Project Logs

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• Final work (22/05/2024-03/06/2024)

  gaspard.marcon • 06/03/2024 at 21:29 • 0 comments

  We printed a holder for the bike suspension, it was made with 20% gyroid infill to withstand the compressive force of the spring.
  

  We sanded the inside, inserted the suspension inside and tried to compress the spring by using the previously bought steel pipe.

  We tried different orientation and even multiple pipes but they got bent in all cases, so we switched to a 3D printed part with 20% triangle infill.

  Then 25% infill with concentric infill due to it supposedly high compressive resistance.

  Due to our inability to compress the spring, this part of the project is temporally halted.

  We could make this part longer, but this will create additional problem since it's already quite tall and need to be positioned through the skateboard body like so.

  If we didn't have a issue with compressing the spring, we would have started to install the quick-release mechanism, consisting of a fixed cutter's blade on the suspension holder and another cutter's blade at the front of the moving rack. 

  They should be installed in a way that when the rack move (at thus trigger the bolt-mechanism), the string retaining the suspension will be stuck in between the blades and cut, releasing the suspension that will strike the ground.

  We updated the necessary components and the electric schematic.

• 21/05/2024

  gaspard.marcon • 05/21/2024 at 23:00 • 0 comments

  The first thing we did today was to start a print for a much stronger (12hours time to print) gear and rack), we just stole it from here since we don't have the luxury of waiting for yet another not useful print.

  https://www.thingiverse.com/thing:4666006/apps 

  Since we probably won't be using the scissor lift anymore and just rely on the spring and gaz, a very heavy duty rack will be fit and won't interfere with the clearance necessary for the scissor lift.
  

  Using information from this tutorial, we were able to finalise the remote control part of the skate, initial scope included "movement at random" but that's a bad idea overall, mostly because once you have a good laugh you just have something that will just ram very fast into wall.

  https://dronebotworkshop.com/radio-control-arduino-car/ 
  

  Our ESC was made for a drone, and doesn't have reverse control, so it can only go forward.

  We then replaced the makeshift motor-wheel holder with the sturdy and perfectly size one we printed last time as showed here.

  We also tested it to make sure the whole skate can move when powered, and it work seamlessly. 

  We also started working on the spring part, and started by removing excess mass that is supposed to connect to the bike, but since this is not a bike, flat surface would suit us better.

  We had to made sure both end were flat, otherwise the spring would bend on one side.

  The spring holder will probably be a circular casing, allowing us to compress it with vices then secure it with some kind of spring. We will need a quick release system for it to be efficient. Details will be discussed at a later date.

• 14/05/2024

  loris • 05/14/2024 at 11:06 • 0 comments

  Today we worked on the timing issue by reducing the frequency of the ESC, for that we updated the code  as showed:

  Then, we remodeled the part holding both the wheel and the motor-wheel:

  We also broke the scissor lift, good thing we have a backup.

  We found a test pilot.

  To-do next week:

  -Finish the arduino code so that the remote can control and shut down the spinning motor.

  -Print the parts that were made today.

  -Print the rack-gear

  -Work on the skate suspenstion
  

• 07/05/2024

  loris • 05/07/2024 at 10:59 • 0 comments

  Today, we worked on the informatique part of project, namely the Arduino code to spin the main motor with the ESC. We also remade the rack in PLA with the 3D printer to make it more resistant. In this session face some issues, firstly the Arduino's program didn't work, then we fixed the issues and so the problems was coming from the motor, probably due to a timing issue.

  We were not able to solved it, despite slow and incremental change to the timing and power of the ESC, thus we were not able to work on the remote control. Lack of documentation on this specific model is not available online and is slowing us.
  

  The next problem's was rack witch wasn't the same size as the gear.
  

  To do next week:

  Remade the rack (or the gear)

  Fix the timing issues 

  Work on the skate suspension

• 30/04/2024

  gaspard.marcon • 04/30/2024 at 11:31 • 0 comments

  We made installed the radio receiver in the same fashion as the ESG and battery.

  We also soldered 2 of the 3 cable from the large motor to end that can fit into the ESG
  
  

  
  We also reinforced the lifter mounting mechanism by adding another set of screws and a an additional, larger emplacement for said screws.
  
  An order was also placed for a bike suspension, the goal is the use compress it and release the huge amount of energy (about 300 kilos max, but we won't be able to use most of it) the the spring can hold to flip the stake.
  
  The lifter will be reinforced, same with the rack that we will 3D print with a wore width than the laser permit.
  
