Tiny set screws on new pinions

[Chuck Keysor]

Hello Shopbot Friends:

In 2017, I bought a full set of 5 new 20 tooth pinions from Shopbot ($125 total). I noticed today that the set screws on the new pinions are really tiny, and neither the metric or English Allen wrenches fit right!

I have a full set of metric and English Allen wrenches. The best fitting English allen wrench measures .091" (3/32), but it is a little bit loose. The best fitting metric Allen wrench measures .096", and I can not even force it in........ close, but not quite...... (Hmmmm, added note, .096" doesn't convert into a nice metric,,,,, so this set screw isn't even even close to a metric size.)

The set screws on my old pinions accept a .125" Allen wrench, and the fit is perfect........

I am afraid to use these new pinions, especially for holding up my 5HP spindle on the Z axis, as even if the Allen wrench fit right, I can't imagine being able to really torque these things on tight. With the loose fit, I think it would be foolish to hope these would be reliably tight. (Especially since getting at this pinion later, is really difficult.)

I have thought of:

1) reusing the best of my old pinions for the Z axis, since I know I can really tighten it and it won't come loose. The best used one is only slightly worn.

2) drilling out the holes on the new pinions and tapping them with 1/4-20 holes. (I have only done tapping of soft steel before, and had good luck..... but are these pinions hardened, such that I might expect to have problems? I'd hate to mess up my expensive pinions.)

3) Other ideas????? And I wondered, why on earth would the new pinions have such tiny set screws,,,,, and why would they not match either metric or English wrenches????? (does someone have an adjustable Allen wrench I can borrow??? )

Thanks, your input is greatly appreciated! Chuck