flat head

[Ray Rogers]

yano - 'you know'

i want to countersind the scales pass the screw through the scale thread into the liner pass through the spacer and thread into the other liner

If I understand that correctly, it seems like you still intend to try to thread both liners. If so, that probably isn't going to work for all the reasons discussed in the earlier responses. Just countersink the scale, pass through the liner, pass through the spacer, and thread the other liner. If you are worried about the strength then use a thicker liner OR use more screws.

Since you are using steel scales you could let the screw pass all the way through the right hand liner and thread into the scale if you wanted more material for threads .........

[Osprey Guy]

Bill-

I have yet to make my own folder, but I have made a lot of liner lock kits. My most recent is one of the new DDRIII folders...it is a big, brawny folder constructed in the same way as all the other liner lock kit folders designed by Darrel Ralph. Get one of these kits and this would all become so crystal clear!

There are typically two, sometimes three screws (depending on the size of the folder) holding the liners together...one liner has countersunk holes and the other liner is tapped. The screws pass through the countersunk holes, through the backspine, and then screw into the tapped liner.

The scales completely cover the countersunk screws holding the liners together. The scales are typically screwed to the liners with 2 or 3 screws on each side...(these are in addition to the 2 or 3 screws holding the liners together). Just like the holes for the liner screws, these holes are drilled and countersunk in the scales...and corresponding holes are tapped into each liner...the ends of those screws initially go through the scales, through the tapped liners, and poke through the back side of the liners (and have to be cut off and sanded down flush with the back of each respective liner).

To describe it another way, for this particular method, each of the two liners will have 2 or 3 tapped holes for the scales, and then one of those liners will have an additional 2 or 3 tapped holes for the liner screws.

I'm quite certain that two or three screws will solidly secure your 440C scales to their corrsponding liners (in other words, you'll have a total of either 4 or 6 screws securing the two scales to the 4 or 6 tapped holes).

And similarly, those other two or three screws used to hold the liners together, will also prove to be plenty strong and secure.

If only to put it together, and then take it back apart, do yourself a favor and buy one of Darrel's kits...You'll get a great education, and wind up with a respectable, nicely made, liner lock folder!


Dennis Greenbaum

Yeah Baby!

[Frank J Warner]

And here's yet another reason for the search function:

Common machinery wisdom says that you need minimum of three full threads for a secure screw hold. Any fewer and you risk stripping the hole when you tighten the screw or put any other kind of stress on it. More threads are better, which is why common SAE nuts have eight to thirty threads depending on pitch.

The designation "2-56" means there are 56 threads per inch along the length of a wire gauge 2 cylinder. (Wire Gauge: a whole other subject.)

Anyway, a little math here:

1/56 (one full thread) = .0178"

and

.040" (thickness of your liner) divided by .0178" (one full thread) = 2.24 (total number of threads)

That means, with a 2-56 screw, you've only got two and one quarter threads in a piece of titanium .040" thick. It's enough, barely, to securely hold the screw. The operative word is "barely," since ideally you should have at least three full threads.

It WILL work, but it's on the edge of unacceptable.

I like Ray's idea. If you're using steel scales, tap the far scale at the same time you tap the liner and give the screws a bit more to bite into.

-Frank J Warner

[Omega]

ok took your advise and tapped only one liner and drilled clearance holes in the other liner and backspacer, so far so good. quick question though does anyone know the diameter of the head of the flatheads from tks?

Bill:evil