  To-do:
  Check if a currently available step or servo motor can be used to turn the gear.
  Install the bike suspension to that it will be triggered by the rack when the lifter is at the end of it's course, just like the gas mechanism.
  Goal is to have everything centralized for that the flip energy is maximum.
  
  

• In-between session progress (24/04-29/04)

  gaspard.marcon • 04/29/2024 at 19:47 • 0 comments

  25/04/2024

  Since we now have access to 3D printer and laser cutter alike, we made a more refined version of our lifter mechanism (and it's accompanying gears) as well as the housing for the definitely-not-a-gun bolt action.

  
  

  Comparaison with the prototype lifter:

  
  We mounted the new version of the lifter on a test-bed that will then be attached to the skateboard. This allow for easy access and testing. It has a lot less friction than the saw-made one but since it's thinner we are having some concern that you could bend and break laterally. 

  We anticipated this problem and that's why there is two set of lifter, we could double them to reinforce the structure. But this cause too much friction between and the part, meaning the second set will act as spare part for now.

  Otherwise it's working fine, we 3D printed an additional small part that will act as an anchor for the lifter. (Here seen in black.)

  All bolt are M2 by 12mm.

  
  

  Showcase of the "double" arrangement.

  
  

  We then mounted the gas-propulsion part of the skateboard with the planned layout with the exception of the screwdriver that was replaced with a smaller and shorter bolt. We used a 80*8mm compressive spring that can reach a force of 2kg, more than enough for our need. It's house in the bottom red square and push against the barrel bolt.

  And successfully tested it. This was a low-power test.

  While the system is technically working, it's not working as good as we wanted it to be. Probably due to internal design of the gas chamber to avoid catastrophic leak, even if engaged, the gas chamber will only realise it's content in small burst and not a fast and continuous burn like we expected. 
  

  We may switch to Co2 cartridges which have the desired effect and are much more powerful in the future but single-use.

  26/04/2024

  We installed the lifter mechanism on the skateboard after reducing the size of the test-bed.

  
  

  Then we added the home-made linear actuator with a placeholder for where a future step motor will be to rotate the gear and create horizontal movement. 

  
  Further down the rack gear we have a twisted screw holding a long bolt whose just is to push the bolt and engage the gas-mechanism. If placed correctly, this will only happen when the lifter is fully extended. 

  Added a bit of glue to help rigidity, otherwise the bolt would just fall off. This is the only part of the project that can't be dissembled at will but it's just not feasible to insert a screw in the rack without breaking it. (We tried!) 

  29/04/2024

  We realised the motor place-holder and the gear were too tall and touching the ground while the skateboard was moving.  We needed to reduce both their size and did just that.

  But the lowering of the gear necessitated to lower the rack level, and since the lifter bolt that fit in the rack is slightly elevated due to the test bed and the thickness of the lifter itself, meant it would no longer move the lifter reliably.

  To solve this issue, another twisted bolt (made by securing one end and slamming the other with a hammer) now act as a hook. This work even better than before since the connexion between the two is sturdier than simply insetting the bolt in the rack.

  We used to opportunity to reinforced the gear and motor-place-holder connexion with a M2*35 bolt instead of the thinnest screw we could find. 

  We used a piece of 3D print waste as structure to install the motor-wheel in contact to the rear wheel. Hopefully, this should transmit enough movement for the skate to be able to move while flipped.
  

  Other electronical components such as the ESC, the Arduino and a battery holder (here empty since the picture was taken before storage and Li-po should be kept in a fire-proof container)  were added to the top of the skateboard using similar discarded materials and screws.

  To-do: Make a transmitter fixation on the skateboard...

  Read more »

• In-between session progress (09/04-23/04)

  gaspard.marcon • 04/09/2024 at 19:59 • 0 comments

  09/04/2024
  
  Removing how skateboard "skin" was necessary to remove all the screws and components currently attached.

  Here is a picture of the disassembled board, down up.

  Up-up view

  The main issue come from the motor section, in theory it's only held by three screw with hex socket. But for two of those, the hex is more of a circle. Removing of said screw was made harder by the very tight grip it seem to have been manufactured with/somehow strange other factor due to it's long time in storage, and a position that make access hard due to the hanger being in the way of the potential Allen key.

  Due to theses factor and the fact that hanger aren't necessary or part of the project, since the wheels will need to be place on board level to be able to touch the ground even upside down as showed here:

  With hanger: 

  Without hanger (axis going through the board or directly on it :

  
  Neither are at scale since the board 3D model isn't accurate and we wheel model is outdated.

  Thus:

  We cut the hanger.

