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PostPosted: Fri Mar 22, 2013 11:14 pm 
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Joined: Thu Nov 12, 2009 12:36 pm
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Location: Mexifornia
Hello all, long time no post. I’ve discovered a neat trick for my small mill and thought I’d share. It makes a dandy key cutting machine.

Recently, I work for a real estate company that rents properties. When a tenant moves out, the locks must be changed right away. We use Schlage locks on our properties, so all info below pertains only to Schlage C keyways (the common 5-pin configuration). When rekeying a lock, you can choose any particular pin combination that suits your fancy. The new key is usually cut with a key cutting machine, or a key punch. I’d sold my key cutting machine years ago, not thinking I’d ever need it again. But rather than buy another, I gave cutting keys on the mill a shot, and it works really well. I think it’s actually more accurate than a key cutting machine, because when I rekey the lock to match the cut key, the pins are dead-on where they should be at the shear line…no adjustments necessary.

Just a couple things are needed. First, a 90 degree countersink, 3/8 in diameter. Purchase one that comes to a point (Enco sells none, but McMaster-Carr does). Then flatten that point ever so slightly on sandpaper. The flat is .035 on a from-the-factory key. I widen mine a bit more than that to .055 so I have a little more leeway if I’m not exactly precise on where the pins are cut on the X-axis. (The cut on the X-axis can have some "slop." The Z-axis can have almost none.) See the modified countersink below...

Image

Next, you need a parallel that’s a few thousandths narrower than the key blank. You probably have a nice narrow parallel set. I didn’t, so had to make my own…what a pain to machine something so thin.

Image

Next, I follow this process: Clamp the key in the vise with the bow to the left. Dykem the key. Edgefind on the shoulder of the key and zero the X axis, then center the quill (CCW .100 for my .200 edgefinder), then CW .007 to adjust for backlash (unique to my machine), and zero again. Now move .100 away from the shoulder of the key. Inset the keycutting bit. Crank the Z-axis up to .000 on the scale. Now lower the quill to lightly contact the key (which you’ll recall is now positioned .100 to the right of the shoulder). Remember the tip has been flattened, so this direct contact is OK, you'll not cut anything or damage your bit (the key blank is brass, anyway...no worries). Clamp the quill. Move the X-axis from .100 to .231, the correct L-R placement for the first cut. Move the Z-axis to the appropriate depth for the cut, and move the vice in the Y axis to make the cut.

All you need now are the Z-axis depths that match Schlage pins, and the various X-axis locations (which are .156 from each other, starting at .231). Here’s my cheat sheet.

Image

Feel free to ignore the column headed “Seig X3” because an X3’s Z-axis is graduated in .0005 rather than .001 like a respectable mill, so on an X3 you always have to remember to “double” the cut depth. I also have a column for Schlage pin sizes, and “Key Area” refers to the area you pinch between the bottom of the cut and the bottom of the key when you measure a cut with calipers or a mic.

Here's a shot of a key that allows you to compare the mill-cut profile (in back) to a factory cut key (in front). On the back key, the last two cuts (at tip) are made on the mill. Notice mine are slightly larger at the base (as I wanted, for greater tolerance). The larger base would limit having a very deep cut next to a very tall cut. I probably could not cut a 0 cut or a 1 cut next to a 9 cut with my wider base. But such variances are frowned upon anyway, being very hard on the lock.

Image

The last step is to file the "peaks" that are between the cuts...all they do is add wear to the lock, so I generally soften them. This allows the key to slide in and out easily, and greatly reduces wear on the lock's springs.

Suggestions for further improvement appreciated.

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PostPosted: Sat Mar 23, 2013 1:21 am 
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Joined: Tue Mar 27, 2012 12:37 pm
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Location: Silly Cone Valley
I had thought of making a tracer attachment, just a hinged jig that would hold the master and blank, with the master riding on a fixed blade and the blank against a small end mill, or 90 degree cutting wheel (actually thought of it for my lathe, but could be adjusted to a mill). This would basically duplicate how a standard key duplicator works. But your method is good when a master is not available - you can make a key from a key code. I wonder how many key combinations there are?

5 pins, 10 positions each, so 10x10x10x10x10, a hundred thousand minus about 10k problematic combos.

