Originally shared by Donald Bailey Still working on the drag knife, still having issues...

CNC Routers DIY CNC
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#1

Originally shared by Donald Bailey

Still working on the drag knife, still having issues… not sure what the exact problem is. I am starting to think that the length might be an issue as my z axis has a bit of flex due to the unsupported wood the router mounts on, it is minor but 5 inches lower it is magnified quite a bit. I modeled this as close as I could to the Donek 1/4" knife, the blade is centered to the rotation, with the blade tip offset ~.16", using VCarve Pro drag knife gadget to generate the path… I am starting to think a tangential knife might be easier.

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#2

My initial reaction was that your blade angle is too steep or your blade isn’t sharp. It’s catching, not cutting.

#3

Hmmm… blade is new, not sure what to do with the angle, it it modeled after other drag knives… will give it some thought… thanks.

#4

It could be that the weight is pushing it too hard into the material. Corrugated wouldn’t be my choice to cut. Have you got some packaging card, like a cereal box?

#7

Drag knives, like cutter plotter blades can only cut thin materials. Actually you can cut thicker materials with a cutter plotter blade than a drag knife that has the type of blade shown in the pictures. This type of blade has no room for manoeuvre when cutting whereas a plotter blade is normally ground to shape so the leading edge can rotate to the direction of cut.

Try cutting paper, you should see a marked improvement because it is only the slightest edge of the tip of the corner of the blade that is used for cutting.

Tangential cutting is probably (ready to be shot down here) way to cut cleanly with this type of blade.

#8

FYI, neither @Donald_Bailey nor @Mike_Thornbury have yet joined MakerForums after this content was rescued from the demise of Google+, so they aren’t seeing responses to this content from five years ago. :slight_smile: