Drag knife

My wife asked if I could cut the cardboard mats that are when framing pictures. I think this could be done with a drag knife but I do not see an obvious choice for the MPCNC. Does anyone have any recommendations?


The one I use can’t cut that deep, liyu plotter knife.

Something like this should easily do it. https://youtu.be/-MThK035omE

The youtube video is pretty cool but I can not find the plans anywhere. How do you mount/hold the liyu knife? I have the Dewalt 660 mounts on my cnc.

I bought the Liyu plotter knife holder and some blades. Have you figured out a way to spring load the blade in the down direction?

That cutter is spring loaded. At least mine is.

Mine is too but the spring raises the blade not lowers it

The spring is to controlnthe pressure of the blade, just enough to cut through the vinyl and not the paper. Is yours backwards? I must be misunderstanding the question.

Mine is/was backwards. I took it apart and put the spring on the top so it should work well now.

Hi, Curt. I know this a really old post, and I’m not forum-savvy enough to know if it’s bad form to follow up on something this old; if so, my apologies.

I have run into the same issue with the Liyu holder that I purchased–the spring tension is in the wrong direction.

How did you disassemble yours? The only way I can see is to remove the bearing, which seems to be pressed in?

Are you sure it is backwards? When you push the little button it should push the blade out, so you can remove it. It is not for tension against the material Cutting vinyl requires a good smooth flat surface, I use a large glass mirror.

To contrast this a pen plotter is the other way to compensate for a poor paper surface.

Ah, I see. I misunderstood how it is supposed to work. I thought it was meant have tension the way we want with a pen plot.

I will just make sure I am flat & parallel prior to cutting. Thank you!

What Ryan said. I ended up putting it back together the way it came. There is a good design for a drag knife holder on Thingiverse that I blended into a standard plate mount I use with my MPCNC. I like to leave my DW660 mounts in place and attach everything to them. Look at this and here is mine that I created from this