Information on counterbore/countersink for folder handle scales

[Misanthropia]

So I've finally decided to take the plunge and try and make handle scales for my Emerson Mini Commander. The most arcane part of this whole thing is trying to find out what countersink or counterboring equipment I need for the handle scales. I know I would need to counterbore the pivot and countersink the handle screws, but can anyone shed more light on this whole thing? I'm not very mechanically inclined so all of these numbers and sizes are starting to hurt my brain

 

[1husaler]

Well I will take a stab at it! Countersink- is preformed after a hole is placed and will allow a fastener to lay flush with the intended material. A "special" bit is used to achieve the countersink and can be purchased at your local hardware store. Be careful for they do come in various sizes so be sure to choose the correct one. Also pay close attention to your depth for it is very easy to go too deep when using a hand drill. Now the fun begins! Boring- we use a Bridgeport milling machine for this process. Using the correct size end mill we plunge the scale to the specified depth(.046 example). They do make counterbore kits to do this with a drill but its hard to maintain the correct depth and keep a 90* angle at all times. The YARD STORE sells these kits, lots of $$$$. You can find a small local machine who could preform this step for you for a reasonable price. We would normally charge $10-15.00 for this on a slow day and sometimes nothing at all! I hope this helps!

 

[tiguy7]

Countersinks are used for flat head and oval head screws. Be aware that they are available in several tapers. IE you can get countersinks with 60,90, and 120 degree inclusive angles. Be sure to match the angles on your screws with the ones on your countersinks.
Counterbores are used with cap screws, pan head screws, round head screws, etc. that are flat on the under side of the head. I like to use counterbores that have a pilot on the tip. The pilot fits into the screw clearance hole and keeps the counterbored hole concentric with said clearance hole.
There is quite a bit of information on CS and CB standards on Google.

 

[phillipsted]

I've got a wide variety of counterbores for scale work - they are incredibly useful and make a nice clean looking hole for the screw head. However, my favorite among them are the "step drill bits" sold by some of the knife making supply houses (e.g., Step Drill Bits). They make nice clean holes.

TedP