PDP8 key (Was: Text encoding Babel.

Fred Cisin cisin at xenosoft.com
Fri Nov 30 22:38:00 CST 2018

>>> Or, if you prefer, I can dig through some old posts on this list, and tell
>>> you the depths of the cuts for XX2247.  It has been widely discussed a few
>>> years back.
>> On Mon, 25 Apr 2011, Ethan Dicks wrote:
>>> 1 - 0.0155"
>>> 2 - 0.0310"
>>> 3 - 0.0465"
>>> 4 - 0.0620"
>>> 5 - 0.0775"
>>> 6 - 0.093"
>>> 7 - 0.1085"
>>> 8 - 0.1240"

On Sat, 1 Dec 2018, Guy Dunphy wrote:
> How come there are 8? The lock only has 7 pins.

Those are not the depths of this key.  Otherwise, it would just be a ramp!
Those are the "standard" depths for the different key cuts on Ace locks.
I think that those are the OFFICIAL depths.  Expect a little variance.
(as shown in the measurements listed below)

Lock manufacturers have a very limited number of different depths.  in 
this case 8 different depths.  The "key code" is a list of the depths 
used on a given key.  Then, each combination is given a totally arbitrary 
number, in this case "XX2247". An arbitrary number is used, rather than 
the depths, so that the number can be stamped on the key, but somebody 
looking at the key and reading the number won't be given the actual 
depths, without having to measure.

A locksmith will look up that arbitrary number in a "code book" (now 
usually online), which will use that arbitrary number as an index into a 
table, and give back the specific keyblank, and the list of cuts.  In this 
case, looking up "XX2247" gives back "Ace tubular blank, cuts: 5, 1, 7, 3, 
7, 5, 7"  Each manufacturer has their own names for the same blanks, such 
as "Ilco 1137"
The locksmith then looks up "depth and spacing" for that line of lock, 
which tells him how far apart the pins are, and what the standard depths 
are.  (Q: "How deep should a # 5 cut be?"    A: 0.0755")

On your HOUSE key, for example, there will probably be 5 or 6 cuts, each 
of which will be one of 10 possible depths.
House keys instead of an arbitrary number will often have the depth 
numbers stamped on the key.
"Depth and spacing" tells how far from the stop each of those cuts will 
be, and what the standard depths are for that brand/model of lock.

There will usually be 7 cuts.  Each one of which can any of those 8 
possible depths.
means one pin at depth #5 (0.0775"),
followed by the next pin being at depth #1 (0.0155"),
then a pin at depth #7 (0.1085"),
then a pin at depth #3 (0.0465"),
then another pin at depth #7,
then another pin at depth #5,
then another pin at depth#7

After you cut your key, stamp "XX2247" on it, so that you will know which 
of your keys is the one for the PDP8.

Here's another post with less assumption of locksmith terminology:

> On 25/04/2011 04:37, Vincent Slyngstad wrote:
>> Patrick is correct -- there appear to be 7 cut positions, one of which 
>> actually uncut.
>> Looking down the barrel of the key with the tab in the 12:00 position, 
>> reading clockwise, I measure approximately 0.8", 0.0", 0.11", 0.44",
>> 0.11", 0.8", and 0.11".
On Mon, 25 Apr 2011, Pete Turnbull wrote:
> You've apparently misplaced the decimal point :-)  A 0.8" cut, which is 
> 3/4", would be longer than the key's tube...
>> Actually, rechecking this with the 10x magnifier and reticle (more
>> accurate) gives right at 1mm, 2mm, and 2.6mm for the 3 depths
>> of cut.  (That's 39, 79, and 102 mils).
> Here's what I got from two original XX2247 keys:
> tube OD 0.377" (9.58mm), tube ID 0.310" (7.87mm).
> The cuts are arranged in 7 out of 8 evenly-spaced positions around the 
> circumference of the tube; the eighth position is occupied by a
> rectangular-section key approx 1.5mm wide, and 1mm deep inside the tube,
> about 1.3mm high on the outside.  The outside part of this key is short,
> extending from approx 0.8mm from the end of the tube to about 3.6mm 
> while the inside part extends almost the full length, from about 0.8mm
> inside.
> The cut depths, clockwise from the first position, looking into the open
> end with the key at the "twelve 0'clock" position are:
> Key 1         Key 1           Key 2           Key 2
> 0.0770"               1.94mm          0.0785"         1.95mm
> 0.0150"               0.37mm          0.0155"         0.39mm
> 0.1055"               2.68mm          0.1070"         2.72mm
> 0.0435"               1.13mm          0.0455"         1.13mm
> 0.1075"               2.72mm          0.1085"         2.74mm
> 0.0780"               1.96mm          0.0785"         1.98mm
> 0.1075"               2.72mm          0.1095"         2.77mm
> These are actual measurements from a depth micrometer.  As you can see 
if you
> do the conversions, it's not easy to get consistent results; the ends of 
> keys aren't perfectly flat.
> Key 1 has "Chicago Lock Co", "ACE" and "DO NOT DUPLICATE" stamped on it 
> last in quite small letters).  Key 2 looks older but has the same 
> slightly differently arranged.

More information about the cctalk mailing list