Tool Path to Create Screw Pocket Hole

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dschultz
Posts: 7
Joined: Fri Jan 06, 2023 6:18 pm

Tool Path to Create Screw Pocket Hole

Post by dschultz »

Hello, first post here,
I use FreeCAD quite bit with my CNC router running LinuxCNC for cutting sheet stock.
I would like to use it to cut pocket holes along the edges of parts for joinery.
Does anyone have an idea how to toolpath these pocket holes? It is basically a slot cut but is ramped in from the surface at about 15 degrees.
Similar to the hole a Kreg Pocket Hole jig makes. I know some of the Cabinet CAM packages do it.
I wish there was a "dressup" fuction to space them along selected edges of parts.
Any thoughts or ideas would be appreciated.
I've attached a file with a modeled example of the pocket.

Thanks,
Attachments
PocketHole_Example.FCStd
(19.86 KiB) Downloaded 49 times
chrisb
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Re: Tool Path to Create Screw Pocket Hole

Post by chrisb »

It would be best to span the stock angled. Otherwise you can use 3DSurface or 3DPocket.
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GeneFC
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Re: Tool Path to Create Screw Pocket Hole

Post by GeneFC »

dschultz wrote: Fri Jan 06, 2023 6:35 pm I would like to use it to cut pocket holes along the edges of parts for joinery.
At this time FreeCAD Path WB works only with a vertical spindle axis. You will need to tilt the workpiece appropriately to the correct angle in order to generate G-code.

I do not know anything about your tool controller, so I cannot say how you might get the vertical orientation converted to the axis you will use in your shop.

Gene
dschultz
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Re: Tool Path to Create Screw Pocket Hole

Post by dschultz »

GeneFC wrote: Fri Jan 06, 2023 9:37 pm
dschultz wrote: Fri Jan 06, 2023 6:35 pm I would like to use it to cut pocket holes along the edges of parts for joinery.
At this time FreeCAD Path WB works only with a vertical spindle axis. You will need to tilt the workpiece appropriately to the correct angle in order to generate G-code.

I do not know anything about your tool controller, so I cannot say how you might get the vertical orientation converted to the axis you will use in your shop.

Gene
I should clarify that this operation would be cut in the same setup as cutting the part from the sheet, so the tool and stock would always be perpendicular with the tool on Z axis.
Here's a link to a video of the operation
phpBB [video]
spanner888
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Re: Tool Path to Create Screw Pocket Hole

Post by spanner888 »

From the video at 8 minutes and also the earlier design which shows only a single line cut for each pocket, ie not a multi-pass clearing of a slot, then it seems that the required cut is a single straight cut, which slopes down into the material. The cut would start above top surface and cutting tool center would presumably finish at center of the stock.

Thus the screw pocket hole has the outside cutout, instead of a round hole in material for the screw, I certainly was confused until watching video, as I was imagining the standard round hole for the ssrew pocket.

This is all vertical, ie 2.5D cut and the finished cut shape in video implies a ball endmill is used.

If this describes what you require, then the first step is to actually draw each sloping slot in your material. Second step is the Path operation to cut.

Alternately as you are cutting wood, I assume only a single pass cut is made, so it is very easy to define a move to start position, cut from start and end point of each cut,p retract and repeat for each slot. Then your gcode can be added manually to your file, or using Path Supplemental, Custom.
dschultz
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Joined: Fri Jan 06, 2023 6:18 pm

Re: Tool Path to Create Screw Pocket Hole

Post by dschultz »

spanner888 wrote: Fri Jan 06, 2023 10:54 pm From the video at 8 minutes and also the earlier design which shows only a single line cut for each pocket, ie not a multi-pass clearing of a slot, then it seems that the required cut is a single straight cut, which slopes down into the material. The cut would start above top surface and cutting tool center would presumably finish at center of the stock.

Thus the screw pocket hole has the outside cutout, instead of a round hole in material for the screw, I certainly was confused until watching video, as I was imagining the standard round hole for the ssrew pocket.

This is all vertical, ie 2.5D cut and the finished cut shape in video implies a ball endmill is used.

If this describes what you require, then the first step is to actually draw each sloping slot in your material. Second step is the Path operation to cut.

