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Designing and 3D-printing a simple slot car body


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#1 tjallen

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Posted 16 January 2019 - 07:13 PM

I was toying around in TinkerCad and realized I could design a simple slot car body, with mostly flat surfaces. Here are a few pictures of the result.

 

Scale 1:24, wheelbase 3 7/8 inches, weight 1.16 oz.

Shapeways Versatile Plastic (PA12, Polyamide)

 

Feedback?

 

 

mb-7.jpg

 

 

mb-7a.jpg

 

 

mb-0000a.JPG

 

 

MB-0001a.JPG

 

 

mb-0002.JPG


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#2 olescratch

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Posted 16 January 2019 - 08:10 PM

  How much does it weigh?


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#3 tjallen

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Posted 16 January 2019 - 08:16 PM

Just over 1 ounce, 1.16 ounces, or

33 grams


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#4 tjallen

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Posted 16 January 2019 - 08:37 PM

This Polyamide or PA-12 is by far the best material I have worked with. It is quite strong, but still flexes. I did not need to build the extra rim around the base - it would have been strong enough without it. This material has a minimum thickness requirement of 0.7 mm, and my model varies between 1.1 mm and 1.8 mm thickness, except where I made it thicker for strength (the rim). So I could lose some of the weight, without sacrificing the strength.


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#5 brucefl

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Posted 16 January 2019 - 11:49 PM

now you have a master to make a mould from,food for thought.


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Bruce Schwartz

#6 tjallen

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Posted 07 February 2019 - 03:26 AM

Last month when I posted this topic, I had intended to say something about designing a slot car body in the simple 3D software available online, free, at Tinkercad.

 

In the Tinkercad software, I can manipulate the size and orientation of a variety of simple objects - cubes, wedges, cylinders, and more. For a slot car body, I plan to assemble a variety of simple objects into a complex solid object, and then hollow it out. The resulting virtual slot car body can be exported as an .stl data file, which I upload to a 3D printer, or send to a 3D printing company, like Shapeways. The data file serves as the instructions for making a plastic model out of my virtual design. In my case, the polyamide-12 slot car body arrives by mail in about 2 weeks.

 

I measured the chassis that I wanted the body to cover, my replica* of a 1/24 scale jail door chassis, with 1/2 inch wide x 7/8" diameter rears, 1/4" wide x 7/8" fronts, and an inline motor. As a first drawing step, I arranged some rectangles on a graph-paper plane, to represent the minimum chassis shape that my slot car body must cover.

 

mmb1.jpg

 

 

A helpful tip - I lower the virtual wheels 1/16th inch below the graph paper building plane. This allows me to build the body directly on the building plane, and still be sure to meet the 1/16 minimum clearance.

 

mmb2.jpg

 

 

Next, I create and arrange rectangles and wedges to cover up the minimum chassis shapes. This is an easy, if somewhat tedious process: I grab a basic shape with the mouse, place it near where I want it to be. I change the dimensions and orientation by pulling on handles which appear when an object is selected. I fit the shapes together one at a time, slightly overlapping each shape to avoid gaps in the design. When the shapes on the left and right side are the same, I can make one side, and duplicate the shapes automatically, and place them carefully on the opposite side.

 

 

mmb4.jpg

 

 

After assembling the pieces, the shape must be hollowed out. In the software, I can designate any object as a "solid" or as a "hole." To hollow out a shape, I place a hole inside a solid object, and group them together - the hole hollows out the solid.

 

In simple cases, a hole can be a duplicate of the object itself, scaled down by a few percent. In more complex shapes, a duplicate can be used, but each individual shape may need to be narrowed by hand. In the picture below, you can see that I duplicated the solid design, then made some surfaces 1/32 narrower. I also lowered the inside piece by slicing off 1/32" from the bottom.

 

mmb5.jpg

 

The inside object will be designated as a hole, and when the 2 shapes are overlapped and grouped together, I will have a virtual slot car body, ready to export and 3D print.

 

mmb6.jpg

 

 

As noted in comments, this process has resulted in a body whose thickness and weight are excessive. Most of my flat surfaces ended up closer to 1/16" thick than the intended 1/32", so I made some errors somewhere. This trial and error is expensive! Never-the-less, I must say I am pleased with the outcome, and ready to try again.

 

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*You may have seen my 3D printed replica chassis in an earlier post in this Slotblog forum.


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