Things are coming along slowly but surely, setting up a CNC and kitting it out in itself is a huge project. Most of the CNC tooling is here already, I’m gonna finish up the wiring and order the last of the accessories that I still need this week.
I’ve more or less finished learning the basics of CAM in Fusion by doing the toolpaths for the base of the swingarm. Some polishing still left for both parts I’ve done so far, but not too bad for first and second CAM projects ever.
I’m not sure if that will work. There is going to be a lot of load on those pivots.
I would love to see a set of these suspension units that can be fit onto a more traditional flat deck.
You are not the first one to ask for that. It’d offer less benefits (lose the major benefit of completely eliminated torsional flex - which here is done by effectively having a big box section through the whole length).
That said it could still be a good option for something like a carbon wrapped idea style deck, but I think the actual idea decks arent very long?
One issue I foresee with universal compatibility is that the deck essentially needs to be chopped to be like a bracket deck, and only stiff decks can work well as a baseline, due to how far out the axles need to be from the bracket mounting. Also I’m standing directly over the mounting bolts. So some sort of big antisink for the bolts integrated into a separate footpad would still be very advised - I could make something like that as well though.
Before I make something like that I want to get the drivetrain components around the chassis up for sale as well ideally.
Added some weight saving cutouts
Probably the pin constraint for the M8 mounting holes wasn’t the right call, as there’s a sandwich assembly in reality and it seems to put most stress there. That said that’s definitely a high stress area in the part.
Trying to run FEA for the complete mechanical assembly, but it’s a big model so still playing with the settings and simplifications just to even get it to run at all.
The cutouts look great on the swingarm
Refined the mesh and did a bit of simplification and now its running. The sandwich construction did reduce the stress around the bolt hole as expected, I’ll refine the constraints tomorrow. Cool to see the bellypan also taking up some of the load though.
Probably constraints still aren’t perfect, but saying that the axles are fixed (tried fixing the cylinder part and the flat end as well, probably fixing flat end is most realistic as middle of tire contact patch is more or less around the end of the axle) is a decent enough statement and close enough approximation for me.
Worth noting that I have the whole trucks modelled in steel, and they aren’t exactly accurate measurements.
That said. The 23.3^2 hangers and 12mm axles seem to be the weakest spot in this even when everything about the truck is modelled from steel. Which are pretty much known to be indestructible already from alu (from which duality hangers are made). So this pretty much assures that the chassis will be indestructible as well.
Seems like the parts I’d make max out at around 20-21 MPa at 120kg total static load on the footpads (probably around 80kg rider weight if board is built out to full spec)
If we don’t count the (already indestructable) trucks, then the weakpoint is the neck of the swingarm base. That’d leave enough safety margin for around a 25G impact. 25G getting past the tires and the pivot cups and the suspension is probably a knee breaking impact so I’m happy with that.
I’m glad to see I feel like I can still call this a skateboard in this form.
I wonder how I will feel by the end of it…
By the end of it it will be very much up to how you define a skateboard.
Unsure on fitment with smaller wheels but I want to try. 8" might work out without too much compromise. 6.5" would probably require too much compromise regarding axle to standing platform height, max lean, and suspension hardness. That said I do kinda want to set it up once just to see how bad that would ride… Might not be as bad as I’m imagining.
It’s probably bigger than it looks. Having internal space for a 3 cell wide double stack 20S5P + 2x2G300 kills ground clearance while turning… The kart wheels make up for it though. The internal space requires the deck to be super wide but I like wide decks. This will definitely be great for bigger people. 286mm wide deck with a long standing platform. I feel like the size and design definitely makes the kart wheels look more proportional and much less out of place though.
I think adding complexity between the deck and the wheels shouldn’t be disqualifying, since there’s no hard boundary you can draw. But if you install a seat, handlebar, steering wheel etc. that clearly turns the machine into a scooter/bike/whatever. So a criteria based on how you ride it can be defined more clearly.
excuse the mess.
(obviously) that bead breaker is a pretty DIY solution. Good thing I have a CNC to wedge it under. I’m just barely heavy enough with this setup. I’ll probably build a better bead breaker for the next tire change, this kinda sucks… It did work out for now though.
The fresh tires mounted up very nicely onto the rims thankfully, I think I was supposed to use 5.5" width rims for these tires but mine are only 5". Also they are 11", 10" would probably be preferable, but it should work fine, especially for 8€ a piece on clearance sale. The rubber feels almost like glue when touching it, pretty crazy.
