I've been a locksmith for 40 years now, and I usually work out my own solut=
ions, but this time I could use some help figuring out a better one.
I need to modify several thousand "finger pins" so I can use keys from 2 di=
fferent series in the same locks. The pins are made of a hard, high-nickel=
brass called "nickel silver" about 1/8" diameter (actually 0.115") and are=
roughly 0.33875" long, give or take 0.00025". (Okay, I'm kidding. Contrar=
y to myth, nothing in even a high-security lock needs to be accurate to mor=
e than 0.003".) They have a short hole in one end and a "finger" sticking =
out of the side of the other end. There are a pair of cuts 1/16" wide and =
1/16" deep on each side leaving a bar that fits into a slot in another piec=
e called a sidebar. You can easily find a picture thanks to someone misspe=
lling the caption on a photo of one. Use Google Images to search for "here=
s's finger pin" and it will be one of the first images in the results. =20
Anyway, I need to make a second pair of the same kind of cuts in around 500=
of each of 4 shapes of pins and am wondering if there is a better way to d=
o it than what I've been doing.
Currently, I've modified a quick-release vice to hold 1 pin and mounted the=
vice on a lazy Susan so I can get at both sides of the pin. I put the pin=
in, and then use a Dremel flex-shaft tool spinning at 35,000 RPM with a 1/=
6" carbide 2-flute end milling cutter to make the cut on one side, spin the=
vice and make the cut on the other side. I wear a double magnifier on my =
head to see what I'm doing, and, well, my hands aren't as steady as they us=
ed to be, so the cuts don't always end up as neat and clean as I mean them =
to be. If the cutter is new, I don't have to deburr, but after it starts t=
o get dull, I need to brush off the burrs on each pin by holding it in a pa=
ir of tweezers against the wire wheel that I use for brushing off keys. I =
take a few more seconds to test each pin before putting it in my pinning ki=
t, since a bad pin in a lock cylinder will waste a lot more time than testi=
ng it before the lock is closed up.
I can modify and test 60 finger pins in two or three hours, and then I have=
to stop and do something else. (I would not make a good assembly line wor=
Is there a machine that could fit on my workbench that is designed to repea=
tedly make precise cuts on tiny pieces of metal like this? =20
If not, is there a place to look for designs for jigs or tool holders so I =
can mount the end of the flex shaft in a way that will limit how far it mov=
es? I'd like to have something where I slip in a pin, swing the tool down =
and up to quickly make the cut, and then slide out that pin and pop another=
Is 35,000 RPM the best speed to use when making 1/16" cuts 1/16" deep in ni=
ckel silver? I saw a pneumatic pencil grinder that spins at 100,000 RPM, w=
hich might make cleaner cuts faster, but might have some other problem I do=
n't know about. The cuts are so small and take so little time, that heat m=
ay not matter, but I have no experience with such a tool.
Is there a formula or something to figure out what is the best working spee=
d for a particular kind of metal and size of cut?
The carbide cutter manufacturer claims it is for cutting "Aluminum, Carbon =
And Tool Steel, Cast Iron And 300 Or 400 Series Stainless Steel," but no me=
ntion of brass alloys. Is there a kind of milling cutter that is better fo=
Thank you for any help you can provide.
10 years ago