internal sharp corners in a surface

[Smit]

I've noticed since loading version 8.1.1 that when I create a coons surface with a tangent line from an arc that Mastercam will report this as an internal sharp corner. This doesn't seem right...if the line is tangent there should be no corner but a smooth transition from the arc to a straight path. I don't recall this being an issue in prior versions. Anybody else have problems with this? I've sent a file named coons.mc8 to CadCams FTP site if anybody wants to look at it.

Thanks,

Larry

[Tim Scott]

I looked at your file. I tried creating a sweeped surface. This did not give me internal sharp corners. I will upload this file on the ftp site. The file name is sweep_no sharp corners.mc8.

[Mark H]

I have noticed that I get more internal sharp corner warnings in the latest version than from previous versions of MC...

For a work around, I would create two (or more) coons surfaces. One for the radius cross section and one for the tangent line section.

[Bill]

Or just click DON'T SHOW ME THIS AGAIN. More often than not it will not affect the toolpath.

[gstephens]

Your coons surface was created with "linear" blending. Think of it like the way that ruled creates a surface with 3 or more cross sections. The same principle applies between patches in a coons surface. Change the blending to "parabolic" or "cubic" and you'll get tangencies between patches (just remember that your surface is going to be slightly different).

[Smit]

Thanks to all for the input. Looks like the best thing might be to play with the blending method when swept surfaces aren't an option. I've usually used the default (linear) blending in the past, and over time had forgotten the other blending options. So thanks for the reminder!!

Larry