Were there tiny pebbles all over the road surface?
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It is probably the one road in my area that is consistently clean and not covered in rocks or other debris. No loose dirt either (which can also make my board loose traction)
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CAN bus and UART related questions:
- If two ESCs are connected over the CAN bus, is it possible for the slave ESC to also use its UART port? Say master ESC has a UART remote, can the slave run peripherals like a robo/metr?
- Is the VESC implementation of CAN capable of being run as below with a shared bus, or is it purely end to end? I haven’t messed with CAN before but I was under the impression this was a large part of the point of the protocol, but it seems the only cables and stuff I’ve seen in esk8 are 1-to-1 with no other nodes
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Yes
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Yes, you can daisy chain CAN components
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Does this mean the connections need to be series?
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Er, no. Pls don’t do that.
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A shared bus, but with a few notes for VESC:
- Twist the CAN-H and CAN-L wires together.
- 5v line should only be used if the receiving device needs power.
- Pay attention to termination resistors (see below)
A bus network has a backbone that is terminated at each end with a resistor. Stubs come off the backbone to go to devices. The stubs shouldn’t be terminated.
The termination resistors are used to stop the signal from bouncing back and forth along the network and causing data loss.
Most VESCs have termination resistors on the PCB. This is both a pro and a con.
The standards for total canbus network resistance is 60 ohms, and this is achieved by using two 120 ohm resistors on either end. Functionally it depends on cable length and you might be able to get away with a network that has anywhere from 50 ohms (2x 100ohm) to 150 ohms (2x 300 ohm).
VESC 4 based designs have a 100 ohm termination resistor next to the can bus port.
VESC 6 based designs have a 220 ohm termination resistor next to the can bus port.
VESC Express has a 220 ohm termination resistor.
You can verify this by measuring the resistance between CAN-H and CAN-L on the can bus port with a multimeter while the device is unpowered.
If you connect two VESCs together, the total resistance is in spec because of the PCB mounted resistors and it just works.
It can be an issue when you start adding a bunch of stuff to the CAN BUS network.
4x VESC 4s would be 25 ohms of total resistance, which could either overload the CAN BUS chips or not work reliably. Add in a VESC Express and a CAN BMS and you you are down to 20 ohms. Ideally only 2 of the VESCs should have termination resistors, and the other two along with the VESC Express and CAN BMS should not.
As more and more add-on devices go from UART to CAN, I think we will see more improperly setup can networks which will cause sporadic issues.
Here is an example of an ideal can bus network setup (NMEA2000 for boats).
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has anyone seen partially thread, button cap (hex drive) 2 inch stainless hardware? I can only find Phillips or fully threaded. Thanks.
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McMaster maybe?
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I had checked and can only find Phillips, or fully threaded. Interestingly Phillips pan head in this rare instance bc of the partial thread would be the best option I can find. I need a low profile head with load dispersing and partial thread. also my machined part uses 10/32 and probably not m5 in its current state.
I feel like I mostly see the partially threaded bolts in socket head or hex head for whatever reason. I’ll keep an eye out. May I ask why the partial thread is necessary just out of curiosity?
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To be clear im looking for 2 inch button cap partial thread, but i find the partial thread to reduce slop between risers and in the deck. Im running an idea style set up scenario to be posted soon but the boolts will be running through brackets.
Button cap because i will be standing over it
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Why wouldn’t these work for you? They also come in 1 and 1.25 length units.
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I have a unique design consideriation, 2 inch seems necessary.
I need a spacer of .5 inches to accomidate the angle of the bracket
Have fiberglass layering going over everything adds thickness too.
I believe they come in 2, but I just don’t see them in Google results.
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Same, will keep looking.
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Maybe a shoulder bolt works? Not sure if it works in your instance, but generally they’re mostly unthreaded aside from the end, but also thicker on the unthreaded portion.
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Its 2023 in both metric and imperial units.
Got a question. I managed to find someone who can CNC my custom wheel pulley, I went with the cheapest aluminum (6061 T6) that has a tensile strength of 300, I was recommended to go (7075 T6) that has a tensile strength of 600, knowing that it’ll be spinning at a decent speed with a belt causing friction. What’s the best option here?
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I’m not a machinist, but I do play one on TV.
My opinion is to ask, how many teeth does it have? Because the more it has, the less it matters.
I’d be worried less about tensile strength and more about resistance to abrasion personally, assuming the pulley was designed in a way where it’s not going to physically fail by deformation.
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