JUMPINATOR | Trampa lightweight build

rich · July 28, 2019, 8:02pm

Finally I have all parts together to finish this build which is not meant for riding. A lot of them are spare parts from my MTB and urban carver which I already had plus bought the missing parts to make a complete build. The focus was to keep it as light as possible. I might (or need to) change single parts every now and then because of destruction. So here the initial setup

Board only (weight: 7.5 kg / 16.5 lb):
Urban carver deck 14ply
ATB Vertigo trucks
Superstar wheels
MBS T3 tires
Trampa bindings & heelstraps

Mechanics (weight: 0.58 kg / 1.28 lb):
Unik motor mounts
14T motor steel pulleys
ABS 62T wheel pulleys
15mm belts

Electronics, motors & battery (weight: 3.3 kg / 7.28 lb):
Flipsky V4.12
Modified 6364 150kv motors
3x4s 30C 5Ah Zippy lipos
12s BMS 60A (120A peak)

Wires & enclosure (weight: tba)

Final weight approx. 12kg / 26.5 lb

This deck is cracked because of an accident with my urban carver in skate park and glued with epoxy. Hopefully it won’t break apart and if then at least with style. I flipped the deck so the crack is on the rear, should be safer.

Possibly the 14ply is too flexy, with the 16ply HolyPro I bottom out already when landing.

I drilled holes for bindings with this cardboard template, the center line helped a lot.

For true running pulleys I use different slim washers between spacer nut and pulley, works very nice. HK sells washer sets with a range from 0.05mm-0.3mm thickness.

Initially I wanted to use 6355 motors (and save 0.3kg) but then decided for 6364 for a little more power.
There were some loose windings so I glued them and also filled the gaps between the magnets.

Covered the connections on the hall sensor PCB with silicone for electronics.

When I ordered the motors I thought these have 12AWG phase wires but unfortunately it’s not. It’s the end of the windings covered in shrink tube, stiff AF

I read terrible things about solder windings because of the enamel coating so I decided to desolder the 4mm bullets and extend them from this point. It was really strange and almost impossible to desolder. With pliers and 100W iron it worked, not funny at all but I managed to solder silicone wire extensions.

That’s it for now, more progress soon…

Venom121212 · July 28, 2019, 8:39pm

Wow, what a beauty!

You’re constantly a year (optimistically) ahead of me. I want a lightweight jumper so badly that I’m about to buy a manual deck to practice with until I can afford to electrify it. I’m forced to live my mtb life vicariously through you and I don’t mind it one bit. I can’t wait to see how this goes the first time you jump it. Great work as always bud.

Mobutusan · July 28, 2019, 8:47pm

Very cool build. I like the component weight breakdown. Crazy how easy it is to surpass 25lbs. I’ve got a lightweight jumper build on my to do list too, so this will be a good reference for comparison. Do you have weights for a single truck, single wheel/tire/bearing, bare deck and the battery, since these seem like the largest weight factors? No problem if you don’t, I was just curious if you had those weights on hand. I was going to take a minimalist approach with 10mm axle trucks, 5065 motors, 12s 6Ah Graphenes, and 6 shooters to see if I can possibly keep the weight under 10kg. total, and see where that gets me.

Are you going to try 180s or 360s with this, and if so, are you going to mount all electronics in the middle of the board to reduce weight at the ends of the board? That was another consideration I was thinking about, and why i want to try 5065s to start.

Definitely looking forward to some awesome videos.

rich · July 28, 2019, 10:12pm

#metoo

Thanks

Hmm not for components like trucks but you can find the info on Trampa’s page.
A complete wheel (hub, tube, tire, bearings, spacer) including ABS 62T pulley weights 0.69kg .
The 12s 5Ah battery 1.6kg, 6364 motors 0.75kg each, Fsesc 0.09kg each, BMS 0.14kg. An ABS pulley weights 44 grams only.

Yes

Yes, also I want to try dual diagonal one day to get the center of mass in the middle.

My plan is to use the threaded inserts to mount a simple “enclosure”.

Enclosure means weight which I want to avoid but also don’t want to stick parts to the deck so for the first version I’m thinking about this solution: I cut 1mm ABS sheet and bent it on the sides, it’s very flexible.

Each of this 4 segments get cushioning and shrink tube and then glued (or velcro) to the ABS sheet.

On top just a dust cover or something, need to keep it light. I haven’t decided yet if I install the BMS permanently like planned and also if anti-spark switch or not.

Chibatterysystems · July 29, 2019, 1:06am

Another beauty ! Always admired the trick boards

Andy87 · July 29, 2019, 5:02am

Nice nice nice!
Finally this project gets rolling.
What about your dual diagonal thoughts?
Looks like you now decided to stay with dual rear?

