An Alternative 3D Finish Cut Strategy?

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TReischl
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An Alternative 3D Finish Cut Strategy?

Post by TReischl »

I am working on a model that is fairly deep, about 2 inches. There are places on the model where the sides are vertical, the rest has varying slopes. I am not at liberty to share the image for this model, sorry.

Obviously roughing is no issue, it is the finish pass that got me thinking. A roughing pass leaves material. A 6mm ball nose that will cut that deep does not have 2 inches of flutes. The shank of the tool is going to run into wood. Raster strategy does not help, nor does offset, they both will eventually run the cutter into the wood.

It became obvious that I needed to control the depth of cut, but the Finish strategy does not allow that. I could control it by putting a false bottom in the model, cut, remove bottom and cut again. That will work. But what I did was use the Roughing strategy for a finish cut. The roughing strategy depth of cut is controlled. It does not care if you tell it the stepover is 10% and only leave .0001 stock for clean up. Worked like a charm. And yes, it does take longer than a standard finishing strategy. But it also does not run the shank of the bit into the work which is a huge plus.

I do quite a bit of deep stuff and this has always been an issue, only took me years to have this one finally dawn on me.
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Re: An Alternative 3D Finish Cut Strategy?

Post by highpockets »

Great tip Ted.

Thanks for sharing...
John
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Re: An Alternative 3D Finish Cut Strategy?

Post by Rcnewcomb »

where the sides are vertical
I'm anticipating a feature request for flow line and pencil line toolpaths. :mrgreen:
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Re: An Alternative 3D Finish Cut Strategy?

Post by 4DThinker »

TReischl wrote:
Tue Feb 25, 2020 2:24 am
... only took me years to have this one finally dawn on me.
That's the nice thing about years. They give you time to assemble the required data, experience, practice, and chutzpah to break the "rules" and find the solution needed. Well done! :)

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Re: An Alternative 3D Finish Cut Strategy?

Post by scottp55 »

Nice work-around Ted!!
You're using Roughing as a Finish toolpath...and I'm using Finish passes as Roughing passes :) :)

2" vertical face..spooky:)
scott
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highpockets
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Re: An Alternative 3D Finish Cut Strategy?

Post by highpockets »

I'd really like to see then incorporate the roughing strategy into the Finishing Toolpath like they did with the V-Carve Toolpath that would give us REST machining built in.
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Re: An Alternative 3D Finish Cut Strategy?

Post by rtibbs »

Interesting. Now that’s out of the box thinking Ted.
Something I must try as I tend to cut some deep models.

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Re: An Alternative 3D Finish Cut Strategy?

Post by rscrawford »

I would love to see some improvements on the finish toolpath!

Another thing I'd like to see is to vary the stepover on vertical surfaces (like the option on the moulding toolpath). This would give far superior finish on more vertical surfaces. I'm not sure this is possible using voxels though, which is probably why they haven't done it. The moulding toolpath is far superior to the finish toolpath because it uses vectors rather than pixels to define the 3D shape, which allows much more control over the cuts.
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Re: An Alternative 3D Finish Cut Strategy?

Post by TReischl »

Rcnewcomb wrote:
Tue Feb 25, 2020 3:06 am
where the sides are vertical
I'm anticipating a feature request for flow line and pencil line toolpaths. :mrgreen:
Well, all that and a few others. The other one I would like to see is adaptive clearing. But, having been a developer in CAD/CAM for a lot of my career I don't start harping at anyone. I have no idea what their vision is or where they want these products to go. Couple that with everything costs $$$ to implement and support I tend to be quiet when it comes to this stuff.

Frankly I have not upgraded since 4.5 because there have not been any really stellar changes in tool pathing that I could use on a regular basis. Lots of other nice features that benefit lots of folks, just not me so much.

Sometimes I have to jump through a few hoops to get where I want to go, but having started with this stuff when it was known as NC and high tech was using an HP 41C to do calcs and I got to type it all into a Friden Flexowriter I am a pretty happy clam with what I have available these days.
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Re: An Alternative 3D Finish Cut Strategy?

Post by BillK »

My first job in 1980 I was sent for training on an Agietron Wire EDM, primarily to program it. Draw all your lines, circles and points, then go left line 1, go right line 2, go left circle 3. Draw out the test program on a B size pen plotter. Was great compared to making them by hand for sure, but glad it developed from there.

My next job, a defense contractor making missile guidance systems we had a room full of contract programmers writing G-Code for the NC milling machines and lathes.

When I found Vectric I thought it was a miracle. Generating G-Code in seconds that used to take weeks by hand.

I too had stuck with 4.5 for many years. It was enough. Finally broke down and bought 9 last year. The relative costs to functionality has come down a lot, so who knows what direction it could go in the future?
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Re: An Alternative 3D Finish Cut Strategy?

Post by Rcnewcomb »

Another thing I'd like to see is to vary the stepover on vertical surfaces (like the option on the moulding toolpath). This would give far superior finish on more vertical surfaces. I'm not sure this is possible using voxels though, which is probably why they haven't done it. The moulding toolpath is far superior to the finish toolpath because it uses vectors rather than pixels to define the 3D shape, which allows much more control over the cuts.
I suppose they could use an interpolation technique -- similar to upscaling that better disc players use to help a DVD look better on a 4K television.

Wesley Essink has done some interesting research on using machine learning to optimize toolpath strategies:
CNC Milling Toolpath Generation Using Genetic Algorithms

Possibilities abound....
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Re: An Alternative 3D Finish Cut Strategy?

Post by ger21 »

Another thing I'd like to see is to vary the stepover on vertical surfaces (like the option on the moulding toolpath). This would give far superior finish on more vertical surfaces. I'm not sure this is possible using voxels though, which is probably why they haven't done it.
One of their competitors has this feature, and I believe that their 3D toolpaths are done in a similar way.
Gerry - http://www.thecncwoodworker.com

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