the insert and cut it off just over flush and flat file it to flush.  My job requires me to do just this sort of thing several times a year on molds I build.  I plan to use aluminum for this due the the heat expansion differences between steel and aluminum.  I want the insert to stay put and never be heard from again.  Good luck to me! LOL

To what ever the threaded hole is.  There is some slop in the thread.  I had a thought that woke me up last night, just solder the current insert in??  It might save a lot of dinging around.

A couple things I have made. First one is a pin mold using a 1/2-20 bolt inserted, cut flush and finished with a 1/4 dowel pin for alighment


Second is a threaded insert and thread protector for a Taurus .22 conversion kit.  The gunsmithing is my fill in work when the mold making is slow.

No CNC.  The threading was done on a plain old lathe.  The mold was made using a cutter I made.  Being able to make form tools is what has kept me self employed for 22 years now.

These are some of the form tools I've made.



This is a simple rail mold.