We have friends who have a family beach house that they built together as a family, about 50 years ago. Because it’s on the ocean and is not a climate-controlled mansion, steel and zinc (and to some extent aluminum) degrade quickly, so they use a lot of stainless, brass, and plastic. The kitchen drawers are plastic (PVC, I think), and one of them broke years ago, and of course there’s no chance that these are still in production to replace. Initially, they just placarded the drawer to be opened only halfway. But I found the broken part in the cupboard under the drawer and, since it appeared to PVC, used pipe weld to reassemble it, and put the drawer back into normal service.
That worked great for a few years, until someone accidentally opened the drawer with too much force a few months ago, and re-broke it. This time, the missing piece is nowhere to be found.
I designed an assembly to fix it.
I accidentally parted off the wheel about 0.5mm too narrow, but it doesn’t really matter, I think. Just looks a little wierd.
Without the wheel mounted, from the other side:
First, I didn’t try to reproduce the missing injection-molded part exactly. Instead, I tried to design a compatible part that would take advantage of the strengths of 3D printing, and be orientable for printing without supports. So instead of a braced shell like the original, I made a fairly solid piece, printed with lots of perimeters and layers.
I printed in ABS because I can; if I didn’t have an ABS-capable printer, I would have printed in PETG. (If I’d had to print the wheel, I would probably have printed it in PLA+ for lower friction than PETG and hoped that it didn’t creep too much under load.)
If I’d had only a 3D printer, I could have printed a wheel and even a bushing. It wouldn’t have been as good, but it would have been at least functional. But having a lathe, I was able to make a new wheel out of HDPE (“poor man’s teflon”) and make a brass bushing for a screw as an axle (instead of a shoulder screw). I was going to make a brass spacer, but found that I’d made extras the last time I’d needed some, so that just came out of the spacer drawer. And I had enough stainless M5 screws on hand to complete the assembly.
Because this is at the back of a drawer and should more or less never actually be seen, I printed it with thick layers and didn’t worry about making it look good. (I wasn’t thinking about posting pictures of it on the internet at the time…)
Then for prep, I just needed to 3D print a drill guide, cut off the broken bits of the drawer with a dremel, and tap 5 M5 threads in the 3D printed block; once for the axle screw, and four for the screw that hold it to the drawer.
For the CAD design generally, I made the center of the wheel my origin, and worked out from there with my best attempt at measurements from a non-broken drawer. I used some shape binders to make the parts respond to changes in related parts.
To make the drill guide, I created a new body with a sub-object shape binder to the main block, then was able to just copy the attachment holes in the main block, guaranteeing that they would be aligned. I drilled first with the 4.2mm drill size for M5 taps, then opened out to 5mm as a clearance size. Normal clearance for M5 is 5.5mm but I wanted minimal slop.
Approximately no one else in the world has these particular drawers any more, I suspect, so I doubt that there’s any worth in sharing the actual model. So I’m just sharing the approach instead.