Destroyer 12s Urban Racer Build

beto_pty

1 kW
Joined
Dec 17, 2013
Messages
480
Location
Panama City, Republic of Panama
So I played around with the 4238 mini motors (see boosted boards reverse engineering build http://endless-sphere.com/forums/viewtopic.php?f=35&t=56839 ) and had a lot of fun.. very strong and awesome... learned quite a bit

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Then i moved on to build a run of the mill 6s, ezrun, tacon bigfoot build using the same 36" aluminum board... again awesome and an incredible learning experience. Played around with the design (specially the 10 iterations of motor holders) as well as some of the electronics to find a design that would hold up 200 kms without having to tighten or do any work on it as I have really gotten to really enjoy my daily rides, and now venture farther out...

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However living in the republic of Panama our roads are not the greatest... they are more concrete than asphalt and more than a little on the rough side. Speed bumps also tend to have 1" -1 1/2" lips as do the wheelchair accesibility ramps making even my 98mm abec 11s either come to a complete halt or at least give me a significant jolt and sometimes force me of the board. Figured I either dealt with it... or asphalted every street in my country, or took up bicycling. Well guess what.. there was another option
http://endless-sphere.com/forums/viewtopic.php?t=55266, Thanks to made_in_the_alps_legacy I saw the 7" wheels I needed.. if I could not make the potholes smaller I could go with bigger wheels, these babies are over twice as normal 83mm tires and 80% bigger than my already oversized 98mm abecs.

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Using these wheels required me to completely redesign my aluminum board, so this became a whole new proyect...(or use 3 " risers LOL). So a new aluminum board had to be milled... Worked for a couple of weeks on alternatives till I settled on a 45" long tapered dropthrough design.. cut it out of ply just to verify the huge wheels had enough leeway, nope.. back to the drawing board... the second plywood one worked fine so I milled that one out..... Also I wanted a 12s capable system, although I changed my batteries (and extended my life expectancy) to 8s the first day after (very) briefly trying the mockup on 12s power. However the 12s ESC does not have a break alternative, (and my foot braking leaves much to be desired at 50 km/hr) so an alternate breaking system had to be implemented as well... so again a couple of weeks went by while the solution made itself aparent. Scooter Band brakes controlled by a servo.. and hopefully a secondary emergency braking system...
Being the SW nerd that I am.. I figured a couple star wars designs would break up the monotony of the aluminum finish... so I engraved my ubiquitiuos "Do or do not, there is no try" as well as an Imperial shield and Fett's shoulder emblem.. as well as some grip tape (or sandpaper stickers? dont know the name) on top


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The Name of the board is my son's nickname " Destroyer " and o yes..he earned that nickname...

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Well the parts got ordered.. Including
Electric scooter parts 60mm band breaks http://www.electricscooterparts.com/bandbrakes.html
#25 sprockets and chains http://www.electricscooterparts.com/sprockets25chain.html
Turnigy 10 kg servo, 2 5000mah 4s batteries in series, a Quanum controller, a Sentilion 12s HV ESC all from Hobbyking International Warehouse as several are backordered in the US,
Tacon 245Kv 6264 from http://www.hobbypartz.com/96m608-bigfoot160-5335-245kv.html
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Run of the mill bicycle wire tubes and wires to conect brake and servo...
Onda wheels http://shop.ondamotion.com/onda-vibe-polymer-wheels/
Custom made aluminum motor mount , aluminum brake holder, both welded on Bear 10 inch trucks
45" long 10" wide 1/2" thick Custom Aluminum board with dropthrough truck mounts

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The brake servo is connected to the third output of the controller.. originally thought it might need to be squeezed carefully so as not to throw me off, but the band braking compares to normal 25% braking on my HK150.. I might actually be tempted to add another one in the future, maybe next week future...

