I think it’s about time I post an update. Lot’s has happened over the past couple of weeks. Let’s start with the enclosure…
This part of the project had me stumped for a long time and is the cause of an excessive amount of procrastination. I see now why it is best to pick an enclosure and deck combo first, and work the rest of the build around it!
There are many options out there when it comes to enclosures. I could have bought one, but it would never have fit perfectly to the contours of my deck, and it would never look quite like my idea of perfect. So that was out of the question.
There are three main options when looking to build an enclosure.
- 3D printed
- Vacuum formed thermoplastic
- Composite
Due to the cost and labour associated with options 2 and 3, I initially planned to go with a 3D printed enclosure. The plan was to 3D scan the deck, clean up the mesh and work from there. The enclosure would be printed in multiple parts, joined with adhesive or hardware.
The problem with taking this apparent path of least resistance is that a 3D printed enclosure is not as simple as it initially sounds. I’m pretty good when it comes to CAD so that wasn’t going to be a problem, but the 3D scanning would take much more work than anticipated. I would require an NVIDIA Cuda enabled GPU for meshroom, which immediately bumps up the cost (there are ways around it, or other 3D scanning softwares that may be used but truthfully I just couldnt be arsed to spend a few weeks learning a whole new software package and workflow) The I would need to try out different settings and iterate the 3D reconstructuon process until finally producing a mesh close enough to the shape of my deck.
Then my 3D printer mainboard blew for the third time and I was PISSED. So I threw this idea out of the window entirely. Besides, waterproofing it, applying filler, sanding and painting would still have taken just as much time as any other enclosure build and at the end of it all, would not be as strong as composite or vacuum forming due to the weak inter-layer bonding (even if designed in such a way to optimise the print direction). I considered fibreglass reinforcement but at that point why not just fibreglass the entire enclosure?
Vacuum forming was out of the question because I dont have a shop vac, or the money to buy one, or space to store it, or the equipment to put a vacuum former together, or know anyone who has one. Plus, it would not be as strong as composite.
So I settled for fibreglass composite, which from my research appeared to be the cheapest and most robust method. There are so many ways you can make an enclosure with fibrelgass, using directional sheets at altenating angles, applying finishing layers, gelcoats, negative moulds, positive moulds, the list goes on. I settled for the cheapest and most crude method available which was to use polyester resin, 450gsm chopped strand matt and a mould made from blue foam, covered in sellotape to act as a mould release.
My first attempt at making the mould was a huge failure. You can read all about it above. My second attempt however, went much better.
I began by laying out the battery, ESC and wiring on top of some blue high density foam, on top of my deck. This enabled me to cut out the bounding box of the enclosure mould and stick the foam blocks together with double sided tape. I also made sure there would be enough clearance on the flange which will host the deck mounting holes for some neoprene backed domed washers I brought which will help waterproof the enclosure.
Then with a contour gauge, I traced the curvature between the platform of the deck and the truck mounting holes. I cut the excess with a utility blade.
I wanted to add a nice chamfer around the edge, so with my crappy plastic geometry compass I marked 3cm all around the top surface and approximately 1.5cm around the sides. I tried using a handheld sander to shape the foam before but it gummed up the discs and dust collection so quickly, and made a huge mess, so this time I opted to use a steak knife. I was going to use a bread knife originally, but it was too long and imprecise. Im hindsight i don’t know why I didn’t consider using a coping saw… but this worked perfectly. I sanded the chamfer by hand to make it smooth:
Once I was happy with the finish and shape, I applied sellotape to the deck, then double sided tape on top. This would prevent the double sided tape from ripping more epoxy from my gorgeous deck. I still need to fix that…
I carefully positioned the mould, and painstakingly applied overlapping layers of double sided tape to the mould and deck. This took a while as I didn’t have any filleting wax for the transition, so the tape had to sit perfectly betwen the foam and the deck.
I couldnt be fucked with taping each end, but they still needed protecting, so I used some plastic gloves. Some duct tape was also applied to even out the transition between mould and deck, and prevent any polyester resin leaking through gaps in the tape.
Once everything was protected it was time for the fibreglass.
I got suited in my finest work trousers, respirator, old shirt and safety goggles, opened all the windows, and laid out the newspaper.
I accidentally mixed up way too much resin. Off the top of my head I think I calculated I would need 300ml per fibreglass layer. I mixed up 500ml. I guess it’s better to have too much than too little?
I thoroughly wetted the sheet with a chip brush, then as it began to cure I went around with some metal fibreglass rollers to keep the flange fillet nice and tight and remove air bubbles. The wide rollers were absolutely crap and just kept ripping up the fibres so instead I used the end of the chip brush to dab any air bubbles down. The thin seam roller was fantastic for the fillet though.
After about 10-15 mins the first layer was tacky and holding shape, so I applied the second layer. That went well, and after I was confident it would hold shape I hit it with my heat gun to make it cure faster so I could get this over and done with. It was 1AM and I needed to get to sleep.
I applied the third layer and all seemed to go well. I could see there were some air bubbles, and knew it wouldn’t be perfect in the absence of a vacuum bag and finishing layer, but was happy to take on board the challenge of sanding.
I demoulded it the next day which was incredibly difficult. But once it released from the tape I was extremely glad to see that there was no immediate damage. The heat during curing has deformed the edges of the foam mould so that can’t be used again, but apart from that, everything was in working order.
I marked where to cut with a sharpie, and got to work with the dremel.