Can you use a #3 or #9 pin in a 2-progression MK system?

[WOT]

The official Schlage spec sheet says Schlage locks are two step progression.

Bottom pins are offered in sizes 0 to 9 in one step increments.
Master pins are offered in 2 to 9 in one step increments as well.

Schlage says their progression is two step, but they also offer #3 master pin and I just can't see how you can legally use it.


5 is legal

*(top pin)
5
2
1<bttm

yields cut depths 1,3 and 7, cut depths are in increments of 2, so it's legal.

7 is legal

*
7
2
1

yields 1,3,9

3... I can't think of a way to use a #3 master pin that follows the 2-step rule. can you?

pin total allowed = 9
#9 master can only go with a #0 bottom pin, 0+9 can't be expressed as 0+2n, so, no go.

[Raymond]

I clearly understand your confusion. The same question applies to not only the 3 wafer but also the 5, 7, & 9. When you add an even to an odd you always get an odd and when you add an odd to an odd you get an even. It would have to break the "rules." But....... I have created systems that use a three step progression. Many times when a customer wants a specific lock mastered - one that is not part of a legitimate system - then use what ever wafer makes his two keys work. In pureness of the art this is not correct but the customer is always right.

Check some of your examples for accuracy. There are 10 depths - 0 to 9. Some of the additions are not accurate but I still understand your confusion.

[WOT]

ugh. What was I thinking? my math does not add up. I wish I can erase that post.