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 and try to remote control it. 

Find a way to make the lifter more stiff, currently it tend to bend on the side at an angle and doesn't lift the whole structure enough.

Find a way to reinforced the rack, which always seem a bit brittle when we try to lift the skateboard.

Find a way to make the gas-propulsion more powerful.