Quote:
Originally Posted by 75vs1885
I like the idea of 3-D printing the plates. I don't know why everybody is so against it, last year we (1885) used 3D printed parts to join an axle for our intake, it worked very well and only "broke" when we didn't check it and a shaft collar was loose. Then the axle would fall off and we would have tighten the collar up again.
Just use a high quality plastic and use a dense pattern while printing AND MAKE EXTRA'S!!!!! Better to get into 3D printing now while it is still being developed heavily, we all know it will only become more and more common, so this is a great foundation to build off of in the future.
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What you have described to join an axle isn't the same as gearbox plates.
Gears (especially bevel gears) require very accurate positioning. If the gears are to close together, or the shafts aren't parallel, the gears wear much, much faster. Team 254 made some delrin side plates a long while ago and one of their mentors said that the flexibility of the plastic didn't keep the gears well aligned. The thrust loads from the bevel gears will only worsen the problem of the deforming side plates. Also, you can't really get a press fit for the bearing with a 3d printer. First of all, the printer isn't accurate enough to get the right size hole, and secondly, the plastic has a high chance of cracking if you try to press in a bearing.
The side plates can be made on a mill and a bandsaw. The outer profile doesn't need to be accurate, so you could just print and cut out out a correctly scaled drawing, and trace it with sharpie on a piece of 0.25" thick aluminum to cut on the bandsaw. The mounting holes/bearing bores should be fairly easy to do on a mill.
Personally, I wouldn't go with the ratios you have chosen for your shifter. I'd recommend using smaller wheels, or adding an extra stage of chain reduction first. 9 feet per second with 4 CIMs in low gear is on the fast side, and you'll experience breaker tripping in low gear. Also, 20 feet per second with 4 CIMs will have very poor acceleration, and will really wear down your batteries quickly.
Which bevel gears are you using?