Plate Bushings

[A440A@AOL.COM]

 Newton writes:

<< Is there anyone out there who has a source of 0.500" plate
bushings? >>

Greetings, 
    Last time I had need of these, I stacked a pair of the smallest ones in 
there, I think they were 1/4" but may have been 5/16".  I leveled them to the 
top of the webbing with a block, and sanded the underside (pinblock side) of 
the plate to level any that protruded slightly down.  I needed to clamp a 
block down on the top to keep the sander from pushing them back up, but it 
left me with a very even and clean appearance on the top, and  no 
interferance below.   
  Will that work here?\
Regards, 
Ed Foote RPT