This is encouraging! I’ve spent a lot of time thinking about how to solve the challenges of printing the window crank on my Prusa MK3s 3D printer. Solving for the printing issues with fit and print quality.
What are the issues to solve you ask?
- Tolerances – The surfaces that print on support material tend to be rough. Thus need to add in a bit of offset to allow for that.
- Threaded VW Cap. The cap that goes over the bolt that holds the crank to the door. It was difficult to remove the way I had it designed as a bayonet clip. As a threaded cap, as you turn it pushes out of the crank making it much easier to remove and easier to print.
- Knob snap assembly- In my first prototype that broke. I had the knob tongue and groove friction fit and glue. This worked fine but required glue and I’m not confident PETG glues well. Plus I hate glue, super glue always comes in those dumb small tubes. After 3 tries I got a snap to work quite well.
- Fit to Door- After printing this crank many many times I took another look at the very small teeth that interface with the gear that comes out of the door. Turns out I was off by 1mm. This is why in the past those teeth pushed into the plastic and made it hard to install. Now the fit is perfect. We will see how well it survives in practice.
So this is pretty exciting for me. I feel as if I’m very close to having the crank designed in a way that makes it manufacturable as a 3D printed product. There are still some streamlining of support structure that needs to happen. As far as print quality and functionality it is there.