Stacking tool paths and using "Inset" for finish pass

[heftyh]

I am trying to do a standard machining technique to get a smooth finish pass.
- Cut path "A" is a step cut with a max pass depth of 0.070". Material is 3/8" polycarbonate. Inset = 0.000"
- For cut path "B", I am copying and pasting cut path "A" on top of itself (with a new name). Then I turn OFF max pass depth so it cuts all the way through. I also set Inset = 0.015" to try and get a nice skim cut that gives a fine edge.
Here is the problem: when I do this, the machine cuts "B" first even though it is second in the carvings list. So, I did it again but first changed the order of the cut paths in the carving list. Same thing happended.
Dos anyone know how to take control of the order of the cut paths so I can do the step cuts first and then come back with the finish pass?
Thanks,
John

[fwharris]

John,

What appears in the carving list has nothing to do with the order of cut. I do not have a good answer for the correct way to set up what you are doing other than 2 different mpc files. first one with your A cut pass and the second with your B..

[Carl H]

Would it be possible to set up one of the cutpaths on the reverse side of the board. When the board asks for it to be flipped, Don't flip it. just set it to do the cut. I am not sure if the CW carves the rear of the board first or last I havent done any two sided carves yet, but it may be worth a try.

[heftyh]

FW,
I was woried that creating and running 2 different files would create an offset between the 2 cuts (with all the rehoming and measuring). I am only skimming 0.015 so it is a very small cut. If we can figure out a way to make this happen, it will give you beautiful finishes on edges. The most recent ones I have done using an Onsrud O flute 1/8" bit give an edge almost equal to a mill. So- I guess this will be a head scratcher for a while. I will continue to experiment but suggestions will be very welcome.
I know the machine picks its own sequence for carving but I think it would be a nice feature to add this functionalilty for cut paths. As an interesting side note- specifying the tabs the same way on the 2 cut paths caused them to land in the exact same location so at least that worked as I hoped it would.
Thanks, John

[fwharris]

John,

That would be one concern of not lining up properly for the different carves. Maybe Connie can get one of the engineers to chime in here and share their knowledge with us on if it is possible to set up the cut paths in the order we want them to cut.

Carl,

Yes another way of possibly doing this. The machine will do the back side carve first and then ask for you to flip the board to the front....

[dltccf]

I seem to remember something about cut paths being ordered inside to outside, but can't be sure. Reviewing the last carving I did, It did cut the two inside paths before it cut the outside one.

[heftyh]

Carl/ FW,
For the 2 sided cut concept; would this work for an asymetrical pattern? Also, how would it treat the tabs? I've never done this before or even thought about it. Will look for some tutorials tomorrow. I'm having trouble imagining how the machine would treat the tabs or if they would still line up with each other.
Thanks, John

[bergerud]

FW,
I was woried that creating and running 2 different files would create an offset between the 2 cuts (with all the rehoming and measuring). I am only skimming 0.015 so it is a very small cut. If we can figure out a way to make this happen, it will give you beautiful finishes on edges. The most recent ones I have done using an Onsrud O flute 1/8" bit give an edge almost equal to a mill. So- I guess this will be a head scratcher for a while. I will continue to experiment but suggestions will be very welcome.
Thanks, John

If you do not lift the head between running project files, the machine will not remeasure the board. The two project file suggestion of Floyd should work.

Another thought might be to make the multiple passes by assigning the bit to the path and also do a cut path. Do the multiple bit passes only to the depth of the tabs which will be left later with the cut path. The machine always does bit paths before cut paths. When you do the cut path to full depth, it will only have to cut out the material that is left between the tabs. A slight offset and you get the clean up.

[cestout]

Even without a second path a little closer, if you just run the project a second time without moving anything you should get a smoother cut.
Clint

[mtylerfl]

If you do not lift the head between running project files, the machine will not remeasure the board. The two project file suggestion of Floyd should work.

If true, this is definitely something I did not know. It defies my logic...seems like the machine would always remeasure when selecting a different project, regardless of leaving the board captive under the head...but, I have ZERO first-hand knowledge of this and have not tried it (never had a reason to.) I know you have really put the machine through a lot of experiments and tests, so I am guessing you HAVE done this before and know this to be the behaviour. Question...does the machine behave this way ONLY if the second project selected has the same board dimensions? This has me really curious.

Another thought might be to make the multiple passes by assigning the bit to the path and also do a cut path. Do the multiple bit passes only to the depth of the tabs which will be left later with the cut path. The machine always does bit paths before cut paths. When you do the cut path to full depth, it will only have to cut out the material that is left between the tabs. A slight offset and you get the clean up.

The issue of a "final cleanup pass" around cutouts has come up many times over the years. The current generation of the software has no direct settings for that level of control on a Cut Path. However, the procedure you outlined above is very clever and sounds reasonable to me. I'll bet that method will work like a champ!

I'm confident the "next generation" software will have a lot more control over many things, including toolpaths. In the meantime, I am constantly impressed by the creative thinking so many users have come up with to work within the features of the current software.