Failed to impression: DOM RN euro-profile

[mapafe]

I'm having trouble impressioning DOM RN euro-profile cylinder locks. The lock gives very clear marks on the key, until a certain point after a "false-set" (few degrees of rotation, but no opening). I suspect this is related to the "torpedo" shaped key-pins. I'll use this topic to document my research into this issue. Any ideas/suggestions are more than welcome!

The DOM RN lock:

dom_rn_front.JPG

The torpedo shaped key-pin:

dom_rn_torpedo_pin.JPG

I use a Silca CB6 brass blank for impressioning this lock.

Next steps:
* Document the exact point at which markings on blank key fail to appear
* Isolate which pin (combinations) fail to mark the key

[mapafe]

I took a photo after every impressioning step (= look for marks, file, take photo), so I can see the progression. Pin 4 is the torpedo pin. It stops marking in step 20, and in step 21 there were no markings of any pins at all.

Animated GIF, click to open the image to see the animation

dom_rn_impressioning.gif

In an attempt to get markings I tried many techniques; various types of wiggling and the "pull-out" method. None of them yielded any pin marks for pin 4. The normal wiggling movement does appear to feel different when it's hung up on this torpedo pin, but I cannot describe the feeling.

After filing cut 4 another 0.2 mm deeper, pin 4 starts marking again, so I could finish impressioning.

Solutions I tried:
Visually detect any torpedo pins in the lock by peering down the keyway
This works reasonably well, but it gets hard after pin position 3. Not all torpedo pins are copper, I also have a lock with a stainless steel torpedo pin.
Detecting torpedo pins by touch
No luck so far.
Adding ink to the blank with a permanent marker
Does not yield any good pin marks.

Solutions to try:
* Altering the blank key for a more "sloppy" fit
* Filing the blank exactly on pin depth

[JamesOzment1]

a key clipper would help cut each progressive depth better,but not getting marks from the pins leaves you no clue as to which stack to clip.I will have to think about this for a while...

[JamesOzment1]

I apologize for the double post.the torpedo pin will stop marking untill it becomes the binder pin again .once all the other pins are cut to proper depth it should begin marking again.try more rotational force as you wiggle.I had issues with a custom schlage I built I just used more force.

[mapafe]

I apologize for the double post.the torpedo pin will stop marking untill it becomes the binder pin again .once all the other pins are cut to proper depth it should begin marking again.try more rotational force as you wiggle.I had issues with a custom schlage I built I just used more force.

This is indeed what you would expect; only the torpedo-pin is binding, and as it's binding, it should leave marks on the blank. Except that it doesn't! I suspect the shape (and perhaps the material, copper being soft) was specifically designed to defeat this technique.

To reduce the complexity of the problem I emptied all pin chambers except for the 4th stack with the torpedo-pin. I then impressioned the lock again, and it gave me the same behaviour. Only the 4th pin is binding, yet it isn't giving any marks on the blank key.

I tried your suggestion of more force; even switched out my small Vise-grips for big 20cm Vise-grips (extra leverage), and wiggled the key up to breaking point. There's only the faintest polishing mark; so faint I would not call it a "mark" (non-binding pins sometimes give me these faint polishing marks).

Next step; grind down the warding on the blank key to create more "wiggle-room".

[Oldfast]

This is indeed what you would expect; only the torpedo-pin is binding, and as it's binding, it should leave marks on the blank.....

lol, I too expect that it would/should mark. But it seems you've found otherwise.
I like the research you're doing. I found your 'time lapse' photos interesting too.
Keep up the good work. Looking forward to hearing about it.

[jones]

I wonder what shape the part of the bottom pin that touches the key is. I know some pins just don't mark very well, maybe smoking the key or using a marker would help

[Altashot]

Dom locks are high quality locks. Their tolerances are very small, thus more difficult to impression.
If I remember correctly, the bottom pin are rather quite blunt and possibly distribute the force over a larger
area on the blank, so the marks are not as obvious as if they were pointy.