On Friday I’m going to be trying these in Cologne on the slick indoor track, we will see if they work in there at all. Last time I was on linns and those werent that bad but definitely weren’t great either. Here’s some pretty cool footage of @TZDKB chasing me on this track from a little over an year ago:
You stay so low…
Designed some heatsinks/ bolt head covers on the underside of the deck. Idea is these will scrape instead of the boltheads on the underside. Plus of course offer bunch of ESC cooling for intermediate electronic setups.
Been working on finishing up the CNC as well, looks like the electrical wiring should be finished later today (there were, of course, difficulties along the way…). After that just enclosure and it’s ready to rip through material. With some luck the alu should arrive on Friday.
Do you have an estimate on what this portion alone will weigh?
How about the whole thing?
How much does your current board with the big tires weigh?
Some ride footage from the Cologne track from 2 weeks ago. I was actually relatively slow, I picked up all the grime and dust and rubber from the track with the tires, and didn’t end up with much grip after. Smooth indoor track. Also broke a motor pinion loose, still yet to fix that. So I was riding around on the track on my chill boards most of the time. I quite enjoyed the Cavity CS1, and got the bushings dialed in decently in those DKPs, zero power though.
In other news, been making progress on the CNC at a slower than ideal pace.
Made this circuit which takes low voltage logic input from the cnc control board and drives the stepper driver which operates at 12v logic. This is tested to work on a breadboard, got a pcb design done, been trying to cut that out at university and failing miserably with makera’s buggy cam software. Will go back to uni and keep trying or just make it on prototype boards if I can’t figured the carvera pcb work out.
Once that board is assembled the cnc will be running with maybe 2 hours of extra work.
Materials for enclosure aren’t here yet. And the shop I wanted to source materials from isn’t super responsive via email regarding b2b sales, didn’t get the invoice yet. Will try to look for some alternatives to that shop as well.
I could (and probably should) cut the parts from wood first to make sure I’m doing the correct things before starting on the expensive alu, so it’s not a delay necessarily yet, but annoying for sure.
I can get some reasonably accurate weight estimates in a few days. Rough estimate is 10-12kg total bare chassis weight.
Full board with full spec electronics, super rough guess but likely 45kg±5. Reasonable electronics spec more like 35-40 i think. I should actually calculate things.
Also no idea how much the final gear drives will weight yet, as I’m redesigning the double stage for SLM M300 gears as soon as I have a bit of time and enough capital to start experimenting with that and the inrunners (most likely may). I learnt quite a bit from the design of that drive, that’d make sense to apply from the ground up for a new design, plus the manufacturing tech is more viable with SLM.
My current setup is 32kg with the wet tires, which are slightly heavier than the slicks were. With the liion pack it used to be slightly heavier still, switched to lipo due to overheating issues, rather than building a better temporary pack.
I sort of refer to it as the psychoframe of raceboards. Not very comparable to anything else around. Still much lighter than a psychoframe’s 70ish kg though.
How many pev Riders usually show up for these indoor cart sessions? Do you guys get like a whole evening? Or some hours or what?
Seems like it would be a really fun scene even for a Guy like me that is not looking to go fast.
32 kg is wild..45 is wild.
I would injure myself just putting them in the van…
There were definitely a lot of riders just chilling, it was only 2 riders going super fast and then me and one other guy going decently fast. If I had to guess there were around 25 people this time? Onewheel, EUC, esk8s with PU, esk8s with pneu. Even had a trike on the track.
We had the track from 8pm to 1am this time. It was a lot of fun. Also a good time to gather and talk with your fellow pev enthusiast friends.
Most events we have are races, but the races we have in europe by xerace are very beginner friendly. Everyone gets group to ride with people around their level in the heats, and it’s just time trial usually. (Sometimes top group does one final head to head heat, but there’s 6 time trial heats). There’s many who attend and not ride fast. For race events usually the day before the race, and sometimes also the day after the race, we get some tracks (often different ones) for 2-4 hours of practice, where again, everyone is welcome regardless of skill level. Also they are usually accompanied by group rides which are also a lot of fun. They do tend to turn into pub to pub / restaurant skating often, and they are 100% worth to attend, especially if you are attending the event without racing seriously
32 is definitely doable but not super convenient. Honestly the worst part of the 45kg or so will be putting it in the car. I highly doubt I’ll feel the weight under my feet with the truck/suspension setup I’m going for.
