Mini Rolling Fortress | Modified Bamboo Skateboard | 6x2 wheels | DIY Geared Drive | Dual Flipsky 4.20/6355 | 10S2P Sony VTC6 | DIY 3D Printed Enclosure

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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:

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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.

IMG20180902120012 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.

20degRiser 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.

IMG20180902122759 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.

IMG20180909112843 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.

IMG20180909113359 These are currently printed in PLA2.0 (or PLA+) but I’m getting them printed in HP Fusion Nylon PA12 for added durability.

IMG20180912215630 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.

IMG20180906170700 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.

IMG20180901075654 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!!!

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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.

The Enclosure 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. Enclosure
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.

IMG20180915171955 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).

IMG20180912190344 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… IMG20180901075602

Now to wait for good weather and fast asleep babies to know more about how this performs.

43 Likes

Well done! It looks almost identical :grin: I wonder how long these risers gonna hold up considering they gonna be under a lot of stress.

This looks great! Let us know how it feels

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Do this! Lol.

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Love it man! Awesome job!

That’s why I plan to swap them to nylon…

looking forward to you experience with nylon. you mentioned theres a bit of a rolling resistance, did you have a chance to do a range test with it?

Will let u know soon… Haven’t had a chance to ride it properly because I am dead tired from building it… Haha…

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So I did a quick, but very wet, 10km ride. Here’s my findings thus far.

The Good:

  • Goes over cobble stone, twigs, puddles, leaves just fine
  • Noise from geared drive is acceptable and didn’t alarm any pedestrians, in fact it served as a good indicator of my presence
  • Turning radius is much smaller than the LaCroix

The Bad:

  • One of my tires was completely deflated, not sure if it’s leaking because I managed to pump it back up. Others retained their pressure just fine.
  • Rolling resistance is bad… It’s almost as if the brakes engage as I go downhill. Seemed to be requiring 6 to 8A just go keep it at cruising speed (15km/h)
  • Range as a result is much reduced, current estimate puts it at a pathetic 15km only. Will need to test again after making sure tire isn’t leaking
  • Wheel position throws water all over my legs and deck, I rode the LaCroix last night in similar wet conditions and was surprised how clean it came out
  • Antispark switch got stuck due to the muck, had to knock it loose

Will update more soon…

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5 Likes

I think it’s a good board overall. Do you think the rolling resistance is high due to wider contact patch of the tyre. I ve had very good experience and minimal wear with standard evolve tires I wonder if they can be installed on those rims

Talking about these ones and they also come in black color http://www.evolveskateboards.de/index.php/en/shop-buy-online/all-terrain-tyres-and-more/evolve-gt-tyres-blue-detail

Not sure honestly… But it’s something someone else in the forum realised… He swapped to these and immediately lost like 20-30% range…

I forgot what he was comparing it to though…

I don’t think the evolves will fit. They fit a 7" hub I think…

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Thanks for the feedback I’m in a dilemma to go with these or trampa hubs after seeing your experience it’s kinda discouraging but cant think of anything else if free rolling is fine and weight is the same it must be the tyres

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Okay so I found out one of my tubes was leaking… (checked pressure after an hour or so and it dipped 10psi)… Swapped it for a new one, now to see if it will result in better mileage.

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How has the ESC worked? Are you running BLDC or FOC? Mind sharing your settings?

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I’m running FOC… So far no issues…

Not sure what settings you want to know…

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Motor and batt currents

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65, -60, 40, -15 I think…

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Great build !! Love the sweet tiny mode like ! :open_mouth: that setup of the dual 4.20. Ride safe :v:

@ervinelin what are your motor settings? And you are running BLDC sensored or FOC?

See above. 10char