Another design assistance request.

[old man emu]

BACKGROUND:

From the 1940s to 1960s there was a cartoonist whose work was published in the Sydney, Australia tabloid newspapers. One of the recurring items in his cartoons was this three-wheeled motor car:

Profs car.jpg

I'd love to make a print of this, but need some help in creating the body. It is hard to describe, and the closest thing I can come up with is this balloon chair:

balloon chair.jpg

Another thing that is similar is a child's toy car like this:

P1013748.jpg P1013749.jpg P1013750.jpg

I was thinking of making this in at least three parts: printing the body as one unit, then making everything forward of the firewall, and finally the tailwheel. If I can get an insight on how to make the body, I might be successful.

OME

[old man emu]

A few more images for reference:
gravypie.jpg

Gravy pie rhs.jpg

[curious aardvark]

easiest way - for me - would be to use HULL to get the basic shape. And then difference a rescaled version. Doesn't look too difficult.
But I don't have time at the moment to do it.

[old man emu]

Doesn't look too difficult. But I don't have time at the moment to do it.

OK. I'm still researching the ways and means. I'm going through the Rhino videos to see what tools I can use and how to use them. I don't think that it's a job for OpenScad at this stage. The big problem is tying down the 3-views.

OME

[Roxy]

Did you ever get your Auto Bed Leveling going? Is this distracting you from making progress on that?

[LambdaFF]

Hi EMU,
The soft I use has a feature called "multi section surface generator" where you specify a curve profile, then place several sections along the profile and let it generate the necessary NURBS in between. See sketch below of what it would do here.
I would handle the wheel covers separately. In fact I would design half and do a XZ plane simmetry afterwards.
If you tell me the rough dimensions you have in mind, I can look into it one of those evenings.

edit : it might make it easier to print the 2 halves separately.

EMU.jpg

[bford903]

What about something like this? A Ford Model T.

58921.jpg


Cut off the back end and shorten the front end a little. Might be a good place to start to get the basic shape. Lots of good photographs of the Model T from just about every angle.

[old man emu]

The Model T front end would be OK. However, it's not that part that is giving me difficulty. It's the bodywork. The closest thing I know of that it is like is an egg chair, like this:

Replica-Arne-Jacobsen-Egg-Chair.jpg

That is pretty close to the shape I want, and I can draw that in 2D. Just turn this picture upside down and do some cutting.

I need to be able to produce a plan view. I'll play with it later today.

OME

[Mjolinor]

It looks like a Hansom Cab with a caster on the back.

[Roxy]

If you load this into Open_Scad, it approximates the shape you are looking for... In order to actually use it, you would need to add more points to better define the shape. The red circles are there so you can see how the cut_out() is formed and to make it easier to play with. Adding the # symbols to the side_profile() module might be helpful to get its shape closer to what you want.

After the side profile is defined, a large block of that shape is made at [10,0,0].

side_profile();

difference() {
translate([10,0,0]) hull() { 
    side_profile();
    translate([0,0,5]) side_profile();
}
translate([10,0,0]) hull() { 
    translate([0,0,-.1]) cut_out();
    translate([0,0,5.1]) cut_out();
}

}



module side_profile() {
difference() {
    main_body();
    cut_out();
}
}

module main_body() {
hull() {
    translate([0,1,0]) cylinder(r=1, h=.1, $fn=30);
    translate([1,0,0]) cylinder(r=.25, h=.1, $fn=30);
    translate([2,.5,0]) cylinder(r=.5, h=.1, $fn=30);
    translate([3,1.5,0]) cylinder(r=.5, h=.1, $fn=30);
    translate([3.25,2.5,0]) cylinder(r=.5, h=.1, $fn=30);

    translate([3.5,3.5,0]) cylinder(r=.25, h=.1, $fn=30);
    translate([3.0,4.25,0]) cylinder(r=.5, h=.1, $fn=30);
    translate([1.75,4.7,0]) cylinder(r=.5, h=.1, $fn=30);
    translate([1.5,4.5,0]) cylinder(r=.25, h=.1, $fn=30);
}
}

module cut_out() {
hull() {
#    translate([-1,2.75,-0.01]) cylinder(r=.5, h=.2, $fn=30);
#    translate([1.,2.15,-0.01]) cylinder(r=.35, h=.2, $fn=30);
#    translate([1,3,-0.01]) cylinder(r=.25, h=.2, $fn=30);
#    translate([.75,4.25,-0.01]) cylinder(r=.25, h=.2, $fn=30);
}
}

But probably, it might make sense to make the shape nice and smooth by starting with a couple of spheres and scaling different dimensions and then putting a hull() around that? Do the work with 3D objects instead of doing a 2D object and making it 3D ????