Alternately as you are cutting wood, I assume only a single pass cut is made, so it is very easy to define a move to start position, cut from start and end point of each cut,p retract and repeat for each slot. Then your gcode can be added manually to your file, or using Path Supplemental, Custom.

Yep, that describes it exactly.
I'm no expert with FC, what is the quickest method to draw these sloped slots?
I created a sloped datum plane, then sketch and pocket, but this there another way to do it?

Thanks everyone for the responses!
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dprojects
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Re: Tool Path to Create Screw Pocket Hole

Post by dprojects »

dschultz wrote: Fri Jan 06, 2023 6:35 pm Any thoughts or ideas would be appreciated.
I've attached a file with a modeled example of the pocket.
In fact you can create pocket holes with several clicks at Woodworking workbench, don't expect someone tell you about it here.
There is no auto-adjustment, so you need to play a little bit with options but it is quick, precised and repeatable.
I know nothing about CNC, because I don't have one, but it creates PartDesign normal Pocket objects, so it can be processed by the FreeCAD later.

Image
Attachments
PocketHole_Example.FCStd
(111.51 KiB) Downloaded 29 times

Thanks
Darek
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workbench for woodworking is available at: github.com/dprojects/Woodworking
dschultz
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Re: Tool Path to Create Screw Pocket Hole

Post by dschultz »

So, I have created a script to generate these pocket hole paths as mentioned earlier in this thread.
It has a basic GUI popup that take a couple perimeters from the user and creates a toolpath object based on that.
It all is working fine and the results in the 3d display look perfect, however, I can't get it to post process (at least with linuxcnc)
It simply outputs the preamble and postamble with none of the actual toolpath.
Using the Inspect Path Commands tool, the gcode looks fine...
Also, if I run this script first and then try to run a profile operation afterwords, I get "PathOpGui.WARNING: No tool controller, aborting op creation"
Somehow it is screwing up the toolcontroller even though the job has a toolcontroller added.
What am I doing wrong?

Code: Select all

OS: Windows 10 Version 2009
Word size of FreeCAD: 64-bit
Version: 0.20.1.29410 (Git)
Build type: Release
Branch: releases/FreeCAD-0-20
Hash: f5d13554ecc7a456fb6e970568ae5c74ba727563
Python 3.8.10, Qt 5.15.2, Coin 4.0.1, Vtk 8.2.0, OCC 7.6.3
Locale: English/United States (en_US)
Installed mods: 
  * fasteners 0.4.21
  * FreeCAD_assembly3-master 0.11.4
Attachments
PocketHole.py
(9.11 KiB) Downloaded 26 times
Panel.FCStd
(21.61 KiB) Downloaded 24 times
Samu
Posts: 51
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Re: Tool Path to Create Screw Pocket Hole

Post by Samu »

dschultz wrote: Thu Feb 02, 2023 4:15 am It all is working fine and the results in the 3d display look perfect, however, I can't get it to post process (at least with linuxcnc)
linuxcnc only postprocesses active operations. Just add the following lines to your macro:

Code: Select all

    o.addProperty('App::PropertyBool', 'Active', 'Path')
    o.Active = True
dschultz
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Joined: Fri Jan 06, 2023 6:18 pm

Re: Tool Path to Create Screw Pocket Hole

Post by dschultz »

Samu wrote: Thu Feb 02, 2023 10:02 am
dschultz wrote: Thu Feb 02, 2023 4:15 am It all is working fine and the results in the 3d display look perfect, however, I can't get it to post process (at least with linuxcnc)
linuxcnc only postprocesses active operations. Just add the following lines to your macro:

Code: Select all

    o.addProperty('App::PropertyBool', 'Active', 'Path')
    o.Active = True
Got a chance to add that last night and it worked great, Thanks for the solution!
It still causes a "No Tool Controller, Op Aborted" issue if I want to add another operation after I add this PocketHole operation.
If I do the Profile or Pocket operation (or whatever operation) before I run the macro, there's no issues.
It seems that something in the macro is removing the tool controller or disabling it.
If I delete the PocketHole operation, I'm back in business.

Thanks,
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