How to Use Drag Knife on CNC to Cut Leather | ToolsToday

Making a leather tool pouch on the CNC machine using the Donek D4 Drag knife on the new Stepcraft Gen 3 D.840 CNC machine, available on our website
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The drag knife cut the leather perfectly leaving nice clean cuts, I love watching it work!

What do you think of how this turned out?

Feed, Speed & CNC Running Parameters

Donek Tools D4 Drag Knife 1/4 SHK x 1/4 CH
Drag Knife Cuts
Spindle Off
Feed Rate: 60ipm
Plunge Rate: 30ipm
Ramp/Lead in: 0.75
toolstoday.com/donek-tools-d4-drag-knife-1-4-shk-x-1-4-ch.html

VIDEO TRANSCRIPTION:

There is no substitute for having the tools that you need with you all the time. I made this leather tool pouch to carry what I use most on the CNC machine. Here's how I did it:

I started by taking a picture of the tools that I use daily. Then I took that image and dragged it into the vectric software and rotated it to get it in the right orientation. Because of the grid on the mat, I know what size the rectangle needs to be to fit all those tools in there. So, I'll size out a rectangle to 7 by 9 inches and get that all resized so that way the size of the photo matches the size of the design. And now, I know how big those tools are going to be.

After I had that done, I went and drew some basic shapes around each one of the tools. And you can see all of those shapes there. I started with some different layout ideas of ways that I wanted to organize these tools and ended up changing the way that I wanted to do things quite a bit throughout this process. This took a little bit to come up with all the different designs and ways it's going to be best to store everything. But I finally settled on one.

So, that design now needs to be broken up into layers. I started with the tape pouch and figuring out how all that was going to work. And then, with the pocket, I wanted to have some room in the pocket. I didn't want it to be perfectly flat up against the other piece so that way things could fit inside that pocket and it would stick out just a little bit. So, I came up with an angled design here. This isn't something that I've tried before, and it's something that I needed to test a little bit on. So, we'll get to testing that on paper later. But I went through the design process, and this should work out really well.

Then, I came up with the individual tool holders and figured out all that I needed for that. And then decided that all of those individually would be too wide. So, I put all of it together as a single piece. So now, we have the final piece all put together. So, it took quite a bit of work to get here, but we do now finally have our pieces all ready to go. And I applied all my tool paths to them. For this, I'm using a drag knife and some carbide drills.

So, on my tool paths, basically, with the drilling, they're just standard drilling tool paths within the vectric software. And then with the drag knife, I have everything set up as a profile cut. So, it's basically going to go through and run the tool on the line. It doesn't really matter what tool I have set here because everything is going to be on the line. And I added a ramp in to the tool path so that way it starts above the material, slowly ramps into it, and will orient the drag knife in the correct direction. I also have this set as my zero position is the wasteboard, not the top of the leather, as the leather is slightly different thicknesses in different areas. So, we're making sure that it cuts all the way through the material.

The drag knife is slightly offset from center, so we will show you how we handle that here in a little bit, as we are using tools that will rely on center and tools that don't. So, we'll show you how we set all the zero positioning up, but we can see what that tool path is going to look like, and we're ready to begin cutting. But first, we needed to test the pocket design on paper to make sure that this is going to work, as it's not something that I've done before. So, let's head out to the shop and get started on that.

I put some craft paper down on the StepCraft Gen 3 D840 CNC and sucked it down to the vacuum table. I am certainly no expert at working with leather. This is only my second project, but I absolutely love it. So, cutting this design in paper lets me see how everything's going to fit in the real world on cheap material rather than expensive leather.

With a drag knife, the spindle is off while cutting. There's a bearing on top that allows it to freely spin with the knife being off-center simply follows the machine as it moves around. With this test, I'm also seeing if my idea of how to set my X and Y zero position using an off-center tool will work out as well.

I can attach the tape holder, make sure the rivets are going to line up as well, and get the pocket assembled. My stitching holes all line up even with the angle cut and created the gap between the two pieces I wanted. So, we can move on to the leather with confidence that this will work out. The tip of the Donek D4 drag knife is off-center by a little over an eighth of an inch. I have to compensate for this since I'm also drilling stitching holes to make sure everything lines up. With the knife installed roughly parallel to the x-axis. I move it over until the tip of the knife was even with the side of the leather and set my x-zero position. I rotated it until it was roughly parallel with the y-axis and moved it back until the tip of the knife was even with the front edge and set my y-zero position.

