Drag knife gadget swivels

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Drag knife gadget swivels

Postby mjuliana » Thu Oct 20, 2016 7:24 pm

Hi All,

My first post here.

I work at the Center for Furniture Craftsmanship up in Maine and we just bought a drag knife for our Shopbot CNC. I'm having an issue using the gadget to generate cutting paths. If I try generating a tool path on a rectangle, the corner swivels that result leave the rectangle still attached at the corners. It's not at all what I was expecting.

Please see the attached image to see the generate tool path.

Any thoughts or suggestions would be much appreciated.

Thanks,

Mark
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Screen Shot 2016-10-20 at 2.19.30 PM.png
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Re: Drag knife gadget swivels

Postby Adrian » Thu Oct 20, 2016 7:49 pm

Run the preview and you'll see how it works.
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Re: Drag knife gadget swivels

Postby mjuliana » Thu Oct 20, 2016 8:53 pm

Thanks for the reply Adrian. The preview and actual cut both do the same odd thing to the corners. Here it is pictured below.

Thanks again!

-mj
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Screen Shot 2016-10-20 at 3.50.19 PM.png
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Re: Drag knife gadget swivels

Postby kzeyus » Fri Oct 21, 2016 2:35 am

The odd corners are to orient the drag knife to the new cut direction. The size of the corners is dependent on the blade offset you enter when setting up the toolpath. If the offset entered is correct for the knife you are using, it should cut a square corner.
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Re: Drag knife gadget swivels

Postby CosmosK » Fri Oct 21, 2016 2:46 am

those patterns are correct. The cutting point trails behind the toolpoint, so the toolpath overshoots the corner (actually brining the knife point to the corner), then the swivel should pivot the spindle around the blade point (blade turns about its point). There is an option to lift Z during this pivot which can reduce tearing, but the blade point has to be in something to hold it is position during the pivot. Thickness of material can play into this. What are you cutting?
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