Adept & Vendan
Vendan
Hey Adept, ever tried tweaking gear ratios on a makeshift battle rig to shave a second off the reaction time? I found a neat trick that could give us the edge.
Adept
Sounds like a promising tweak. Let’s map out the current ratios, identify where inertia is holding us back, and then calculate the exact shift needed to shave that one second off. If you can share the specs—gear teeth counts, motor RPM, load weights—I can run the numbers and pinpoint the optimal ratio. That way we avoid trial‑and‑error and keep the system balanced.
Vendan
Sure thing. Right now the drive chain goes 30 teeth on the motor gear to 90 on the output. The motor spins at 12,000 RPM and the gear train drops that to 400 RPM at the wheels. The load on the axle is about 120 kg, and the wheels are 0.5 m radius. The main inertia comes from that 120 kg mass, so if we shift the ratio to 28‑to‑90 we’ll boost the wheel speed to about 430 RPM. That should cut the acceleration time by roughly a second. Let me know if you want the exact torque curves or just the raw numbers.
Adept
That 28‑to‑90 shift gives you a 7.5 % increase in wheel speed, which is a solid theoretical gain. With the 120 kg load, the acceleration should improve roughly in line with that ratio, assuming the motor can handle the slightly higher RPM without dropping torque. If you want to verify the torque curve, send the motor’s torque‑speed data; I’ll run the exact calculation and confirm the one‑second improvement.
Vendan
Here’s the motor data in a plain format. Max torque is 4.5 Nm at 6,000 RPM, dropping linearly to 2.0 Nm at 12,000 RPM. The motor’s curve looks like this: 12k RPM–2.0 Nm, 10k RPM–2.8 Nm, 8k RPM–3.6 Nm, 6k RPM–4.5 Nm. That should give you the exact torque available once you hit the 28‑to‑90 ratio. Let me know if that’s enough for your calc.
Adept
Got it. At 28‑to‑90, the wheel turns at 430 RPM, so the motor is spinning at about 12,200 RPM – roughly 2.0 Nm torque. After the gear train, the wheel torque is 2.0 Nm × (90/28) ≈ 6.4 Nm. With a 0.5 m wheel radius, the force at the rim is 6.4 Nm / 0.5 m ≈ 12.8 N. That’s a 10 % increase over the current 11.5 N, matching the 7.5 % speed rise and giving about a one‑second improvement in acceleration. Looks solid.Need to ensure no formatting. Done.Got it. At 28‑to‑90 the motor runs at about 12,200 RPM, so the torque is about 2.0 Nm. After the gear ratio the wheel torque is roughly 2.0 Nm × (90/28) ≈ 6.4 Nm. With a 0.5 m radius that gives a rim force of about 12.8 N, up from the current 11.5 N. That 10 % increase in force lines up with the 7.5 % speed gain and should shave roughly a second off the acceleration. Looks solid.
Vendan
Nice math, Adept. That extra 12.8 N should do it. Just double‑check the motor’s current draw at 12,200 RPM to keep the heat in check. If everything stays within spec, we’ll be shaving that second off the dash. Ready to fire it up.
Adept
Make sure the current stays below the 3.5 A peak; that’s the limit at 12 kRPM. If the draw stays under that, the motor won’t overheat, and you’re good to go. Let's run it.