The chain/sprocket mount lenght calculation was complicated and actually intimidating till I found the http://www.killerbotics.com/kbtools/SprocketCenterDistanceandChainlengthCalculators/ it does for chain and sprockets what the SDI table does for pulleys and belts. The motor mount design was quite easy and straightforward from then on... The chain looks and feels ok, although not as elegant or quiet as the 15mm belt design in my smaller board. Belt slipage however I believe is now a thing of the past.

The board comes in at under 9 kilos which is not so bad.. maybe wouldnt want to lug it around for blocks and blocks but to and from the car to the riding area it is ok.. also cut out come carrying handles, although since the board is quite rear heavy they turned out to be " not so comfy".

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I have riden it twice, and have gotten up to 48.5kph on 7s and will go again next week at 8s... I skate in full motorcycle body armour as I like to go fast.. and am seemingly uncoordinated... (this pic is of me on my other board, no pics of me on the destroyer yet)

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It is quite roomy and confortable with a nice degree of flex, the wheels roll over everything and eat just about all the bumps... will have to work on the brakes a bit.. but the acceleration is awesome, for now maybe too awesome.. very ahppy with it so far..
It is not practical or a good last mile vehicle.. it is a head turner, attention getter... and does this very well.
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Reserved for riding/problems update
 
Nice! I have plans for a very similar board, although I will probably use onda's trucks as well because they allow a very small turning radius at low speeds while still being fairly stable at higher speeds. My friend has an onda core and I love riding it. The onda deck is a little narrow for my taste and has too much drop, so the clearance height in the middle of the board is a little low. Anyways I have a couple questions.

How did you get the onda wheels to fit onto the bear trucks? I tried putting those exact wheels on my longboard trucks (I think they're churchill rkp's) but there was not enough axle length left for the nuts.

Also how good is their traction? I don't want to slide; I ride my longboard to get to class, so when I make a turn, I am trying to turn and I want my wheels to carry me through the turn without sliding out or anything like that. I don't have very much experience riding my friend's onda board and he can't really help me because he's very cautious when he rides his board and never really pushes the limits of their traction.

Thanks.
 
Thepronghorn: The destroyer turns like a boat... turning radius is not it's strenght, also since i ride fairly fast my trucks are tightened to the max. The onda wheels will not fit any but the bear trucks. I had 3 other sets of trucks which i had bought to be welded on... and had to go with the bear trucks on my non electric longboard due to necesity. They are 10 inchers and the wheels fit on with barely an extra screw thread over the safety plastic ring... As far as sliding.. If you mean purposely going sideways on the wheels... I have never done that, if you mean the wheels involuntarily sliding while you turn I have had no problem with that.. again the limiting factor might be my riding ability.
Ipbug: Go with the armour. I have taken 2 really bad falls at over 40 kph and not had a single scratch on me... protection plastic on right elbow, wristprotector, right knee had scratches up to 1/8" thick.. would hate to think what that would have done to my skin and bones... Also it looks cool...You feel the impact like a freight train hit you..but roll with it and (hopefully) nothing gets broken... Also knowing what it feels to crash at that speed makes you a much more careful skater... INterestingly if you look at the armour pic you can see the flex on the aluminum board.. contrary to common assumption they are quite comfy.
Benj: The band brake was a necesity since my controller did not have braking options, and I trully dislike foot braking and will only do it when absolutely necesary. That said I would suggest double band brakes to anyone interested. Got them at www.electricscooterparts.com the service was really excellent and the shipping times unreal, also at under 20 bucks they will not break the bank...
 
Yeah, I'm actually quite digging the aluminum shortboard I made, it's a comfortable ride. It is probably not as flexy as yours but I am planning on milling pockets. The machine marks on your pockets look like they've been CNC milled, is that so? Would be a pretty big CNC machine I am assuming.
 
lpbug said:
The machine marks on your pockets look like they've been CNC milled, is that so? Would be a pretty big CNC machine I am assuming.

I have a DIY 24" x 48" aluminum/wood router/cnc contraption. I cut/milled/drilled the destroyer as well as the motor mounts (from the left over sides of the slab) in 10 hours or so. 1/4" aluminum single flute, 20 ipm, 0.125" DOC, 2 ipm Plunge rate.

