An Understanding of the A50Mxx & A41Nxx Lid Locks & Keys Glitch-Condition
My whole working career had been in the manufacturing industry. Logic is a strong suit. I’ve been trying to understand how in the heck the glitch occurred with the Eagle A50Mxx and A41Nxx clasp lid locks and their keys. After studying this situation for a long time and cutting many trial keys, I have determined the root cause.
Eagle went out of business in 1975. Since then, keys for the A50Mxx and A41Nxx locks are duplicate cut by locksmiths from ILco key blanks 1013GR or 1013G, or Eagle (after market) brass blanks 08792M or 08792MR. The cause of the lock and key glitch-condition is that the noses of the above blanks are too deep for some key barrel nose openings, if the opening ended up near or at the minus manufacturing tolerance range. All blank nose heights I’ve measured are near or at the maximum plus tolerance range. Therefore, the blank’s nose won’t fit through smaller barrel nose openings to allow the key to seat properly. If all blank noses were manufactured at the minus tolerance range, they would then fit through any key barrel nose opening without filing and seat properly. The proper key nose depth should be .085” maximum. To reduce the depth of a key nose, make sure there’s not any internal radius in the corner of the nose bottom you filed and it’s smooth to the vertical .000” plane for the tab spacing end of the key. A radius, or not being smooth, may not allow the key to seat properly.
The second problem that can exist with today’s purchased A50Mxx keys, is that the master keys used for cutting duplicates may not allow all the key tabs to work properly for all the tolerance ranges. The original Eagle keys were cut such that they did work for all manufacturing tolerance ranges and didn’t require a customer to file the keys.
After analyzing all the data that I have accumulated, I developed, by reverse-engineering, an A50Mxx Key Cutting Chart that includes all dimensions for all 48 keys. Later, I also received copies of Eagle’s original Key Cutting Code sheets for A50M1 – A50M48 and A41N1 – A41N60 keys.
I own an A50M2 and M30 glitch-condition locks. Thinking they were good locks when I obtained them, I had bought the Gerstner keys and filed their noses down per their instructions. Neither key worked.
Using my key cutting table, I cut a key for each of them. After filing down the nose height to .085”, each key worked its lock with no changes. I took both locks and keys to the Gerstner factory. A person there retrieved their in-house, key testing, M2 and M30 locks. That person worked my locks with my keys and then used my keys to work their in-house locks, no problems. Their keys would not work my locks. That person was surprised and started asking questions. Scott appeared and that person explained to him what had just happened, he showed little interest.