How to generate a 2D plan of the ouside of a cone for laser cuting?

[fourchette]

Hello,

In order to get flat pieces laser cut, I generally either export a clone of that part that i move in xy plane to dxf, or create a 2D projection as a svg. Albeit a few annoying join/join/join operations in adobe illustrator prior to cutting, it works great

This time i would like to try something different by bending acrylics that is not flat in the 3D model.

For starters, I would like to bend a 3mm acrylic sheet of the outside of this cone :

deleteme.png (11.97 KiB) Viewed 2773 times

I was thinking of build a structure, slowly blend a few centimers, get then glued to the structure, and repeat operation until done

but how do I -- in freecad 16 -- convert the outside of the cone to a 2D dxf or svg that I can laser cut ?
I mean i could do the math on paper, create the C-shape 2D part in freecad in order to get the corresponding dxf/svg. But can't freecad do it alone already?

any idea?

thanks

[ulrich1a]

but how do I -- in freecad 16 -- convert the outside of the cone to a 2D dxf or svg that I can laser cut ?

You can try the macro from here: http://www.freecadweb.org/wiki/index.ph ... ed_Surface

It is known not to work in some cases, but you could give it a try. I added a function in order to get also circles, but still needs more work. I am considering to write something complete new. Attached is my edited version of the macro.

Ulrich

[DeepSOIC]

I wonder, why does the macro promise (by its title) to unroll any ruled surface, when it seems impossible in general? Hyperboloid, for example, cannot be unrolled.

[fourchette]

i can't answer for the marketing name of a macro...

however, in the mean time, i actually made the math to build the 2D plan on a smaller scale, got it printed on paper, built it, measure base diameter and height and.... => it didn't work

now i used the suggested macro, did the same thing and now it works.

ohh well... so much for my ego and thanks freecad community for preventing me from getting stuck

[ehb]

Hey there,

not sure if the macro should work on this piece, but I'd need this lofted surface unrolled.

manifold.png (36.28 KiB) Viewed 2635 times

The macro creates lots of elements with errors in groups.
Is there any other way (I haven't found yet) to do this?

They're two differently sized rectangles with rounded corners, one at an angle of 20°.

[murdic]

Did you check the ruled surface parameter when you lofted the profiles?

[ehb]

Hey, thanks for your reply!

Did you check the ruled surface parameter when you lofted the profiles?

Yes, "ruled" is checked (now - sorry!).
I now also added a slit where I want to weld it later.

The macro now creates the correct number of drafts in the right order, but they're not arranged correctly yet (edges 1 to 4 would be the generatrices):

manifold_slit.png (24.42 KiB) Viewed 2615 times

I've tried putting them next to each other, but it seems the scale of some is also off:

manifold_slit_rearrange_draft.png (43.72 KiB) Viewed 2615 times

The file in question is attached. It's supposed to become a connector piece for turbocharger flanges (T3 -> T25) for a friend.

Edit: I'm using 0.17 (git 7989 from ppa)