Another design assistance request.

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:

Attachment 3984

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:

Attachment 3985

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

Attachment 3986 Attachment 3987 Attachment 3988

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

A few more images for reference:
Attachment 3989

Attachment 3990

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.

Quote:

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Originally Posted by curious aardvark

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

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

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.

Attachment 4026

What about something like this? A Ford Model T.

Attachment 4027


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.

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:

Attachment 4032

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

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

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].

Code:

---

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 ????

Hi EMU,
Got around to it. Here's what I could come up with. If you're still interested in either the method or file, I'll post them.
Attachment 4130Attachment 4131Attachment 4132Attachment 4133

C'est mangnifique, mon ami.

What program did you use to create it?

Please post all the details and the file.

Old Man Emu

Quote:

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Originally Posted by old man emu

C'est mangnifique, mon ami.
Old Man Emu

---

Thank you.
Step 1 : Create the outlay
Attachment 4139
Step 2 : Create sections along the profile.
Attachment 4140
Step 3 : Connect all the loose ends of the sections to create a second guide.
Attachment 4141
Step 4 : Multi section surface
Attachment 4142

Step 5 : Redo most steps for engine cover. Be careful to ensure tangency at the seam for aesthetic purpose.
Attachment 4144
Step 6 : Use mirror function (though for printing I think it would be a nice place to divide the model)
Attachment 4145
Step 7 : Do a thick shell
Attachment 4146
Step 8 : Prepare the front lights with a profile
Attachment 4147

Step 9 : Do a revolution on the profile of step 8
Attachment 4148
Step 10 : Do a pocket for the rear view mirror
Attachment 4149
Step 11 : Do the profiles for the wheel cover
Attachment 4150
Step12 : Do a sweep
Attachment 4151
Step 13 : Do a thick shell
Attachment 4152

Et voilÃ*. Design uploaded here :
https://www.youmagine.com/designs/tricycle-cabby

I can't thank you enough for doing this for me. It is amazing to see that the files have been downloaded 8 times (as at 0:0Hrs UTC 28/12/14)

The car was a frequent element in the newspaper cartoons of Emile Mercier, published in Sydney, Austrlia in the 1950s and 60s. Emile was born in French Polynesia, so there is a connection to the Tri-color. http://en.wikipedia.org/wiki/Emile_Mercier_(cartoonist) Apart from being topical at the time of publication, his cartoons record the Common Man in Sydney in the 1950s before massive intakes of European migrants changed the culture, and as such form a useful historical record.

The car was probably created in response to the many micro-cars that were produced just after World War ll. The make of the car was never given, but a favorite letter group that Mercier used was "ETAOIN". I think I'll use that because there are cartoons depicting the "Shrldu Special", 'shrldu' being another of his letter groups (see Wiki entry for an explanation of these letter groups).

The car had a number of variations, mainly around the front of the engine and the tyres. In this cartoon,

Attachment 4153

the car is being driven by the character "Argylle. There doesn't see to be a name for his lovely passenger.

Here is another model:

Attachment 4154
which show some design changes.

These types: Attachment 4155 Attachment 4156 show how the car was depicted in the background of many cartoons.

At one time in the early 1960s, a full-sized car was made and a novelty item and driven around the site of an international trade exhibition in Sydney.

What I would dearly like to do is make a good print of the car and visit Emile's grave and place the car on it.

Old Man Emu

Glad to help, it was a nice project. Might do it again if it's of use and interesting.

very cool - I particularly love the way he makes the design process look easy.
Yeah right !
lol

This is as far as I have gone. I cannot figure out how to create the curved sections that will allow me to make the solid. I'm using Rhino 5.


Attachment 4230

QUESTION: When I finally make this shape solid, how thick should the solid be? I was thinking 2mm.

OME

Why not model it out of clay? Modeling clay will have some issues with the thin stuff.
Then you could scan it. Just my 2 pennies.

As to some one making the real thing. It isnt that far off from a zero turn radius drive for a landscaping mower. The question would be if you wanted it as a go cart or a actual car to be driven. Presuming this is where you were going with some of the above posts.

Can't model and scan - I don't have a scanner. Besides, creating the object with CAD is half the fun of making an actual object.

That's a good idea about using a zero-turn mower if one ever made a person-carrying vehicle, but, unfortunately, Mercier is unknown to most people because he was working in the 50s & 60s and the adults of those times are mainly plucking harps.The significance would be lost on Gen Y. I remember him because I was introduced to his work when I was a child, and I'm a nostalgiaphile.

OME

Quote:

---

Originally Posted by LambdaFF

Step 9 : Do a revolution on the profile of step 8
Attachment 4148
Step 10 : Do a pocket for the rear view mirror
Attachment 4149
Step 11 : Do the profiles for the wheel cover

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Its these kind of things that really show the power of the graphical 3D Design tools! I don't think OpenScad can do this stuff so easily.

I wish LambdFF would get back here. All I've got at the moment is a 2D shape for the body in one plane. I need to know how to make the curves to make surfaces in 3 planes.

OME

Quote:

---

Originally Posted by old man emu

I wish LambdFF would get back here. All I've got at the moment is a 2D shape for the body in one plane. I need to know how to make the curves to make surfaces in 3 planes.

OME

---

The download has the body suitable for printing doesn't it. Both the STL and the IGS seem OK.

Quote:

---

Originally Posted by old man emu

I wish LambdFF would get back here. All I've got at the moment is a 2D shape for the body in one plane. I need to know how to make the curves to make surfaces in 3 planes.
OME

---

Hi EMU. Sorry for the delay. On a good note I am now a father (again) and both my wife and son are OK. On a less good note, my CAD soft is CATIA. I'm not familiar with RHINO.

However, here is a bit of advice : if you look at step 1, I just designed a single line, not a section.
-> this allowed me to use a function that creates a plane at a given point , perpendicular to the tangent of the curb. From what I see in the rhino documentation, it seems what you are looking for is CPLANE
http://docs.mcneel.com/rhino/5/help/...nds/cplane.htm

Once i had those planes on several key points of the profile line, it was possible to do the sections.

On the STL I uploaded I think I gave the hull a 3mm thickness and the overall thing about 200mm height. Figured it would make it printable for most printers.

First, congratulations to your wife and you. Your son must be the best Christmas gift you have ever received.

I have only read your post quickly as I have other work to do around the house, but I think I understand now what you did. A small problem I'm having deciphering your diagrams is that they are labelled in French. Are your axes labelled differently? If so can you complete this?

X =
Y =
Z =

OME

ome, there is a video tutorial for rhino on exactly what you are doing. its by far the best video i have seen for rhino. they guy goes step by step in making a toy car. it was extremely informative and loaded with alot of cool tips.


http://www.infiniteskills.com/traini...echniques.html

Quote:

---

Originally Posted by old man emu

First, congratulations to your wife and you. Your son must be the best Christmas gift you have ever received.

I have only read your post quickly as I have other work to do around the house, but I think I understand now what you did. A small problem I'm having deciphering your diagrams is that they are labelled in French. Are your axes labelled differently? If so can you complete this?

X =
Y =
Z =

OME

---

Hi EMU, no in fact all those sections are designed in 2D, so it says H and V, stands for Horizontal and Vertical.

jimc,
I had a look at the free videos of that whole project, and have got some good help from them. It seems that the new "Gumball" facility in Rhino will be of great use. It reminded me of the way Sketchup works. I'll have to try to produce a decent set of 3-views to make a start. I can do the side and front views, but the plan view will take some thinking about.

LamdaFF, please check your PMs. I've sent you an important email.

OME