Bob - Do you really think that a discussion of material is pointless? If I were planning to do this mod, and someone had info about getting better results with a different material, that's exactly the sort of thing I'd want to know about.
No lock screw has been necessary. Other than when I have taken the saddle off, I have not even had to adjust them after the initial break in.
With the little I have had to adjust them, If I were making them again, I would forego the taper all together. Just make the holder face and gibs flat and put adjustment screws in from the bottom.
Your tapered gibs look great!
I shimmed my gibs on the mini lathe and it worked great.
I read that the underside of the bed gets a little thick near the tailstock on most mini lathes. Mine definitely was thicker near the tailstock, and required scraping followed by lapping of the underside of the bed to make it the same thickness all the way across.
did you run into this variation on your mini lathe?
Blue Skies!!
Chris