Masterkeying Lessons

[Raccoon]

1. Check to make sure your lock can take a MACS of 6. With Key 4, the fourth cut is 2 and the fifth cut is 8. 8-2 is 6 and that would exceed a MACS of 5 (which is a pretty common value).

2. Work out your pinning from these keys. I see an excessive use of master pins that are unnecessary unless you are paranoid of someone taking apart the lock to determine the master key's bitting. In your system, every chamber has a master pin, when all you really NEED are two chambers with master pins. The other 3 pinning/bittings can remain identical between master key and change key, unless you need room for expansion.

To go into this more, let me give you this example:

TMK = 02468
CK1 = 93267
CK2 = 41552
CK3 = 22146
CK4 = 99999

These locks can all be pinned to accept the above change keys and the master key. The pinning is arbitrary, but as long as a second sheer line matches up with the master key, it still "works". It's not good or purposeful in any way, but still works. It will also be easy to pick.

Try

TMK = 02468
CK1 = 02462
CK2 = 02464
CK3 = 02466
CK4 = 02448

Work out the pinning for the above example, and see how few master pins are required. Note how cuts 1-4 have the same bitting as the master key, until CK4 where the 5th bitting is the same but the 4th is not.

3. Look up the term "rotating constant". It is good to rotate (use apparently random) chambers so that progression cannot be easily identified when comparing 2 or 3 keys from the system.

4. At this point, there are really so many things you can do. Try making it so that a Grand Master Key can open all 4 locks, and 2 (sub) Master Keys can open a pair of locks each, including each lock having its own change key.

[Eyes_Only]

Thanks for the input. I'm using a Schlage lock and the MACS is a 6 so I don't think 2 and a 8 cut next to each other would cause a problem.

I like the second example you layed out, really simple to understand and follow but the FB course specified not to use a change key with the same bitting in the same location as the master key. Thats the main reason my draft came out kinda funky.

[zeke79]

Schlage has a macs of 7 actually. Just so you know as it may help you along the way .

[Eyes_Only]

7? Thats weird, my LAB pinning kit says 6. But then I just checked the dlaco archive and it does say 7 there. Hmm. Maybe I should invest in a HPC depth and spacing book.

[zeke79]

Personally for a depth and space book I would buy the framon book. It does not contain macs info however . It is however much more comprehensive on S&D info.

[Raccoon]

I would trust LAB's pinning kit over DLICO.

What we need here is someone to write an algebraic or calculus expression to calculate the MACS of a pinning spec.

s = spacing (center to center)
k = kerf (width of cut)
a = angle of cut
i = increment of depths

all values measured in the same units
use 1/2k for center of cut to bottom of slope
use 1/2a for angle of slope (a is full angle of both sides of the cut)

determine MACS confidence by how far into 1/2k the adjacent cut has gone. once it has passed 1/2k (center line) then the key will no longer function.

(k = 0.052")
MACS 4 = 0.000" (-1/2k = 0.027")
MACS 5 = 0.000" (-1/2k = 0.027")
MACS 6 = 0.012" (-1/2k = 0.015")
MACS 7 = 0.067" (-1/2k = -0.040") x

So a MACS of 6 would suffice, leaving enough flat portion of the key (at worst peak k = 0.030" instead of 0.052" when two 6 cuts on either side). A MACS of 7 would not work, because the wheel went 0.040" over center.

Such a formula can be useful if you are cutting with a generic angle/width cutting wheel, and not a manufacturer spec wheel.

[UWSDWF]

odd, my lab kit lists schlage as 7

[selim]

When you guy's start talking about MAKs there all different ! Maybe not now , but what if you have to deal with Corbin Russwin,they have so many different shit throught the years that theye even have a book to look up the certain keyway to figure out the MAKs. It's all about knowing what your dealing with (one step two step progresion,or more ) Learn how the KBA (key bitting array ) works ,and try it on paper a few times. I't's fun for a while until you have to do a GGGM system ,software does make it easy,but how many gost key's will show up ?Maybe I just don't like the way theye do it these day's but it does make it easy. Theye wan't everyone to carry one key to make it conveinte for them,but how safe is a building when everyone has a key ??

[Schuyler]

When you guy's start talking about MAKs there all different ! Maybe not now , but what if you have to deal with Corbin Russwin,they have so many different road apples throught the years that theye even have a book to look up the certain keyway to figure out the MAKs. It's all about knowing what your dealing with (one step two step progresion,or more ) Learn how the KBA (key bitting array ) works ,and try it on paper a few times. I't's fun for a while until you have to do a GGGM system ,software does make it easy,but how many gost key's will show up ?Maybe I just don't like the way theye do it these day's but it does make it easy. Theye wan't everyone to carry one key to make it conveinte for them,but how safe is a building when everyone has a key ??

Maximum Adjacent Cut Specification. MACS

now you know

[Schuyler]

And I hope that didn't sound short or condescending or anything, sorry if I did. You obviously have some experience in these matters. I assume it's just one of those things where you hear it verbally and never need to write it down, then one day you find out it's different that you had it in your head.

[Raccoon]

But it should be pointed out that the MACS value is static as long as 3 variables remain the same: The depth/space specification, the cut width, and the cut angle.

It's important to know that, if you're cutting a key for a brand of lock that specifies a narrow cut-width or a steep slope angle, you will effectively reduce the MACS value by using a generic wheel with a wider cut or shallower angle. This is easily noticed when cutting Sargent keys, specifically. So take that into consideration with any master keying job you pick up-- get the right wheel.

[selim]

schuyler,yes I do know what MACS stand's for! It may not have come out right I was was late when I wrote that. You seem to just love to **** on others to make your self's look good. I do know masterkeying,if you want to know what I was trying to say look at the cyl. manual at the Corbin Russwin website. I was there for a week in there advanced masterkeying course.

[Eyes_Only]

Great, all i wanted was to get some insights on masterkeying and now it's been hijacked into a flame war.

[Raccoon]

Has it?

BTW, how are you progressing with your master keying project?

[Eyes_Only]

I was finishing up some paper work and junk after I left my work place so I had been putting it on hold right now. You can tell I'm sure because I haven't posted back on this thread in a while. Everything should be finalized after tomorrow so I'll start writing up a new system on paper again in the next couple of days.