How would I draw a random rough finish for machining?

[fishtruk]

I have to simulate a "spark eroded" finish on a mold with rotary tooling. I have some rough grit media coming in next week to try to sandblast it but if that doesn't work I may have to machine it.

Anybody ever have to do this?

[mike.mattera]

In the past I've done something similar. A customer wanted to do some stippling on a knife handle. I suggested he raise the value of the tolerance for the cut on his 3D surfacing toolpath. Try a tolerance of .004 - .002 (inch) and try a test case to view the finish.

http://i311.photobucket.com/albums/kk462/Tonecod/handlemods003.jpg

[mike.mattera]

http://s945.photobucket.com/user/billy-jazz/media/P9090016.jpg.html

[fishtruk]

Thanks Mike,

I had given up - just now in fact.

The last image is exactly what I need albeit scaled down. Could you tell me how it was drawn?

And you mention 3D surfacing, which cut operation are you referring to?

Thanks a ton!

[mike.mattera]

You dont need to draw anything. The surface is flat. You can use any toolpath you like. The one you choose will also effect the stippling appearance. A spiral toolpath would probably make it look more random than a linear/parallel. A small step for the cut and a large tolerance. You're essentially asking Fusion to create a sloppy/inaccurate toolpath over the surface.

[I_Forge_KC]

Another method is to use the script for image2surface. It is basically a way to provide displacement mapping.

https://github.com/hanskellner/Fusion360Image2Surface

[fishtruk]

Thanks I_forge, I think I have to go that route.

I'm looking for image2surface.  I searched for it on 360. No luck. Could someone give me a clue?

Thanks!

[I_Forge_KC]

Use that link I included. It will take you to the download section and has a simple how-to.

You ought to be able to find a random noise bitmap for the displacement mapping or you can dig into the Fusion texture files and find the bump maps for things like the random texture plastic.

[mike.mattera]

Spiral Toolpath. 1/16 Ball Mill.  .01 step over.  .03 tolerance.

[fishtruk · Accepted solution]

Thanks Mike.

That's a lot closer to home. The image2surface might be too much too soon. I have a 3 page printout to install and use the script.

[mike.mattera · Accepted solution]

Nothing to design or draw with my method. You use the existing model.  You should probably add .020 stock and then use a .03 tolerance, so you dont cut to deep into the part.  Hope you found this useful.

[I_Forge_KC]

Just keep the script in your toolbag. This was done in about 2 minutes...

It works with a lot of images too... random patterns, diamond plate, moon surface, etc.