Currently in progress. I have been acquiring parts for this build over the last few months and its finally coming together.
Components:
- Bustin Sporster 35"
- Unity with VESC FW 5 and METR unity module
- @Eboosted MK3 enclosure
- 12S4P Molicelli P42A
- SR TKP’s with SR adjustable baseplates
- @Boardnamics fixed axles (effective hanger length is 225mm - 24mm per side)
- @Psychotiller quick plates and TKP clamps
- Maytech 6365 170 or 190 kv, currently TB6355 190kv
- @Boardnamics 40T kegel Pulleys, @Janux-esk8 15T motor pulleys (290 15mm belts)
- @torqueboards TB110 74A
- Hoyt Puck
I kick pushed this board around for a bit on the TKPs and the TB110s which honestly wasn’t bad. Absolutely love the deck and the SR TKPs really drop the wheels in the perfect spot in the deck.
I was considering making an enclosure to maximize the space I had for a decent size battery while staying single stack. Alan did such a nice job on the bustin enclosure that I decided to pick one up and save the work.
I ultimately decided to go with the MK3 version which has cable channels down to the baseplates. Heres where my first challenge occurred. So the MK3 tunnels go all the way to the back edge of an RKP baseplate that is mounted in the furthest holes from center.
Theres Alans build
The SR TKP bushing seat was already a problem with the MK3. The SR Adjustable TKP baseplates created even more interference because they are longer. The adjustable baseplates cover all 4 holes on the deck.
I picked up the adjustable baseplates for two reasons. One, they will raise the ride height which this low pig needed on the 110s and stock TKP baseplates. Philly streets are rough as is my riding style. Second was the ability to drop the rear hanger angle a bit. This will be my first board with TKPs so stability improvements in geometry should be helpful. Also had to file a smidge of the cutout to get the baseplate all the way into the channel so the bolts would line up. Currently have some Krank 95A barrels in there. You can see the baseplates are longer. This actually made a noticeable impact the the flex feeling of the board just because the baseplate mounting point moved inward slightly from the original baseplates that fall a hole shorter.
After a bit of trimming with the dremmel and a file we had a rough shape. I’ll be sealing the enclosure behind this so I’m not worried about it. Will use some rubber channel to clean up the edges around the baseplate. The only pic I have at this point was this one in progress check.
Anytime the enclosure isn’t flat and moves around the shape of the deck, its very important to have the gasket installed that you will be using. If you have to use a thicker gasket later, your holes may not line up. As the enclosure moves away the alignment of the holes is lost because they’re on an angle with the sides of the deck.
Returning from a week at the beach I went back to work. there, I discovered bulkbattery.com was carrying P42A cells at $4.80 ea delivered. Ordered up what I needed for this build and another. If you’re wondering, the order was shipped direct from 18650store who is an authorized Molicelli distributor. They were waiting for me at home.
Next up, I had picked up a unity heatsink from @3DServisas at the beginning of the pandemic for this build. While I dont expect to overheat the unity running on thane, ya gotta admit they look cool AF.
Im building all of this out of a 1BR apartment in Philly so my tooling is limited. To cut the hole as precise as possible, I 3D printed some jigs to use a flush cut router bit with.
First I marked the center and test fit the heat sink with the P groups. Space inside the pocket of the enclosure is very very limited. The heatsink had to be all the way against the back of the pocket and i had to sand the fillet a bit to get it sitting flat here. I picked my spot and drilled the heatsink mounting holes. Once I placed the heatsink onto the enclosure it was clear the center mark I made was not centered. This is a pain on a surface with nothing but round edges. I corrected my mistake and will fix the holes with some epoxy and FG.
inside the enclosure was very snug.
The 3D printed jig I made. One I mark everything and drill the mounting holes, I will bolt the jig in place on the inside and follow it with a router with a flush cut bit.