Actually, a single bump key will open them all... :(

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Logan 10x24 Lathe, RF-30 Mill, 20 Ton Press
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PostPosted: Sat Mar 23, 2013 9:28 am 
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Joined: Thu Nov 12, 2009 12:36 pm
Posts: 102
Location: Mexifornia
I would like to see a mill converted to a key duplication machine, that would be interesting. Never seen a lathe converted, but as you say, that's what a key duplication machine is, a small lathe. To duplicate a key with this setup, you'd first have to mic the existing key and then use those measurements to cut another.

The perpetual problem with duplicating keys is that you don't know how much wear is on the original. My local ACE hardware willy-nilly adds about .010 to the height of each cut, "to compensate for wear." Which means, if you dupe a new key, the copy won't work!

For my work I actually find it easier to just open the lock, re-pin it, and cut an entirely new key. I always specify pick-resistant combinations with highs and lows, and use good springs. No modestly priced lock is guaranteed resistant against a bump key, a pick, a pick gun, or a drill, but a good lock will keep out 99.9% of the population, and that's worth something.

Any suggestions on how to improve this sequence?

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PostPosted: Sat Mar 23, 2013 10:24 am 
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Joined: Sun Dec 16, 2007 12:41 pm
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Location: Palo Alto, CA
Bolsterman wrote:
. . . that's what a key duplication machine is, a small lathe.


I see a typical key duplicator as a sort of simplified horizontal mill. . .

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PostPosted: Sat Mar 23, 2013 10:36 am 
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Joined: Wed Jan 30, 2013 10:51 pm
Posts: 68
Location: Cheyenne
I have a key machine I would sell if anybody is interested.


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PostPosted: Sat Mar 23, 2013 12:57 pm 
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Joined: Mon Jan 14, 2008 7:49 pm
Posts: 286
Location: Upstate NY
Not really addressing the question but perhaps of interest to the originator, we have found an easier way to deal with lock changes related to ski condo rentals. We bought 10 extra door handles and we change door handle rather than locks. Removed door handle goes in the box and a random one comes out. No re-keying and we can replace a key by just ordering the correct number.


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PostPosted: Sat Mar 23, 2013 2:08 pm 
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Joined: Tue Dec 22, 2009 12:36 pm
Posts: 851
Location: Vancleave, Mississippi
What a great way to cut keys.

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PostPosted: Sat Mar 23, 2013 3:44 pm 
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Joined: Wed Dec 12, 2007 11:21 pm
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Location: savannah ga.
Popular with large apartment complexes and many commercial users...

http://en.wikipedia.org/wiki/Interchangeable_core


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PostPosted: Sat Mar 23, 2013 8:57 pm 
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Joined: Mon Feb 20, 2006 11:04 pm
Posts: 4075
Location: mid atlantic
A milling type key cutter is a miniture tracing mill. A Best lock core was beyond that, for me anyway. They had slightly different angles to where the key pins would rotate the lock pins to vary their height. It was a big deal to convert a thousand doors but not anyone had the knowledge or codes to defeat one. I tried once to my ability on a decent key machine. I could duplicate Shlage or anything with similar blank Sometimes you have to mill off one side or groove first but it worked for the standard locks.
Being able to duplicate a key on a mill takes a lot of initial work. I don't even remember the .156 spacing. I remember it took too long for me but if you know that on your mill, you're pretty good at making other parts.


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PostPosted: Sun Mar 24, 2013 8:03 pm 
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Joined: Mon Jan 28, 2013 1:38 am
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Location: Como, CO
Or just buy re keyable locks.


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PostPosted: Tue Mar 26, 2013 4:17 pm 
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Joined: Sun Jul 08, 2007 7:39 pm
Posts: 425
Location: Tigard, Oregon
Or the mechanical resetable key lock, slide in the existing key, insert a "learn tool" , slip in the new key you want to use, and its done,,,
I spent a few years building tooling and gages for the lock pieces but have never seen one personally,,
the lock set is called "kwikset" ,might find it interesting to look at them?
Grant


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PostPosted: Tue Mar 26, 2013 7:45 pm 
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Joined: Tue Mar 27, 2012 12:37 pm
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Location: Silly Cone Valley
Had a locksmith tell us kwikset was not re-keyable and that schlage was a better lock. Maybe he just dealt with schlage...

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Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Logan 10x24 Lathe, RF-30 Mill, 20 Ton Press
Disclaimer: I'm just a guy with a few machines...


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