I too file off some of the warding to get more wiggle with the blank sometimes, I've even filed the bottom a few thousandths to achieve the same result.

Some impression easy, some are really hard and there are some I couldn't impression at all...
maybe it depends on where the torpedo pin is located, the length of the pin it sits on, or the pins before and after it, or the entire bitting?

M.

[mapafe]

I wonder what shape the part of the bottom pin that touches the key is. I know some pins just don't mark very well, maybe smoking the key or using a marker would help

The key pin is the "torpedo"-shaped pin pictured in the first post. All key pins, including the torpedo-pin, give very good marks while impressioning.

[mapafe]

Dom locks are high quality locks. Their tolerances are very small, thus more difficult to impression.
If I remember correctly, the bottom pin are rather quite blunt and possibly distribute the force over a larger
area on the blank, so the marks are not as obvious as if they were pointy.

All pins (including the torpedo-pin) give really good marks while impressioning, until the point torpedo-pin "catches".

I too file off some of the warding to get more wiggle with the blank sometimes, I've even filed the bottom a few thousandths to achieve the same result.

I have yet to try this.

Some impression easy, some are really hard and there are some I couldn't impression at all...
maybe it depends on where the torpedo pin is located, the length of the pin it sits on, or the pins before and after it, or the entire bitting?

M.

I tried to account for these variables by removing all other pin stacks, leaving only the torpedo-pin behind; same behavior. I will experiment with different sized/material torpedo-pins in different configurations.

[mapafe]

I think I just discovered why the torpedo-pin stops making marks on the blank key, even though it's the (only remaining) binding pin in the lock.

The torpedo-pin gives very clear marks on the blank key, up until the point where only the "tail" of the pin (see arrow in image below) is protruding from the plug.

torpedo-pin-where-it-catches.png

At this point, any rotational movement of the plug (like the CW and CCW torque we use to bind the pins during impressioning) will cause the "tail" to catch and slightly lift the pin out of the plug, away from the blank key. So after applying torque, the torpedo-pin will bind firmly, but no longer contact the blank key, thus no longer leaving any marks.

You can see the "tail" catch in this frame from the animation posted above; this is the frame where the torpedo-pin stops marking the blank key:

torpedo-pin-when-it-catches.jpg

torpedo-pin-when-it-catches-zoom.jpg

I'm not sure whether DOM designed the torpedo-pin specifically to defeat impressioning attacks, but from now on I'll consider it an "anti-impressioning pin"!

Now how do we defeat this "anti-impressioning pin"...?

[mapafe]

Solutions to try:
* Altering the blank key for a more "sloppy" fit

Just tried this; made all the lengthwise warding-cuts in the key blank deeper, and removed material from the bottom of the key blank. This created a very sloppy blank key, but the torpedo pin still doesn't leave a mark when it's caught as described above.

[GWiens2001]

With some spooled key pins, have had to take a risk and pick a pin stack (usually a higher key bitting location) and just start filing again. After a couple depths of cut difference, if it did not work, make another key at the previous depths, and pick another pin stack to try.

Gordon

[mapafe]

With some spooled key pins, have had to take a risk and pick a pin stack (usually a higher key bitting location) and just start filing again. After a couple depths of cut difference, if it did not work, make another key at the previous depths, and pick another pin stack to try.

Gordon

This is also the only approach I've come up with; File a copy of the impressioned key so far. Then, starting with the first pin stack, file deeper, and hope that this pin starts binding again (and it not "over-cut"). If the lock doesn't open; make another copy of the original impressioned key, and try with the second pin stack, etc. Sadly it's quite a wasteful and time-consuming approach..

Small optimizations:
* peer down the keyway to visually identify torpedo-pins / spooled key-pins; or at least identify which ones are not spooled pins; you can leave those until last
* try the deepest cuts (highest bitting) first

I have a medium-cut torpedo-pin that I can test the last optimization with.

[jones]

It looks like You could just measure how much further till the torpedo pin is in the right position & when it stops marking, just cut another 20 to 25 thousands & leave that pin alone, after that until all the other pins are done marking