Building a Drag Knife to Make Stickers and Friskets.

I enjoy working on my CNC router that I designed and built. I also like to find ways to make it do other things. I decided to make a drag knife to cut out stickers and friskets.

Dictionary

fris·ket

/ˈfriskit/ Learn to pronounce

noun

PRINTING a thin metal frame keeping the paper in position during printing on a hand press.

US fluid or adhesive paper used in painting or crafts to cover areas of a surface on which paint is not wanted.

https://www.google.com/search?q=frisket+definition...

Supplies

A 3D printer.

A drag knife ( about 5$ US.) https://www.wish.com/product/59e80f8dd6ad9e301bed8...

A CNC router.

A 1/16" router bit with a 1/4" collet. https://www.amazon.com/Freud-Double-Flute-Straight... (10 $ US.)

Fusion 360.

A spring from a ball point pen.

The small piece that goes on the end of the ink cartridge (this is called the Thrust Device).

Step 1: Designing the Drag Knife.

I used Fusion 360 to design up this project. The first thing I needed to do is to find what size the 3D printer will come up with as the size of the parts are not always matched when I am using inside holes. To do this I used Fusion 360 to design up a sizing card. I wanted the card to hold the bit closely but not to tight as it might break. I measured the OD of the router bit and found it to be .246". I don't know why it is that size, as I was expecting it to be .250". Anyway, after making the first part I found that the router bit was not going to fit into the hole. That's alright as the side has two flutes on the side of it and I can cut the hole to perfect size by inserting it into a drill and pushing it through the existing hole.

I wanted to know what size the drag knife hole was going to be, so I put some holes in the sizing part I built to see what the actual size was going to be. I found that even though the drag knife itself was .468" I ended up making the size of the hole .020" bigger to accommodate the shrinkage of the materials. I have added the sizing part above so that you can see what your printer is going to do. I am using PLA as the material.

This worked for my project. I drew up the drag knife holder project in Fusion 360 and then I saved it as an .STL so that I could print it on my printer. The file is above.

After the file is printed you need to make up something that you would like to cut out with your drag knife. I choose the head of an elderly gentleman but you can use anything.

Step 2: Putting It All Together.

Insert the drag knife into the holder that you just built on your 3D printer. Next you are going to want to make sure that the "Thrust Device" is located on the top of the drag knife. This will hold the spring on this end. The other end of the spring is going to go to the router bit. Make sure that your thrust device has room to move so that the cutter will be exposed. After this you can adjust how much of the cutter is out of the case by adjusting the router bit in and out. As you can see in the photo above I had to cut off the thrust device so that it would push on the top of the Drag knife case.

I used Fusion 360 and the Trace command in the Manufacturing part of the file to copy the part I wanted to cut out. Set your height to the size of the material that you are using. I just take and put my "Z' at the bottom of the material to make sure that it will cut through.
In order to do this you are going to have to find a way to keep the material down on the table. I use Super 77 spray adhesive but as long as it can not move it will work. Make sure that you have the top part (router bit) pushed down enough to expose the cutter. A frisket is used to air brush things and usually takes some fine cutting to do. This speeds up the process for you. As you can see you can also make signs for use without air brushing as stickers. I used some shelf paper to make the sign that I put on my car door. Important: When you use this drag knife do not turn the router on! The part will cut without the part turning and if you turn it on this will EXPLODE. I have found this to be a very inexpensive way to make some easy patterns.

I am going to cut some Leather if I can find a way to keep it down. I believe it may do this easily however I might have to take more than one pass. As you learn more about things it is fun to do different things to learn more skills. Good luck.