where am I after a day of iterations…
(everything starts with your motors….dimensions & power requirements)
{it does work on linoleum and low plush carpet…It definitely has an ramp up of speed as it gets going. https://youtu.be/2CIcVGoaL1M https://youtu.be/UfN0g6KKDAA }
Chassis :
I adjusted the holes around the motor so that I could use a 3D printed motor holder. Tie wraps & hot glue are not a permanent solution. I decided to NOT etch out (engrave) a recessed area for the motor. Though I did score where they go. I moved the battery forward to leave more room for 3D printed motor holders….though I didnt need to move it that far. Battery is crooked because I had already cut the wires to length for original location. I put some holes in the front for a way to mount something to hold front axle. I was thinking eye screws. I ended up laser cutting an “eye screw” then sanding the square peg to fit in the round hole.
I used 3 mm holes on everything – thinking 3 mm nylon screws. We happen to have 4-40 1/2″ screws in the space (& associated nut) – they work fine. (1 car uses 20 screws/nuts)
You need tiny screwdrivers!
chassis file https://cuttle.xyz/@makervan/chassis2-bhz9x7RKoMmE
eye screw file https://cuttle.xyz/@makervan/front-axle-holder-GSPl5oJQuaNE
make the hole to fit your axle. I have the eye screw lines 2 different colors so I can cut the hole first.
the rectangle is 3 mm wide (& cut out on 3 mm draft board)
I was going to use skewers for the front axle…but they all seemed to have a bend. 1/4″ dowel might be best unless you have some metal rods…like we do. We have some Aluminum rods for welding that are slightly smaller than skewers.
Motor holder :
I made the shape of the hole in cuttle, imported that svg into tinkercad and cut it out of a rectangle. I also made the base with the screw holes in cuttle and sent that to tinkercad.
The hole is a combo of 1 circle and 2 rectangles.
motor mount hole file https://cuttle.xyz/@makervan/motor-mount-hole-2-RilzLnXM1a7f
motor mount base file https://cuttle.xyz/@makervan/motor-mount-holes-32mm-i6MqVep4HHbI
the first one i didnt make the hole the “perfect shape”, the screw holes where too close to the wall & the edge.
motor mount file https://www.tinkercad.com/things/63ymrXdISZf
Wheels :
Various size circles with 3 mm holes cut out to attach to hubs.
wheel file https://cuttle.xyz/@makervan/wheel-v40-VzRj8F9gNazm
For the hubs, I used that file and shrunk the outer circle to a 25 mm diameter, then took that file over to tinkercad. I added a cylinder with a hole. The motor has a 2 mm nub, but the hole ended up being 2.4 mm. For my front wheels, I made the hole 4.2 mm. Since i switched to Al rods, I had to use some tape to get them snug in the holes… settle on the front axle then make the hubs. We could probably get away with only 3 screw holes.
hub to fit 2 mm motor nub https://www.tinkercad.com/things/fSIMy9KTR5p
hub to fit skewer/Al rod https://www.tinkercad.com/things/4q3u6Kg8L2Y
CAUTIONS !!!
every printer prints a little differently (tolerances), and we are looking at holes that are in the millimeters. Even my 2 Ultimakers2+ printed the holes slightly differently. I wonder what the vans Prusa’s will do with those files…
Tinkercad does not import correct size from cuttle svg… I had to import at 35.3% (about there) to get things the correct size
CONSIDERATIONS :
It is 10 cm wide, it could be 9 or 8. The battery pack needs to fit.
It is 13 cm long….again battery pack fit and do you want to add weight to car as an experiment.
We could use Lego Technic connectors to attach wheels to hubs. That requires a different size hole (~4.7 mm)
higher torque motors – these start very slowly but do get going
what to wrap around wheels to get better traction
Leave a Reply