I very much admire how you got that heat sink so nicely in place. What’s the total weight of the board?
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Dunno yet on the weight. I’ve only added about 1 lb with all of the rubber inserts but tbh, I forgot to weigh out items before and after.
I’ll get a total weight when it’s built and will be able to compare it to original components.
The heat sink is honestly the source of most of the issues. The height it added caused problems, locating it was difficult with 12S etc.
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What’s the depth of your enclosure?
Edit: if you still have the part you cut out, may be you could get rid of the heat sink if it causes too many problems?
Oh no, everything’s being built to work out. It’s been a lot of fun working through these problems and not limiting myself on solutions. A lot of time, sweat and money has gone into this but I’m excited to see the finished product.
I could’ve cheated with a thick gasket and used a D140 and gotten away with it I think. Still would’ve been tough with the heatsink.
Getting some ideas about motor phase wire routing. Too much length on the maytech motor sensor wires so I’ll shorten them
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I see a build of the year contender here!
I always look forward to that battle, specially with this much love for the builds this year!
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Figuring out if I can mold MR60s into a tail gasket to seal off these channels. This would have the motor phase wires plugging in from the outside, although the distance is really short so they may have a tendency to get tugged out
May have to just stick with bullet connectors
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I would epoxy male (with pins, not holes) MR60 in there.
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It’s gonna be a tough area to form and pour this urethane or epoxy too because it’s pretty runny. Might get some of the brushable stuff they sell which is much thicker. Don’t really wanna make a whole mold for this and then glue it in.
There’s a rate of return on all of these products that’s rapidly diminishing. Like a $40 bottle of urethane to make the gasket is getting excessive. 
I’m also considering fiberglassing an end cap with the MR60 plugs sticking through for a lot less effort and cost then making a big urethane plug for the tail.
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Making plans to keep approval from @b264
Rather than a whole rubber plug, I’m going to fiberglass an end cap on the tail cable channel which I’ve cut down quite a bit now.
Worth going to a GX12 or something similar for sensor wires or should I stick with a grommet for those? I’ve seen the haggy plugs, but the overall connection gets pretty long
lol hopefully the finished product is straighter
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I’ve been following this with great interest Bwah! There are many new techniques that I haven’t seen anyone do before here, potting the batteries with urethane, fucking genius! Looking to essentially build something very similar with the Sportster and this has been an extremely valuable writeup <3
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Mistakes were made…humbled update
After waiting for new fiberglass materials, I was able to get a good layup of fiberglass reinforcement for the bottom. I used 4oz cloth from the ends into under the foot areas and covered the entire bottom with two layers of 2oz over all of that. Dried perfectly, trimmed it up, and got ready to layup the final top layer…
Then I decided to bolt it to the trucks and do a little flex test to see how much the flex had changed after the FG. Bounce bounce everything feels good and there’s a noticeable addition to rigidity but the board feels good still. I stepped off the board, mulled around for a bit, and came back to it. This time recalling that I had bounced on the deck once and the center touched the floor. Someone posted a video of the Sportster doing this as well. I gave it a light bounce to get an idea of what it would take and i bounced with both feet dead center of the board… an audible POP! let loose from beneath my feet. As the sound faded it became a chilling rush down my spine that sent icicle daggers into my soul…
In hindsight, i think the guy that did just this on his Sportster was on 90mm wheels. Thinking back, I might have done it with 110s, or it may have just been sitting on top of two wheels on their sides. This time, im on 110s and adjustable TKPs that add 13mm – so essentially the effective diameter of 136mm wheels. WTF was I thinking. It would never have flexed like this in real life, especially once the enclosure and final top layer were attached. Regardless, I sort of didn’t expect it to fail.
The fiberglass layer on the bottom split from one edge to 25% of the way through at the bottom of the flex. This was dead center on the deck under my feet. The reinforcement layers around the edge and below the FG there cracked. At this point, I knew I wasn’t going to move forward with the deck and the consequences were final. I hopped again to explore the failure location and do some more investigation, it continued to split at the center. The original deck only split on one edge from the original crack, through a bolt hole and does not appear to have split the whole width.
Observations: I took a bit more off of the deck in the original cut than I had planned to but still very minimal. I also could’ve made the pocket slightly smaller. This will make aligning the pocket location within a few mm per side a little bit of a pain but worth it to reduce the pocket size. Other than the failure I caused, no layer separation or other issues.
