How did you do the serpentine calculations? Gates IQ?
Looks good. Why do you have two encoders? Is one for rotation?
Is the shifting shaft custom or vex?
What pitch is the belt?
Also, out of curiosity: is the gear running on a bearing or is it just bolted to the wheel? I designed mine with a bearing in the gear for safety, but is it necessary?
Is the wheel running on bearings or just on an aluminum hollow axle?
No, I just did an approximation with the center of the belt backing. It does’t need to be perfect. If the belt length was off by up to a half inch in either direction the tensioner would adjust.
Yes, one measures wheel orientation, and the other measures travel speed.
It’s vex, but it’s shortened on both ends.
I doubt that a bearing in the gear is necessary. With a dead axle that’s well
supported, bearings on either side of the wheel, and a gear that’s close to the wheel, you shouldn’t have any trouble just bolting the gear to the wheel.
The drive wheel is running on two ball bearings on an aluminum hallow axle.
Can you put one bearing in the gear and one in the opposite side of the wheel? You still get the support that way, as well as alignment. And you still only use two bearings.
really amazing. Now all you need is to be allowed eight CIMS on the bot. and a refrigerated main breaker.
you could do that, although it’s not the optimal solution in my mind because the bolts would be loaded in shear by the weight of the robot.
this accually only uses 1 CIM and 1 mini CIM. The breaker would most likely be okay, assuming that auto-shifting code was used.
Good to consider.
What miter gears are in there? Are they the vex ones?
And I assume those pulleys are aluminum… just a random thought.
They are 20 tooth 20 pitch steel gears from SDP/SI.
Yes they are aluminum pulleys from B&B man.
Ok, good. It just seemed like they would be heavy for this design due to their solidity.
What are you referring to as being solid? Are you talking about the aluminum pulleys or the steel miter gears?
Also, what roller bearing did you use as an idler? I just put a solid steel stand-in to fill the space.
The pulley is solid aluminum, unlightened. The miter gears I would highly recommend against shorening the hub (widening the bore it fine) due to the strange geometry making it hard to machine.
For the bearing, I used these:
Thanks for the resource! I’ve never used them.
Although, I was wondering about the bearing that you used to tension the lower belt, not the 0.75" bearing for the shifter. lol
Oh. For the lower belt, I just used a steel sleeve around a slightly longer aluminum sleeve. The aluminum sleeve had a 10-32 screw go through and clamp to the top plate. Then the steel sleeve was still free spinning, but constrained in place.
You could just use a 1/4" or 5/16" aluminum sleeve and use a 1/4" or 5/16" bearing from McMaster or Boca Bearings. I know 192 used Boca last year for their gearbox gears, but personally I haven’t used them.
Thanks for the good info! I’ll do some looking around for a needle bearing that will do the job. If I don’t find one that fits the bill, I’ll probably resort to a brass or IGUS bushing.
Bronze over brass. Brass does not have the same bearing qualities as bronze.
I’m going to use a 0.3125" ID 0.5" OD 0.5625" width needle bearings from SDP-SI. They’re only like $5, so why not.
Make sure the shaft has a surface hardness that can use it with out destroying the bearings/the shaft.
Love the out of the box design.
What are the ratios, it looks like it has a tiny spread?