Question about 3d surface toolpath efficiency

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dkwvt
Posts: 53
Joined: Sat Oct 16, 2021 10:26 pm

Question about 3d surface toolpath efficiency

Post by dkwvt »

Hi all, I have a question about setting up a concave 3d surface for an efficient multi pass cut.
The toolpath is fine as far as accuracy but has way too much redundancy cutting the upper layer surface contours 3 times over while working down thru the cut depths.
Is there a way to set this up to eliminating the overcuts?
I have tried using the optimize step over transitions but it just cuts below the specified cut depth. this might work with an additional finishing toolpath single pass but its an awkward solution?
This is by no means an impasse but it would be nice to find a workaround.
thanks again for all the help. dkw

The toolpath file in question is AT17 right inner face zzmp 50

Code: Select all

OS: Windows 10 Version 2009
Word size of FreeCAD: 64-bit
Version: 0.20.29177 (Git)
Build type: Release
Branch: releases/FreeCAD-0-20
Hash: 68e337670e227889217652ddac593c93b5e8dc94
Python 3.8.10, Qt 5.15.2, Coin 4.0.1, Vtk 8.2.0, OCC 7.6.2
Locale: English/United States (en_US)
Installed mods: 
  * Curves 0.3.0
  * Help 1.0.3
  * ocl.pyd
Attachments
concave 3d path.FCStd
(637.04 KiB) Downloaded 8 times
herbk
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Posts: 2438
Joined: Mon Nov 03, 2014 3:45 pm
Location: Windsbach, Bavarya (Germany)

Re: Question about 3d surface toolpath efficiency

Post by herbk »

Hi,
if i get you right, - just change from Multilayer to Single Layer at the Op setings.
Gruß Herbert
dkwvt
Posts: 53
Joined: Sat Oct 16, 2021 10:26 pm

Re: Question about 3d surface toolpath efficiency

Post by dkwvt »

herbk wrote: Mon Sep 19, 2022 5:44 am Hi,
if i get you right, - just change from Multilayer to Single Layer at the Op setings.
Yes that solves the repetitive cutting layer to layer but I need multiple passes to get the full depth, a little over 5/8". I limit my cuts to 1/2 bit diameter, 12.7 bit-6.35 cut depth. Feeds and speeds calculation allow for some variation but this is the sweet spot for my rig.
Thanks for looking at this, dkw
dkwvt
Posts: 53
Joined: Sat Oct 16, 2021 10:26 pm

Re: Question about 3d surface toolpath efficiency

Post by dkwvt »

I have attached the same file with the toolpath settings changed to multiple pass, 6.35 cut depth, optimize step over.
The path sequences "correctly" not overcutting the 6.35 layer surface when it steps down to 12.7 depth but the material from 0 to 6.35 is not cut.
Attachments
concave 3d path.FCStd
(552.05 KiB) Downloaded 3 times
dkwvt
Posts: 53
Joined: Sat Oct 16, 2021 10:26 pm

Re: Question about 3d surface toolpath efficiency

Post by dkwvt »

Some additional information.
These toolpaths take anywhere from 30-45 minutes to run on my machine depending on wood type and bit condition, 2-3 hrs for a complete top, inside and out.
I am not in a hurry, this is not "production" work and I am not unhappy with the functionality "you all" have given us. That said if I could knock half or better machine time off the deck with a more efficient toolpath it would be really nice.

Thanks again for looking and offering thoughts and advice, dkw
bmsaus4ax
Posts: 163
Joined: Sat Nov 14, 2020 9:16 pm
Location: Bargara, Queensland, Australia UTC+10

Re: Question about 3d surface toolpath efficiency

Post by bmsaus4ax »

dkwvt wrote: Mon Sep 19, 2022 6:44 pm I have attached the same file with the toolpath settings changed to multiple pass, 6.35 cut depth, optimize step over.
The path sequences "correctly" not overcutting the 6.35 layer surface when it steps down to 12.7 depth but the material from 0 to 6.35 is not cut.
Just a couple of suggestions,
Since you are using a 1/2" ball endmill , presumably the flute depth is more than 1/2" so a single pass is possible.
Reducing the step over below 30% or 25% will greatly reduce the cutting load and improve surface finish. The smaller the stepover the better but there is a trade off in run time, (15% or less will give near smooth finish). You are just shaving the edge of the material each pass.

Set the Start Point to the larger extremity so the start is at the material surface. Starting with near zero cut.

Disable Boundary Enforcement, and Set Boundary Adjustment to MINUS half the cutter diameter, this will cut up to the shape edge but not down the job thickness. (no overcutting)

dkwvt wrote: Mon Sep 19, 2022 7:12 pm Some additional information.
These toolpaths take anywhere from 30-45 minutes to run on my machine depending on wood type and bit condition, 2-3 hrs for a complete top, inside and out.
Whether the above path will reduce the total time depends on the stepover selected but reducing the number of depth passes may give some gains.

I am not in a hurry, this is not "production" work and I am not unhappy with the functionality "you all" have given us. That said if I could knock half or better machine time off the deck with a more efficient toolpath it would be really nice.
The reduction in load on both the material and tool can allow an increase in feed and possibly cutter speed to reduce process time.
dkwvt
Posts: 53
Joined: Sat Oct 16, 2021 10:26 pm

Re: Question about 3d surface toolpath efficiency

Post by dkwvt »

@bmsaus4ax us

This all makes sense and a couple of options I had not considered.
I am trying it all now, thank you for the tips...! dkw
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