Moving on…
So this was a $200 mistake. Not only did I need to buy another deck, but I also needed to buy more maple veneer from roarockit because I had run out. Insult to injury, bustin didn’t have a labor day sale so the deck cost me $20 more than the original one.
New sportster came in two days. Maybe I just haven’t seen it for some time in its original state - but the new sportster feels different this time. Definitely stiffer, the colors along the edge are different and the overall color looks different. The logo is also black now and not just laser engraved on
I contacted Bustin and asked if they would make a deck with extra layers and they said that they couldnt. I reached out to Roarockit and had a great conversation with the owner about what I was working on. He understood the challenges getting the material to meet some of the complex curves in the bustin (the evo deck was a piece of cake to get the wood conformed to), but made a few suggestions:
My technique of spraying the maple with water and vacuuming against the deck to “preform” it was definitely helping with getting the contours tightly matched. However, he thinks that pre-wetting and drying likely contributed to some stiffening of the maple. It expands when wet and when it dries after that it becomes much more brittle. Something looking back now I observed while doing this.
He also recommended pre-cutting the panels to shape match the board before hand to reduce splitting and hopefully help with the contours. This means ill be using paper templates to trace the deck shape and then applying to the veneer and cutting out. Theyre thin, so i clamp them to the bench and cut out with a utility blade.
I was a bit defeated by this setback and in addition, my current board died and Im throwing together this falcon 36 quickly so Ive got some transporation. Bustin took the back burner for a bit.
Plans for this go around.
Similar 4 panel layup for 6mm of additional clearance. I wont be doing the FG layer between the deck and the new veneers this time because the epoxy doesnt soften the wood like titebond 3 does. I need the water based glue to get the wood to bend properly.
Since Ill be pre-cutting the veneers to shape, Ill also be cutting out the majority of the battery compartment so I wont have as much material to remove later on. For this go, Ill avoid cutting into the original deck at all - if possible.
Lastly, dont jump on the center of it - its not a vanguard
More to come in the next week or so. A few quick pictures below.
I’ll add some more of the work ive been doing to the enclosure, which has required a lot of re-work in the tail section to get the connector interface I want. Coming along good.
I’m not feeling too far from finished, but school has restarted so my free time has gone down a little
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Yeah idk what to make of this as well. I also saw the same video as you did of the person flexing the deck to the ground, but the sportster I got for my little brother is quite stiff, very comparable to my Switchblade. Wonder if they’ve changed something in the manufacturing process 
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They may have. This new deck is definitely different from the first one I had in appearance and I “feel” like its stiffer. But hard to compare now.
I was actually pretty surprised that it cracked where it did. This was not the weakest area of the deck in theory after the cutting I did.
However, theoretically, I stiffened the ends and that may have put more of a bend point on the center. Regardless, the flex seems to have exceeded the elongation/tensile strength of the FG layer on the bottom. When that popped, things failed beneath it. Given that observation, I think I just exceeded the amount it should have flexed. Measurement currently on the wheels and TKPs to the floor is 3.25", so it was quite a bit of distortion from where it started to reach the floor, especially over 35" in length
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Extra reinforcement layers this time?
The strengthening you did won’t have changed the fact that the highest bending load on the board is in the centre. Nearer to the trucks, loads are resisted more in shear, rather than bending. Additional strength for reinforcing layers or (as well as) thickness between the layers will help resist bending loads.
@rosco, theoretically, the extra re-inforcement should be laminated to a mostly untouched original deck. For this go, it will be 4 layers with the center pocket removed from them and the original deck will remain untouched. Thats 6mm of additional material that will only border the majority of the board but will fully cover the ends. That makes the ends stiffer and leaves the center much less affected. Ill be adding a FG reinforcement layer again to the entire bottom after the veneer layers are on top lock the whole thing together.
I think last time I removed slightly more matieral than I had intended and I flat out overstressed the deck trying to achieve too much flex.
Even after speaking with the roarockit founder, the wetting of the maple may have made those more brittle. So the FG might not have broken under tension, the reinforcement veneer may have cracked and caused the FG above it to split.