Creavenger · July 29, 2019, 9:07am

Awesome! Looking forward to seeing it finished and in action! I should weigh my board sometime, I think im close to 13 kg

rich · July 29, 2019, 1:08pm

I’m just starting with dual rear because I’m used to it and can compare it better to my regular MTB. It could be that dual rear is better for straight jumping, especially for lifting the front /ollie and dual diagonal better for rotations. On my Dirt Machine it’s quite a different feeling when lifting the front with the new battery which is more than 1kg heavier. And the weight is just in the middle of the board, with dual diagonal drive I would add 1kg to the front truck. I guess both have pros and cons and I gonna find it out.

Meanwhile I was working on cable managenment for the phase wires for minimal movement. I have no 3D printer so as usuallly my hands have to build things like this

Wood, 2mm ABS and M3 spacer nuts (15mm&10mm)

Some black magic

Assembled

2mm rubber

Done, only the zip ties on the hanger are missing.

Saturn_Corp · July 29, 2019, 3:12pm

Are you a tad uncertain about doing jumps on the repaired deck? It cracked pretty good when you rain it into that rail.

rich · July 29, 2019, 6:22pm

I wouldn’t call it repaired just sanded down a bit and filled with epoxy glue. I don’t feel 100% comfortable with the crack but am also curious if I can enlarge or break it. At least I would have a reason to buy a new deck.

stratoglide · July 29, 2019, 6:42pm

I mean you won’t have to buy a new one according to trampa’s website.

rich · July 29, 2019, 6:52pm

You are right and I already got a new replacement deck from them under warranty which I use on my urban carver Can’t claim it twice if it breaks

bevilacqua · July 29, 2019, 6:53pm

What did you use to protect the insides of the motor? (sorry if this was already discussed, I saw a pic on the nowords thread some weeks ago)

Thanks

stratoglide · July 29, 2019, 6:53pm

Lmaooo I guess that’s even better

rich · July 29, 2019, 7:01pm

I did this to 4 motors, in theory it’s “battle hardening” but instead of fluid I used an epoxy putty which made it easier. Time will tell if it holds, it should be good up to 140°C. The hall sensor PCB connections I secured with silicone. My aim is to prolong the life of the motors with this procedure and make them more robust.

sk8l8r · July 30, 2019, 11:21am

I’m about to try some battle hardening for the first time, I like the idea of putty seems easier and much less messy

rich · July 30, 2019, 2:30pm

Just be sure that the epoxy is for higher temps (at least 125°C, better higher). Putty works well when pressed down with e.g. wood sticks, it needs a little pressure to stick. And you need a lot of gloves.

I think battle hardening with a fluid epoxy on the can is better because it can float into possible gaps below magnets which putty can’t. But I was afraid to mess up, also I’m a noob regarding epoxy therefore the putty. On the stator/windings I’ve tried retaining compound first but it is too thin and floats everywhere without any control. I didn’t want to risk any damage.

The intersting point would be if there is a difference in heat dissipation between fluid epoxy and putty. Of course filling all the gaps is not best for keeping motors cool.

sebaszz · July 31, 2019, 10:32am

This is a very cool build!. Looks like fun to see how you reduce the weight as far as possible.

Curious how this performs for doing tricks against your other board.

rich · July 31, 2019, 3:52pm

I have some interesting numbers comparing both boards. I put a scale on each hanger and measured how much force is needed to lift the board.

Jumpinator front 4.65kg (10.25lbs) / back 6.95kg (15.32lbs)
Dirt Machine front 6.53kg (14.4lbs) / back 11.14kg (24.56lbs)

So I guess it will feel like a feather
The Jumpinator actually weights 11.4kg (8.82lbs, almost final weight) and the Dirt Machine 17.6kg (38.8lbs).

I have some updates.

Handmade segmented angle brackets which go on top of the 1mm ABS sheet

The brackets are not necessary but act as a big washer for the bolts and spread the force. Furthermore it helps with cable managment and hopefully prevents parts from flying away when crashing.

On the bottom of the ABS sheet is 2mm self-adhesive neoprene foam.

Covered the lipos in 2mm EPDM foam and clear shrink tube.

Then glued with 2mm double-sided self-adhesive EPDM foam to the ABS sheet.

I don’t think it will stick forever beause the glue is like on double-sided tapes. The glue on neoprene foam sticks forever but unfortunately I couldn’t find it double-sided self-adhesive that’s why EPDM. Time will tell.

Next is to solder hall sensor and phase wire extensions. Just a hint, when soldering sensor wires I mark them with a paint stick on both sides. In the past I put different colored duct tapes on them which took way more time.

b264 · July 31, 2019, 4:19pm

Do you have a link for that?