After working through the Dodge Monaco, I decided to refocus the project on making a no-mag car that could be FDM printed and would actually be fast. I also set out the goal of coming up with something that could be made for a total cost of about $4 (excluding decals and paint). Obviously, you need a little bit of economy of scale to get the per unit cost down to $4. However, if you were making 20 or 30 of these, I believe you could get down to around this price point.
I’ve always liked the Group C JaguarXJR-9. I decided if I was going to make a custom car, it would have to be one of these.
With this price point in mind, and based on the issues I had with the King Crown Gears in the Monaco, I redesigned the chassis and drivetrain around 2mm components. This allowed me to get ball bearings very inexpensively, as well as allowed me to use crown gears that I can buy in bulk in China for a few cents each.
This is the very first version of the chassis. The axles are both 2mm shaft. You can see the wheels have a wide deep recess in the middle (where the setscrews are).
The frame and body have provisions for 4 screws. I typically just use two on the diagonal to secure the body (with a little bit of rattle).
This version still has de-soldering braid for the pickups and screws to secure. I ditched this in the next iteration and just run the motor wires through the guide flag. Here is the fully assembled chassis. I added several mount points to the rails to allow attaching magnets and lead weights. The loose pieces next to the car are plastic versions of the lead weights (just to check space claim/fit)
The magnet that is in the middle of the car works really well. It provides enough extra downforce to mask a lot of performance problems. I tried finding a way to tuck a pair of very small magnets towards the rear of the car (they are near the crown gear). There just wasn’t room to tuck them in.
I entered a pair of these cars into a Pro No-Mag proxy race. They ended up getting a DNQ primarily because I didn’t clue the tires to the wheels. The track they were on in the proxy race is much larger (and much faster) than my home track. Issues with the tires coming off the wheels didn’t show up in my testing.
Stickers on the Jaguar were from a 1/43 model kit. Paint and stickers really bring things to life. The other paint scheme is my personal paint scheme I use on all of my cars. I guess that makes it a fantasy livery.
All of the stl’s as well as a text file with sourcing information and other tips and tricks can be found here:
http://www.lightsout-industries.com/wp-content/uploads/2019/11/Export_20191013_OpenSlotCar_V00.zip
I have done a lot of work on wheels and tires since I made these cars. Stay tuned, as I plan on writing up something on what I believe to be the best overall strategy for making wheels and tires.