Rat | Kicktail | 6S1P | Dual 6354 | Mini Foc+ | DIY Wheels

This is a build thread of my latest board. I call it Rat :rat:. I thought I might share it with you all.

Story
My first eskate below was a lot of fun. It was not perfect but it sure put a smile on my face. Sadly it’s parts gave up on me many times.

Last year I built something else. This board is super sweet although it is far from practical. I can’t carry it with one hand, doesn’t turn quick enough and it is a pain to carry up/down my 3 floors.

So that is why I had to build Rat :rat: :smile:
Rat is a board made by old dirty stuff mostly (hence the name)… yes I don’t think I bought anything for this build :thinking:. It will look dirty, because it will be dirty. Snails and land dust does that to a board.

Goals…
Comfortable
Carry-able
NO noise, NO rattling
Cheap (I really don’t care too much about the cosmetics… I don’t even plan to paint it)

Parts…
Deck: DIY…I have no idea what kind of deck this is/ was… My colleagues son gave it to me for free :heart:
Enclosure: DIY Fiberglass
Battery: DIY 6S1P 15Ah
ECSs: Mini FOC+
Motors: SK3 6354 260kv
Hardware: Trucks, mounts and Pulleys… An entry kit bought from Dork Boards many years ago
Wheels: Rock hard 83mm ABEC clones (with glued tire strips from my friends passed away grand fathers bicyle) Don’t miss this! :sunglasses:

Building process…

The deck was too long and I needed a shorter wheelbase to be able to make quick turns.
Forgot to take pics but here is how it looks now after I cut the nose 1dm.

I made the fiberglass enclosure for my old board and now it does not fit the deck. It had to be shortened

Chop!

I cut off a segment from the enclosure and reattached the end piece. (yeah I like reusing things)

Okay, now the length is ok but the there is a huge gap since the new deck is not flat :scream:

I modelled and 3D printed some pieces to get the correct shape

Some epoxy work to get the pieces to stick.

Fused XT30 for charging and XT90s will be used for antispark



The battery is 6S1P 15Ah pouch cells.

The tabs are screwed together in series using these metal bands with holes in them. My collection of nuts and screws from old PC builds came in handy. (I did my first battery like this but with rivets instead of screws. It became a shit show with tabs loosing connection after about 500km :flushed: :-1:)

Then I kind of wrapped it into this foam material for protection.

I didn’t plan to use a BMS. Instead I was thinking of using one of those lipo warners for monitoring. However due to its design and the low tolerance resistors, the voltage readings was too much off to make sense. I did try to Macgyver it to something better with other resistors I had at hand but the reading was still shitty on the last cell. A for effort at least :joy:

For ESCs I have my two Mini Foc+ from the old build. They have proven reliable to me. However, since I want around 2kW out from my 6S battery, these escs need to take ~50 battery amps each. I beefed up the DC traces with some solder… Just in case.

I used bullets instead of XT90/60 since it allows me to more easy route the cables inside the enclosure

3D Printed a little piece to prevent the two esc from flying around.

From my last board, my SK3 motors were suffering due to the open can design.


They were cleaned up and I gave them an epoxy shield and new bearings. (I remember one motor dying shortly after this. Had to replace that one)

MT60 on the motor phases.

I wanted to get the enclosure as dust proof as possible, therefore routing the phase wires through the enclosure.

while having a good seal, I also wanted to be able to pull the MT60 through the enclosure in case of maintenance. I came up with these printed pieces and some screws to achieve this.


Yeah this does not look good (but it works at the moment). I will have to print something more reliable to prevent phases shorting against the motor can.

Alright, we are almost there… but still some more to go through

I previously had issues with the belts touching the wheels. To come around this I printed plastic shims which acts like a distance for the wheel pulley.

Now the wheel pulley has use of its edge near the wheel, making it impossible for the belt to move further.

I designed my own version of belt covers. They help a lot from keeping small stones out of the belts. This new design is smaller and has even more cover than the old ones.


The old build had bones reds bearings in them. I remember they made terrible noise also they seemed to have gotten worn fast. I think it was due to my crappy wheels had the shape like cones from excessive carving, putting extra stress on the bearings.

I learned how to disassemble bearings and this must be by far the fastest way to clean bearings (instead of shaking them in a bottle).
I took all the tiny balls from each bearing and mixed them all together… then put the bearings back together, greased them up and now they all run smooth and quiet :ok_hand:

The fitment of the kingpin and the baseplate of my caliber II clones was horrible. There was so much play and caused massive rattling. I cut small sheets from an aluminium can and folded around the kingpin. Then hammered the kingpin into place. No more wiggles, no more noise!


VX1 got a battery upgrade, and some glue on the solder joints.

Now it is very close to be finished, Its rideable and range is is good. 27km. The riding comfort could be better though

Now this wheel mod is by far my most satisfying achievement of this build.
I cut a bicycle tire into pieces.

…long enough to encircle the wheel

Contact glue on both wheel and tire strip. Wait 10min then attach. Used tension straps around over night.

yesss

I have not done more than 40km yet on these wheels, but I have been stressing them with carving and there is no sign that these tire strips will come off. The ride is now really smooth, I can’t feel the small annoying stones any more… I like it a lot! :star: :star: :star:
The draw back is the 30% decrease in range I got now :roll_eyes:… but still enough for what this board was built for.