Marks laid out. Sorry @eboosted, damn thing landed right in the middle of the logo
One the holes were drilled I check center by bolting the heatsink to the outside of the enclosure and measuring and giving it a few looks from a distance. Then the heatsink came off, the jig for the bearing of the flush bit was placed on the inside and bolted through from the jig on the outside. The outer jig gives the router a nice flat surface to run across as I would have been running out of base to move the router on in some areas during the cut. The outer pieces also had easy to align center marks to make sure I didn’t twist it or get it out of square. Once the outer jig was aligned, I used the bolt holes to bolt it through the enclosure and through the inside jig. I hot glued the jigs to the enclosure as well to keep things in place.
Perfect! Literally snaps into place. Ill seal it once I fix the missed screw holes and fill the logo. Screw holes are easy to fix. A messed up hole would not be.
Good thing my main battery terminals wont be right next to this piece of aluminum
I had dropped the cells into the enclosure with the unity and used some modeling clay to get an idea how much space I had between the deck and the components. I pressed the deck down onto this setup and was left with something measurable.
The above photo was taken before the heatsink was installed. Prior to the heatsink going in, I had just 5mm between the unity and the deck at the narrowest point. Each of the cells groups had roughly 4mm of space. This was with no gasket on the enclosure.
Already Im thinking about how Im going to handle this. The 3DS heatsink for the Unity has raised it 4mm off the base of the enclosure so I now have 1mm of space left before the deck – with a gasket in place I’ll get some back. However, it wont be enough for the 10mm thick BMS that needs to fit in here above the unity. Ill come back to this in a bit
I got to work on the battery. P42As are rated to 40 amp burst with temperature control and have remained temperature controllable around 30 amps. I dont intend to run a urethane board at 100+ amps continuous. However, I’ll build the pack to support the amps its capable of.
First the P groups were glued up using high temp got glue. This stuff from gorilla glue doesnt peel off, it will tear the cell shrink wrap if you make a mistake.
Hot glue, fiberglass tape around the whole P group.
Added fishpaper rings to the positive terminals and applied adhesive fishpaper from 145PTags.
For nickel, I cut down some 50mm wide 0.2 strip into 74 mm x25 mm pieces and rounded the corners with the infamous corner chompers. Both those and a paper guillotine cutter made this go much faster than scissors. 0.2mm x7mm nickel is good at 13 amps oiptimal, acceptable at 20 and hot at 27. The strip is 10.5 times wider than that so those values scale. 130 amps optimal, 200 acceptable, 270 hot. More than sufficient for a battery I will likely set at 80 amps and rarely turn up to 100. After this I added adhesive fishpaper pieces that covered the terminals at both ends of the group and only left the bent over strip on top exposed.
In hindsight, I wish I had notched the nickel above the cells so that there was a gap through the center of the pack from end to end. This would allow the BMS wires to run up through there without resting on the nickel. But this will work out fine.
So at this point, im realizing that I screwed myself. The Unity heatsink has eliminated valuable height in the enclosure and I didnt check before putting the holes in the deck. Theres not enough room for even a D140 BMS in the enclosure without at least a 1/4" or taller gasket (and thats once compressed). And I have a bluetooth BMS from @thisguyhere that is 10mm thick I would prefer to use. Further more, the distance the enclosure has to move away from the board is creating some issues with my enclosure bolt hole alignment now.
For one, I used m4 insert and I did not drill all the way through the deck. I used the steel version which are only 5mm long. However, because they are shorter (the deck is 12mm), they grip less wood and I was feeling nervous about their longevity given the weight of the enclosure. Plus, now theyre not lining up well because I installed the enclosure with an 1/8" gasket and now I need a 1/2" one. I tried to remedy this with the through the deck inserts that eboosted provides, but was still having alignment issues. Also thinking that tall gaskets suck and look like poop and cutting a pocket in the deck is tough because the deck is already thin.
What I decided to do was go all out. I pulled my spare maple veneer fand bag from Roarockit out. I stripped the board, removed the inserts and made a plan.
I had a deck snap behind the front truck and toss me to the ground that was drop though. I prefer to reinforce these areas, especially on split tongue decks. ESK8 puts a lot more stress on these decks than the average kick pusher does.
