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Unread 25-11-2013, 21:33
MrRiedemanJACC MrRiedemanJACC is offline
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Re: Practical 3D printed parts

Here's a project my senior students worked on. I don't have access to the printed part (at school right now and I'm home), but the second one fit extremely well to a VEX Versa hub. The original intent was for our 6 WD test bot and the driven wheels would used this design. Last year's bot used an 8" drive wheel and 6" driven wheels, but we used chain drive. This year we want to use belt drive and we couldn't find the tooth ratio we wanted so we started to draw this in Inventor. The tooth profile wasn't too hard to get, but the hard part was getting the right diameter for the circular pattern of the tooth to work out in Inventor and in real life. So, this one is 39 tooth to match the Andymark double pulley, so if we use this design, wheel sizes will be common. But I'd like to cheat the driven ones to be smaller to increase the wheelbase of the bot. Therefore we redraw it with the right tooth ratio and off we go. The problem will be getting a smaller tooth profile to fit with the part. If we keep the 39 tooth drive with a 6" wheel, we need a 26 tooth driven for a 4" wheel. Not sure how that 26 tooth will match up with the Vex Versa Hub Pattern. But in the classroom that becomes an absolutely great design exercise to go through!

BTW, Project Geometry is your very good friend in Inventor. Just make sure you have the parts in an assembly, constrained correctly, and then you can modify the part you are working on to match very, very well with the mating part.
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