Back into 3D printing

After a long hiatus I finally dusted off my 3D printer today and started working on a tiny project. I have a trailer for my bike, a Burley Flatbed, that, as mandated by germany's road code, needs a couple of reflectors and lights. On my first ride with the trailer, an asshole kicked off one of the reflectors while it was parked while we went shopping. Nice! I tried to buy replacements, but unfortunately, these are a bit hard to get as the diameter of the tubing used for the burley is rather small compared to normal bike tubings. I also have an old battery light lying around here, with an integrated reflector that would fit the trailer pretty nicely, but the clamp can only clamp a minimum diameter of maybe 31mm, which is pretty far away from the 22mm of the Burley tubing.

If you don't have a lathe, this is a pretty nice task for a 3D printer. I started of with a rough sketch of an idea and then briefly tried to start modelling it in FreeCAD before closing it again and starting over in Fusion 360. I really would want to work in FreeCAD, but this needs more work from me in form of learning how to properly use it.

Initial sketch of the part

The end result in Cura looks like this:

3D rendered part in Cura

Before I arrived at this version, I actually did another version (and, stupidly, printed it as well), which you can see here:

the inital printed part with an obvious problem

I wonder if you can see what's wrong with it. :)

4 Time's a charm

I had to print this 4 times before I was satisfied. It went like this:

  1. I printed the version with the small opening. Actually, I think this might work, as the tubing in the Burley is easily disassembled, but it felt like way too much hassle to me.
  2. The second version was much better and I threw in some rounded edges as well, and, well, the printer stopped printing half way through due to a detected thermal runaway. This is probably a good thing, as it shows that the detection works, but after thoroughly checking all connections and the sensor data, I still have no idea what caused it.
  3. The third print actually went fine and then delaminated while I was trying to pry it (a bit unelegantly, to put it mildly) from the print bed.
  4. Okay, to be honest, the fourth print also delaminated partially, but I test fitted it and it still seems to work. I will probably try to print it again with a stronger walls and without reducing the infill as much as I did.

Designing for a filament printer.

If you look at the initial sketch and the resulting part, you'll notice that not only did I have to change one important part of the design (the opening), but also I turned what were hard overhangs on the initial design into tapered edges. This is actually not for aesthetical reasons but done to be able to print without support material. A filament printer can print overhangs just fine without support if the angle is doable. I chose 45° and that is more that enough for making this a printable part. The problem with support is that not only does it waste material, but also makes it much harder to clean up the part afterwards.

If you're interested, the used material is Refil's awesome ABS which prints really well (granted, it's a small part so I probably shouldn't be worried about the usual ABS warping) and is hopefully a bit more resistant to wear, tear, sunlight and temperature changes than your average PLA (unfortunately I don't have any PETG in enough quantities lying around). The cool thing about Refil's filaments is that they are all made from recycled plastic, in the case of ABS from old car dashboards, which I though was especially fitting for my bike trailer, which, since I bought it, saved me many a car rides. It does come with the usual fumes of ABS and I'm still trying to get this toxic stench out of my flat, but it's a pretty cool material nevertheless.

I'm still pretty much a n00b in 3D printing but small projects like this are easy enough and are always fun, as you can get your results pretty quickly.