Finish toolpath

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Finish toolpath

Postby Daniel S » Mon Sep 18, 2017 12:20 am

Hi To all and thanks for any help or suggestions.
When I carve the 3D last supper the roughing tool path never advances lines from start to finish but the finish tool path will miss areas and then come back to clean up. But with my machine carvings it seems to cut deeper Z when going back and I have groves that are hard to clean up. Is there a way to program tool path to stay on track?
I guess I mean never bypassing areas. I had problems like this on older machine and was told the new machine was much improved and very ridged. My roughing pass is with a .250 ball and finish pass with .125 tapered ball at 100 in per and plunge rate at 20 in per. I will add a picture of my current carve to show the groves. I have a Shark HD4 with spindle at 8k rpm. Thanks for any advise you might have.
Dan
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carve cut2.jpg
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Re: Finish toolpath

Postby honestabram » Wed Sep 27, 2017 1:58 pm

Are you carving that in solid wood?

My guess is that what is happening is not a drop in your z-axis over time, but just tension release in the wood as you are cutting. So when the toolpath bypasses one area and cuts another, that cutting releases more of the stored up tension in the grain which causes the wood to change shape.

Perhaps there is a more refined method of doing it, but as far as I know the only way to reliably progress through the toolpath with no bypassed areas is to switch the your finish toolpath from "Offset" to "Raster." If you don't like the result of the cut doing it that way, You could perhaps section your modeling area in a logical way so that you can create a separate toolpath for each smaller section, ensuring that one section is complete before moving on to another. If you do that, I'd make sure your boundary vector offset is minimal as to avoid major overlaps.

Hope that helps.

Luke Ferrell
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Re: Finish toolpath

Postby dealguy11 » Wed Sep 27, 2017 2:10 pm

Even switching to raster won't necessarily avoid skipped areas if the outside boundary is irregular. You can set the boundary vector to a rectangle (meaning it will be carving over some of the flat area that was already pocketed), and I think either of the carving strategies will cut without skipping, but you'd need to check.
Steve Godding
D&S Artistic Woodworking http://www.dsartisticwood.com
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Re: Finish toolpath

Postby Daniel S » Fri Sep 29, 2017 10:35 pm

Hey Thanks for the suggestions.
I am carving in solid wood, the one I pictured was alder but mostly I use cherry same results. I was at newly formed CNC club meeting last night and a CNC person has volunteered to try carving it on his machine to help me see if it is the machine or maybe a file issue. In preview mode I see the start and stops and return to skipped areas. I do cut using raster, and I have tried 45° angle and 0° angle. I have reduced speed and plunge thinking that might help, but so far no luck. I was hoping that there was a way to program the carve to progressively move form start to finish on each line, one at a time. It seems when carving a rectangle or oval it moves one line at a time, but when it is a cut out of the image, it behaves differently. I may have to try an outside rectangle boundary that may be the only solution, but probably adds time to the cut. When I change raster angles it only changes where skipped area will be. Thanks again for your suggestions.

Dan
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Posts: 37
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Re: Finish toolpath

Postby Daniel S » Fri Sep 29, 2017 11:44 pm

Deal Guy you are correct...
I tried a rectangle and even modified the corners, and in preview mode it now will carve from corner to corner without jumping forward and back. The suggestion was very helpful. I will give it a try on my next carving. I'm am trying to complete several carvings for family Christmas gifts.
Thanks again for the help from both of you guys it is much appreciated.
Dan
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Posts: 37
Joined: Thu Jan 08, 2009 6:24 am
Location: Orange, CA
Model of CNC Machine: Shark HD4


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