21 replies to this topic

[Carlos Arista]

Hi guys,

 

I'm Carlos, new to this forum. I work as an engineer for Ford in Mexico.

 

For some time I've wanted to build a 3D-printed slot car and see what can be done with the technology. I really enjoy sprint car racing so that's what I will base the model on. I'll be posting updates of the development here and hope I can get some advice from the experts as well. 

 

I've started with the frame which is a very simplified version of an actual chassis. 1/32 scale. It will require precision to fit a motor there...

 

 

 

[ejgehrken]

Best of luck with the project, Carlos!

[Cap Henry]

Excited to see how this turns out!

[Carlos Arista]

Thanks! Should be an interesting experiment, I recently saw some materials first hand and they are impressive indeed. It appears to be progressing really fast.

 

So the basic layout of the chassis is now modelled. The wheelbase in a sprint car is between 84 and 90 inches which translates to 66.7mm - 71.4mm in 1:32 scale. We'll give it 72 to try and give it the best possible stability.

 

The space for the motor will be tight but still possible to fit without going out of scale.

 

 

 

The gas tank is now modelled and this will allow finishing the design of the rear frame.

 

 

[SlotStox#53]

Very exciting project Carlos! Really looking forward to seeing this come together

 

Welcome to the Blog !!

[Carlos Arista]

I hope to make some good progress during the weekend. I'll be busy following WEC in Brazil as well...

 

Question. Does it make sense to make holes for the crown gear on either side of the chassis?

 

The frame and chassis now have their respective fixing points. I'll get a second chassis built with a stiffer setup in case this combo flexes too much. 

 

The rear frame is now complete and the gas tank will attach to it, with a small guide on the bottom simply to keep it from moving. Body panels are next...

 

 

[MSwiss]

Super job but if you plan to run the car hard on the track, you might want to beef up the front and rear axle/bearing uprights.

[Carlos Arista]

Duly noted Mike, thanks. 

[Carlos Arista]

Body panels are now finished. I went for a design that looks similar to Kasey Kahne's cars which in my opinion have the classic sprint car look. They should be easy to install on the frame. Exhaust pipes will definitely be a challenge, not sure of how to solve that one yet...

 

Stronger version of the chassis is in the workshop!

 

[CoastalAngler1]

How you gonna get to the motor and gears in order to service/change them during a race?  Where do you keep the tequila for the driver?

[SlotStox#53]

can't wait to see this in it's printed form   

 

Will have to look at some software, definitely interested at having a go with the printing at some point.. Seems such a great experience if only making /prototyping bits for yourself.

[Bill from NH]

Paul, how about the possibilities of a 3D-printed SlotStox car? Maybe if when you can find a high-strength resin?

[SlotStox#53]

Paul, how about the possibilities of a 3D-printed SlotStox car? Maybe if when you can find a high-strength resin?

That's exactly one of the ideas I was thinking of Bill !

[Cap Henry]

Hey Carlos, look up Losi Slider Headers in Google images, I think a scaled down version of that maybe effective

[Carlos Arista]

Made some progress during the weekend. Eventually I'll need to catch up and buy Christmas presents...

 

The chassis is now reinforced in various key areas, especially the uprights as MSwiss suggested and the motor mount all around. I do wish to install a pretty powerful motor to emulate the spirit of sprint cars of massive power in a very light package so this part is critical. Can't wait to test it out. 

 

 

@TeamCHR Thanks for the tip! I ended up with a pretty similar exhaust, but instead of screws this has a big block joining all the pipes together. It'll need to be installed with glue to the side panels. Probably epoxy to make sure it'll stay there forever.

 

 

 

@CoastalAngler1 Removing the gas tank will allow access to the gears and rear axle, and the body panels can come off as well which should allow good access from the sides. The chassis and frame are two different components, but taking them apart requires that both axles are taken off beforehand. I didn't want to cut the frame and sacrifice its looks 

 

Tequila for the driver! Inside the gas tank I guess...

 

[Carlos Arista]

The rear wing is now designed. The weight is a concern here, mainly because it significantly raises the center of gravity. It is placed as low as the looks allow. On high speed tracks however it should provide downforce and be useful. It has a steep angle of attack and a gurney flap. The printed component should have a weight of around 6 grams. The supports are designed to flex and keep the wing in one piece during heavy crashes.

 

It'll be interesting to see the difference in handling of the car with and without wings. Initially I believe it'll be faster without them. Could depend on the type of track I guess...

 

So all printable components are ready. I won't make an interior mainly because I suck at modelling organic stuff. There should be nice figures that fit the cockpit.

 

Next step is printing and also finding the proper components. Any suggestions for rear wheels and tires? I've always used aluminum wheels and rubber tires but I haven't been able to find the proper size.

 

 

 

 

 

[Race O' Rama]

Nice Carlos but how are you going to put a motor in?

[CoastalAngler1]

What Tire Size(s) are you looking for?  Ready to Run - what do you think it will weigh?  

 

There are a lot of folks here that can help choose the motor/gear/tire setup...

 

Karl - I wondered too - the body snaps to the chassis, once removed easy access to axles, gears, motor, guide, wires, etc.

[Carlos Arista]

@Karl - like Charlie says, the chassis and frame are two separate components. It would be possible to fuse them together, however this arrangement makes it easy to install the motor, cables and guide, which would be a hassle with the frame in the way. 

 

@Charlie - I'd like to find tires that provide a good compromise between looks and driveability. Something around these numbers would work well:

 

Rear tires

Diameter: 22-24mm

Width: 14-15mm

 

Front tires

Diameter: 19-20mm

Width: 6-7mm

 

There is a fabricator in Australia with pretty nice stuff: http://mjkeng.com- those rears for Fly trucks look great but it could be a little extreme...

 

What about Pro-Track? Those look nice and seem to be quite popular. I only have experience with rubber tires but I'm sure foam is a good option. How long do they last?

 

I'm very open to suggestions. 

 

The weight of all printed components will be between 19-21 grams, depending on properties of printed nylon. Full weight will be pretty low... we'll see after finding the best combo of wheels/tires and putting one together. 

[CoastalAngler1]

Pro Track are good.  Other foam rubber tires will have slightly better grip (like JK Products, or Parma PSE).  Making the car and making it run is one thing...a slot car racer would lower the axle and reduce the cg as much as they could get away with.  I'd epoxy everything for crashes (they WILL happen), slap a fast motor in it with JK small plastic hub tires and run it like I stole it.  Lead (Pb) strips mounted low on the chassis can sometimes be a racer's friend.  

 

Carlos - Your design work is outstanding!  Can't wait to see the youtube video of your maiden voyage! 

[SlotStox#53]

It just keeps getting better & better!

 

The Stock Cars I raced certainly handled better with the roof fin/spoiler, although we kept the weight up top to a minimum.. The attachment was also flexible to allow a little give in the spoiler..

 

If you can keep the weight down on the printed rooftop parts it's gonna be a winner !

[Carlos Arista]

@Charlie Thanks mate, I appreciate it. Long way to go until it becomes a proper racer though!

 

@Paul - I made one last change to the wing and it should have a weight of around 5 grams. 

 

Regarding tires and wheels, I'll do some testing with NSR products as there is a wide range available here. It should give good information on what compounds to use, width, etc. It should be easier to find the perfect combo after this. 

 

Printing is in progress. There seems to be a long queue at Shapeways so they'll be leaving on January 10th, apparently. They have really cool colors for nylon plastic, we'll see how they work on the car.