3D spin - toolpaths irregular

[knedert]

Hello Folks,

We've created a Relief using the SPIN function to copy a profile of some rosettes. Once we had that figured out, we went on to test cuts, but have noticed significant roughness that we think is due to milling or something in the cut file, rather than a dull bit or wild grain.

We are cutting rosettes that are about 3" in diameter. Sectionally, they consisit of a "button", an ogee profile, and then a ring with a roundover to the base. The vector that is being spun has very few nodes... Can't see anything wrong with it.. I have attached it here.

Then we created 3D toolpaths,
1) Roughing path that leaves an offset of .1875 above the relief, raster using .375 End Mill
2) Mid-way path that leaves an offset of .0625 above the relief, Offset, conventional, using .125 tapered End Mill
3) Final path, no offset above the relief, Offset, conventional, using .125 Ball Nose

Saving the tool paths as (arcs)(inches)(.sbp) like we do everything else....

What we have noticed is that in milling a circle, where the Z depth *should* be consistent, we are getting a "hunting" where over the course of a "lap" the Z height will jog by almost .1". It shouldn't need to jog at all, since we want smooth horizontal circles and even stepovers.

What do you think is going on? We didn't price this job to include acres of sanding...

Thanks in Advance,
Rose


rosette-vector

4207 (0.9 k)

[knedert]

Hi again Folks,

I looked back and did have it right at one point.

The "original" Prototype file toolpaths were exactly what I was striving for. I exported the vector and imported it into a new model that reflected the size of board to be cut. Same relief creation steps as before. I even exported the original toolpaths and used them on the new relief.... and that's when these squiggly toolpath jogging shows up.... Somewhere along the line I have messed up and done something wrong... any ideas?
Again, thanks in advance.
Rose

[knedert]

To clarify even more.... as I try to recreate the problem/solution.....
I have a circle vector around the spun relief that I use during the Offset conventional toolpath creation.
I thought that maybe this circle got nudged off-kilter somehow and that was why the toolpath was off... but sadly that was not the case. I forgot to show that earlier. I'll post it correctly right after this.
.
.Good Toolpath
.

4208
.
+++++++++++

.
.Bad Toolpath
.

4209
.

I will keep trying to figure this one out, and will gladly post the happy ending - if there is to be one.
to be continued....
Rose

[knedert]

The vectors for the above:
.
.Good Vectors
.

Good Vectors

4210 (4.5 k)
.
.Bad Vectors - but not every time *
.

Bad Vectors - but not every time

4211 (4.7 k)
.
.
* I have created toolpaths from these same "bad" vectors, that looked good. Something is getting fried somewhere along the line...
I think I'm gonna go for a walk, before it's me.
Rose

[Brady Watson]

Rose,
A couple of questions:

1) Are you using a scaling factor when you spin the Xsection? If so, what value?

2) Is the rosette male or female in Z?

You can eliminate the 1/8" end mill roughing pass. Do the 1/4" ruf with .02 or .03 allowance. Then just finish it with the 1/8" ball with a .0125 (or less) stepover using offset.

-B

[knedert]

Sorry about the delay of this reply....
1) I don't think I am using a scaling factor, since I'm not sure how to do that. So that must not be it.
2) rosette is male in Z.

I was able to get a good file.... The only thing I can figure out was that I somehow started a new file for the production run that was at too low of a resolution.... I try to have the lowest setting at around 1000.
I finally went back to the "good" model and continued forward from there and am happily milling away as we speak... they look good ~ finally!
Anyway... thanks for your time... Sure hope that it was "just one of those days.."
~ Rose