  Removing those circle-screw is still going to be hard, we tried to make a cut in them to insert a flat screwdriver with no avail. 

  It's also possible to forgot about this problem as long as the hanger still attached to the motor is attached to the board.
  

  ---

  16/04/2024

  Printed (Laser-cut would have been easier but machine wasn't available) a pattern to cut wood to make the following system to lift one side of the skateboard.
  

  Pattern:
  

  The mechanism is a combination of the these, with the first one creating the horizontal movement necessary for the second one to work and lift the structure.
  
  First (1:40):
  

  
  Second:
  

  Also bought 20cm beam that will be used as axle.

  Wheels can be maintained in the same position while still be allowed to spin.

  Will cut the board place the wheels along the center of the board and try to free the motor from it's wheeled prison.
  

  ---

  17/04/2024
  

  Was able to make the lifting mechanism but making gears by hands (and electrics tools) is not easy. Will probably wait for laser cutting to be available.

  
  
  
  We found a way to finally free the motor, a steady pliers and a drill were required.

  The internal access main benefit was the possibility to drill a hole through the ball bearing to allow the axle to be installed creating a steady connection between the motor-wheel and the main body, with a bit of tinkering maybe offsetting the cable would permit having symmetric axle (it can't be a singular one since the motor is in the way.)

  "Worst case" scenario was the impossibility to remove the cable and needing to enlarge one of the hole that was previously housing the problematic screw, putting an offset axle through it and accepting the less symmetric but working solution. The offset wouldn't affect the movement since its connected to the stator, which doesn't move.
  

  But really proved worst than the worst case, the casing (on either side) is harder than the metal drill we have. Here is a picture of the outside part of the casing as a showcase.
  

  Also the case for this part (see blue arrow), preventing a clean body-axle-motor connection since even the currents bores can't be enlarged.

  We will either need to find really longs screws (probably a bit weak, especially if it's only on one side of the wheel and the diameter is quite small), weld the axle (sub optimal for the safety of my fingers and above my pay-grade), glue (too weak) or find a better drill (may be hard depending on the material).

  The idea of putting the axle through the body was abandoned due to risk of permanent structural damage to the skateboard, thickness of body is only a few mm greater than axle width. We will install it on the board instead, see pictures as reference.

  Wheels will still be able to touch the ground on both side. Axle could be maintained using small wood blocs but we should be able to buy something cleaner for cheap tomorrow. We will also need to enlarge the...

  Read more »

• 09/04/2024

  gaspard.marcon • 04/09/2024 at 11:00 • 0 comments

  We acquired the skateboard today, the battery is dead but we can salvage the structure and the brush less motor that is still attached.

  We checked if the battery and ESC worked by doing a test  with a small brushless motor and using this tutorial.

  https://arduino.blaisepascal.fr/controler-un-moteur-brushless/

   then with the one on the skateboard. We could solder everything to technically have a pretty bare-bone electric skateboard.

  We will probably drill holes through the skateboard to have the wheel having clearance on top and bottom, allowing it to be on its back and still working. Omni-wheels are also considered to create more chaos.

  Before changing the scope from "building our own hanger and structure" to "use the one available" we finished the 3D model to be used with the old wheel. It won't be used but I'll still post it since it was a bit of work.

• In-between session progress (27/03-09/04)

  gaspard.marcon • 03/26/2024 at 16:54 • 0 comments

  26/03/2024

  Made a 3D model of the connexion between the wheel and the drive shaft.
  
  

  Made the model for the main body of the hanger (rough), how the motor is supposed to connect the main structure and transfer the mecanical movement to the wheel. Gear ratio is currently no-existent since caculation showed it probably wasn't needed. 1900 RPM on a 60cm ball is 5m/s, around 18mk/h or 49.2125 hand per second. Assuming 50 to 100% efficiency, the final speed is appropriate to be dangerous wihout causing legal trouble.
  
  
  

  Made the minimum electrical circuit to power two brushless motor with a lipo battery with control it with a radio receiver. A secondary batery will power the arduino via a driver. While this could be used to guide the skateboard, the receiver main use will be to turn on and off the dangerous skate. Later version will include the selected sensors to allow the chaotic silicion brain of the skate to be dangerous.

• 27/03/2024

  gaspard.marcon • 03/26/2024 at 10:52 • 0 comments

  ---

  Created the hackaday file

  
  Listed all component and added "have", "don't have and need to order" category to each of them.
  

  Draw the basic schematic for the wiring and skateboard structure.
  Added rudimentary instruction as to how to build the skateboard.
  

  Structure drawing : 
  

  Wiring drawing : 
  

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