My cue doesn't have a 3/8"-10 pin, but the tpi, is 10. The shaft on the cue, does fit a 3/8" -10 pin pretty snug, but it's very loose on the cue it came on. Other than changing the pin size, what can be done to make the shaft fit better?
You can either try to get the wood of the shaft to swell (pour some water into the cavity, let it sit a little while, then dump it out or try to stuff a wet rag or paper towel into it) or wrap some very thin tape around the pin. Don't know for sure if either of these methods would work, but may be worth a try.
And if you were to wrap tape around the pin, what would that accomplish?
It may fit tight once. And there after, would leave little remnants of tape inside the hole.
Then, they would surely be packed further down every time that you screwed the cue together.
Just one possible problem.
In the long run, then the repairman would have not much choice as yo whether he will have to
Drill, Plug and Retap the hole. He could just retap the hole but then no guarantee that the tap
will clean out and bring back any left over bits of tape.
Plus then, the Repairman will have a funny story to tell his mates at the Pool Hall.
After all the frustration, you will have no choice but to take it to your Repairman
and have him have a look at it, and do the job properly.
People have used water, yes, and even CA Glue as a coating to strengthen the threads.
Many Repairs are better left for folks that have done them before.
Cost ya nothing now, but much more later in terms of money and grief if you mess something up.
I can tell you 100%, Cue Repairmen and Makers didn't become good at what they do over night. Much Trial and Error, so they do know.
Never once in Chris's Book, DVDs and Joe Barringer's DVDs was wrapping tape around a pin one of the possible repairs for your situation.
If it were, I am quite sure that it would have been included.