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Author Topic: How to setup a Drag Knife in Mach3  (Read 5286 times)

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How to setup a Drag Knife in Mach3
« on: July 07, 2015, 09:41:52 AM »
Is there MACH3 technique to compensate for the knife offset so that the drag knife cuts sharp corners?

I purchased a drag knife for use with my setup.  The drag knife cuts nice but I can't get sharp angle changes because the knife cuts across all the corners.  Ideally the knife would continue past a corner just a bit then the tool would be moved in an arc around the pivot point before starting the next leg of the path. 
 
Drag Knife User Manual
   
Programming Tips From User Manual: "Create your CAD/CAM file (G-Code) using the same software and methods used to create standard 2-D cut files. To prevent incomplete cuts and ensure sharp, angular, cuts and corners, avoid using radius value less than 0.05 inch. By programming line overruns and ensuring start points are located on straight-line segments, the knife edge will point in the correct direction at the begging of each cut and manual material trimming will be reduced."
 
..."If using CAM software, use “Lead in, Lead out”, “Additional approach,” “Along Curve” or similar functionality."
 

Offline BR549

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Re: How to setup a Drag Knife in Mach3
« Reply #1 on: July 07, 2015, 09:49:10 AM »
Mach3 ONLY follows directions(Gcode) It is up to YOU to create the Gcode need to draw what you need/want. Most time the CAM does all the hard work creating the Gcode. You just have to set it up to output Gcode suited to a drag knife type operation so it KNOWS how to compensate the drawing to the cut file.

(;-) TP

Offline ger21

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Re: How to setup a Drag Knife in Mach3
« Reply #2 on: July 07, 2015, 10:59:03 AM »
Vectric's software has Drag Knife support.

Or try the "G Code Swivel Program" here:
http://donektools.com/free-cnc-router-software/links-2/
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: How to setup a Drag Knife in Mach3
« Reply #3 on: July 07, 2015, 12:16:14 PM »
I took a look at the Ventric Cut2D Desktop Trial version 8.020, nice software but the Tool Database does not appear to have any drag knife support.  Apparently drag knife tools are only supported only in Vectric Aspire $2000 and Vectric VCarve Pro $700 products.
 
Are there any other suggestions?
 

Offline ger21

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Re: How to setup a Drag Knife in Mach3
« Reply #4 on: July 07, 2015, 12:29:06 PM »
Drag Knife toolpaths are created with a Gadget. You need Cut2D Pro for gadget support.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: How to setup a Drag Knife in Mach3
« Reply #5 on: July 07, 2015, 01:24:01 PM »
You don't need vectric, just use donek with any cam or gcode file .... just follow the donek Z rules.
Seems to work fine wit free cad and free sheetcam (180 line limit)

Russ
Re: How to setup a Drag Knife in Mach3
« Reply #6 on: July 07, 2015, 01:45:34 PM »
Overloaded, that looks exactly like what I need.  I found this video on YouTube that demonstrates what you are proposing: "Adding corner actions to tool paths for the Donek Drag Knife" https://www.youtube.com/watch?v=tNMvzJu9VO8 now I need to try it out!

Offline ger21

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Re: How to setup a Drag Knife in Mach3
« Reply #7 on: July 07, 2015, 02:11:27 PM »
I posted a link in my other post.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: How to setup a Drag Knife in Mach3
« Reply #8 on: July 07, 2015, 02:43:17 PM »
Thank you Russ, Gerry and TP.