[the timetrap] | 2WD | scate deck | unity | sk8 6384 | GT2B | 4s2p3s lipo | gear drive | no bms

once upon time, an urge to build started.

It was not called…

[the time trap]

…it was called the AT. mostly referred to as “my AT” :smiley: in LoB as DYI3

back to storytime. I built a build (I never wrote that :smiley: ) which I might get deeper into later.

but the deck went to dreamland, and my main build with him. time to rebuild!

some lipo batteries were laying around, so I might rebuild it quite differently!
but first, let’s clean the filthy mess packed up after few months of riding. we wanna see clean and beautiful parts!

now the biggest change - from quite a long board to something short. trying again skateboard deck with trucks on the tails I’ve been pushing some time ago. guys were buying the decks for some fun projects as well, so why no to join

and this is where the reason for the time trap starts.

got the deck, pretty neat, interesting colour.

drilling the holes

this is where my usual “sorry, living in a dorm, don’t have everything” starts. I don’t have a flexible straight edge. if it looks straight, it is straight

drilled from the underside, countersunk for some peace in mind

truck assembly

the deck with pads and baseplates.

baseplates from old caliber II trucks, I’m giving them hard time and they still hold up quite nicely. I’ll not torture them much longer though, will be replaced in a future build

the pads are actually sleeping mat, that kind for 2 bucks or something, great padding material. can be drilled with a wood drill by hand. cool and oddly satisfying!

feels kinda fine. little less torquy, mainly because of those 94a deck-side 91a road-side bushings.

wheels

here they are!

btw, michondr, you might ask, what hanger is that? that’s pretty wide! that is a 240 fatboy hanger. love them so much! with those 6" china pneu they are similar width as the Thorium AT with 6.5" urban threads and 230mm hangers. nice!

now, you might say that those tyres look disgusting. and you’re absolutely right! I pulled them through hell (7th screen) and a lot of kilometres

so, lets change that!

fix the orientation of the inlet, the pattern, take pulleys off

the pulleys need to be changed ASAP anyway. (new already printed few days after this build finished to have some spare) but now, we wanna ride!

so, lets throw in the drive, and lets go!

drivetrain

chose the esk8 in desperate times after my motor journey. ok, let’s break up my motor journey:

step 1) - APS 6384S 170KV 4kW
well, this sonovabitch kicked the journey with my previous board. the journey of power, fun and speed. after shredding it uphill, at the peak, I slowed down and realized that a magnet in one of those motors came loose. great news!

step 2) - dual APS 6384S 170KV / SK3 6374 168KV
this is probably the era when my boards started becoming a Frankenstein every single time. but hey, it works! quite a quick fix, I had the motor laying alone in a closet, I could give him the taste of sunshine and neverending tarmac. and the KV kinda matches.
and for those wondering, it worked quite fine! then the phase wires started to short circuit inside and the sk3 was glitching when under no speed. nevermind, possibly too much water?!

step3) SK8 6374 149KV
kinda fine for the price. a bit bulky, a bit pain to shorten axles, a bit janky on fast riding setup.

and mounts and belts - 50t wheel, 16t motor. 270ish belts. boardnamics mounts without idler

battery

ah, yeah, the battery. reused the same lipoly pack from the drowning board. I already had the wiring for that - two xt90 in parallel, 4 of those in series. there is a bit of cable clutter in this configuration, but hey, it works.


some case for the battery? naaah, takes too much time ti acquire. I wanna ride the board!
this might do it, for now

you might have noticed that the similar theme is noticeable on the unity case/enclosure. it’s fine, temporarily, basic… definitely nonpermanent :smirk:. paper tape and zip-ties are gonna save the world

riding

…and this is where the reason for the time trap continues…

I went outside in full armour, without a surgical mask at that time.
first step on the board was fun, I managed to step partially on my unity, and the JST connector slightly bent outwards. oops, will be careful next time :smiley:

the first turn. this board does not turn at all.

