Last year my old eBike’s hub motor gears broke down. First I tried to replace the upper part of the gears with a POM part but that failed after 300km of driving (last picture).
But now having a 3D printer I wanted to give it another shot so I bought some Taulman Alloy 910 and printed these. Getting it to stick well to my Dauerdruckplatte was a bit tricky, the first layer stuck well but it curled after just 2 layers. Since I don’t own glue-stick I put down a raft of PETG and swapped filament after that.
I was very surprised at the hardness of this filament and cut my finger with the sharp teeth of one gear.
I’m not sure how well they’ll hold up in Berlin traffic but my first test drive went well.
I love the PETG raft, that’s really creative thinking.
I’d also be interested to know how the Nylon 910 holds up. On paper it should do at least as well as the machine POM you had, but I would suspect that the lower friction and higher temperature resistance of the nylon will get you better results in the end.
And worst case scenario, in the event of another failure, you can always print a new one now.
Usually I dislike rafts but in this case it was really easy to peel off.
I will report back when it breaks but I don’t use this bike very often because the motor has only 500W and I build a new one with 1.5kW.
Do you guys think lost pla is precise enough to redo all three gears in aluminium that would be premium as hell (and overbuilt too) xD what do you think?
Potentially. Assuming you vent the mold correctly so you get a solid casting with no voids.
But you would also need to take the shrinkage factor into effect, which I believe is ~5%. And that approximation isn’t going to be accurate enough to get good gear meshing, so you’d either need it more exact or be ready to do post-casting machining on the part.
There is a lot of sliding motion in meshing gears - aluminum on aluminum may result in severe galling. Typically in gear sets, you will see one gear in steel or brass and the meshing gear in nylon. You basically decide to have one gear be sacrificial. Plastic on plastic is seen quite a bit because it’s cheap and resistant to galling.
@Carsten_Wartmann 0.4 nozzle and 0.2 layer, which is horribly slow but I needed it precise. @NathanielStenzel taking the bed removal, cleaning and general messiness into account hairspray would take more effort than swapping Filament even if done manually.
I find the best approach for Nylon (at least onto glass) is to use undiluted PVA. Spread it nice and thin or it’ll be a nightmare to get off after printing, then remove whilst the bed is still hot. However, I don’t think what I’ve just suggested would work for a print like this without a significant brim, so the idea of a raft in a different filament is a good one – like it.
@Nick_Johnson it’s an e3d BigBox and it extrudes very well @Dave_VanderWekke removing a PETG raft from nylon is like ripping off a band-aid, no cleaning required
that would be premium as hell (and overbuilt too) xD what do you think?