If you have seen my other rolling fortress build and feel a sense of déjà vu, don’t worry it’s because I decided to build a mini version of my LaCroix. The LaCroix is a great ride, but it’s also very heavy and very bulky. I’ll still use it for longer runs but for shorter ones I contemplated for months to build a mini AT board. I also happened to have some parts lying around which I have been tinkering in my head on how best to re-use them.
Just to give some context, this is not meant to be a long distance/mountain conquering board, it’s just meant to give me a comfortable ride to the grocery store or on small errands. Light enough to lug up and down stairs but tall enough to go over cracks and bumps. I also typically don’t ride very fast (speed limit is 25km/h in my country, some places 10km/h), so I’m fine with the durability issues associated with 3D printed parts.
Anyway back to the build. Specs of the Mini Rolling Fortress/Poor Man’s LaCroix are as follows:
- 8.5" Bamboo Skateboard Deck modified to mount trucks on the tails
- 6x2 Pneumatic Tires with Aluminium Hubs with bearings replaced with better SKF ones
- Torqueboards 218mm trucks with custom 20deg riser
- Custom 15/67 Geared Drive with wheel adapter for hubs (15T pulley bought off the shelf), Repurposed Torqueboards 50mm Motor Mounts.
- Dual Flipsky FSESC4.20 with Flipsky Dual 6355 Motors
- DIY 10S2P Sony VTC6 with 16A charge only IP67 BMS with an electric skateboard repair anti-spark switch
- 3D Printed PETG Segmented Enclosure
- DIY Triggger Style Remote with Telemetry
Here are more details about the build:
The Deck This is not the first time I’ve used this deck as an esk8 platform (you’ll notice older holes in the deck), the previous iteration of this was not fantastic, I didn’t have risers set to the proper angle, wheels were too small so the enclosure would get scraped, waterproofing was bad, etc etc etc… So I left the deck alone for a while with the intention of re-purposing it in future. Anyway, I decided to give this deck a new life but I had to modify it to be able to accomodate the wheel bite of the 6x2 tires.
I drilled extra holes at the tails, mounted the trucks with custom risers (see below), tilted the board, worked out how much I needed to remove and then jigsawed away.
I designed and printed a 20deg riser to correct the angle of the truck, this also meant that the ride was a little higher than I had hoped even though I mounted the truck as far off to the tips as possible. This is currently still in PLA+ awaiting a better material.
The end result looked almost like a mountain board, and the board even flexes quite nicely. The original wheel wells also create a nice feedback for feet placement and the truck placement and cutouts ensures there is no chance of wheel or shoe bite.
The Drive I had a pair of Torqueboards 50mm motor mounts left over for when I upgraded another deck to geared drives. Because geared drives require shorter motor mounts, i did some measurements and was pleasantly surprised that this can be repurposed for my Mini LaCroix. Other than that the drive is put together very similarly to all my other drives.
This would consist of the wheel/hub, an adapter to the hub, a 67T gear bolted to the adapter, and a 6806 bearing with an adapter to fit it around the 218mm truck.
These are currently printed in PLA2.0 (or PLA+) but I’m getting them printed in HP Fusion Nylon PA12 for added durability.
A casing to reduce debris getting gummed up in the gears goes over the entire assembly, seen here is a 20T pinion but I have since dropped this to a 15T.
One point to note about the 6x2 wheels, I did not like the bearings that came with them. Some were a little rusty and they rolled terribly. I hammered out the stock bearing and tried to replace them with a better SKF one, however when I hammered the bearings back in, I realised the hubs were so tight that bearings would not roll properly. So I ground the bearing seat just enough so that the bearings were now push fit as opposed to hammer fit. This seemed to work for me but I am not 100% sure if I introduced imbalance in the hub as a result. I did have to check every wheel and added the necessary weights to try to balance the hubs as best as I could.
Despite free-rolling on the bench pretty effortlessly, these wheels are absolutely impossible to manual skate with. The rolling resistance is insanely bad, one kick gives me only a few meters even on smooth concrete. I would assume this would also translate to losses in efficiency once I go electric.
The Electronics I can’t comment about the reliability of the Flipsky Dual FSEC4.20 yet as I haven’t ridden this enough, but these make it so much easier and more compact to run dual setups!!!
One less set of power leads, no CANBUS wire, inbuilt heatsink, it’s just awesome… Seen here next to my 10S2P cells. Why only 10S2P (seen here with 16A charge only IP67 rated BMS)? This is meant to be a mini, didn’t need anything more than 20km range nor was I going mountain climbing.
To be honest, enclosures for me are the hardest thing to get right. This is my 5th ot 6th DIY enclosure and I decided to go with a segmented 3D printed (PETG for its hydrophobic nature) version to accommodate for some flex in the deck.
The enclosure segments had lips which were then attached to each other using silicone (again for flex). Holes in the side were meant for the anti-spark switch and charge port. No voltage display needed because I run my remote with telemetry.
I even went to spread a layer of silicone on the inside of the enclosure as a safety precaution. Connectors allow me to completely remove the enclosure, leaving the electronics on the underbelly of the deck (attached by industrial strength velcro).
A natural rubber (oh my god the smell…) gasket sits between the enclosure and deck. M4 bolts then hold the enclosure down via inserts in the deck.
The Ride Unfortunately I haven’t had the change to give it a good ride yet, but I’ll update more once I do. For now it rides a little taller than I had hoped but the flex + pneumatic tires provide for a comfortable ride. The concave of the deck provides for a nice platform to perform much tighter turns than my LaCroix (also slightly shorter wheelbase).
Again, I’ll update more soon.
To finish, here’s a look at the two rolling fortresses next to each other…
Now to wait for good weather and fast asleep babies to know more about how this performs.