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E-Freeboard Open source Electric Caster

Intro:

I have had an interest in the leiftech and now Summerboard since I first saw it long ago. I was not however interested in paying that much to get one, so I decided to make my own.

My first real effort was to buy a broken Freebord and attempt to replicate the slip rings and motor mounts that the leiftech used. After a lot of research I saw that it wasn’t really feasible to do this. A great inspiration for me was this thread I came across as really the only DIY electric freebord out there. Very sadly never completed that we know of. (btw anyone know this dude?)

I cry thinking about the parts sitting in a bin somewhere possibly never run.

This brings us to the present.

Freebord MFG. launches a campaign to produce a new product line, the Freebord 5 and 5-X. I got excited since I had been sitting on this broken freebord for months not getting anything done, and this was exactly the kick I needed to get working on the project seriously once again. Being stalled on my ESK8 endeavors due to Covid-19 helped make me focus on it too.

A couple of things about the new models stood out to me as being useful for electrification. Both the caster bases being separate from the hanger baseplates, and the casters separating from the rotating base is great.


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This gives you options to either remove the casters from the board entirely and replace them with some kind of powered caster like the one seen from VillainousJackal. Or you can take the small frame that holds the wheel off the pivoting caster base and bolt on your own version with a motor mount, and add a pancake slip ring around it somehow.
Modularity FTW!!

So here I am, Freebord pre order in hand, thinking about the simplest way to make this thing electric. I have very few manufacturing abilities, I barely have access to a working 3D printer basically all I have is a hand drill and a hacksaw (tools I think 95% of people have). So with the exception of a couple CNC/laser/plasma cut parts most of the design should be able to be assembled without a shop. I even berifly thought about making one of these electric broomsticks to mess around with but that would kinda suck.

The idea I settled on for now doesn’t seem very simple at first but I wanted it to be as independent from the rest of the freebord as possible so I could engineer it without actually having the board that I’m developing it for.

Background:

This design I have come up with is similar to something used in FRC robots called a “Swerve Drive” this would be a “Caster Swerve” due to the wheel offset from the rotational axis

I present: The E-Caster


older models:

Mechanics: Most of these parts are from Dickyho!

The whole design is built around a cheap 200mm lazy susan bearing. It isn’t very strong but I think it might be just good enough, and avoids either something really expensive or manufacturing my own. Hey if it’s able to support a whole table it could probably survive the weight put on it from some springs.

I’m still deciding what kind of motor set up I want to use. Having two motors obviously drives up cost significantly, requiring more ESCs belts pulleys and crap. It would allow me to use smaller diameter motors to achieve a lower profile and hopefully fit below the Freebord 5 and well as the 5-X as they have slightly different ride heights. The construction on the drive is very simple, using a 8mm shaft and a kegel wheel. Two bolts on kegel pulleys, one drilled out so the bolts slide through and into the other pulley. This could also easily be done with press fit pulleys, I’m not sure if you can put one in either side of a wheel but the pins could be shortened if not.

For the suspension aspect I need to put springs on it somewhere, for the moment I am thinking torsion springs because that would fit cleanly into the design but compression springs could be used instead and would match the look of the springs on the 5-X hanger arms.

I also really like this design:

single motor design with double sided motor axles inside the suspension arms as it looks sick but it has a couple issues as well, one being that the optimal choice of the APS 80100 50KV costs more than two of the small motors. It would require the belt drives to be outside the suspension arms, and also use a live axle with bearing press fit into the suspension arms (hard to manufacture and flanged bearings are expensive) instead of the dead axle. It could be possible to have a spacer that allows the motor to be center mounted and have the belt drives on the inside but it would be weak to 3D print and expensive to machine out of aluminum. Lastly it has the issue that if a rock or something gets kicked up it could jam between the motor and wheel. Still possible to pursue this design avenue, it looks much more clean and the motor would be protected. For now I’m going with the dual motors because it’s a balanced design and a great use for the Cheap Focer’s that I’m hoping to be having quite a few of.

