what is the proper drill bit size (metric or standard) to use to dril pilot holes for those little silver wood screws that came with this old futabe pcm radio?

Servo screws? I'd use a 1/16"

When it comes to bit size, as a general rule I will select the bit that is a hair smaller the width of the center column of the screw as if you had taken off the threads of the screw. This works well especially for the smaller sizes.

i tried 1/6 and it was to big. Futaba lists them as pan head truss screw part # 550360 in the manuel. I think they still come with every radio they sell. The screws go through the holes on the servo and then through a small brass sleave and then they can be screwed into a wood servo mount if the supplied plastic or nylon servo tray is too big to fit in the fusalage. The radio is a disscontinued Conquest PCM FP-T4NBP or just 4NBP on their website.

jsesere,

1/16" or 1/6" ?

1/16" is a tiny drill bit. If these are servo mount screws you're drilling through a relatively thin depth of wood for the screw, which is why I recommended a tiny 1/16"

And even though I agree with Kitbuilder, just last weekend, as an example, I drilled 1/16" pilot holes into a Fender Precision Bass for a friend of mine to mount Fender string mutes using screws that were a little too big for the pilot holes - I was sweating bullets but I didn't want any vibration in the Bass - and so you can go with smaller pilot holes sometimes but in a full depth hole you have to screw the screws in very slowly and carefully, making sure it's not so tight that the screw breaks - which happens.

Hi...
Here is a link that will help


http://www.littlemachineshop.com/Reference/tapdrill.php


bert