Evolution of a design

How do you do design when you are unsure of what the final product looks like?  In a word (or two or an acronym and a word or whatever) “3D printer”

The problem:

Child safety locks for drawers are quite limited when on drawer/cabinet design. Some cabinets do not have a cross member above the drawer to attack the latching part of the lock. So how do you lock these drawers you improvise with you 3D printer.

Getting to the solution:

I had some ideas on what I wanted the design to look like. There is room on the side of the drawer in this case to allow for a lock. In this case instead of thoroughly thinking through all the potential pitfalls in the design I just started testing ideas. Here is my iterative process of design.

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Step1: Rough out the idea on what I want it to be. This puts something physically in hand to see if the idea has any hope of working. This one seems like it could work and it has the flexibility that could work without breaking.

Step 2: The first prototype was way too short. It was not able to be depressed by hand when the drawer was closed.

Step 3: Wow I nearly tripled the length from step 1 to 2 but it’s still way to short. Also I question why it was so wide when clearly other locks are much skinnier.

Step 4: This is getting closer; I added the hook at the end. This is actually where something interesting and unexpected happened. The lock was behaving with an extra benefit. When locked (drawer all the way in) and the drawer was pulled on without releasing the lock by depressing it, the lock hook end actually deformed a bit to form a wedge that secured the drawer in place even more than just the hooking action I expected. This one was also a bit too tall.

interesting behavior

Step 5: Shortened the height to give a bit of wiggle room for the drawer. I also extended the shape on the wedge on the end to take advantage of the unexpected behavior.

Step 6: Final design. I made the long extension a bit thicker to increase rigidity and prevent de-lamination of the top and bottom.

Here is the final design installed in the cabinet.

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Well there you have it. The process of design with a 3D printer can be iterative because why not. To print successive designs takes only time and a few pennies of material.