Tuesday, October 15, 2019

Do I Need to Make This?

I need to put a 1/4"-20 screw securely in a .385" square hole.  1/4"-2- to 3/8"-16 adapter show up when I ask for 1/4"-20 to 3/8" bushings.  I need a tight square, not threaded 3/8".  I could I suppose do a .38" x .38" square, then drill and tap it, but this does not seem this odd an item to buy.

I managed to make the square so it was a press fit into the spider.  Then I drilled a pilot hole in the center.  Whoops!  Not quite centered.  I could not drill the .203" hole for tapping all the way through because I had forgotten to put something under the block in the mill vise, so I went to the drill press and ended up with a hole out the side.  Let me try this again in the morning unless someone points me to a bushing.

McMaster-Carr, purveyor of everything, has female threaded standoff, aluminum, 1.4"-20 fully threaded, 1" long, 1/2" diameter.  So just turn it down on the lathe to .385" and press in, I think,


  1. My first thought was a square nut, but a quick check has them at 7/16 across the flat on 1/4-20 threads. Milling one down is probably more trouble than drilling and tapping....

  2. Use a drop of methacrylate to make sure it stays in place