How to create a surface with 3 curves

[danatoem]

how does mastercam handle this? I seem to recall back in the ole days we could make a "bezier" surface? Any suggestions would be appreciated.

[crazy^millman]

Power Surface. Thank you Verisurf for sharing this awesome tool with Mastercam.

[JParis]

Coons

Alt + C

Pick 2 lines(2 sides) and a line and an intersection point(top line & opposite intersection point)

[danatoem]

it did not give me what i hoped for?

[JParis]

How small is that?  It looks like it's possible it's extremely small...

and what tool did you use?

[SuperHoneyBadger]

Your desired shape looks like a quadrant of a hemisphere, is that true? Might have some luck starting with a sphere and trimming it up with planar surfaces/wires to get what you're after. If not, nevermind me - I honestly thought it was a flat "shield" shape at first and was going to tell you to cut it out of a flat plane.

I've always had better luck trimming up surfaces to get what I want, as oppose to making the initial surface behave how I think it should come out.

[danatoem]

here are the 3 curves for anyone who wants to give it a go. I was unable to get anything with the coons option as well. The cures are tiny. (we do micro molding here!)

3 curve surface.mcam

[jstell]

It's definitely a size issue.  I did it as revolved surface, revolved solid, surface from solid.  That thing is .1mm!

I scaled the wire x100, and then the revolved surface is smooth.  Of course scaling adds another tolerance/rounding issue.

When scaled back down, it becomes triangulated again, and not a nice curve.

You could go into your config settings and add a couple decimal places to some of the math for CAD.

 

 

3 curve surface.mcam

[JParis]

1 hour ago, danatoem said:

here are the 3 curves for anyone who wants to give it a go. I was unable to get anything with the coons option as well. The cures are tiny. (we do micro molding here!)

3 curve surface.mcam 304.4 kB · 6 downloads

.003"  yes, definitely a size issue....scale it up 50 times...make your surface, then scale it back down

 

to make a Coons, the selection order

 

[danatoem]

Thanks for your help everyone!  I did scale it up and than create the coons surf, and scale it back. It looks like it  should  work for me.

[bird2010]

Use CoonsSurf or Net to create a surface, Net will be more convenient!
No need to doubt, the surface is correct, it's just a tolerance issue in shading mode...
Because it's so small....if you're bothered by visual problems
You can adjust the tolerance and perform a redisplay after adjustment...

Net...

 

[JParis]

Try bringing in a full model with a Chord height set that tightly  

[bird2010]

4 hours ago, JParis said:

Try bringing in a full model with a Chord height set that tightly  

Adjust tolerances only when needed, the surface is correct as it is small...just a display issue!
It doesn't actually affect...it's just visually bad
I tried 3 computers, zooming in and then zooming out...none of them worked??
I have the same situation as jstell, after zooming out... it returned to its original rough state.

Maybe you use a very good and expensive graphics card?....If you execute "Fit or Regenerate Display List" after zooming out...how will the surface look like? Can you test it? Thank you!

[JParis]

17 minutes ago, bird2010 said:

Maybe you use a very good and expensive graphics card?....If you execute "Fit or Regenerate Display List" after zooming out...how will the surface look like? Can you test it? Thank you!

You're going to hate the answer but here it is....

After you scale it up and are certain you've made a good clean surface, you scale it back down and stop worrying about how it looks...the math behind the surface is correct. It will cut properly. That chord tolerance is simply how it is visualized.

[bird2010]

25 minutes ago, JParis said:

You're going to hate the answer but here it is....

After you scale it up and are certain you've made a good clean surface, you scale it back down and stop worrying about how it looks...the math behind the surface is correct. It will cut properly.

I tried 3 computers, and it didn't work if I zoomed in and then zoomed out...?

I have the same situation as jstell. After zooming out and pressing OK, it will update immediately (the original tolerance set by mastercam)...so it will still return to the original roughness.

But you and danatoem don't seem to have this problem... Is this a graphics card issue?

[crazy^millman]

On 4/8/2024 at 11:16 AM, danatoem said:

it did not give me what i hoped for?

Sorry I just tried it with power surface and not the right option to use. The other options mentioned were good choices.

[gcode]

I saved the three curves out as an IGES file and imported them into SpaceClaim.

The SpaceClaim command Blend produced a surface that looked exactly like what we ae looking for.

Then I IGES'd the results back into Mastercam and the beautiful curved surface came into Mastercam looking like a flat surface.

However, if I launch the command Analyze Dynamic and inspect the "flat" surface, the arrow moves in a curved pattern.

I believe this is a Mastercam graphics issue.  I think the surface is actually correct but the graphics tolerance setting I'm using

prevent it from being correctly displayed.

If I had more time, I'd trying applying a scallop toolpath to the surface and see what the posted code looked like.