What screw size for building lock kits?

[Rolf]

I've been looking at the screw hole markings on the the Le Paige lock kits I've got from Blackley. The holes seem to be a little less than 3mm in diameter. Has anyone used #4 screws for building locks? What size taping drill should I use? I'm a bit afraid of snaping the tap in the lock plate.

Best regards

Rolf

[rich pierce]

6-40 is pretty standard.

[billd]

Like Rich said, 6-40.  I think a 3.5 x 0.6 would be as close as you could get.  Nothing wrong with using metric if you have the screws to match.

Bill

[DutchGramps]

I prefer the old coarse Whitworth threads, like 1/8"x40, 5/32"x32, 3/16"x24 and 7/32"x24. There must have been some imports into the USA of these taps and dies from the mid-19th century onwards. And even today you can obtain them quite cheaply from Tracy Tools in the UK!

[keweenaw]

Some of the European locks used smaller screws than #6 for some holes and some makers used countersunk screw heads as well.
This is a Manton V pan lock

[wmaser]

I use 6-32

[Odd Fellow]

I worked on a larger early lock and used 8-32