  • if I have comfortable wide stand, I have wheelbite even while riding in a straight line.
  • or I can have narrow stand, be able to turn, but have no stability to accelerate and break.


the temporariness was definitely fine. this board cannot be ridden. back to the drawing board

…are you starting to catch the flow of a time trap? :sweat_smile:

[the time trap street edition]

sooo… street wheels? but first, time to clean the table

I wrote a friend for some 3d printed parts… either finished STLs or plans like this (when you have handy screenshot tool, its fun)

and the result came some time after that!

wheels

I had old Kegels laying around, so why not to use them? the axles on the fatboys are too long for normal longboard wheels, so I had made spacers 20mm long, 8mm ID 16mm OD. works quite fine, had to fix tolerances with a drill. no big worry though.

perfect sizing!

and that’s fckin wide. megacool!

now time for the pulleys.
went to a hardware store (this time with a surgical mask) and got myself a M5 tap, a tapwrench, a 4.20mm (:face_with_monocle:) drill and some bolts. its like 5 minutes on a board through calm hood waving on my boosted

doing this the second time. previously I used an electric screwdriver and melted the plastic all over the tap. not great. so this time with more effort, time, care and love.

this felt like the first proper craftmanship on the whole build.

and I was gifted with heart-warming amount of trueness in how the pulleys run!

battery

ok, this might fit! and it does!

I kept the charging port inside because it was inevitable that I’ll go inside the enclosure. also, paper tape is not a great obstacle to pass

unity enclosure

this was originally the plan, why to care about waterproofiness, use the minimal space possible!
top mount will be the fatboy unity heatsink

after adding a switch and small adjustments for sensor cables is the time to drill. the plan was to screw from the bottom, through the predrilled plastic in the heatsink which has M3 tapped holes.

what do you think I forgot in there? :weary:

backup plan. I grab the M3x50 screws, hoping that they are sufficiently long. nope! exactly bottom of the deck to top of the case. new plane - I can screw through the tapped holes from the top with shorter screws, and from the bottom with the longer, it will surely hold self-tapped in the plastic.
also the orange condom on the unity is too big. well, here you leave, waterproofing.

throwing it all together

…yeah. still lots of paper tape, zip-ties and sleeping mat. once again gym stretching rubber solves the dilema with holding down the battery enclosure.

sharp eye might notice that the cable from battery to unity is hidden under the deck, held in place with, you guessed it, a paper tape :smiley:

so how does it ride?

it rides. that’s what it does :smiley: sometimes well, more often scary. it’s quite a lowrider. the clearance from the mount bolts is about 7 mm. I aready brought the screw head and aluminium down a bit. I’m thinking about writing the bolts to “hardware store to-buy list”.

the amount of torque is very pleasant. with the sensored motors you can pull the trigger really fast while leaning forward and the board accelerates so fast that wobelling is a thing. definitely more adrenaline during takeoffs compared to having it set for 60kph on AT wheels.

the posture is fine, my front foot is pointing in the direction of transition to the tail, back foot the similar, but it leans against the unity enclosure.

carving-vise, it’s really stiff. the extended angle of the trucks make it so that less lean is required to turn, but the tough bushings keep it mostly straight. will try to change to stock caliber bushings, they are way softer and mushier, it might make it better

to explain some things:

  • the pulley on the front right wheel cannot be taken off unless I cut screws
  • the amount of applied griptape equals exactly the amount of griptape I had on hand
  • the gym rubber was replaced to green, as my roommate wanted to return his
  • the sticker on the battery is just shoved under the rubber. too lazy to open and tighten it

at least we’re having lots of fun out of it in our Prague group

[the time trap clud edition]

this is probably the future. I’ll change the wheels to something bigger to restore some ground clearance. now you have to think about every little bump on the ground and cannot go very fast. also you can feel the mounts scraping the ground. not good!

this will hopefully help the shaking as well. it immensely bumpy ride resonating in the whole back wheel assembly. it almost sounds like all the magnets in the motors will break into dust.

conclusion

well, I can always say “I did it for the science!!” :smiley: I’m looking forward to try it on some sweet tarmac we have here, but that must wait for some warmer weather.

here is a MetrPro record from today’s pilot ride

so guys, how DIY is this build? :smiley: happy to hear your thoughts

16 Likes

That’s a weird ass battery config. 4s2p3s :joy:

4 Likes

Yes it surely is :smiley: I had to fit it under the deck previously, this was the cheapest option :smiley: you cannot add bms to that setup though, but the cells stay balanced quite fine. I charged and balanced each of those 3s after 700km and they were no more than 0.1v apart

1 Like

I must say, this is the kind of build thread that I aspire to write. Awesome pictures and info about a great build.

THANK YOU!

2 Likes

My first didn’t have an enclosure either. My second does kind of.

2 Likes

Quality post! Nicely done!

1 Like

It looks like something out of Back to the Future in its first iteration!
Run it in FWD and you may get rid of the acceleration wobbles.

