Need a strap duplicator and/or transfer screw for 8-32 nutplate holes
 

I need to locate seven, 8/32 screw holes on the periphery of a 12" x 8" plate.

The nutplates are installed on the underside of 0.064 angle. I have to drill the holes in the plate to match the location of the nutplates.

I see strap duplicators for 10-32 (and #21, #30 and #40) and I see transfer screws for 10-32. But I don't see strap duplicators for 8-32.

Why is that?

I did see transfer screws for 8-32 at McMaster-Carr:

https://www.mcmaster.com/3385A32

but I'm wondering if they are long enough such that the threads will fetch up solidly in the nutplate (and therefore center the point) , and sill have the point proud enough to make a solid mark.

I can't find dimensions of those transfer screws.

I also saw these:

https://www.mcmaster.com/3400a12

and there are none for 8-32.

If anyone knows a source - or has a better idea for locating the holes - I'd appreciate the pointer.

Thanks!

you may struggle to get a screw started from the backside of a nutplate unless you run a tap through it first. I must admit that I have never tried that though.

Larry

FWIW I have used these hole finders to get a perfect matching hole. Then I tap them to the correct size.

Not sure if it will work in your situation.

:cool:

Template
 

You could make a template from thin clear acrylic or polycarbonate sheet 1/16 thick. First mark the holes in the template by placing it over the angle nutplates. Then transfer the holes from the template to the aluminium cover sheet by drilling through.

The clear sheeting should be available in the roofing/window department of a home hardware store like Home Depot.

Yeah those are strap duplicators. Problem is I can't find any that will snugly fit and center to an 8-32 screw hole

Several of the screws are up against the fuselage skin and against the gear tower so I would not be able to get my eye over the hole to accurately mark it.

option
 

If a mirror won't help then another option for those holes is to make them oversize in the template, fit the template, put a right sized "washer" over and and a screw into the hole, tape the washer to the template and then remove it intact for transfer to the part. Where there's a will there's a way! :)

Can you change it to a 10-32 screw or is that too difficult? Just thinking out loud.

:cool:

You could use 8-32 Allen socket set screws . Thread them through the nut plate backwards to the appropriate hight to use their point as the transfer punch

Too difficult. Mission creep.