First attempts at 3d design.....a few questions!

[John Candy]

Having spent a couple of hours getting absolutely nowhere with TurboCAD, I turned to OpenSCAD.
Much easier to understand and produced attached as a test template for loco domes.
The "difference" command I have difficulty applying in order to subtract the boiler section .... getting error messages (most likely a syntax issue)..... and still have to work out the commands necessary to put the concave "flare" in the base of the dome (presumably a donut-shaped ring needs to be subtracted using the difference command).

Looks as though process will be relatively simple once one has memorised the commands, etc.
I have a query regarding the resolution parameter $fn= ........ can it be applied only to spheres?
I am concerned that the cylindrical objects have an angular outline.

Guidance welcome....my ageing (probably shrinking) brain is suffering (hopefully temporary) overload!

Regards,
John.

[cabbage]

The default is a fifty sided polygon. The default polygon side is a min of 1mm. You can pre set the Function to be higher or lower. Going over a polygon of 100 results in a preview time in minutes and a F6 render in mega minutes!!!

You seem to need the function called minkowski(). This blendes two shapes into one. Thus you can make a cube with rounded corners and edges from a cube and a sphere. I do warn you that some of the results are extrely Daliesque(!)

Unless the print is rather large then I have never found the polygonal nature to be noticable. Attack ot with some wet and dry.

Regards

Ralph

Ps any scripts for the WIKI?

[IanT]

As far as I know John the parameter $fn applies to any shape that can be defined within 360 degrees - so cylinders, curved surfaces, toroids etc.

It only effects 'rendered' images though - so the simple 'editor' pre-view image doesn't change when $fn is altered - you have to 'render' it to see the change.

Regards,

IanT

[cabbage]

Before Star Trek there were the books of Jack Williamson dealing with CT - Conta Terrene matter. I first explored 3D design using Bryce. One of the boxes you ticked was "Contra Terrene" AKA anti matter. Adding a CT object to a Terrene object cut a CT shaped hole in it.

If you use the same thought mode;

difference()
{
cube ([10,10,10]); // matter
sphere(11); // antimatter
}

Produces a Cube with a Spherical cutout.

The first line is matter, anything after is antimatter. You can increase the list of antimatter cutters by opening up a brace before the list and terminating the list with a brace.

Have a look at the window frames for the 2-nol in the WIKI.

Regards

Ralph

[John Candy]

Ralph and Ian,

thank you for the helpful advice.
Have now managed to produce the above, as a generic loco dome template.
Idea is to manipulate the parameters to produce domes for specific locos, as required.

Whether it will print or not, I won't know for a couple of weeks!

Regards,
John.

[cabbage]

John,
It is fairly obvious that you can write code. The problem I have with it is that you do not use a standard programming format that enables others to edit your code.

You need to put more blank lines in to seperate areas of code. There should be proper "terminators" for a block of code SCAD uses a semicolon. Lock off sections of code with opened and closed braces to show what parts of the code are affected and indent them. One statement per line please.

As I always impressed on the Junior Programmers, you are not writing code for yourself -but for the next guy to use.

Regards

Ralph

[IanT]

Matter/Anti-Matter - I hadn't thought of it quite like that before Ralph but I will from now on!  :-)

Regards,

IanT

[753]

Impressive work John, unfortunately when they were handing out the brain cells I did not get enough to handle 3D Cad, hence have not explored 3D printing. It is useful for many parts, but if you need a brass dome you have to use older tech.
I had this Jubilee wheel printed and was impressed with the result also the strength.
I hope you get good use of your new printer.



Mike