Material remains in pocket operation when step over > 50%

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hans
Posts: 114
Joined: Sun Feb 02, 2020 8:26 pm

Material remains in pocket operation when step over > 50%

Post by hans »

Hi,
I want to mill pockets effectively with minimal overlap. But I can select any pocket method - there will be always some regions which the mill doesn't reach.
I have to set the "step over" value to 50% to reach everything. Even a 60% value isn't enough. What I'm doing wrong?
Does anybody else have that problem?
Best Regards,
Hans
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Les Newell
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Re: Material remains in pocket operation when step over > 50%

Post by Les Newell »

Yes, this can happen. I am afraid the only solution at the moment is to use a smaller stepover.
hans
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Re: Material remains in pocket operation when step over > 50%

Post by hans »

Are you working on a solution?
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Les Newell
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Re: Material remains in pocket operation when step over > 50%

Post by Les Newell »

I have tried several ideas but I haven't yet found a reliable solution.
hans
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Re: Material remains in pocket operation when step over > 50%

Post by hans »

You have added several very nice features like simulation and so on. So I can't really imagine that it would be a problem for you to to find a solution.
What a pity that it's not an open source project. So I can only offer you my help and support!
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Les Newell
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Re: Material remains in pocket operation when step over > 50%

Post by Les Newell »

Unfortunately I can't really afford to open source SheetCam. It's my main source of income. However I am thinking of retiring in the next few years. Open sourcing SheetCam at that point is one of the options I am considering.
hans
Posts: 114
Joined: Sun Feb 02, 2020 8:26 pm

Re: Material remains in pocket operation when step over > 50%

Post by hans »

What do you think of providing the functions that include the pocket algorithms so that me or other users can help to fix this?
Recently I Just wanted to mill a rectangular zig-zag-pocket with minimal overlap. No chance! I don't how, but your algorithm manages that always some rest material is being left. I simply can't understand why that simple task is so erroneous. Just a little gcode script would do this better.

In my company we are thinking of buying some CAM software. When I only cut contours I really liked the software. But now when I am milling pockets I get annoyed that a bought this piece of software. Unfortunately in this stage I can't recommend it.
Jolbas
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Re: Material remains in pocket operation when step over > 50%

Post by Jolbas »

One solution that I think of is to to try one extra pass on spiral pocket that has a 50% overlap after you cant fit any more passes with overlap over 50%.
Jolbas
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Re: Material remains in pocket operation when step over > 50%

Post by Jolbas »

Or pretend the the cut along the outline is centered over the outline when doing the zig-zag part if overlap is over 50%
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Les Newell
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Re: Material remains in pocket operation when step over > 50%

Post by Les Newell »

hans wrote: Tue Dec 08, 2020 6:01 pm What do you think of providing the functions that include the pocket algorithms so that me or other users can help to fix this?
Unfortunately I can't do that. Pocketing is not really a standalone piece of code. You would need access to most of SheetCam's internals to make any sense of it.
Recently I Just wanted to mill a rectangular zig-zag-pocket with minimal overlap. No chance! I don't how, but your algorithm manages that always some rest material is being left. I simply can't understand why that simple task is so erroneous. Just a little gcode script would do this better.
A generic pocketing algorithm that can handle any shape you throw at it is surprisingly difficult. As you say, for a simple rectangle it would be pretty trivial to do it in a script. However it all becomes a lot more difficult when faced with arbitrary shapes. By the way, for a simple rectangle you may be better off using a facing operation followed by an inside offset to clean up the edges.
hans
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Re: Material remains in pocket operation when step over > 50%

Post by hans »

Or maybe you can do a distinction of cases. If shape == rectangular then do a simple algorithm that works with bigger overlaps. That's may no good style but I think rectangular pocket appear quite often.

And a post check whether material is remaining would also be helpful. So there would be no need for manually checking this.

A workaround could be to specify the maximum overlap and let the program find the biggest value for overlap where all material is being removed.
Only decrement the overlap in a loop starting at the specified maximum value down to the value where all material is removed.
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Les Newell
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Re: Material remains in pocket operation when step over > 50%

Post by Les Newell »

I need to take another look at pocketing. I'll see what I can do.
hans
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Re: Material remains in pocket operation when step over > 50%

Post by hans »

Jolbas wrote: Wed Dec 09, 2020 6:10 am One solution that I think of is to to try one extra pass on spiral pocket that has a 50% overlap after you cant fit any more passes with overlap over 50%.
But that's what I wanted to avoid if I understood you right.
Jolbas wrote: Or pretend the the cut along the outline is centered over the outline when doing the zig-zag part if overlap is over 50%
But then my pocket will be to big or how do you mean it?
hans
Posts: 114
Joined: Sun Feb 02, 2020 8:26 pm

Re: Material remains in pocket operation when step over > 50%

Post by hans »

Les Newell wrote: Thu Dec 10, 2020 7:02 pm I need to take another look at pocketing. I'll see what I can do.
Thank you, I really appreciate that!
Jolbas
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Re: Material remains in pocket operation when step over > 50%

Post by Jolbas »

hans wrote: Thu Dec 10, 2020 7:35 pm
Jolbas wrote: Wed Dec 09, 2020 6:10 am One solution that I think of is to to try one extra pass on spiral pocket that has a 50% overlap after you cant fit any more passes with overlap over 50%.
But that's what I wanted to avoid if I understood you right.
Jolbas wrote: Or pretend the the cut along the outline is centered over the outline when doing the zig-zag part if overlap is over 50%
But then my pocket will be to big or how do you mean it?
Sorry for the confusion. That was just some suggestions aimed to the developer, Les. Not very well thought out.
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