The X and Y zero position will now stay the same throughout the project. I switched out for a 5mm solid carbide drill and set the Z zero to the wasteboard and began drilling the holes for rivets. After that's done, I'll switch out for a 2mm solid carbide drill bit to drill the stitching holes. Both bits used a couple of adapters to make them work and fit into a quarter-inch shank of the machine. Those are all listed in the description of the video. For whatever reason, I was a little skeptical that it was actually going to drill out and drill cleanly, but I was really impressed with how well they did cutting the leather. It saves a ton of time not having to punch out stitching holes with 386 of those and 18 holes for rivets.

Switched back to the drag knife and turned the spindle off to cut the remaining parts out. I cut through the leather in two passes, although if I were doing it again, I would likely cut in just a single pass, as I think it would be able to handle it without an issue. The Donek uses standard utility knife blades to cut with, so if a blade dulls it's cheap and quick to change it out. I love watching the drag knife flip back and forth around these cuts as it follows the machine's movements. It's definitely mesmerizing to watch.

There certainly is a lot of time invested in the design here, and I could have cut all these parts by hand much quicker than designing everything out. But if I decided I wanted to mass-produce these, I'm now able to do that repeatably without investing any more time into design and can even modify existing designs to fit additional tools as well if I wanted to. It's a really awesome tool and lets me view leather in a little different light.

With all of the parts cut out, I turned off the fine vacuum to release the leather and pulled off what was left over to use for another project in the future. The pieces were cut very cleanly and are ready to be put together.

I beveled the edges and need to burnish them, protecting and extending the life of the leather. This can be done by hand, but unfortunately, my inexperience is showing, and I chose a soft leather for this project that doesn't burnish well. I took the edge slicker and mounted it into my Jet lathe so that I could speed up this process that would have been very difficult to do by hand with this leather. They do make tools similar to a bench grinder that can do this, but since I don't work with leather all that often, it's not something that I have, and the lathe worked perfectly for this.

Using some needles, I line up the stitching holes and get it clamped into the stitching pony. I measure out my string and get it threaded through the needles. I usually use about five times the length of the stitch plus a bit extra just in case. Please do not take this as a stitching tutorial. There are certainly much better videos out there explaining in great detail how to hand-stitch leather. I'm still learning myself and have a long way to go, but I feel like I've gotten a pretty decent hang of doing a basic stitch and getting things to hold together pretty well.

I use a thread zapper to melt through the thread and in the stitch. I can unclamp the that and I can get the rivets installed. I'm just using some screw rivets here, and they worked out really well, and I think they look really nice. I love the brass combination here. So, this finishes up the tape holder and the pocket. This is the front of the pocket, and so I did all of this off-camera, and you can see that angle there. So now, we need to get that all clamped into place, and I'm using a needle here to make sure that all my stitching holes are all open so that I can begin stitching and ensure that all of that's going to line up.

I use little binder clips to go through and make sure that everything was clamped in place and got everything stitched together again using the thread zapper there to end these stitches. We can get that all pulled out, and we have everything all ready to go. I just need to add the snap that's going to hold the square in place on the tool pouch. After that's done, we need to create the little belt loop that's going to fit around my belt with a couple of rivets, and we now have a hole that the belt will go through. The edge is all lined up for the most part, but just when stitching and everything, there's a slight inaccuracy, so I took it over to the disc sander and sanded everything nice and smooth.

Then we can go through the same process of burnishing the edges as we did before. Just needed to remove those rivets from the belt loop. We got everything all burnished so that all of the edges are nice, smooth, and protected. I'm just going to apply a little bit of oil to the whole pouch. I'm using Walrus Oil Leather Oil. After letting that sit for a little bit, I got everything all buffed off, and we can begin adding our tools in. This is definitely the most satisfying part of all of this. I absolutely love seeing everything fit into their custom slots. The nice thing is that this is completely customized for me and what it is that I use, and now I have a spot where I can put everything, have it all with me, and I can develop that muscle memory of putting everything back in its place every single time. So, I know where it all is, and I don't have to go searching around the shop for it.

If you're like me, you definitely spend a lot of time looking for a tape measure, and this definitely solves that problem and keeps everything else that I need here with me. I could not be happier with the way that this project turned out. I would love to hear what you guys think about it down in the comments below. We definitely want to do another leather project, and we'd love to hear if you guys have any ideas of things that you'd like to see. All of the tools used in this video are available on our website. Be sure to check them out there. Hopefully, you guys enjoyed this one. Have a great day, everyone.

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