[KSky]

I haven't done much nesting, but I thought I had it figured out. Then I try a new part and for the life of me, I cannot get the finish pass on this part to not cut off the tabs. I don't see any option to not cut the tabs in any one pass. Tried deleting it and re-adding it, as well as recomputing the toolpath a bunch of times. It worked great on some other parts.

Also, in SheetCam there is an option to "clean up" tab ramps. What happens is that as you cut tabs with ramps, it goes in and makes them have 90 angles. I know you can make the tabs any angle in BobCad, but it's easier on my end mill to make ramped tabs and then easier to remove them if they are 90 angle.

[mmoe]

You can't really change the ramp angle between the rough cut and the finish cut, but you can get the tabs to work on a clean up pass without removing them.

The trick is this. Change the second op in the DMS portion of the strategy window so that you have a "Rough" pass followed by another "Rough" pass instead of a "Finish" pass. Set up the second rough pass just like you would a finish pass with no allowance and a single pass instead of multiple passes. Once you've done so, you can either click on "Finish" or "Compute Toolpath", but neither will show a change. When you are in the nesting system, you have to go up to the "Nesting" part of the CAM tree, right click on it, and then "Compute All Toolpath" from there. You should get a second cut closer to the geometry at full depth in a single pass, but still jumping the same tabs as the roughing cut. I've attached some images of the general idea. Look at the file name to know what each is depicting as they are kind of out of order.

Another thing is that it can get messy in nesting to have your geometry running into the same quadrant as the stock and nested parts, so try to remember to put your part geometry in one of the other three quadrants. If you get to something more complex, you'll find it really hard to figure out what's going on exactly, so it's just a good idea to try to separate the source geometry from the nested sheet.

[KSky]

Thanks! That fixed up my toolpaths. There must be something special about a finish pass that I haven't gotten yet. I was thinking it was just like a roughing pass but with a different label. Amazing how you can post an issue at 9:30PM on Thanksgiving and get an answer in 30 minutes.

About your 2nd comment, I wondered why everything was all scrunched together. Where do you change that after the fact? , I see you did it on the drawing I sent.

[mmoe]

Glad it worked for you!

I just used the "Translate" function with the "Delta" option with X set to -3, selected all geometry, the clicked "OK" in the side window to move it all over a bit into the second quadrant. (X-, Y+). I then just reselected the geometry and went through the nesting options again followed by going through the roughing to set up a second roughing pass. The Nesting usually looses all it's settings when you translate the part, so unfortunately you usually have to edit everything again. If you start with it out of the way, it's not really a problem since you're using a different quadrant more like scratch paper. The toolpath shown around the part is also a little confusing since it doesn't actually get posted when you're in the nesting system, but I suppose it's good for visualizing how the toolpath fits around the part.

I think the logic behind the finish pass is that a person wants the cut to be good to go right off the machine, so it is meant to remove the tabs. If you were using a vac table but the part was right on the verge of being able to hold down without tabs, then tabbing with an allowance followed by a cut to remove the tabs and finish up the edge would be quite useful, so in a way you have the opportunity to do it either way with the rough/finish passes treated the way they are currently in the nesting system. It could also be an accidental "feature", but I'll give them the benefit of the doubt and assume they meant to do it that way.

Happy Thanksgiving!

[aldepoalo]

This video will show you the steps you need to take that results in the finish pass keeping the tab.