With the necessary space I need for the battery, I cant leave a reinforcement ridge down the center of the deck. Currently though, Im not planning to add more than 4 layers (6mm) unless I have to. I know going into this that ill need to get the majority of 10mm of clearance to fit the bms - hopefully the 6mm addition and a thick gasket once compressed will achieve that and I wont have to remove any of the original deck. If I do need to, ill consider an additional layer of reinforcement or a thicker gasket rather than cutting into the deck. Especially since the deck is only 12mm thick.
the newer deck is definitely much stiffer. For my weight (130lbs) it does not flex.
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Think there’s a typo there b-wah.
Assuming you are using FG or CF reinforcing, it’s tensile strength you are adding and that is best placed where the tensile loads exist on the deck.
In normal use on a longboard that is the underside. (Roadside) Like on this diagram of a structural beam. 
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Yes was definitely a typo and I fixed it. All layers were going on the bottom except one finishing layer for the top. Which may not be needed on the second go.
Re-inforcement was never really necessary. The whole purpose is just to lower the enclosure, creating more space for battery. Rather than just add a thick ass gasket, im adding some wood.
But yes, for a longboard, the bottom is far far more important than the top as tensile strength is the most contributing factor to deck strength and flex
@EDness interesting that you had the same observation. This definitely feels far stiffer than the one I bought black friday last year.
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Annnnnd after a long hiatus, we’re back! Life got in the way of working on this for a while. I’ll bring more updates soon. Just shared some battery updates in the BBC
A few pictures. New deck layers. New deck. New plan.
Got excited yesterday and rode it too soon, forgot the loctite. Broke my own rules about test rides.
Got bucked by a motor plate bolt that came out and wedged between the wheel pulley and plate. A little road rash lesson on my ass for that one. All okay and got back on.
Took another ride today after a proper cure interval. Board rides great. TKPs are unbelievably maneuverable and making me anxious about cranking up the speed. Even on rough shitty Philly roads the board sounds quiet and muted thanks to all the rubber
So on the first ride, it injuries me and I injured it. I’m just a little sore and have a 3 inch diameter spot of road rash the LR jacket didn’t catch. And I put scrates on my new motors with some deck bite as well I overlooked. I guess it’s broken in now never ride without your helmet kids
I’ve got lots to add so I’ll be back to fill in and add more.
Alright so finally an update!
Bustin is complete, waiting on some hardware and new grip tape.
Still have to finish the top of the deck, thinking about having something airbrushed in the center, fresh stain and frit or just grip tape similar to stock
So we left off in september here…
I got a new deck from Bustin, which ironically cost me $10 more than the first one. As mentioned above, the new deck was different from the year prior one I had before. It was significantly stiffer. I had a few conversations with the owner at roarockit and got some advice before attacking this again with what I had learned from the first go around.
This time, I used a few pieces of paper taped together to lay over and create a template of the deck on the bottom. I added 10mm around the entire edge and used that as the template for my new maple layers. This time, I was pre-cutting the shape before glue-up.
I need to track down some photos, but the pocket was significantly different this time. Last time, I glued up entire panels to the deck. This required me to use the router to remove the entire volume of that pocket. Lots of heat, lots of work. This time, I stacked the precut layers together on a flat surface and aligned them. I used the paper template of the deck again which I had located and drawn the battery pocket on too. I attached the template to the stack of panels. Then, using an oscillating multi-tool, I made a few cuts along each edge by plunging straight through all of the layers. Think of it as a very widely spaced dashed outline. There was a single cut at the top and bottom, 3 on each side an inch wide.
I needed to leave the structure of the center or the layers became too fragile. When gluing up, I only applied glue about 1/8" into the pocket along the line. This let the entire volume of material where the pocket will be essentially fall out after the perimeter cut.
Glueup went much better this time with no issues getting the layers commpressed well. Pocket clear out was fantastic. The multitool simply chipped through most of it and I cleaned up the rest with a chisel and finally gave the edge a round off with the router. 1% of the work I did the first time and 1% of the mess.
What I have now is 7.5mm of added layers to the bottom of the deck. The center of the pocket is the bottom of the original deck the entire length and its untouched. Im not cutting the extra 4-5mm into the rear area I had before, So I had to figure that out
The battery came out amazing. So when I poured the urethane, I made sure to get above the centerline of the cells. This moon shape on either side really locked in the buck I created to make the pockets. Securing the P groups was as easy as setting each edge in and pushing them down at the center. The P groups fit snuggly into the pocket and want to pop up from flush in the center. Pushing them down flush and then bridging across them with fiberglass reinforcement tape locks them in place. If they cant come up in the center, they cant come out. I can flip the board upside down and shake it, these wont move even before the series connections. Absolutely love how this retention was achieved
14awg series connections, 2x 14awg per side main leads. Monitoring temps on them. I think its gonna be plenty. 18 awg 5.5 x 2.1 charger for now.
