Yes, I plan to use screw joints for all gears except the ones driven by the motor, and for the wheels. They definitely help reduce friction. Just for reference, about how heavy was your robot?
I couldnāt tell you just a standard 2wide channel drive all aluminum tray bot, as light as possible.
My robot was quite similar to the one @ThirdDegree built and mine weighed around 15 pounds before I added ballast.
How well did your transmission hold up?
Very well. I built 3 iterations of it and by the third one I made sure everything was super tight and close, I used screw joints and HS axles, and greased everything well. It was easily able to push 2 robots at the same time and did great against defense.
Nice. What rpm motor cartridges did you use? Iām thinking maybe 100 rpm with a 3:5 gear ratio but maybe 200 rom could work
I used 200 rpm as 1:7 for the tilter and then back to 200 RPM for the drive. Using 200 RPM is easier to fit because it requires less space but 100 RPM would also work. I was running 100 RPM 7:3 at the beginning of the season but then realized 200 RPM was easier so I switched to that.
I think you could probably get away with 5:1 200rpm so the tilter would have the torque of 10:1 100rpm, still more than the standard 7:1 100 and the drive would be 200. Saves a little more space about 4 holes. Could be significant.
Iām only concerned about 200 rpm for the drive. Iām not sure if a 200 rpm drive with a lift differential will hold up very long. Thatās why I was thinking maybe a 166 rpm drive, 3:5 geared on 100 rpm motors
Nah that shouldnāt be a problem. 200 RPM drive holds up fine and only starts overheating after 10-15 minutes of rigorous practice and/or matches.
^^ also I donāt see a drive any slower than 200rpm being competitively viable.
You donāt think 167 rpm would be competitive? It worked pretty well for me in TT but there was less need for quick maneuvering. Maybe like in turning point it would be tougher.
Its possible to use a slower drive, but for any scarcity games (high level TT) you wonāt be able to keep up. Iām surprised 167 worked for you this season. After ditching the differential, we ran 292 rpm and reached max speed with relative frequency.
I do see what youāre saying. Iām in northern new york, and I guess itās not the MOST competitive region, like SoCal. Maybe if I was there I would struggle with slower than 200rpm, but it worked very well for me here.
How would you make it tilt and not drive? this dosent make much sense to me. It looks like it would either tilt the tray when you try to drive or it would drive when you try to tilt. You wouldnāt be able to control when it tilts and when it dosent tilt
If you can, build it yourself. Youāll see that if both motors rotate at the same speed, the drive will not move at all.
hmmm. But then the motors would burn up because they are working against each other at different speeds
If one is at 50% and the other at 75, the one at 75 would be trying to pull the one at 50% up to 75, but the one at 50 would be trying to pull the one at 75 down to 50, which means the motors get a lot of stress and burn up
That would be true if they were on a fixed system. However, the two motors are on a 4 bar setup, allowing the 4 bar to move as well. So, instead of the motors fighting and overheating, they just move the 4 bar in the direction of the net velocity generated by the opposition of the motors. I know itās a bit difficult to visualize, but itās not difficult to build a mock prototype, so I would recommend for you to build one of these and experiment for yourself. You may see that it is quite interesting as to how the motorsā motion combinations can lead to different results which can be very useful for a multitude of mechanisms throughout the vex challenges.