Can I enlarge the mounting hole on Mosfet?

[BillEpstein]

The nylon shoulder washers I have to isolate the devices (Mosfets, current regs, diode bridge) from their TO-220 heatsinks are a smidge too big to go through the mounting holes in the various devices. Can I ream or drill out the holes slightly without damaging the devices?

 

[AndrewT]

The nylon shoulder washers I have to isolate the devices ..... from their TO-220 heatsinks are a smidge too big to go through the mounting holes in the various devices. Can I ream or drill out the holes slightly ....?

To220 devices have a metal tab. It's usually plated copper.
Easy to ream out. The slightly tapered hole makes it even easier to insert the top hat.
Ream out the minimum to make the top hat a push fit, not a slack or rattle fit.

 

[TheGimp]

Be sure to debur the back side so you don't pinch through your insulator.

 

[jcx]

since it is a soft copper alloy messing with the tab can easily bend it - causing large gaps in the heatsink interface when bolted