I wanted to start a build journal for my 2 y/o DIY project board as well as get some input on if some of my designs makes sense. This community has been an awesome source of information while learning DIY esk8 and I figured its my time to share what I’ve slapped together!
This board has kind of been my introduction to CAD design as a hobby and I have no formal education on design philosophy or best practices. I do have a little electrical experience from FIRST robotics back in high school. Budget was originally (still sort of is) a big factor in the parts I chose. That being said, rip me a new one if I’m wasting my time with the parts I settled on, input is welcome!
My inspiration for the build are the wide 90s style cruisers with big urethane wheels and those dope neon-green skid plates on the sides. I went with a “Relic” from eastside longboards since it has a nice bathtub concave to lock my feet in as well as rear truck mounts far up enough to get that kick tail look.
To keep the cost down I selected and stuck with a relatively off-the-shelf set of parts.
Battery: Four 4S 5000mAh Turnigy batteries connected in a 2S2P config for a total of 8S2P. These are high output 70C batteries picked specifically to never worry about overdrawing and to avoid the complexity of a DIY 18650 pack.
ESC: Motor controllers are two FS VESC 4.20 connected with CAN. The idea behind buying standalone ESCs is I was sure I would burn one of them out as some point and I’d like to be able to skate home on a single motor when that does happen (surely enough it did!)
Motors: Two Flipsky Battle Hardened 6354 190KV. These have been absolutely bullet proof for the 2 years I’ve dogged on this board.
Trucks: Your standard set of Caliper II trucks. The rear trucks have developed a slight bend, probably from pivoting while riding
Wheels: Orangatang Kegel 80mm 77a and later Caguama 85mm 80a after ripping some large chunks out of the softer compound
Drivetrain: 15mm Belt driven 15t motor 36t pulley
I can hit a top speed of ~23mph with the 8S batteries though I’m sure there’s a lot more to give with increased voltage. I can travel 15 miles with no power limits and up to 25 miles with a 300w cap.
That about sums up performance. Battery capacity, voltage, drivetrain, and deck haven’t changed much throughout this build. Lets get into some photos and a timeline.
Here is my board today after over 100 rides and a completely unknown number of miles
Now rewind back to June of 2021
Something convinced my foolish brain to try 3d printing both the motor mount and the pulley in PLA or PETG, because reasons. This ended up being a complete waste of time but great CAD experience. It turns out these parts experience a lot of torque and heat. Who’d have guessed?! I could skate maybe 1.5 miles at a time with batteries velcroed to the deck before these started warping or cracking.
Moved on to some tried and true aluminum parts that can handle the stresses.
My first rideable design was a large 3d printed bottom mounted electronics enclosure. Printed in 2 halves in PETG then plastic welded together with a soldering iron. This was held to the deck with just 3 bolts, 2 in the rear & 1 in the front next to all the heavy batteries. This lasted exactly as long as you’d expect, 7 miles or so until I hit a bump in the road and the batteries fell through the floor.
I refined the enclosure design and reprinted. Thicker walls, a properly fitting contour to the deck, and thicker geometry around the 3 mounting points. This design is where I finally started putting some miles on the board and learned the ins and outs of riding with a remote. (my background is analog LBs) Somewhere along the way I switched to slightly larger slightly harder wheels due to chunking.
The cool part (not) of this design is when you inevitably break the front half because you attached it to the deck with only 3 bolts, you have to reprint the entire enclosure again and re-plasticweld it. This was painful after a handful of 20 hour prints. I decided it was time for a more modular approach, something where I could break a segment of the enclosure and reprint/replace with ease, something with more than 3 measly points of attachment.
I should point out that to charge the batteries, I would have to remove the entire enclosure and untangle the battery cables, connect each battery to a balance charger, then mangle them back into the enclosure. This didn’t do the battery’s lead tabs any favors.
Enter v2.0 of the money pit’s enclosure. Panda colors were chosen this time around. The enclosure is split into 4 unique sections front to back. The rear holding the ESCs, rear-mid with the loopkey and battery wall, front-mid and front pieces contain the batteries. Several iterations of this design were printed and ridden on before the next major failure.
Battery leads Due to the aforementioned charging situation, one of my batteries had the positive lead snap off. I couldn’t get the lead to hold solder at any temperature and I don’t have a spot welder so I had to write off these 4 batteries. Everything I read online said not to mix batteries of different health so a new 4 were in order. Found a deal on some 5100mAh Turnigy packs with the same dimensions.
With the board out of service, I once again spent some time redesigning her enclosure and battery situation. This time I thought if the battery cables never move then they can’t break. I’ve always liked the idea of having cold swap-able battery packs for extended rides so I make a battery enclosure (also PETG) that allows me to connect everything with zero modifications to the batteries themselves. (lithium fires scare me)
Everything connects with XT-90s epoxied to the PETG. This way I can charge the batteries without breaking them. Due to the extra space needed for the front face of the battery pack, I moved the battery wall further to the rear. The battery wall now doubles as the female end of my XT-90 connectors allowing me do away with bulky XT-90 series adapters. The curved black wires in the pack are 12 gauge solid core wires from the hardware store. These are awesome and take up way less space than stranded cables.
This worked swimmingly and kept my new batteries intact. The size of the pack and it’s proximity to the front trucks forces me to remove the top half of the enclosure when I need to install it. Completely defeating the plan to have it be quickly swapable. I have to pull over, power the board off, bust out the skate tool to remove 4 nuts and then swap the battery with a half size one I made. The lack of a BMS will be my wallet’s demise however. I got home from a long ride recently and forgot to pull the loopkey out. Wake up the next morning and every battery was drained to near 0v. This killed one of the four and damaged another.
So here I stand with my current battery failure wondering if I’m wasting my time not investing in a custom 18650 pack. My hesitation is I would likely have to scrap my entire design. Am I overthinking the danger of making my own custom 18650 pack? Does spending another ~$180 on some Turnigy hobby grade batteries make sense? Any suggestions on bolt/nut alternatives that would make removing the top of the enclosure quicker?
Overall I’ve had a lot of fun building this bad boy, breaking it, and building it again.
Future goals are to:
- add minimum voltage cutoff circuit to save batteries from a boring death
- implement custom wireless telemetry stream to a 1" oled added to the remote (think wireless davega)
- replace trucks with Boardnamics billet aluminum trucks
- maybe helical gear drive down the road