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Awesome work. Looks like you put in a ton of hours to it. Definetly not practical for the last mile/daily commute but for a fun board that's got to be pretty fun. I definetly like those brakes. How do they work on your Ch3? Do you press Ch3 and they engage?
 
I'd love to know more about the brakes too! How is the spinning parts connected to your wheel? And could you post a link of where I can find such a servo? I'm new to this so I'd like to see some specs. Do you need SW skills or is this just an off-the-shelf installation part?

Thx!
 
The deck turned out very well considering it was made with a DIY CNC mill!

One item I notice, though, you may want to run a finish pass when you machine something. This last pass will dust off the small amount of roughness at the bottom of the machined pockets.

I love seeing people build stuff from scratch. It is very impressive and resourceful.

Matt
 
Thanks Matt.."impressive and resourceful"coming from you is quite a compliment.. just took a look at the stuff you have made and WOW... :shock: cool stuff!

Band Brakes Fan club... I will try and take them apart to show the workings and post some pics later on today...
Band brakes purchased at scooterparts.
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the servo was purchased from hobbyparts http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=30909
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Here is a (sucky) video of them working.. I had them connected to the trigger (ch2) .. changed my mind.. now they work on ch3
https://www.dropbox.com/s/scknjqmctnwjq8s/20140324_144536.mp4

They are quite underpowered though, so I guess I'll go with another set (bigger probably) on the front wheels..
 
How about running the band around the motor can? That would give more power due to the motor running at higher rpm than the wheel. I am considering that for my board.

Matt
 
beto_pty said:
Thanks Matt.."impressive and resourceful"coming from you is quite a compliment.. just took a look at the stuff you have made and WOW... :shock: cool stuff!

Band Brakes Fan club... I will try and take them apart to show the workings and post some pics later on today...
Band brakes purchased at scooterparts.


the servo was purchased from hobbyparts http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=30909
View attachment 1

Here is a (sucky) video of them working.. I had them connected to the trigger (ch2) .. changed my mind.. now they work on ch3
https://www.dropbox.com/s/scknjqmctnwjq8s/20140324_144536.mp4

They are quite underpowered though, so I guess I'll go with another set (bigger probably) on the front wheels..

If you go to the disc brake section of that website, they have a left and right caliper that you can use instead of these band brakes. With your resources, you can fabricate your own disc rotors and mounts for the calipers and look like this:

http://www.munroboards.com/spares/brakes/munro-disc-brake.html

recumpence said:
How about running the band around the motor can? That would give more power due to the motor running at higher rpm than the wheel. I am considering that for my board.

Matt

Matt, that's brilliant! Make sure you use a motor with a skirt bearing in the can, otherwise the can will warp and destroy the magnets.
 
Heres some closeups of the band brake asembly.
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The donut is welded on to the truck and then the brake assembly is screwed onto it.

anyone know why some pics load and others appear as a link? very annoying.
 
Im an idiot!

The brakes workk incredibly well..
They work only in the counter clockwise direction... Reversed the motor direction and they are awesome!
My rear wheel drive destroyer just became a front wheel destroyer, tried riding it "backwards" and it feels and rides great...

:oops:
 
I went with the band brake (only 1 side) since my 12s HV ESC had none, and I fail miserably at foot braking over say 15-20 kph... If your current ESC has brakes this extra effort makes no sense, if it doesnt then they are a necesity. Acording to what Ive read your builds are mostly 6s and you mentioned a desire to go with a 4s dual or quad... you also constantly mention your interest in lightness and portability, so I would say maybe they are not for you..(although quite lightweight) as you can play around with your dual/quad setups´breaking strenght.. If you still want to go ahead and add them they are quite easy to add, as the mount can be water-jetted easily and you already have the welding skills to mount it on your trucks. The Servo connects to the ch3 of your Quanum controller (or you can open it up and connect it backwards to your ch2) so when you accelerate the servo goes in the wrong direction, and when you "brake" the servo pulls the cable, the wire/tubing/connection parts can be had for under 5 bucks at any bike shop.
Oh and Murfix.. you always need SW skills for this... *Patience you must have, my young Padawan"
 
