I checked with the calculator:
Electric Skateboard Calculator, and it seems the top speed will be more than enough, but it seems I and the calculator must be missing something here. According to your formula:
[quote=“Jmding, post:2, topic:77072”]
Motor torque = Kt * current, where Kt = 1/Kv
[/quote] more KV leads to less torque right?
Hub motors indeed seem a lot simpler, but I have been discouraged to get them in Sweden since we have so much stone in our asphalt (to cope with spiked winter tires) which makes for a bumpy ride, thus a preference for thicker tires. I figure that if I want to upgrade later an outrunner will also be more modular and will not place any constrains on the trucks.
Speaking of trucks, the above mentioned mount featured a round hole, is that a big disadvantage? I see a lot of reference to the calibre trucks, maybe because they are square and thus will avoid slippage.
I would advise against a 400kv motor, it will lack in torque unless geared very unusually.
Your plan started well with the flipsky vesc and 190kv motor. I would use the Keda 190kv motor from hobbyking to save some money. A 6s battery will be perfect to start with and you should get a speed around 25km/h but this can be lowered in the settings of the vesc.
You will also need some wheels 97mm would be best if there are lots of rocks. Truck will be needed and either turnigy trucks and their mount will be a cheap easy fit, or caliber 2 with a mount from the forum.
You also need pulleys which can be bought on the forum or from @dickyho or if you have a 3D printer you can print the large one.
You also may want to use a bms for charging instead of a balance charger and the switch for the board can be made from an XT90s connector.
I looked at the Hobbyking site and I was happy to see they also ship from Europe which is good considering you get around 15$ of extra charges per shipment plus 25% VAT otherwise. The price for a good motor isn’t to bad either.
Does Hobbyking have any ESC worth considering?
I’m also wondering whether I could get away with a cheaper battery maybe. Is 4S enough for my modest requirements? 40C? Maybe a 1200mAh will be OK to start with as well?
Long time, no work on the board, but now I have all the parts.
Got a 12t motor pulley with set screws from Italy. Is there anything in particular I need to think of when filing down the shaft? I need to get down about 1,5mm in so that the set screws don’t protrude and disturb the belt. Could drilling be an option? Thinking of using me Dremel-clone.
Cover the motor can with a bag and tape it closed when filing! Those metal shards will get all over the magnetic motor and could mess things up otherwise
Just wanted to say thanks for the help and share some experiences after the maiden voyage of the board today.
I mistakenly bought Caliber I trucks instead of Caliber II. They looked the same, so I thought it wouldn’t matter. It did, but it seems to work after some work with the metal file.
Second minor mistake was that I bought the biggest Orangutang Kegel 80mm wheels they had in the shop. They seem a bit small in diameter and the amount of space between the dickyho-mount and the ground is disturbingly small. They do however fit very well with the 36T pulley I bought from Eskating Europe. The timing belt that came with the Dickyho-mount (HTD 320 5mm 12mm) is however a bit long. For our purposes, a slow cheap board, maybe a 40T pulley would be better. As it is now I think I need to get a new shorter belt.
During the first ride it also became clear why Loctite on the set screws is highly recommended. The motor pulley quickly came loose and one of the set screws unscrewed itself twice.
The VESC-configuration and soldering of the power cables was relatively straightforward. The BLDC-tool however seems to have a layout issue on Mac OS X. I couldn’t see the panel where you see that the motor was connected so I switched to using a Windows computer. I haven’t done any loop-plug, or on/off switch yet. Will probably do so.
The KEDA 63-64 190KV motor seems fine, though in hindsight, maybe it would be worth it to buy another one with a groove for the set screws. Annoying work with the file again.
All in all, I consider the project to be a success anyway and I think we will have a lot of fun with it. Now we just need to learn how to skate …
OK, so now we have been riding the board for awhile. I bought a new shorter timing belt after some great support from @Boardnamics. I bought a HTD 305mm and this seems perfect for this mount. I also bought a 16T pulley to use if I want higher top speed.
We have some bad problems though with cutouts and stuttering. I will check my phase wires since I skipped on bullet connectors and bought crimp connectors for car use and I have my doubts about these.
I’m also wondering how much better a sensored motor would be. The startup is not really smooth with the KEDA. Speed-wise I’m very happy though. I don’t need more speed right now, what I need is more reliability.
I did some research and fixed the phase cables with zipties to the motor and enclosure. This seems to have fixed the cutouts and stuttering. Also switched to the 16T pulley since I broke the 305mm belt I should have stopped throttling when hearing that the motor didn´t move and screeched. 16T and seems to work fine even uphill. The top speed seems to be about 18-20km/h. Still only using the 6S battery.
I should have stopped throttling when hearing that the motor didn´t move and screeched. 16T and seems to work fine even uphill. The top speed seems to be about 18-20km/h. Still only using the 6S battery.