< > [subtractive](index.html)
### Drag Knife Cutting
_From [AXYZ](https://www.axyz.com/us/2019/02/26/drag-knives-for-cnc-routers-expand-creativity/), various CNC attachments for drag knife cutting._
* Various attachments exist for CNC machines to allow for drag knife cutting
* Other machines are built for this purpose (Zund, vinyl cutter)
* Some require special blades, others use common utility knife blades
* Spring force helps keep pressure constant
* Rotary blade (wheel) vs. fixed blade
* Drag knife cutting has been popularized via cheap "craft cutters" like [Silhouette](https://www.silhouetteamerica.com/) and [Cricut](https://hackaday.com/2021/03/15/cricut-decides-to-charge-rent-for-people-to-use-the-cutting-machines-they-already-own/). These suffer from restrictive firmware and obnoxious subscription fees.
* Many DIY solutions to build drag knife cutters from [printers](https://www.youtube.com/watch?v=jZMQ3P8K2wE), [3D printers](https://www.thingiverse.com/thing:4441625), or [CNC routers](https://www.cnccookbook.com/build-drag-knife-cnc-router-mill/).
#### Vinyl Cutting
A vinyl cutter is a type of computer-controlled machine that controls the movement of a sharp blade over the surface of the material. Applications:
* Stickers and signage
* Heat transfer / apparel
* Circuits
_Examples of vinyl cut circuits and "speaker portrait" by [Victoria Shen](https://www.instagram.com/evicshen/?hl=en)_
### Zund Cutter
Zund makes large-scale high-precision CNC systems that use a range of cutting tools. Most commonly, materials are cut with a knife blade that is actively rotated to follow the direction of the cut (therefore not a drag knife). This machine can be used to cut materials that are too toxic or flammable to cut with a laser.
The GSD Fabrication Lab has [great documentation](https://wiki.dev.tlt.harvard.edu/confluence/display/fabricationlab/Zund+Cutter+Tutorial) for using their Zund cutter.
<img src="https://wiki.dev.tlt.harvard.edu/confluence/download/attachments/219567362/Capture.JPG?version=2&modificationDate=1512061260000&api=v2" alt="zund attachments" width="600"/>
_Tool options for the Zund cutter (Credit: Rachel Vroman)_
* Universal Drawing Tool (UDT) - For drawing lines with a pen
* Universal Cutting Tool (UCT) - For most cutting operations
* Electric Oscillating Tool (EOT) - For soft materials such as cardboard, foamcore, or rubber
* Pneumatic Oscillating Tool (POT) - like EOT but with greater blade throw and faster oscillation for thicker materials.
* Driven Rotary Tool (DRT) - For fabrics and fabric-like materials.
* V-Cut Tool (VCT) - For cutting bevels and v-cuts in foam core less than 1/2". (Not Pictured Above)
### Ultrasonic Cutting
Piezoelectric transducers create high frequency (20-40 kHz), low amplitude (10-70 µm) vibrations that provide the energy to slice through an object with very little pressure.
[Sonotec Cutter](http://www.sonotec.com/en/tec.html)
[WonderCutter (~$400)](https://www.micromark.com/Wondercutter)
<iframe width="900" height="600" src="https://www.youtube.com/embed/BRzRnUbWMKM" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
### Die Cutting
<a href='https://en.wikipedia.org/wiki/Die_cutting_(web)'>Die cutting</a> is the general process of using a die to shear webs of low-strength materials.
* E.g. rubber, fibre, foil, cloth, paper, corrugated fibreboard, chipboard, paperboard, plastics, pressure-sensitive adhesive tapes, foam, and sheet metal.
* Started as a process of cutting leather for the shoe industry in the mid-19th century.
* Kiss cutting: cut through just one layer of a laminate, used on labels, stamps, and other stickers.
* Rotary die cutting is often done inline with printing.
* Flatbed die cutting is slower than rotary die cutting, but the tools are cheaper. (Better for smaller production runs).
<iframe width="900" height="600" src="https://www.youtube.com/embed/pNtWiF0bPrg" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
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