Is the band brake similar to ESC braking? I know that the ESC braking at higher speeds are not as great for stopping quickly. You have to pump it gently to get it to slow down. Stopping quickly isn't as great as at lower speeds 15mph and under. How is the band brake at higher speeds 15+ and around 15mph is the braking exactly like ESC braking or is it better and more smooth? I would think the band brake and disc brakes are much smoother and cleaner stopping than the ESC braking.

Yeah, my build is 6S with dual diagonal 50mm motors. Quad would be nice but isn't necessary I think as it would add to the weight of the board. It becomes more of a fun board versus commuter board. The idea of disc brakes or band brakes sounds great too as well though. Great! Thanks for sharing though.
 
Thanks, the pics and info is very helpful!

Although, I don't understand where the SW comes in. If you connect the servo to the receiver (ch3 for example), then it'll just work? ^^ It even takes power from the receiver it seems.
 
If you connect it to ch3 on your remote, it is basically only an on/off option, right? My biggest problem with the ESCs brakes is that they are only on/off aswell, at least the sensorless ones. I would much prefer to have them work like the brakes on my car where more pressure on the pedal gives higher braking force. So why not connect the servo to the steering channel and make a small adapter on you remote so that you can reach the steering with one hand?

Edit: For got to mention your build looks great!
 
Murfix sorry I guess I did not understand your previous meaning.. to me SW is Star Wars, what is SW to you?
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I have only tested the brakes at slow speeds (inside my warehouse) were they feel nicely... how to say it... incremental... althogh my ch3 is on/off they feel like they touch and i feel them touching.... and a second later they grab on stronger... and as the speed diminishes they grab on better... lets see if at higher speeds the same happens.. they also take another half/full second to release.. so that might be interesting at high speeds if they lock up i will have to try and hold on while they onlock... I will try to test them outside at incrementing speeds till I test them at full speed. The board has the 8s batteries set up now, so 52.5 kph is theoretically posible. I will try to go full speed on it, which I actually am less worried about, as the speed is just a matter of balancing on a straightaway, and the wheels not falling off. Needless to say today is full armour day. :twisted:
 
Awesome :D don't die!

With SW I meant software, sorry my bad. I work with department schedules at work and use this abbreviation all the time...
 
Well survived the test run...


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New personal (and maybe permanent) top speed of 53.8 kmph it was scary enough not to be something I would enjoy on a daily basis...
Put the first 10k real time on the board. The first km was just going back and forth at about 20 kph making sure nothing broke or fell off and getting a general feel for it)
The brakes work very well, and they feel like they work better as the board slows down which is awesome.. I tried them in 10 kph increments (roughly) and worked well in all cases. At 50 kph they felt a little rough, but at that speed any little thing feels rough...
Im very happy with the board overall.. might loosen the rear truck a tad just to get better curving and carving without loosing high speed stability...
The board's lenght makes it quite comfortable as it allows different foot placements which prevent my rear foot from falling asleep.
Road bumps are now more vibrations than bumps, and the board rolls very well on the uneven concrete we like to build roads with here, haven't tried going over speed bumps or wheelchair ramps yet but that should pose no problem, they were passable (uncomfortably) with the abecs they should be fine with these wheels.
Curves at high speed felt insecure, might be me getting used to the wheels but i did feel them sliding as oposed to my abecs superior gripping, it might also be that I was taking the curves at a higher speed... it might be I was scared out of my mind...

Just doing some math... Having reached 53.8 kph using 8s with my current 12s HV ESC and 14s capable motors would give a theoretical board top speed (using 12s) of 80 kph... definitely not something I'm interested in trying... :shock:
 
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