NFGx
Grand Master
After my relative success making a key for my Naomi cabinet I thought I'd try and make a copy of the tubular key for my New Astro City.
The theory was more or less the same: measure it, and create it in 3D using FreeCAD. These things are tricky to measure because the pin depths are measured in fractions of a millimetre, and even a digital caliper struggles. But, like the double sided key linked above, I figured I'd just get started and iterate. But I didn't have to iterate at all.
Measuring it was easy enough, and it was pretty obvious how it worked. Make cylinder, make indents every eighth of a circle around the cylinder, and cut to approximate depths.
I did, then printed it, then tried it out.
Immediate failure.
Unlike the double sided key, all of the torsion force in the tubular key is right at the pins, and that's the thinnest part of the print. The key went in just fine, but I can't tell if my measurements were good because the smallest amount of twisting separated the weakest end of the tube from the stronger part, and what I pulled out of the keyway was a bit of spaghetti, not the key that went in.
I don't think this is possible with FDM printing. Metal sintering should work, and nylon deposition might also. I dunno about resin, they're not super strong from what I hear but maybe the way these forces are applied will make a difference, IDK.
Anyway, yeah. No go.
The theory was more or less the same: measure it, and create it in 3D using FreeCAD. These things are tricky to measure because the pin depths are measured in fractions of a millimetre, and even a digital caliper struggles. But, like the double sided key linked above, I figured I'd just get started and iterate. But I didn't have to iterate at all.
Measuring it was easy enough, and it was pretty obvious how it worked. Make cylinder, make indents every eighth of a circle around the cylinder, and cut to approximate depths.
I did, then printed it, then tried it out.
Immediate failure.
Unlike the double sided key, all of the torsion force in the tubular key is right at the pins, and that's the thinnest part of the print. The key went in just fine, but I can't tell if my measurements were good because the smallest amount of twisting separated the weakest end of the tube from the stronger part, and what I pulled out of the keyway was a bit of spaghetti, not the key that went in.
I don't think this is possible with FDM printing. Metal sintering should work, and nylon deposition might also. I dunno about resin, they're not super strong from what I hear but maybe the way these forces are applied will make a difference, IDK.
Anyway, yeah. No go.