I’m very happy to have resurrected a pile of junk in my drawer to something great :slightly_smiling_face:

Data
15/36 and the new wheel diameter 87-89mm gives me a top speed of ~38km/h
19km after full depletion.
Power ~2kW
Motor A 2*65A
Batt A 100A
6S
260kv

38 Likes

Instant like for the 1st instance I’ve seen of decimeters used in a post here :+1:
Nice build, I dig it

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Been following this build since the start, it’s as crazy awesome as it looks :green_heart:, an esk8 built for a purpose, doing that purpose awesomely!

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Awesome!! Love the approach and execution, buying as little as possible an making good use of what you have. Fantastic little commuter built to last. Respect!

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this is more DIY than some of the build we got before

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Some excellent DIY skills on display. Love it! Awesome work

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Thanks guys! I’m glad you can appreciate it for what it is

I forgot to mention that I made a wedged raiser for the rear by melting hot glue into a mold :grin:

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I’ve had great success with TPU risers (100% infill) since you seem to be good at 3D printing…I would trust them a lot more than hot glue since asphalt can get pretty toasty in the summer.

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Actually I didnt have the 3D printer at the time I made the riser. My friend recently gave me his left over broken wanhao duplicator i3 and I’m learning this stuff now. It’s my first CADs and print attempts you see here😄

The glue riser was fine on the old board but a 3D printed one will reduce some weight for sure :+1:t2:

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Love the little build. I made a commuter back in 2018, I STILL use that board all the time. Is it the best? Nope. Is it light and easy to take anywhere? Hellz ya. And that’s why I still love it.
Really dig all the work you did yourself, nice clean finished product all things considered! You’re gonna love it!

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Update.
I have now done 370km on this board. It has proven to be very reliable. No maintenance needed👌🏻

Front wheels still looks good

Rear wheels seems to wear a lot more though :roll_eyes:

When I took the bike tires, they were 8 years old and already worn. Perhaps a new tire would have held up better.

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Has the wear impacted the ride? I guess if it happens slowly you may not notice, but swapping the front wheels into the back would give you an idea. I’m surprised the glue held up that well though!

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Yes I can feel a difference. The rear has become slighly harder and my range has improved. From ~18 to 21km. I can freeroll a lot better. But I miss the softer feeling it had in the beginning.

I actually just swapped the front wheels to the rear.

The glue is holding up very well. No signs that the strips will ever come loose. I will ride down to the thane to see what happens :slightly_smiling_face:

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What contact glue did you use?

Something cheap I found in the local hardware store

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Here is a bunch of updates of the :rat: board…

The glued bike tires are still on. Now they have seen ~600km. There are zero signs of them ripping off.
They do wear a lot though…since most weight lies on the rear wheels, those worn a lot faster.
I swapped the front wheels with the rear wheels after 400km~to get the soft ride back.

A lot of carving, no hard accelerations.


No pattern left and “cushiness” is gone on both front and rear wheels.
To remember, this tire was worn out already when I took it. I kind of wished that I had used a new tire from the start. Now I just want to see what happens when it is worn down to the thane :grin:. I give it at least 500km more to get there.

Upgrade 1
…So i was belt skipping down the street one day and thought maybe some belt adjustments are needed.

Removed the pulley covers to see that the teeth has seen better days… :laughing:

The other side do have some profile left… Not sure why it differs. Belts have been tightened the same. Perhaps some slight wheel wobbling on one side?

Conclusion: Pulleys had ~1000km on them. Will go steel next time.

…O wait a minute. I found a new set of 14T alu pulleys in the drawer. Ready to be slap on :shushing_face:. Since I never go full speed anyway on this board, going from 15T to 14T wont be noticed when it comes to top speed.

Now with 36/14 ratio (instead of 36/15), esc temp has actually dropped slightly.
Here is a picture from a route I normally take. I usually always hit 70degC when reaching the top of the hill (75degC on a hot day).
Now with the new pulley 67degC is the highest I have seen so far. So maybe ~3 degC cooler with 14T instead of 15T. Cool! :sunglasses:

Upgrade 2

I attached a 3mm alu plate for extra thermal mass.
To be honest I didn’t notice as much of a difference as I had hoped. I was hoping for 5-10min extra ride time before reaching a thermal equilibrium. I think I saw less than 5min :face_with_raised_eyebrow:. At first I thought the plate was not connecting good enough. I ran foc openloop on one esc and could see the other once slowly heating up as well so that proves both esc are thermally connected to the plate. well well… :man_shrugging:

Upgrade 3
@xsynatic sent me a 6S bluetooth cell monitor. Free of charge… well so far at least. What a great guy :grinning:
Since I run without a BMS, I use this to keep an eye on the cells.

Well that’s about it for now!

8 Likes

I had completely missed this thread for some reason. So much DIY in such a small package, looks awesome!

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It’ll definitely stay that way :wink:

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I like it a lot. It’s a super fun morning cruiser.
In eriksberg now… heading for ramberget hill climb temperature test :blush:

:smiling_face_with_three_hearts:

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Our german friend coming in clutch as allways :heart:

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