Tuning Tip Threads

[Ron Nossaman]

> Both Ron. The stripped threads are in the head to shaft joint. But 
> additionally, I find that some tips will fit one extension, but not the 
> other.....
> 
> Terry Farrell

Ok, head to shaft. I've had occasional failures there, and 
determined it was just because the joint wasn't tight. If it's 
not cranked down, any movement in the threads will eventually 
tear them up. I like the tapered pipe thread because it jams 
in very solidly. In your case, I'd start with a new head, and 
re thread the shaft. Then you may have to make modifications 
to make it work. The shaft has to go in deep enough to jam the 
threads. If it bottoms out in the hole, it won't tighten. 
Likewise, if the head contacts the end of the threads in the 
shaft, it won't tighten. In either case, it will soon be loose 
and fail before you're ready. Before assembly, you may have to 
grind the head down at the hole some, and grind the end of the 
shaft some, to get the wider shaft thread into the narrower 
head thread. Put the shaft into a vise, and crank the head on 
with a wrench or other appropriate cheater. Like a plumber 
described it to me once, tighten it as much as you can, then 
take it another half turn. You're actually stretching the head 
some doing this, which you can feel happening. You can also 
feel if it's bottomed out, which you don't want. This won't 
come loose. It'll either eventually break off, or last until 
you're way past sick of looking at it. If you feel the need to 
change heads and tips in the field, either get over it, or 
carry multiple hammers. That's it. We ask a lot of that little 
joint, so we have to give it half a chance to do it's job.
Ron N