Our robot currently has a 5:1 gear ratio in the 200 rpm cartridge, and is not getting enough torque to tilt a 6 stack. Will changing to a 100rpm cartridge be enough in the long term? (We want to add a 3rd stage to have 9 cube capacity) Or should we build a compound gear train
I recommend a 100 rpm motor on a 7:1 ratio. This will have more than enough torque if built correctly and will still have enough speed to be efficient.
Ok thanks, does that ratio give enough torque to push larger towers though?
Yes definitely , I have seen it be able to push 12 cubes when built properly.
Depends on your trays weight, if it is completely steel, then it may have trouble, etc. Although they do work really well (10+ cubes), you still need to build it correctly. Try to have leverage (the concept of a longer bar having more power than a shorter one; think of swinging a golf club with the stick vs with just the tip, what will be better?).
By built properly what do you mean. My instructor said to avoid acute angles, but do you have other advice?
As just stated , leverage can play a key role. The length of the bars and where the joint is connected on the tilter matters as well. If the bar is connected at the very base of the tray it will be a lot harder to push than if the bar was towards the top.
Check out these threads for more detailed info:
Optimizing Speed of Tilter with P-Loop
Tilter Simulation for Torque Calculation
if you have a simple tray bot id recommend 2 motor 100 RPM cartridge with a 7:1 gear ratio.
the abundant power may be excessive but you’ll never have to worry about a motor burnout during a match.
Edit: i accidentally said 1:7.
Depending on the context, your instructor is likely wrong. We designed the tiler in a way to maximally benefit from the acute angles between the crank and the connecting rod - it provides biggest force multiplication in that part of the trajectory - you crank moves a lot to move the connecting rod a little, since it initially goes mostly sideways. Check on the Tray Calculator.
Not necessarily. Yeah, there will be much bigger force applied to the connecting rod, but the travel would be very limited, so you could change the length of the crank arm accordingly. What will be worse are the forces at the joints and the force bending your tray. But for a reasonable initial design (connection to the tray at about 30 holes from the base), going down can actually improve (reduce) the driving torque, depending on the rest of the geometry, as counter-intuitive as it might seem…
1:7 works just fine and communicates it just as clearly (and communicates it clearer depending on who you ask)
2 motors on the tilter is unnecessary as long as you have good tilter geometry and build quality. (even with 1:7 1m works just fine)