Its boating season in the Greater Victoria area and  boat owners are quickly discovering this years maintenance projects! One such project came across my desk in the form of a broken mortise latch. To investigate the problem with broken latches, the owner dismantled them and and uncovered some broken plastic (injection molded) parts inside.

The mortise latch makes use of a small rocker/lever arm, which transmits the rotation of the handle to the tongue, which retracts, unlatching the door. The tongue, the rocker, or both were broken on each of the three latches. This particular brand of mortise latch sells for roughly $350 with no option for replacement parts.

One of the previous owners had replaced one of the rocker arms with a metal piece, which appeared to have been cut out on a band saw, and filed down to shape. Using this piece, as it was the only surviving rocker arm, we created a digital model and printed it! We modeled and printed the tongue replacements, as well.

The final parts matched the old ones perfectly, so it was time for a strength test. Both of the broken rockers we were provided failed at the same spot: around the pivot hole. So I decided to do some destructive testing. With asset of pliers, I applied a load in the same direction as the actual loading and broke one of our replacements. The failure on this part occurred along the tapered section, leading us to believe that it should function adequately, as it did not fail at the former weak point of the part.

These parts will be sent out for testing this week. Stay tuned for an update on their performance!

Following are interactive 3D view cubes of the parts designed using CAD software.


Unavailable parts? Do you have a broken part that nobody makes parts for? For example; plastic body parts, gears, valves, brackets.

We can help you to design models of discontinued, broken or hard to find parts using 3D modeling and fabrication using 3D Printing Contact Us call 250.524.0345 or email

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