Engraving on a spherical surface?

[Dougal]

I have a challenge.

A whole heap of parts with a spherical surface which I'd like to engrave on.
The radius of the sphere is 40-41mm, looking down from the top I am only interested in the area between a 32mm and 12mm circle. Looks like a disc from above but has a spherical surface which drops away to each side.

The total height change from the 12-32mm diameter edges is less than 3mm.

Can I produce a set of surface co-ordinates which I can then apply to each job and just create the engraving lines/text in the way that I would for a flat surface?

I'm seriously impressed with CAMBAM's feature set so far, but all I've tackled is 2.5D work. This is where it starts to get tricky.

[Dougal]

Anyone?
I can pull in the surface as an STL if that helps.

[blowlamp]

Dougal.
I am pretty sure that if you can get your CAD system to sit a polyline of the engraving on the surface of the sphere, then you should be able to export that polyline as a DXF into CamBam and cut it by using an Engrave MOP. The Engrave MOP can follow a 3 dimensional polyline ok.

Martin.

[Dougal]

Thanks Martin.
I'm using solidworks and I'm not sure if it will export lines to an STL format. But I'll give it a crack later

My aim is simply to engrave lines (text, arcs etc) at a reasonably constant depth on this surface. The lines to engrave can be defined on a flat plane, it's just the variable engraving depth that I'm lost on.
I've successfully engraved on 2D with CAMBAM several times, but 3D is something I've yet to crack.

I'm also looking at the possibility of engraving along the side of a pipe. So curving in one direction rather than spherical.

[blowlamp]

Dougal.
I didn't say export it as an STL. If Solidworks can do similar to the attached picture and you can export the text polylines only as a DXF then it should work ok in CamBam. I'll see if I can do a demo file in CamBam soon. I did the pic in ViaCAD

Martin.

[Dougal]

Originally Posted by blowlamp Dougal. I didn't say export it as an STL. If Solidworks can do similar to the attached picture and you can export the text polylines only as a DXF then it should work ok in CamBam. I'll see if I can do a demo file in CamBam soon. I did the pic in ViaCAD Martin.

Unfortunately solidworks can't export 3D DXF's. It can do 2D DXF's for flat patterns but I think that's it.
I will keep looking though, there has to be a way.

[blowlamp]

Dougal.
Maybe something like the attached .cb file could be the basis for what you're after.

Martin.

[Dougal]

Here's a CB file with the STL surface I'm looking at. I know STL isn't the best way but it's an easy way to show the surface.

I'm looking to engrave around that central hole.

[blowlamp]

There's not much I could do with that file within CamBam to get what you need. ViaCad could import the original solid model (STEP, IGES and SAT) and project text or other polylines onto its surface, which can then be exported separately as a 3D DXF polyline file like the demo one I posted.

Martin.

[Dougal]

Thanks for your help.
If I can't find a suitable way around it I'll look into other cad packages. VIACAD seems inexpensive but there will be other options too.