Please explain why it went from 4s2p3s to 2s2p3s and how does it make any sense? It there math involved am I supposed to multiply something to get the result? XD

I want to see a video of you riding that so bad :laughing: Fantastic work documenting the process, was a fun read! :smiley:

1 Like

:face_with_raised_eyebrow:looks like a fun build. But a few things.

You have standard trucks, mounted to a kick tail, emulating the MTB style decks. However, in doing so, you massively de-wedge front and rear trucks. So you might have great turning, but your stability (that wobble you mentioned) will be shit. MTB trucks are designed for those decks, which is why you see adjustable baseplates when people throw regular trucks at MTB decks.

Enclosures are your friend. It’s DIY, I get it. But there’s a lot of masking tape. Replace that with harness tape, or something different if for electrical insulation. Top mounting everything left you with very limited foot room

Have fun with it.

1 Like

I incorectly noticed that I wrote the title incorectly :slight_smile: I had it corect the first time :smiley: i counted to 12 insead of 24

its 8 lipo batteries, 3S each. there are three ways to put these together:

  1. the propper one - don’t do it.
  2. bodge them into 4s2p3s - two 3s batteries in parallel form 2p3s. put four in series for 4s2p3s
  3. bodge them into 2p4s3s - four 3s batteries in series form 4s3s1p. two of them in parallel form 2p4s3p.

it only depends on how you look at it. because its formed out of 3s packs, I don’t wanna call it 12s2p, because that just sounds wrong when there are not 12 individual packs in series consisting of 2 cells in parallel.

a part of me was thinking that this is too much, nobody has the time to read through all of it (similar to catching up with the battery builders thread where I spent half a day just going through the pictures.

anyways, I’m glad you enjoyed! here is a video for you from today :slight_smile:

on our way there I was getting used to the shorter stands and really satisfying acceleration. at the end, some fun in gravel. well, it was fun, however some of that gravel got into the gears (really surprising, I guess noone would expect that to happen :smiley:)
also, this was really nice slow-mo on an iphone. exporting it in .mov feels like a crime

the timetrap - gravel fun

here you can really hear the board scraping the tarmac. well, I got (rode) what I paid for (built).

the timetrap - tarmac scraping

last but not least, the recorded ride itself - or at least part of it. it was pretty good actually!
in the beginning, you can hear a few teeth skipping. that was because of the little stones and stuff.

the timetrap - carving fun

unfortunately the meter session was unusable, as I forgot to change the gears in settings. so I went for the track once more in the afternoon and had some more fun. (well, the meter module shook off of the unity after few kilometers, nothing piece of tape cannot fix).
this time I went to the city after the ride

  • scraped the mounts some more.
  • received a thumbs up from a tram driver while crossing the street and jumping from the board after it got stuck in the cobblestone.
  • next crossroad going over the tram track, fell on the ground immediately
    …center-european-old-city-centers in a nutshell.

here is the record from the afternoon: https://metr.at/r/yLDey

2 Likes

Maybe it’s my internet; but the videos aren’t loading. Maybe YouTube would have been a better choice.

image

you’re actually right in every single point. good job! (I’d offer you a cookie, but then it would feel too sarcastic :confused: also the delivery would be complicated :smiley:)

the stability is fine. I cannot say its great - few points from today’s rides - you lean really a little with quite a lot of force, but it feels bouncy and fun in lower speeds. from 85% of speed upwards, it is wavy, as if something made it to go out of balance. but it can be handled in a straight line.

I tried to change front bushings to stock caliber II, not sure how hard those are. the board felt more prone to wobble, not fun while accelerating. so I switched them back to 94/91 after a kilometre :smiley:

and enclosures are the worst enemy :smiley: this is just fun experiment, not my daily (now if I think about it, even my daily didn’t have a proper enclosure. will change soon though)

2 Likes

im not sure if theres a simple solution to that. Wobble will be an issue as the effective angle is probably like 80 degrees
Id keep speed low, regardless, it rides and thats most important

1 Like

yup, thx for that, I uploaded the videos on youtube.

It seems uploading raw 500MB file with public ACL on S3 and using that as a source of a video inserted in markdown is not a great experience

1 Like

Try not to carve inwards towards pedestrians on bike paths. Doesn’t give us the best look…

1 Like

Just watched the videos, holy shit that looks fun! Like a snowboard on wheels :smiley:

fixed the youtube loading thing. now its a direct link :slight_smile:

@rusins it feels more alive than it looks - like I’m moving my whole body. you can build your own quite easily and try on your own!

2 Likes