Actually the range for magnet amount goes all the way from 1 to 100, which i think will let me get it to divide down to the correct speed with some calculation/experimentation.
Surprising range, since motors never contain more than six.
I don't understand your plan. Your motor doesn't output RPM data in a form that a geared motor controller can use. it does in the form of hall signals, but controllers for geared hubs don't use these signals for speed calculation, because they have to work with motors with varying gear reductions, and be able to provide speed data even when freewheeling, meaning the RPM signal has to come from the rotating hub shell, which is achieved by embedding (between one and six) magnets in the shell, and conducting the signal on an additional wire (additional to phase and halls I.e. a ninth wire in the motor loom.
Without such a signal from your motor there's no need to trick the controller ... you would input the accurate wheel size, set the magnet number to "1", and attach "1" magnet to your rim. Unless I'm missing something.
Wheelbarrow size, yep
Asking about 30cm rims earlier, how big did you think i was building this thing? Wheelbase is about 1m so overall length about 133cm from the front of the front to the rear of the rear wheels.
You mentioned 16", and I thought you meant bicycle size, which are 305mm.
1m wheelbase is same as regular bicycle, so it's not a miniature vehicle, just has smallish wheels.
Most cheap tires like this are only specced for 4kph, less pressure and are usually "2pr", which i gather is the amount of layers of reinforcement, these i picked are 4pr.
I did look up the manufacturer specs, dont recall the name but these are specced for 250kg, 30kph and 25psi max so i can pump them pretty firm for decreasing the rolling resistance somewhat, tho i wont be going rock solid as i want some cushioning of the ride.
They sound good.
I suspect the speed ratings relate to heat. Crappy stiff tires overheat. So, 30km/h rating is encouraging regarding rolling resistance - It can't be too bad for the tires not to overheat at 30km/h.
Got the bolts shortened and the sprocket spaced in place:
Not sure about how bolt spacings are usually measured or what BCD (Bolt center distance is my guess) is but the 42mm was the given measurement from hole center to hole center, not relative to the axle, and there were sprockets listed with those same numbers so i paired them up.
Bolt circle diameter.
If these are typical cheap sprockets sourced from China, they're roughly made. Unlikely eccentric, just that the drilling is imprecise, meaning you should expect the chain to flap.
You've got T8F chain and sprockets do you? I haven't used it, but expect it should be better in all regards to quarter inch #25.
Now working on the "new" mount for the rear axle, re-using the axle clamps form the hoverboard wheels.
Figured that i can use some of the left over aluminium pipe i used to make spacers for the front wheel as shims around the threaded rod axle to make it clamp in firm.
The pipe is only like 1 or maybe 1.5mm wall so it squishes down when the clamp is tightened and as the wheel is on bearings this will be alright. Might make something out of angle iron to bolt in at the back at a later date as it would be more sleek, this is easy for now.
Looks super strong.
Threaded rod lets the team down though, obviously. It's 12mm? Minus thread depth closer to 10mm? Thinner than you'd normally expect for such a long axle. And you'd have something like 50mm each side unsupported between wheel bearings and dropouts? I don't know if that's enough for flex to be an issue. And could threads gouge the bearings? Again I don't know, doubt it since they're hardened whereas the threaded rod is mild steel.
