The standard thread size for skateboard axles is 5/16-24 UNF, and the TB218s are no different.
The only different ones are those with 10 or 12mm axles, such as for mountainboards.
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Or 15mm for craptor 2.1
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Thanks!
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that calc doesnât factor the motor current, # of motors, the motor torque, motor torque multiplication via gear reduction, your frontal area, drag coefficient and the fluid density of air, bldc vs foc
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@tinp123 i think if you switch from foc to bldc you can reach ~64kph (40mph), thatâs the 1st thing iâd try personally
^and if switching from foc to bldc doesnât give you enough top speed, by switching from a 3.33:1 gear ratio to 2.84:1, you can reach 76kph (47.4mph) with 30a battery current limit per motor (60a total battery amps combined) on flat ground in bldc, with these assumptions
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a bit expensive in my opinion. Just a stock and standard China charger.
In runners can have slotted iron stators too. If no slotted steel stator no cogging
cogging is obvious and itâs the pull of iron to permanent magnets. As u say with a better ratio of magnets and teeth or more of them it can be reduced and thereâs other things can be done but the root problem/question is what specifically is it. itâs a loss of kinetic energy as ur roll is diminished and when powered cogging torque is still there overlaid just less noticeable but by what mechanism is the momentum lost. Heat or not?
a magnet has a pull force thats the same whether coming or going. Cogging should be net zero loss but obviously it isnât. traditional iron losses donât explain as theyre high speed losses vs the cogging torque profile at slowest speed
with unpowered cogging you store energy (like a spring) then get most or all of it back:
^when I release the wheel it spins some from stored energy
Thank you for detailed answer!
I never tried bldc and I think I never will. I could settle with 53km/h top speed, I was just curious why is difference between calc and real life so big. I can feel loss of torque from changing 16T to 18T, I wouldnât want it to be even lower.
Cogging is a net loss. Powered and unpowered. Doesnât matter software itâs all motor design dependent. If u have straight slotted teeth with magnets itâs there.
Does somebody have a good idea to cool a vesc?
The vesc itself is inside a metal enclosure from wowgo but it doesnât make much contact.
Cutting holes for air is problematic due to possible dirt/water coming inside.
(bottom left)
i already have a tiny heatsink on it but that just delays the build up.
Got a thermal camera? If there is a loss of energy it should show as heat. If the phase wires are disconnected and there is 0 electrical loss, all other energy loss is heat. Should be able to see a motor heating up from it
I got a question about amps. So in a battery, the higher the amperage (mah) the longer each cycle will last, thereby giving you more range and less battery sag, correct? The thing I am confused about is why do guys have different amperage settings for the vesc and motor, why would you put you vesc at, lets say 40a cont. but then but your motor at 70a⌠how does that work? Is the 70a at the motor the peak it will let the motor accept within your settings you enable, or is that the rating your motor supplier recommends as a maximum to your motor?
^during one part of the duty cycle, current is drawn from the battery and a magnetic field is built in the stator (storing energy in the motor)⌠during the second part of the duty cycle, the motor current is sustained by the motorâs inductance or collapse of that magnetic field. since the motor current is constant, and the battery current isnât, the current in the motor is higher than that which is drawn from the battery, but the motor current is at a proportionally lower âeffective voltageâ than the battery voltage.
by controlling this effective voltage, the motor current is controlled.
itâs more efficient this way than limiting the current via a resistor because that wastes a lot more energy as heat.
the torque is directly proportional to the motor current, and the motor heat is proportional to the square of the motor current, and the duty cycle is the % of time current is drawn from the battery.
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The motors can reach peak amperage without the battery. Think of it as total system power (watts). 40A continuous from battery x 40v would give theoretical 1600 watts capable to the motor. The motor RPM speed is directly related to voltage, so at low speed, the motor might see 5V but full torque at 70A, which means itâs only seeing 350 watts, yet still pushing 70A of max torque. This number increases as speed increases, until it reaches the battery side max of 1600 watts, then torque is traded for speed.
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Dayumn ok ok
Thx a ton bois! Pics taken
I fixed the sound, added another washer in between the motor shaft c clip and the motor bearing and the free-play that causes the sound is no longer there 
One potential loss is magnetic hysteresis.
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is hysteresis reduced with the elimination of cogging? i suspect not.