I opened up the control box, powered up and tried to spin up, but both VESC’s flash 3 red, pause, 3 red.
Attached to VESC tool and looked at the faults:
Fault : FAULT_CODE_DRV
Motor : 1
Current : 1.4
Current filtered : 0.1
Voltage : 36.43
Duty : -0.311
RPM : -0.0
Tacho : -5
Cycles running : 2
TIM duty : -2087
TIM val samp : 3360
TIM current samp : 3360
TIM top : 6720
Comm step : 0
Temperature : 24.71
The Goog seems to indicate that it’s a fried driver chip. The only thing I could find in my configuration that was out of the ordinary (which I didn’t know when I configured it) was that these 4.10 drivers top out at 50A, and I had each one configured at 60A.
So I probably killed them. Given how lethargic it was and how hard it is to push through sand I don’t think upping by 10 or 20A is going to do much good by itself - I probably need to gear down as well.
My drive gear is 20T which is pretty big, so I’d need to cut some smaller gears.
The trouble is this might not be in the adjustment range of my motor, which means that I’d have to modify the inner mount plate, which isn’t a big deal but if the new location is out of range of the covers then it gets more complicated. The thing I can’t move is the cover mount screws.
I guess I’ll go look at the model and see how small of a gear I can get away with.
@DougM have you thought about some 3d printed tpu wheels similar to this? Takes a long time print but probably wouldn’t cost much and could be printed for whatever hubs you already have.
Edit: Fins like these wheels have might help lift you out of soft sand.
@ Badbabyboyo re: 3D printed wheels - I’m not sure how well that would translate to a wheel that’s expected to hold a 200 pound guy, but definitely interesting concept. I could see where maybe you could CNC the outer parts of the wheel and 3D print inner segments. I’ll keep it in mind if the kayak cart wheels don’t work out.
So I started cutting the new gears and as soon as I started it was obvious that something was very wrong. Somewhere along the line during my rebuild process of the gear cutter the Y axis got about 0.060 out of line from the A axis.
I don’t recall making any changes that could have caused this, but it means that the teeth on the driven gears are misaligned with the axis of the drive gear. I imagine this will show up more as a wear (uneven tooth engagement) problem moreso than a have-to-start-all-over-again problem. If not then Plurf’s plan of converting to belt (probably I’d do chain, though, if I can fit the cog inside the housing) is the alternate.
So I fixed it and cut my new 16T drive gears. I cut one in aluminum and the other in brass so I could test both. I think the aluminum gear will be fine and it’s a lot cheaper and lighter than the brass gear.
They are a little sharp on the outer edges of the teeth so I’ll throw them in the tumbler overnight.
But then I’m likely to suspend this until the Unity gets here (if it ever does, they said they shipped it, gave me a tracking number but the number hasn’t shown up at the shipper’s website and it’s been a week, so we’re not off to a good start)
UPDATE: After a day in the tumbler the brass gear smoothed out very nicely while the aluminum one is still pretty edgy. It makes sense to me now why brass is better - you want the gears to sort of work into each-other and eventually smooth out (assuming you don’t have the machining capability to make them perfect from the get-go) and it feels like aluminum would just tear the POM gears apart and never really smooth out whereas brass is soft enough to give a little.
Afaik brass is self-lubricating - that’s the reason why brass bushings are a thing in scenarios where bearings make not much sence due to limited rotation.
The Unity is in Compton! Guess I better do something with those new gears.
2020-06-19 17:03
Compton,CA, DN SEND
2020-06-19 14:13
Compton,CA, ENCODED
2020-06-19 13:46
Compton,CA, RECEIVED
2020-06-19 05:17
LAX, In transit, it's progressing through Post network
2020-06-18 06:58
LAX, Arrival of goods at destination airport
2020-06-18 06:58
LAX, Arrived at the destination airport
2020-06-17 20:26
HKG, shipment departed from airport of origin country
2020-06-17 20:15
LAX, Released from customs: customs cleared.
2020-06-16 19:45
HKG, Hand over to airline.
2020-06-16 17:45
HONGKONG, Arrived at Hong Kong hub.
2020-06-15 17:40
深东凤岗仓, Depart from facility to service provider.
2020-06-13 17:52
Huanancheng,Shenzhen,China, Shipment arrived at facility and measured.
2020-06-13 17:52
Huanancheng,Shenzhen,China, 4PX picked up shipment.
Also, the last 2 of the Kayak Cart wheels have arrived. I suspect they sent out 2 more rather than the lost ones mysteriously re-appearing. Either way I’m happy.
The new Unity has arrived. The box is different than the Enertion boxes, which makes sense since they wouldn’t want to sell/ship it under a different name, but the quick start card is exactly the same, right down to the URLs and the misspellings.
I plugged it in, powered it up and it connected via BT to my phone and it complained about needing a firmware upgrade, so I did that. After a cold boot I was able to power it up and reconnect.
So far so good.
I’ll need to replace all the connectors in order to get it compatible with my current wiring, then I can actually try to calibrate and run it.
In the meantime out with the old drive gears (on the left) and in with the new (on the right)
I have been getting bearings from VXB for probably 10 years now and never had a problem, so I sent them a mail and pitched a mini-fit so we will see how they respond. Unfortunately their return window is only 30 days and there is no warranty on the products.
As of now I No Longer Recommend VXB as a bearing supplier.
I found the same bearings on (ugh) Amazon (Uxcell brand) for about half the price of the VXB. It’ll be interesting to see if they are any better.
The good news is that the smaller of the bearings, the 40-52-7, happens to be the size of a standard bicycle headset bearing. So I also picked one of those up to see if it is sealed better.
In any event, of all the things I thought would go wrong spinning a bearing wasn’t even on the list.
Ok, Focbox Unity is configured and drives the motors. It’s better already than the dual VESC solution because both motors go more or less the same RPM at the same time.
Assuming it doesn’t explode when I field test it.
I think I’m going to install an ammeter on the connection between the battery pack and the Unity to see what the actual current draw is.
Other than that now we wait for the bearings to arrive.
Salt water will kill a bearing almost overnight.
What i used to do was pack my hubs with grease and centrifugal forces would slowly squeeze it out through the bearing.
As it was forcing the grease out, salt water could not enter. I think i have only lost one bearing over the years using this method.
A different scenario here but i would be slapping as much grease on the bearings as possible to prevent the salt doing the nasty.
On another note, and i think i speak for a lot of watchers of this thread, you really need to get some video of this thing running the beach!
Also, one of the things I didn’t think of when I thought I was so clever using the aluminum inserts is that unlike metal, plastic creeps - so won’t maintain tension. Add a bit of threadlock to the mix and and what you end up with is spinning the insert when you try to remove the screw.
I’m working on moving over to the Kayak carrier wheels - have the hubs designed and was able to get the inserts out of the wheels (hey, it’s harder than you think - I had to invent a tool to do it)
I think I can get away with 3D printed hubs for the front/Idler wheels because the bearings will hold it in tension, but the rears I’m going to have to turn on the lathe because the rotational torque from the gearboxes will tear 3D printed parts apart.
To that end I’ve got a foot of 3" dia Delrin rod coming.
ALSO! VXB got back to me - they’re going to send me all new bearings to replace the rusty ones. So I’ll keep you apprised on that front. Honestly I don’t expect the new ones to be better than the old ones, but it’s nice of them to replace them for free. I offered to send back the dead ones, they declined
The replacement for the frozen bearing is supposed to arrive today.
If I’m lucky I’ll be back at the beach this weekend, but a lot of work between now and then. More likely I’ll be able to do rolling tests locally over the weekend.
