Reviving a destroyed Pint
Haven't forgotten about this, just had a few side projects that needed my attention before I set off finishing the Pint.
One thing I've been working on is a DIY footpad sensor. All the OW's appear to use what's known as an FSR sensor either side of the footpad which when pressure is applied it completes the circuit. I won't bore you with a technical explanation of these however if you want to take a look there are a handful of pages that go over them, fewer explaining how to make a reliable one...
Why not buy one? Well the largest FSR's I could find had an active area of 45mm x 45mm which is tiny. If you use 2 each side of the pad you still have some very small contact points with them not really being designed for this sort of thing. I needed something more durable. Being unable to find a place that would cheaply make a custom FSR as a one off I opted to just DIY it as is the theme of this Pint rebuild.
As with most FSR sensors I'll be using metallic traces with a layer of velostat above them separated by a small air gap that keeps them disconnected. Maintaining this air gap is difficult. Failing to do so results in ghosting. Overdoing it and you'll have a pad that might deactivate mid-ride.
I cut the traces out by hand from a 0.1mm copper sheet. That was fun...not! To stop the traces lifting I'm using 4mm wide double sided tape to attach them to the 3d printed lower plate which is only 0.4mm thick (2x 0.2mm 3d printed layers). Built in is some tiny vertical walls on the upper layer to help prevent the traces ever bending into each other.
Using some electrical tape to make sure the ends of the traces never lift and touch the velostat. Then some double sided tape around the edges to attach the spacer that will introduce an air gap. It's 0.3mm thick (single 3d printed layer) which should be enough to prevent it ghosting and require a decent amount of pressure to activate.
I won't use the whole single sheet of Velostat in the final so both pads can act completely independent of each other. With a single piece it's possible under some edge cases that both pads regardless of which side is active could stick on.
Hoping it's reliable enough to last and not kill me while riding. If it's anything else like my other creations it will at least give me a decent injury before I finish it. All my most trusted and favourite creations have done so in the past. I like to think of it like a creator/creation bonding exercise ;)
Enough with the footpad sensor, wanted to move onto attaching the controller housing to the rails. Needed to use a guide to make the mounting points on the rails for the controller so made a little template to give me guide holes.
Worked a treat however I don't have M4 bolts that are short enough to not poke out so going to order some.
Got special plans for the power button. Going to replace it for something a little cooler. Already tested and got the solution almost there but just need to implement it. If it works I won't need to drill a hole in the rail for the power button.
NotSure last edited by
I cut the traces out by hand from a 0.1mm copper sheet.
exacto blade and stencil or snips?
@NotSure Tried using an exacto but it dulled too often and began to tear rather than cut.
Printed off a template, stuck it down then just used a pair of sharp scissors to cut it in the end. Was thin enough to not take a lot of effort.
Using scissors did introduce twisting in the traces so I had to give them a good flattening for a while with the double sided tape helping keep them flush.
blkwalnutgrwr last edited by
@Lia -- Thrilling it is to watch your process and progress!
HanahsDax last edited by
@Lia You should definitely get the “Badass/Genius” badge for this achievement. This project has been fun to watch.
Did lots more testing today. 2 steps forward one step back sort of deal though.
I have managed to replace the power button with one that is operated by magic!
Okay it's not Magic, it's a magnet. More specifically a reed switch replacing the stock switch with a magnet hidden underneath the OW logo on my gloves.
Why did I do this? I have no idea but I did it and it works!
On the plus side it were to ever break it's not like there is any large metal attached to it that could bash the PCB >.>
Now onto if the board actually works...
The board does and sort of doesn't work. It'll turn on, boot correctly and if I bypass the footpad I can prime the board. I can even get it to move BUT.... oh my god the noise that comes from that poor motor!
Typically noise like that on the Onewheel is a loose hub bolt. I can assure you these are cranked down so I don't think it's that. It could possibly be the controller/battery wiggling around as those are still press fit into the rails.
Assuming it's not that it seems like I'll be taking the motor apart, I have 3 suspects as to what's causing the noise. In order of what I think is most likely:
- Bad bearing(s). Considering the absolute state of the hub I wouldn't hesitate to suspect one of the bearings has died. The fact that when pressure is taken off the left side it gets quieter leads me to believe the right bearing might be shot. It does spin cleanly though so I have doubts.
- Damaged cabling between the controller and motor hub. I think the 3 main wires that control the 3 poles are fine but I wonder if maybe one of the sensor wires could be damaged and thus it cannot perfectly locate what position the motor is in which could lead to vibrations as it bounce back and forth between the unknown positions.
- Faulty Hall sensor. If one of the sensors has died then the same theory from #2 applies as these actually read what position rotationally the motor is in.
I don't suspect the controller electronics. If it had a fault I'm sure it would have manifested itself in earlier testing.
Regardless of that, congratulations Pint OW131223 for "passing" your first test ride on the road to recovery.
OneDan+ last edited by
a reed switch replacing the stock switch with a magnet hidden underneath the OW logo on my gloves
You've discovered the solution for someone hopping on our boards and taking off! Let them get up to speed, then shut it down!!! @Lia, you should repost this on the theft prevention thread . . . :D
@OneDan Good idea, I'll finish up the designs for the printed parts and add a post there.
It's unbelievably simple to do. Just the switch alone and some silicone around it would suffice if looks weren't a factor.
NotSure last edited by
@Lia sounds like an old vacuum but it works! Very cool.
@NotSure Not a happy noise at all. I'm sure it's something simple though, just got to find the cause.
blkwalnutgrwr last edited by
@Lia -- Sounds to my damaged ears like the rapid, flutter vibrations of a buzzer. To my eyes it looked like the buzzer noise only occurred while moving -- not just standing still. Interesting puzzle. Good luck with it!
@blkwalnutgrwr Sounds much worse in person I assure you lol. The video doesn't quite capture just how loud it actually is!
Like you say it occurs only under certain circumstances but how it manifests doesn't narrow it down too much.
Will give an update once I've found the issue :)
Holy crap that hub was hard to take apart. It was pretty tight but I eventually managed to break it lose after plenty of oil and destroying a few bits of spare wood to act as a dampener when hammering the axle out. Once whatever was stuck came loose I was able to push it through all the way with just my thumbs.
Looks like one bearing is utterly shot. It's got loads of play in it, enough that I can wobble the plate against the axle with the bearing seal being the bit that moves. Trouble is it won't come off. Since it's 6PM I'll hold off bringing out the big guns to rip it off but tomorrow it's coming off!
The scrapes on the hub wasn't me, that was the Van! Same side as the suspected dodgy bearing so makes sense.
Under close inspection it looks like there is some corrosion on one of the stator cores along with matching rust blobs on some of the magnets within the hub. Doesn't bother me too much as I'll just clean it off. Outside of that I think this might be a simple bearing swap... I hope.
Any recommendations on new bearings? Obvious choice seems to be Craft&Ride but curious if anyone has a special brand they use instead?