Hey guys long time lurker here and finally wanted to share one of my creations. It doesnt really fit in any catagory but feel free to move it if it belongs somewhere better.
Ive got a few builds under my belt/ongoing but this is easily the most fun. I have no idea what they are generally known as but me and the kids have started calling it a Ska-tooter
Obviously still got a fair bit of work to go , Its 2 x 350 Watt escooter motors brought used.
A cheap skateboard ESC (which I had unused from another project) which probably needs upgrading the regren braking is awful , I have to actually prepare myself before braking but i might get used to it.
Battery pack is currently a 10s2P pack which I use for getting my projects to the âworkingâ stages its old batteried and abused. plenty of room in there for cells though so when I decide to.
Welded steel frame and steering linkages which need some proper pivots machining up. just using m5 bolts ATM
Currently working on getting the spring strength right Id like to make it adjustable but not sure how yet (waiting for inspiration to strike)
Then obviously all the bits and peices, I already have a deck made but dont want to put it on until Im sure its not going to get battered up from learning to ride, paint, change to 10" pneumatic tyre on the frount etc etc.
Part of the problem is since Ive never even seen (IRL) let alone rode anything similar before Im learning both how to ride AND how to build it at the same time.
No idea on speed yet , I only set it to top speed once and it threw me (tyre jammed into the steering linkage while cornering) so sticking to level2/3 until Ive got the bugs worked out and I can ride it better.
Some replaceable plastic bumpers on each corner to stop the frame getting bashed up , which as you can already see turned out to be a good idea. That in the background is half of the 3D printed fender for my DIY onewheel project.
Underside as you can see loads of room for cells , Due to rather unfortunate lack of foresight though didnt quite make it wide enough for 2x 18650âs side by side
Thats the sort of thing I was thinking but something smaller and more refined.
the spring is only 120mm long and most of the turnbuckles I have seen are already longer than that. Sure I could fabricate a smaller one but there is a limit before you lose any meaningful adjustabiliy AND on top of that I dont actually know (YET) how adjusting the spring will affect the board and by how much.
Using the two springs I have I know that its ridable without a spring (or a underpowered one) but the steering tends to flop and overadjust , using a overpowered spring means you have to lean the board at a alarming angle to get a small steering output.
But that could be just as much down to learning how to ride it without letting the steering flop Im used to riding a esk8 where there is a force holding the board level and you have to push to âunlevelâ and turn.
This is exactly the opposite YOU have to keep it level and to âunlevelâ the board you have to âletâ it tip by a controlled amount
First EVER test ride ,I literally finished up the welding bolted it all together , duct taped the ESC and an even crappier than it has now battery to the frame and HAD to test ride it.
Rear tyre was completely bald , no spring for the steering , No teflon washers, not even a deck I still had my garage clothes on and my âsafety crocsâ .
Some safety gear is next on the purchase list , I already have a helmet and shall wear it in future and I cant afford to lose any more skin so some elbow and knee/shin pads are a must.
The wife might put a stop to me playing if I have any more spills
Iâve never brought that kind of protective gear before so Im hoping to find somewhere local so I can see it first.
I refer to the general category of single track skateboards as Inline Boards, but Iâm no NIST.
Just drill multiple holes for it. The farther away from the pivots, the stronger it will be.
Was that because you were turning very tightly, or was it a more spontaneous thing? Iâve always suspected that putting Drive forces on the front wheel could make a four bar steering mechanism unstable, but Iâve never tested it.
That seems intuitive, but it wonât actually do anything. When the front wheel is centered, the spring forces are balanced, and the centering Force only comes from the change in the spring length. So the only things that work are to adjust the spring rate, or the physical rate at which the spring is extended.
Spring centering makes it easier to balance at low speed, and reduces the steering sensitivity a little. Iâve ridden my own board with and without a spring, and tbh the difference wasnât huge. The rake of the steering axis has a much stronger effect IMO.
Make that a high priority, metal on metal hinges suck and are difficult to balance on. Teflon handles like butter.
I think it was a combination of things. It was the first and only time Ive had it on full power coming down a hill round a corner and I used the brake which was much harsher then I was expecting. At first Ithought Id just screwed up and overestimated my abilities but upon checking for damage I saw where the paint (and skin) had been scrubbed off.
The main issue was that when I first built it the steering was limited by the linkaged butting up agaist welds on the frame (100% a very happy accident) then I cleaned things up and ground some welds down and it never occured to me that I might have lost my steering âhard stopâ . Something which has since been rectified so it cant physically happen again ( unless something gets bent).
Massive thanks for your insights , they are going to be very helpful , at least i wont be worrying too much about getting the spring âjust perfectâ. Unfortunatly the steering geometry is somewhat set it stone (or steel) at this point without rebuilding the linkages and they were far too much work for me to want to start over.
I did wonder about having a drive wheel on the frount since all of the other ones Ive seen are rearwheel drive only but I figured it was worth a go. My gut instinct is that having a drive wheel on the frount wont be as much of an issue as having the frount do the braking as well , couldnt explain why though.
As a fourbar mechanism steers, the steering axis moves sideways. Steer left and the center of rotation moves right, and vice versa. This means that applying throttle should torque the front wheel straighter, and applying brake should turn in in harder. There should be a tipover point where the instability from braking exceeds the stability from trail, and the front wheel tucks in. Itâs hard to quantify cuz it should depend on a combination of link geometry, trail, lean angle, and a few things about the tire.
Do you experience higher steering sensitivity when braking, and less sensitivity under throttle? That should confirm the idea.
Just so you know I havnât abandonned the project here in the uk we lost the weather so things got shelved , now that the weather is finally brightening up again ive dusted it off and been out for a few short rides.
Things Ive learned , I need some half decent batteries on it and at some point Im going to need to upgrade the ESC as quite frankly the brakes are lethal. It would be nice if there was one which could be programmed to do all or most of the braking on one wheel as it does seem to get a bit squirrely when braking hard to tell if thats just because its get squirelly at lower speeds anyway.
Since Ive put ALL of my crappy batteries on it its got enough ooomph to actually get a bit of speed up which really helps. I think changing the frount to pneumatic (larger) will help as well.
Ive also seen a youtube video of someone who 3D printed his linkages for testing and they held up really well (until they didnt ) so Ive asked him about that since I could 3D print some linkages really easily to test different geometries
Im kind of at the point now where I really need to buy some batteries BUT batteries are expensive and Im debating if its really worth it for a âtoyâ. And of course before I get batteries i need to decide on a ESC and what voltage I want to run at.
Main thing is i have (and use ) safety gear now but havnt had any more spills . Ive mastered the running dismount though.
I think that might be due to how a 4-bar steering mech loses self-centering ability when you brake the front wheel. Maybe rear wheel braking only will help.
Braking balance should be easy to adjust with any VESCs, by setting the max motor regen for each wheel separately. You shouldnât need any particular ESC for that.
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) so Ive asked him about that since I could 3D print some linkages really easily to test different geometries