From: yerazunis@cthulu.enet.dec.com
Subject: Re: Rekeying locks
Organization: Turing Police
Date: Thu, 20 Aug 1992 22:06:20 GMT


In article <1992Aug20.183046.23796@watson.ibm.com>, Larry Margolis <margoli@watson.ibm.com> writes...
>> The rekey kit comes with 2 keys.

Minor nit: if you buy a "rekey kit" that includes keys, make *sure* that 
the key that comes with the rekey kit fits into the cylinder!  Otherwise,
you end up having a big problem!

Of course, if you buy the correct rekey kit, it should all just go together 
with no hassles.

>If you don't want to buy the kit, you can just swap pins around in the
>lock, or you can buy a few different size pins (I think they were about
>a dollar a gross last time I bought them at a locksmith wholesalers).

Swapping pins around is amazingly effective.  Assuming a non-mastered
system (one cut per pin), five pins, and five cut levels, there's 120 
different configurations available.  If you rekey every month, it
will take you ten years to go through them all.

Rekeying to a "desired new key" is also easy- put the key into the
cylinder, put pins that are either just long enough or a tad too
long into each pin-hole, and file 'em smooth (be careful and try to
avoid putting a flat spot on the cylinder...) Then dump the pins
out and file a little chamfer around the filed top of each pin (basically 
just plain old deburring is usually enough.)

One-level mastering is also easy this way- Assuming that you want, say
one key that opens every lock on the house (front door, back door, 
detached garage) and one that opens only the detached garage (so the 
gardener can get to the lawnmower). Cut two arbitrary keys- no, not
quite arbitrary- they both need to be cut from the same blank, and
one key (the gardener key) must be cut to as deep or deeper than the 
owner key at each cut level.  For example, if the cut levels are 0 for
no metal removed, and 6 for removing all the metal down to the first
lengthwise groove, then (for 5-pin locks) :

                    keyhole   keyhole
		    front      back

an uncut blank is:	0 0 0 0 0

the owners key is:	3 1 5 2 4

the gardeners key is:   3 4 5 2 6

The reason for cutting the gardener's key always as deep or deeper is 
that it then becomes impossible to for the gardener to turn his 
garage key into a front-door key, just by filing it down in a couple
of places.  (Yes, he could just get another blank too...).  Note
that three of the five cuts are the same depth- having more cuts the
same makes it easier to "eyeball" how to turn the garage key into
a front-door key, and having more cuts different makes the lock 
easier to pick.  Judge the tradeoff professionally... remember you 
can add some ringed or mushroom drivers if you're worried about
picking.

Another hint: make sure that all pins that are cut differently are 
at least 1/8" different- this means you don't end up with little
wafers of drifter material- the lock goes together easier and the 
lock works well for lots longer.

Now, put the owner key (the key with the higher cuts in it) into the
cylinder core.  Fill the pin-holes with pins that just match or are
a bit high.  File, if necessary.  Remove the owner key but don't dump 
the pins out of the cylinder.  Insert the gardener's key, and add
"drifters" to the pinholes that aren't quite filled up (in this case,
the second and fifth pinholes will need drifters).  File the drifters,
if necessary.  

Now, carefully dump the drifters and pins.  Deburr them all with your
file or an appropriate tool.  Reinstall the pins first- verify that they
work with the "owner key".  Add the drifters, and verify that
they work with the gardener key.  Slide the cylinder into the core, add
the drivers, driver springs, and spring cap, and verify again that both
keys will work the lock.  You now have completed the core for the garage.

Build the cores for the front and back doors the same way, but only
use the "owner key".  This means there are no drifters, just pins and  
drivers.  

-----

Or- you can use a manual that gives pin and drifter lengths and keycuts all 
"by the numbers" if you want.

-----

Exercise for students:  How would you key a system that needed
three keys (gardener/garage, maid/back door, and owner/all locks)?
Hint: two of the three doors will need wafers.

-----

Cheap shot: when really stuck, an 8 penny nail makes good drifter stock...

	-Bill

Copyright 1992 William S. Yerazunis (aka Crah the Merciless)
All rights reserved, no responsibility taken.

     "Where does he get those wonderful toys???"
Newsgroups: misc.consumers