Gas station without pumps

2018 August 29

3D printed names

Filed under: Uncategorized — gasstationwithoutpumps @ 11:57
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To explore OpenSCAD and 3D printing further, I have made two more objects: a key holder for my home and office keys and a nametag.  I’m not planning to put these items on Thingiverse, since they have my name on them and would need to be customized.

The key holder was printed as two plates with holes 65mm apart. One hole had a round surround to accept a socket-head M3 screw, while the other hole had a hexagonal surround to accept an M3 nut.

The basic idea of the key holder is simple: two identical plates held together with M3 stainless-steel screws, with the keys capable of rotating on the screws. The hexagonal socket for the nut was just a little tight, so I had to hammer the nuts into the plate, which turned out to be a good thing, as the nuts are then held firmly by the plate.

I printed a textured surface by designing in shallow V-shaped grooves, and removing my name somewhat deeper. My first attempt printed the lettering and grooves on the top of the print, which resulted in a rather rough surface, due to all the retractions made between printing the separate islands. My second attempt printed face down, to get a smooth surface as seen here.

The keys fold out like a utility knife and provide a more convenient handle for turning the key than the usual small tab. I’ve deliberately erased the information-bearing part in the picture of the key.

Because the name did not stand out well, I tried painting the recessed areas with acrylic paint (no primer). The paint does not stick all that well to the bare PLA, and I got some paint stuck in the little crevices on the surface outside the letters. It looks ok from a distance, but closer up it is rather messy, as can be seen in the photo above.

The key holder holds 6 keys—3 at each end. The keys were not of equal thickness, so I added some 3D-printed washers with the thinner stack of keys. I printed several washers in different thicknesses (1mm to 3mm in 0.5mm steps), and tried different combinations until I got a pair that provided the right spacing. Putting the spacers outside the keys seems to work better than putting them between the keys.

I’m still not sure about the wisdom of having my name on my key holder—it makes it easy for someone to return my keys if I accidentally leave them somewhere, but it also makes it easier for a thief who finds the keys to figure out where they are keys for! I haven’t lost my keys or had them stolen in my 32 years of living in Santa Cruz, so I’m not too concerned about either outcome.

One problem I have noticed with the key holder is that the stainless-steel screws can work loose, particularly from repeated use of the bike key, which has high friction to the screw passing through it. I may want to get a little threadlock to reduce the chance of the key holder coming apart accidentally.

The nametag is thinner than the plates of the key holder (2mm instead of 4mm), and printed with finer layers, but its diagonal size (103.8mm) is almost the largest that can be printed on the Monoprice Delta Mini (which has a 110mm limit).  It took about 2 hours to print.

I printed this only 2mm thick with the lettering recessed 1mm. Once again it was printed face down and I tried painting the recessed areas with acrylic paint.  I had a little less paint in the crevices around each letter, but still enough to look a bit messy.

The nametag was slightly too large for the holder I had designed it for (probably due to a combination of spreading of the first layer and my not allowing for the 2mm thickness), but it works ok in this somewhat oversized holder.

The nametag “worked” but does not look very good—I think that a maker would be better off with a PC board or laser-etched nametag, either of which could provide much better quality.

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