Summary

Lock design by: BCaron

This is a working combination padlock design that can be used in place of a standard Master Lock on a locker or whatever. It's relatively strong, but it is plastic it's, so not for high security.

Features:

• Configurable combination: up to 10,000 possible combinations
• Selectable security options: 3 or 4 tumblers with 6 or 10 digit numbers
• Spring loaded detent feature on tumblers for precise positioning and satisfyingly tactile feedback
• Similar dimensions to classic rotary Master Lock for compatibility with most lockers and other latches
• Strong lock body and shackle that resists forcing open
• Normal or long shackle options for securing larger latches
• SolidWorks files for your own customization

v2 Improvements:

• Print-in-place springs for detent works far better than old design which would break after a while
• Option for 3 or 4 tumbler lock and 6 or 10 digit tumblers
• Threaded cap eliminates glue and allows for easier changing of combination.
• Taller wall next to shackle latch better resists forcing open of the lock
• Flipped tumbler position tor easier right-handed operation
• Tumblers can now be printed without supports
• Various changes to make printing easier and cleaner

Assembly

1. Break free the print-in-place detent springs. I push them into the edge of a table or block until I have heard a few snaps and feel nice and springy. Adjustment of the springs may be required if they are pushed in too hard by pulling them back out for a tighter fit against the tumblers.
2. Select your combination by printing the digits you want to use and stacking them with the inside notches all lined up. Rotate them against each other to smooth out the sliding surfaces for smoother operation.
3. Slide the tumbler stack into the lock body then up into the hole.
4. Insert the spacer under the tumbler stack
5. With the selected combination aligned with the arrows, insert the shackle through the tumblers and lock body. Make sure all of the tumblers are aligned with the keyway or you won't be able to fully insert the shackle
6. Slide the cap over the shackle and screw into the threaded hole.

Notes:

You can color in the numbers with a permanent marker for better visibility.

To unlock it, enter the combination numbers aligned with the 2 arrows on the body then pull the shackle up.

Detent tension will probably need to be adjusted by disassembling and pushing or pulling the detents slightly out of the body to stretch or compress the springs to a better position.