drag knife

3 Articles

Tangential Oscillating Cutting Knife Makes Parts From The Ups And Downs

February 27, 2020 by 21 Comments

If you thought using a utility knife manually was such a drag, you’re not alone. [luben111] took some initiative to take the wear and tear off your hands and put it into a custom machine tool they call TOCK, or Tangental Oscillating Cutting Knife. TOCK bolts onto your typical CNC router, giving it the ability to make short work of thin materials like cardboard. Rather than apply a constant downward pressure, however, TOCK oscillates vertically at high speeds, perforating the material while cutting through it at a respectable clip.

TOCK’s oscillations are driven by a radially symmetric cam mechanism, allowing the blade to completely pivot full circle while still performing the oscillations. While traditional inexpensive methods for bolting a blade to a CNC machine passively swivel along the path they’re directed, [luben111] has taken the generous extra step of powering that axis, commanding the blade to actively rotate in the cutting director with a custom script that converts PLT files to G-code. The net result is a tool that preserves a tremendous amount of detail in cumbersome thick materials, like cardboard. Best of all, the entire setup is documented on the Thingiverse with CAD files and light instructions. A few folks have even gone so far as to reproduce their own!

It’s great to see some dabbling in various disciplines to produce a working machine tool. As far as knives go, we’re starting to see a good spread of other utility knife augmentations and use cases, whether that’s a traditional CNC retrofit or a solid attempt at a homebrew ultrasonic mod.

Continue reading “Tangential Oscillating Cutting Knife Makes Parts From The Ups And Downs” →

Delta Printer Morphs Into CNC Flat Coil Winder

June 16, 2018 by 21 Comments

Anyone who has ever wound a coil by hand has probably idly wondered “How do they do this with a machine?” at some point in the tedious process. That’s about when your attention wanders and the wire does what physics wants it to do, with the rat’s nest and cursing as a predictable result.

There’s got to be a better way, and [Russ Gries] is on his way to finding it with this proof-of-concept CNC flat coil winder. The video below is a brief overview of what came out of an intensive rapid prototyping session. [Russ] originally thought that moving the coil would be the way to go, but a friend put him onto the idea of using his delta-style 3D-printer to dispense the wire. An attachment somewhat like a drag knife was built, but with a wire feed tube and a metal roller to press the wire down onto an adhesive surface. The wire feed assembly went through a few design iterations before he discovered that a silicone cover was needed for the roller for the wire to properly track, and that the wire spool needed to be fed with as little friction as possible. Fusion 360’s CAM features were used to design the tool paths that describe the coils. It seems quite effective, and watching it lay down neat lines of magnet wire is pretty mesmerizing.

We’ve seen a couple of cylindrical coil winding rigs before, but it looks like this is the first flat coil winder we’ve featured. We can’t help but wonder about the applications. Wireless power transfer comes to mind, as do antennas and coils for RF applications. We also wonder if there are ways to use this to make printed circuit boards. Continue reading “Delta Printer Morphs Into CNC Flat Coil Winder” →

CNC Drag Knife Upgrade With Off-the-Shelf Blades

June 5, 2016 by 20 Comments

Drag Knives seem to be the overshadowed awkward kid on the playground of CNC equipment, but they have a definitive niche making stencils, vinyl stickers, and paper cuts. Unfortunately, the drag knife blades for CNC routers are pricey — over $100 for a single blade. [Brian] at the Grunblau Design Studio took the price point as a challenge to build his own end-effector. A few iterations later, he’s created his very own drag knife blade tool that accepts replaceable steel blades for cutting.

From constraint-driven concept, to a 3D printed proof-of-concept, to a fully machined aluminum prototype, [Brian’s] efforts hit all the highlights of a well-engineered project. At the end of the day, dull blades can be swapped for a few dollars, rather than shelling out another $150 for the off-the-shelf variant. We’ve seen bootstrapped CNC vinyl cutters before, but nothing that takes an original re-envisioning of the tool itself.