My plan is simple, Lay up several layers of 1/16" veneer to the bottom of the deck and then rout a larger pocket from the center. This will add thickness to the deck allowing me to more safely create the pocket size I need to clear the BMS and internal components. I’ll reinforce this area with FG when its finished up. This will allow me to continue to use a thin enclosure and preserve external aesthetics.
Stripped. Will add 3-4 layers (4.5-6 mm) to the bottom and one (1.5mm) to the top (after installation of through the deck hardware which will then be hidden). I may skip that step if I skin it. Cutting the large battery pocket out will help to keep the board from getting too stiff from the extra thickness.
A small tongue and drop down reinforcement with fiberglass went down first and then the first layer of crossband veneer went over it. Crossband has the grain running perpendicular to the length of the board and will have virtually no impact on flex in the length. The first two layers are cross band. Into the vacuum bag the assembly went. I did need to add clamps to the outside to pull the veneer to the deck at the drop downs.
I used West Systems epoxy with 206 hardener and a bit of black dye so I could see it better after drying.This has the third piece in the bag right now. Im doing a lot of sanding and work in between. Tapering the edges beyond the enclosure to keep the deck appearing thin from next to it. Additionally, this third layer only covers the bottom of the deck and i will blend it in to the start of the drop down. The final layer will cover the whole bottom of the deck end to end. Basically the 1st and 2nd layers and well sanded towards the ends of the drop down and the 3rd layer doesnt even go there. This prevents me from over stiffening the tongue and drop down which contribute to the flex of the deck. Ill remember to take some photos tomorrow when im prepping this for the final layer.
Next up and the part of this project im both most excited about and most proud of. During the last few months, Ive been running a COVID medical equipment volunteer team making faceshields. During that time, I got a lot of exposure to Smooth On products as well as just general molding and casting with silicone and urethane resins.
Within the enclosure, I wanted to accomplish a few things. I needed to figure out how I wanted to secure the P groups in place. I also had the idea to coat the inside of the enclosure with something rubberized to reduce the hollow sounds it can make and amplify little stones and other things. If it kills me, this board will be rattle free and ride as nice as a urethane board can. Finally. a flexible pocket the P group could sit in would reduce vibrations and shock that the cells are constantly hit by - especially on a thane board in philly streets.
I looked around and found very very little about potting electronics with something like this. Sure, you can pot electronics with epoxy, silicone, urethanes etc. But I was also concerned about a permenant solution that eliminated my ability to service the battery if needed.
I considered some materials like MG 834fx a flame retardent, thermally conductive and dielectric flexible epoxy. It was a bit pricey, but I was concerned that given its epoxy base it would be firmer than what Im imagining. Its main advantage was that it was a thermal conductor - where as all urethanes and silicones are going to be thermal insulators.
I settled on a urethane rubber compound from smooth on called Vytaflex 50 - a 50A shore hardness urethane. I determined the volume required and ordered some up.
The full cure time is long at 16 hours, but you can demold after 8. I dont have a vacuum degasser so there are a few bubbles but it does clear well on its own in general.
I sketch up in CAD the 2S4P groups in each channel and 3D printed two plugs. They have a small 2mm protrusion on the bottom that sets them up off the base of the enclosure to provide some rubber under the groups as well. I had the extra overhead space since I was doing all this deck work anyways. I sanded it to 400 grit and coated them with universal mold release from smooth on. I clamped them into place in the enclosure and poured in the liquid urethane using some black dye to tint it. Heres where I’m at tonight. Theres a few P groups installed to show you how it works. I can flip the enclosure upside down and they stay put. If the centers are held down they cant fall out. They fit snugly and the rubber is nice and soft. You can see one of the plugs I printed sitting in the large front channel. The 5.5x2.1 mm charge port wiring is protruding from in front of it.
Really happy how this is coming along.
Thats enough for tonight. more updates tomorrow.
Also, still looking for inspiration in the form of a name/theme and skin idea for the top. Happy to hear ideas
still working
I’m surprised you decided to go all out and add more thickness to the deck; if I were you I would have just tossed out a single p-group and used the board at 11s 