I removed the GX16 two pin I was planning to use for high amp charging and filled the hole. Im done looking at high amp chargers now that Ive found now reason why dual charging isnt appropriate when needed.
Adhesive fish-paper connect the BMS to a a strip that runs down the center of the battery. The strip is broken and overlaps in two sections where the larger humps exist in the BMS wiring and they are un-taped in that region. The fish-paper runs along a smooth area, all the series connections were kept outside of that region. The charge wires extend from the front of the enclosure to the rear, between the balance leads. They pass between fish-paper layers as they go underneath the balance leads. Foam beneath the BMS keeps it from crushing the sensor wires that must plug in beneath. All series connections just kiss the top foam when things are back together. There’s extra foam in the center applying gentle pressure to the balance leads as well.
On one side, the XT90S connection to the Unity and the short antennae for the METR are secured. I poured rubber here but did not like the outcome and removed it. On the other side, rubber was poured around some 3D printed plugs for the power button, Hoyt puck receiver and the unity itself. The Hoyt Puck receiver, BT BMS receiver and the power button sit on that side.
Without the additional cutaway over the BMS, space was tight as expected. I wound up adding a 1/8" foam gasket to the rear of the enclosure to provide more clearance. The deck has a 1/4" foam gasket around the perimeter and a 1/8" gasket along the inside of the pocket. This gives me 3/8" gasket in the rear which is just under 1/4 in when compressed and the BMS leaving a slight indent in the top foam. Its super tight
In hindsight, I shouldve bought the MK2 model from @eBoosted … The MK3 did not work out with the TKPs and I opted to re-FG the rear and nose of the enclosure. The the rear, 3D printed plugs were again used to mold in press fit and removeable slots for the MR60s. They snap in, dont pull out but got glued up behind anyways. They were a ton of work, came out a little lower (further from the deck) than I wanted, but it looks nice.
Ive got more to dig out of my phone, and more to add. Duplicolor truck bed coating for the enclosure and I opted to do the edge and entire bottom of the deck that way. The edge and bottom looked good, but I could only realistically see 5% of the bottom of the deck anyway. Just wasnt worth going through prep and color or a fancier finish.
Waiting on some new hardware for a few locations. Currently on 15/40 with plans to move to 16.
Back to school work for me today.
A few thoughts:
- If youre considering 12S4P 21700 for this deck, think long and hard about it. Its very doable, but the space is very tight. Make compromises around the BMS. Dont add a heatsink
On space being really tight. As mentioned above, the unity and cells had roughly 4-5mm before the addition of gasket - lets call that 5-6mm. D140 BMS is 7mm thick +2mm at the corner bolt heads on some. BT BMS units are 10mm thick +2mm at the corner bolt heads. Unity heat sink brings the bottom of the unity up 4mm.
So I started with 5 mm, lost 4 to the heat sink which left me with 1 mm. + 7.5mm of deck addition, +5mm of gasket = 14mm to clear a BMS thats 12mm thick and has wires under it, fishpaper and foam.
Dont do this – if you want to build a bustin, its a great 10S build. Its a tough 12S build you will probably make some compromises for, even more so for 12S 21700 build. Its a moronic idea to try to put a heatsink and anything but the smallest BMS on if doing 12S. Theres just not enough vertical room at all. You get 25mm + a gasket, thats it. I did all the above, and while im happy, it wasnt easy getting here. - battery pcbs are just for looks
- psychotillers clamps and mounts are garbage. Searching for something better still. Might have to give my money to @IDEA
- wont buy anything but hoyt from now on for remotes
- thank you to the METR team for the BT BMS integration!
The TKPs are awesome! Final board weight is 31 lbs. Its heavy, feels solid, is totally muted and makes hardly any noise. Theres no rattles and rocks hitting the enclosure from the road sound muted. Rattle free, quiet, stable and smooth. Loving it.
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Awesome work, dude!
love that build so much.