Hi, enjoying this thread.
i think your tyre choice is going to cause you problems, firstly they are going to fling sand everywhere and that will become annoying very quickly, also they are only 2ply and you stand a good chance of ripping them to pieces.
Can i recommend looking at slick tyres that are used on mini moto bikes and quads. Will fling a lot less shit and stand up to the abuse. Trade off is that they are a bit heavier.
@aardelandings good call on the tires. They were my second choice because half of (2 of the 4 I ordered) my first choice got lost in the mail. However, the good news is that the vendor (China of course) has sent out 2 new ones, so I will continue to use these wheels/tires for development and hopefully for test runs, but when all 4 of the other ones are in Iāll switch.
Of course this means Iāll have to completely redesign and re-manufacture the rims. Ugh.
Ok, so despite some setbacks my goal this weekend was to have a rolling chassis and here it is!!!
If you look closely at the deck youāll see it has 2 sets of screw holes - it is recycled from an earlier board, so Iāll have to fill the empty holes at some point. Or not.
The setbacks were that I removed a feature from the outer rim and in doing so I didnāt notice that the air valve opening (which was dependent) got removed, so I printed the part first in black, then more of the midnight blue came in so I printed it again - all the time not noticing that there was no hole for the tube valve.
So 5 hours later a new print of the part.
The new tubes came in and hold air, so we are fully rolly.
Next up I went to order batteries. Iāve been buying these Lishenās from LiIon wholesale because they are super cheap and high capacity, but only 12A (which is actually perfect for this project since beaches are flat Iāll never need more than 60A) But they are out of stock.
Amazingly these Molicels are only slightly more expensive, higher capacity and a whopping 45A, so I immediately ordered a set. However, they are too nice for this board - I want to transplant them into my daily driver.
Back story, I ride with a friend, and since I DIY and he off the shelfās I can usually easily out power and/or out distance him just by making subtle upgrades to my board. However, his last board is both a better hill climber and has more range than my board (his is thanes, mine is 6" pneumies). I was going to let this go because I donāt really care (I might care about the range thing, but weāre only talking a couple of miles - mine does 20, his probably does 22) but with the above Molicelās I could dominate once again!
So now I have a much more complicated project because I have to transplant the Molicels into the old board and then take the old cells and put them in the new board. Normally this would be easy, just swap the pack across, but I mount each P pack to the rails, and the ralis are different widths between this board and the Daily Driver. So itās much more complicated than it should be.
Iāll keep you apprised as to how this goes.
Next up the electronics box and I am working on a no-spot-welding implementation of the battery pack, so Iāll outline more details in a subsequent post.
Iām not sure what the consensus here as to what constitutes Dead Sexy, but I canāt imagine this doesnāt come close 
Yes these are Molicel 4200mAH 45A 2170ās
Over the winter I was trying to figure out ways to put together a battery pack without welding, and I came up with gold contacts on PCBās with a sort of a rack mount.
This is sort of partially assembled - the black plastic wings will bolt (the holes arenāt there yet) to the aluminum extruded frame of the board under the deck.
As it turns out not all 2170ās are the same diameter, the Molicels are 0.839 vs the LIshens which are 0.851. Not a huge difference but enough that I need to make some adjustments to the plastic carrier before I make more of them.
I hope to have all the packs made by the end of the weekend but, as I said, these wonāt be going in the Sand Runner, they will get transplanted into my Daily Driver and that pack will get moved over to the Sand Runner.
Getting all that done by the end of the weekend will probably not happen, but Iāll keep you apprised.
Those cells are 30a btw
According to mooch at least
Well, I got totally off target this weekend. I posted a week or so ago about my belt slipping on my Daily Driver and the end result of that was when I converted it from chain drive to belt drive I got the wrong belts. I got HTD 3M where I needed HTD 5M.
So that meant replacing both the motor pulleys, the wheel pulleys and the belts. the Daily Driver runs 6-shooters and I had been complaining about the fact that I didnāt quite have enough hill climbing power and slightly too much top speed, so this was an opportunity to change my ratio a bit. I wanted to go to 4.4:1 from what I have now which is 4:1, but running 3M belts. With the new battery pack going in Iāll be able to bump up the battery current too - probably an additional 10A will do the trick
So I needed a 66T and a 15T. The 15 wasnāt a problem, you can get those at any esk8 shop, but without spending a horrendous amount of money you canāt get a 66T. So I had to make one.
Now Iāve made chain cogs before, but Iād not made pulleys. Turns out they are almost exactly the same. I grabbed a CAD file for a 60T off SDP-SI and modified it a bit to make it 66T, then I had to order a special cutter because all the ones I had that were a usable diameter werenāt long enough to cut the depth I needed.
