Originally Posted by Spider!
What did you end up doing with the 10-32 threads?
I'm still waiting for the brass inserts to arrive. So, I actually modeled 10-32 threads in Fusion 360. Surprisingly the pump rod threaded right in without issue. They seem to be holding tight too. I'll still put out a version for inserts since I think they'll hold up better over time. But, for those who don't want to bother with that, this design actually seems to work. I can't say how long the threads will hold up, but they seem good for the time being.
I've also tweaked a few dimensions on the original model. The pump handle has a bit more drag on the body than I'd like, so I increased the inner diameter by 1 mm. I also lengthened the top of the handle a bit to close the gap at the barrel. The threaded hole was a bit close to the body too, so I moved it left by 1 mm. Lastly, I took these changes and created another version with 1 mm knurling instead of 2 mm knurling. This last part was based on input from my son who thought that the 2 mm knurling was a bit too rough on his hands. It's a personal preference thing though, so I'll end up releasing both versions.
Here's a comparison of the old knurling to the new: https://i.imgur.com/yigix7y.gifv