Velomobile steering coupler (Quest / Mango / Others)

thingiverse

Many velomobiles rely on a plastic coupling part to form a universal joint, which eventually wears out and introduces play into the steering. At first, this play can be eliminated by simply tightening the bolts that hold the steering coupling in place, but as more wear develops, this solution no longer works. This replacement part takes the place of the original steering coupler in a Sinner Mango or Velomobiel Quest or Strada (and possibly other models), removing the slop from the steering caused by using a worn steering coupler. In the first photo, the very worn original part is on the right and the newly 3D printed equivalent is on the left. Note: This is currently an experiment. I have 3D printed this part for use on my own velomobile and am currently testing it. Since the part is in compression due to two bolts that run through it, I believe it will be strong enough even though a chunk of 3D printed plastic is not as strong as the original milled and drilled solid plastic version. At 300 km, there is no apparent wear on my steering block. It continues to perform well. Another warning: The safety of using a 3D printed part in this position is still unknown. It may fail. If you print your own and it fails, you have done so at your own risk. I am not responsible for any consequences. Update after 10,000 km: The part finally broke after approximately 10,000 km of riding. This occurred quite suddenly (see the two new photos). I went from normal steering to having no steering at all in an instant. Luckily it happened in a place where I could simply brake and stop, and then fitted the replacement that I have been carrying with me for the last 10,000 km and continued on my journey. I am actually quite surprised that the part lasted this long. It appears that PLA is slightly harder than the usual material used because there are no wear marks to speak of and no play had developed in the steering as happens with a worn coupler, but this failure mode is undesirable. I had hoped to have some slow indication of failure before experiencing something like this. As such, I do not recommend using this design for a 3D printed part. If you choose to do so, it is at your own risk. Find other parts for velomobiles and recumbents in our webshop: http://www.dutchbikebits.com/recumbent-velomobile-parts Print Settings: Printer Brand: RepRap Printer: MendelMax 1.5 Rafts: No Supports: No Resolution: 0.3 Infill: 75% Notes: I used 75% infill because this part needs to be strong in compression and it is replacing a part originally constructed out of solid plastic. My steering block is printed in transparent PLA. Post-Printing: I suggest sanding the surfaces absolutely flat and smooth before use, and also rework the holes with a 6 mm drill or round file to ensure they can easily accommodate an M6 bolt.