Then the Delrin that I had in stock turned out to be 3/8" and not 1/2" as I thought it was, so I had to make each one twice (which actually works out better since I need to be thicker than 15mm, which is ~0.59"
Anyway, here it all is:
The grey things are what was originally going to be the edges of the pulley when I thought my Delrin was 1/2", they would extend the thickness just a little bit, like this:but I wonāt use them.
The 4 in the center are the 66Tās and the two on the right are 15Tās. I figured Iād make a few for testing since once you have the tooth profile itās easy to make them in any size you want, you just have to math out what the OD of the pulley is and then attach the right number of teeth to it.
Hereās a picture of the mill cutting the 15Tās
Now I wait for the belts 
I did get a little bit of work on the control box (electronics housing). When I have that baked Iāll talk a lot more about it.
You mean I can only put 150A at the wheels? Iāll be lucky to survive the week 
Why not just get the right belt instead of new pulleys? Iām pretty sure belts are cheap and easier
Belts and pulleys are matched - 3M belts work with 3M pulleys and 5M belts only work with 5M pulleys.
This is the profile of a 5M
Battery packs are all built up and control box, aside from the top, is basically complete.
A couple of detail shots on the control box. As you can see itās all 3D printed and segmented. This way I can change the input and output configuration just by printing new grey pieces in the format I want.
Itās turned out to be a pretty good design, I used it on the Daily Driver and Iāll likely retrofit the Mountain Board with it if I ever find myself cracking it open for an upgrade.
Next is a lot of work. I need to disassemble the Daily Driver, remove the battery pack, install and wire this battery pack and then reconfigure the Daily Driverās original pack for use in the Sand Runner.
In a perfect world Iād like to have the Daily back on the road both with new batteries and new 5M pulleys and belts before the long weekend. Unfortunately the new belts donāt arrive until Tuesday, so thatās pretty tight.
The control box is pretty cool, great 3D printing skills out there
Ok, the Daily Driverās upgrade to 5M pulleys and belts is complete The pulley turned out unusually wide.
So now I can get back to what Iām supposed to be doing. I made a nice carbon fiber cover for the control box
I know what you want to ask - Doug, how do you cut carbon fiber? Well, you use a tile saw blade, you wear a decent air filter and you have a lot of air movement - like a big fan running while you cut it so the dust doesnāt get into your lungs.
You can drill it with a standard drill bit.
this is the carbon fiber I used
Iāll probably work up some slightly better looking screwsā¦
Next up is the battery pack. Iām going to wait a week because I donāt want to cannibalize the Daily Driver right before a really sunny week, but next weekend Iāll swap the PCB pack into the DD and start to figure out how to retrofit that pack into the Sand Runner. I donāt have enough plastic in stock to make the brackets anyway, so I guess tomorrow will be a non project day.
Can you speak to, and show better pictures of, how you secured the bullet connectors to the 3D printed part? Following, excellent work!
@Redeye sure,
First, get some heat shrink tubing, preferably adhesive lined and after youāve soldered the wire to the female connector heat-shrink it. This gives the plastic something to grab on to.
Then I just built a little shelf into the insert:
And made a clamp to squeeze the connectors in place
I took about 30 thousands off the half-circle on the clamp for some extra clamping power
Then get some of these high-low screws to screw it together
Here are the step files:
SR Control Box 1v0 insert Cable Clamp.STEP (52.6 KB) SR Control Box 1v0 insert Cable Clip.STEP (122.4 KB)
Clearly, youāve thought this through, nice work. You live in Seattle I believe, so anything for water ingress purposes? Silicon glue?
@Redeye not really. I do make sure everything is up off the bottom of the box a little bit so if water does get in it wonāt affect the electronics; and the box is sufficiently not water-tight that water will drain out between the bottom of the walls and the aluminum base plate.
With the insets the way Iāve designed them it would be very difficult to get IP67 out of it. I suppose you could put a soft rubber gasket between the top plate and the walls, and maybe design in some channels and overhangs so that water wonāt be as likely to seep in.
But the truth is I just donāt ride in the rain
I used to live in Northgate and commute 10miles on bike to downtown for work. I never planned on riding in the rain either, but it happened more than I liked 
Not sure why youāre avoiding welding a battery, but if its due to a lack of a welder, i can help in Seattle.
Just pour epoxy into the enclosure once all the wiring is done and everything is where you want it. As an added bonus it is also resistant to vibration and fire
@Redeye I got caught out in the rain one time - torrential downpour on a little-used trail. It even hailed for a while, which made the going a bit tricky. I tried to ride back to the car through the rain, but the board shut down, amazingly, only about a quarter mile from the car.
It was the anti-spark switch that gave up the ghost because it had a cover on it and the cover filled with water. I think thatās the definition of irony.
@NuRxG thanks for the offer, but I have/started with a battery welder. My problem is I am constantly upgrading (or as in this case re-arranging) these boards and I want to be able to re-use the batteries in future projects without having to de-weld them and clean them up. So I want to find a reliable way to pack them without welding. If it doesnāt work Iāll fall back to welding.