Electronics:

Thanks for reading (or skimming?) So far! You hopefully noticed the giant hole in the deck, it would be needed to fit batteries on the E-Caster, but once you cut the hole, the sky’s the limit! (or at least your genital height)

It’s pretty darn simple due to not needing a slip ring, basically just esk8 electronics packed into a round shape. One thing I was thinking is that you have a reasonable but not too large battery like a 12S2P 21700, then stacked on top of that a swappable high capacity charge and ride module. Then riding could go on quite long! I think the battery consumption while sliding around would be quite extreme, even with a 350Wh pack I could see it going empty in like 5-7 miles. So the charge and ride packs would be fairly necessary, therefore making them easy to swap would be important. Given the footprint of the battery, 3D printing a battery + VESC enclosure would definity be possible so that is a plus for sure.

The total cost for this is fairly low, here is a guestamate

Item Price x Qty Total
200mm lazy susan bearing $20 x1 $20
Aluminum and other shafts Idk $60 $60
Motors 5065 $36 x2 + $6 ship $78
Pulleys wheel/motor $60 $60
Single Kegel wheel $20 $20
8mm Bushing ID 8x12x15 $9 $9
VESC (cheapfocer2) $69 x2 $138
12S2P 30T + bms $150 $150
totals $570 ish

What I’m interested in from you all in input on the general idea, good and bad. I’m hoping some of the great ESK8 parts manufacturers we have on here could help me find COTS parts that would make it more robust and still cheap and easy to make without a real shop.

This post is a work in progress, I’ll come back through and put more details about the current design where need be.

Thanks for the interest. Create and Skate on everyone.

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I love this project!

I have a Summerboard SBX and before it a Leif V2 so I know my way around these boards and can help you a little. After reading your post I immediately was surprised when you said you were thinking about a big motor. I think you really dont need to go bigger than 6355. You dont want nor need to produce a lot of torque on the motors as you are only driving 2 wheels and resistance is pretty minimal to get going. The summerboard SBX drives with very little current afaik.

I’m very keen on your project and will he following this! Good luck!

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I’ve been interested In a powered freebord for a long time. The thing that keeps me away from Freebord as a company is how the treated OKP publicly. The thing that keeps me away from Leiftech is the quality/QC issues they’ve had. I haven’t heard of a single person that did not have issues.

All that being said, a DIY version would be epic. I would suggest looking into to some low KV hub motors or maybe 5065 motors. I think the powered parts will be size dependant to make this doable.

Just thinking out if the box here. Maybe get 2 motors from hummie and afix the caster hardware through the hub, instead of fastening against the hub rim inside use a thin nut in both sides.

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How will you transfer the power? One of these?
#Aliexpress € 10,32 5%de DESCUENTO | Envío Gratis Micro anillo de deslizamiento de energía eólica 2/3/4/5/6/8/12 circuitos 5/10/15/diámetro 21,7 30A/22/31mm piezas de repuesto

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@Lee_Wright @mmaner Thanks for the replies!

The motor situation is the most up in the air, the 6355 motors in the model are definity too large. 5065 Is probably the largest side that would fit. I haven’t found any good models for those yet :frowning:.
wait lol nvm


you can see in this pic that the suspension is basically bottomed out on the motors when it is just resting on the floor.

I have been thinking about hub motors as that would make it really clean overall and give a ton of room to possibly put batteries below the deck instead of making my own deck with a hole in it. I was concerned about torque because I was hoping that it would be able to actually slide uphill as silly as it would seem.

@Rojitor I was thinking about putting the batteries and all the electronics on top of the E-Caster module and creating my own deck with a hole in the middle for clearance. It would have to be heavily reinforced on the sides.
Those wind turbine slip rings were part of my original plan with the broken freebord I got but they are just too long to fit…

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Sooo I feel like I’m reading the message I wrote in another life : I got really into building my own leiftech and it’s done now, using leiftech parts I got from them directly, because I couldn’t solve the drive design issue :

*You have the idea of “the rotating electronic” : would work but will need a lot of room up on the board and in the foot position it’s not possible, and is too fragile : it will not handle well jumps and other shenanigans
But you could do the rotating electronic with a small esc and a small but high discharge lipo installed to the mount of the wheel
*Using slipring is the way to go, pancake slipring because they’re flat, but they would need to be custom made with a big center hole and can handle +30amp : I asked several companies and sadly they would cost around 150/180 euros per unit… Using more traditional slipring goes back to the first issue of room under feet

I thought about it and came to the conclusion that whatever I’ll do, leiftech hardware would be better

I didn’t think of you idea, but I think the feeling could be different from a leiftech, being in the center especially during slides and 180/360
The windmill turbine could work, if you design your battery around it (like with a hole)

Good luck on your design if you go through it !

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How about those 5095 motors that @moon had a while back?

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Maybe a brushed slip ring like that – or instead some sort of brushless custom DC-DC converter using a custom coil that is incorporated into the caster itself. So like a transformer-caster where each side can rotate around the magnetic axis

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haha all that complicated stuff is what I was trying to avoid by just making it all one integrated system.


@Balta_6 pretty sure I remember talking to you in villanusjacksons thread about getting those leftover slip ring/drive parts from leiftech.
This is a crude model of what a custom deck with additional reinforcement would be like, got the 5065 motors on there and they nearly reach the edge of the edge of the deck which is pretty darn wide at 10".

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Oh I forgot the battery was on the caster too. :+1:

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Putting the cells on end allows you to fit a whole nother parallel just barely. Not accounting for fish paper or anything 12S3P 21700.


still a good amount of room for VESCs

Non-offset just barely fits, the hole could be widened slightly.

Also I realized the dickyho motors I was looking at were sensorless which would be fine but I wanting as much torque as possible so I think Racerstar 5065 140KV would be a good choice for a cheap motor. Jeff teased his motors in a 50mm diameter so that could also be an option.

The only thing I would say about the hub motor is the wheel profile, I don’t know if a wide square profile wheel would cut it. You want to transfer from edge to edge and the profile of the center wheel determines how that feels.

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Oh that’s a great point!
This is why I made this thread so people could bring up things I couldn’t think of.

One of the wheels I was thinking of using was the new Boa wheels because if I need the wheel to be very small like 60mm they are one of the only quality small kegel wheels available. They also have a good rounded edge.

Now I’m thinking about how to cut wheels to be rounded lol. I need a wheel like SR rough stuff or foamies but in less than 80mm. Don’t think anything like that is out there.

Finding a drive wheel that anyone could get ahold of is going to harder than I thought.
https://twenty4action.com/shop/jmkride-wheels/?lang=en
Freeskate wheels to the rescue?

Actually something like that would be perfect! You really do want that almost spherical shape. The centre wheels on the SBX are wide and spherical like that and feel great on transitions

You could speak to @NoWind about how he previously made boro center wheels fit for being driven by a pulley.

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@NoWind was one of the people I wanted to pull into this thread!
Due to his expertise in producing excellent ESK8 parts and having experience with the problematic leiftech drive system. I read about him making those parts while making sure I hadn’t missed anything while writing the first post, thanks for the reminder.

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Looks like diy rounding wheels is definitely possible and actually pretty easy. I love how with skateboarding most anything you can think of dumb or smart has been tried before and you can probably find pointers on how to do it properly.

While those Freeskate wheels are a good off the shelf solution I would have to 3D print pulleys/hub adapters for them which would be annoying. I might keep them on the table as an option, going to plan on rounding some kegel wheels for now just so I can use esk8 pulleys.

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Is there any need for a centering mechanism (bushing/spring)? Or does the combination of the oblate spheroid geometry work with the center line radius to give you the stability you need?

(still wrapping my head around the physics of the setup)

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on the leiftech and summerboard it is the resistance of the slip ring that prevents chatter.
This could be added in some way if need be but I was actually thinking about using a small pack somehow below the deck with a somewhat diy crappy slip ring above. free resistance

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:joy:

If you have some freedom with the mount of the ring, you could consider ‘wedging’ it to be higher in back to give it some trail and get a bit of centering?

That way in neutral stance, it’d have a slight forward bias. …basically using gravity as your spring :thinking:

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you trying to make a freebord a ripstik?

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