This was a really cool project and seems to be successful. I’m hoping to continue and try some more interesting forms beyond text. I think cutting-edge fabrication technology is at it’s best when combined with established/non-digital techniques–it’s the best of both worlds!

This pour took place at the Butler Street Foundry in Chicago.

Laser-cut Form for Bronze Casting

The Final Product: A Cast Bronze Plaque

A Deep Raster Engraving With a Tapered Shoulder Makes for a Great Plaque Form

A Two-part Sand Mold Will Recieve the Molten Bronze

Casting Sand Packed into the Mold Holds an Impression of the Laser-cut Form

Casting Sand is a Mixture of Sand & Clay; Imagine the Best Sand-Castle Sand, Times Ten

A Gas Furnace is Used to Melt the Bronze

Solid Bronze Goes into the Furnace to Melt

Solid Bronze Goes into the Furnace to Melt

Lifting the Lid off the Furnace

The Molten Bronze is Lifted Out of the Furnace in a Container Called a Crucible

Molten Bronze Hoisted out of the Furnace

Molten Bronze Hoisted out of the Furnace

Molten Bronze in the Crucible

Molten Bronze Poured from the Crucible into the Two-Part Sand Mold

Molten Bronze Cools in the Two-Part Sand Mold: Weights are Placed on Top to Contain the Hydraulic Pressure Created in the Mold

After About 20 Minutes, the Bronze has Cooled Enough to be Released from the Two-Part Sand Mold

Bronze Casting Released from the Two-Part Sand Mold

The Final Product: A Cast Bronze Plaque

Laser cutting is a great technique for quick fabrication, in part because of the very small point size of the laser beam. The minuscule kerf of a laser cut allows for very tight 90° angles on interior (and exterior cuts).  This makes it easy to laser-cut thin panels of material for joining, as oomout demonstrates in this post on instructables.com (example pictured below). One of the drawbacks of laser cutting is the limited depth of materials that can be successfully through-cut; the laser cutter that I have access to can get through about 1/2″ of MDF or plywood, but the cuts are very charred and not perpendicular due to the hourglass shape of the laser’s focal point.

T-Bolt connection using laser-cut 1/4" panels

CNC routing is another great technique for quick fabrication. The range of material depth is much greater, there’s no burning, and through-cuts are perpendicular. One of the biggest drawbacks, however, is the inability to route interior corners due to the cylindrical shape of the cutting tool. This can require tedious hand-finishing to file or chisel out the interior corners to 90° angles, which is not worthwhile for projects that don’t have to look pretty, i.e. prototypes.

The technique pictured above is achieved by simply routing an extra bit of material out of interior corners to allow for 90° butt-joints. To set the paths for the corner knock-outs, a circle is created at each interior corner using a 3-point definition; the first point is set on the corner’s intersection, the second two are placed on each edge of the corner at a distance equal to the diameter of the router bit you plan on using. This will make sure enough material is taken away to allow for a 90° joint.

Vector path for 1/4″ laser-cut t-bolt joint (.dxf)

Vector path for 1/2″ CNC-routed t-bolt joint (.dxf)

Above is an example of varying speed settings with vector cuts and engravings on a 120W Co2 laser cutter. The ratios of power to speed are roughly the same on both groups of cuts, producing approximately the same depth; however one speed setting is much higher (30x) than the other, producing the wobbly lines on the fast group. The faster setting was enough to cause the laser’s Y axis to lose registration, as you can see on the two bottom lines of text.

Keeping a low speed is not necessary for all cuts, just those with small or intricate paths which cause the head to change position rapidly. Straight cuts with a higher speed usually look just fine.

Because of the cost of die cutting, using a laser to cut felt is great for prototyping and experimentation. The only downside to this method is the burnt smell. It fades somewhat after time, and is not terribly noticeable, but if you are really trying to make a finished product for public consumption, I would look into getting a quote for die-cutting. However, if you are trying to figure out the fit and proportion of an avant-garde garment or take pictures for a portfolio, laser cutting is more than sufficient.

Buying the material:

Use 95-100% Wool Felt. This is a good idea for the laser cutter in order to avoid the release of toxins into the air, but it’s also a good idea in general, as the material quality of 100% wool felt makes a huge difference in any project.

There are two types of high-grade wool felt you can buy. Industrial/SAE felt is fabricated to standards set by the Society of Automotive Engineers and comes in cream (new wool) and grey (a mottled recycling of old wool and other materials). There is also 100% wool felt that is usually sold for doll making which comes in a multitude of colors. Stick with the plant-based dyes. Don’t get the craft-store felt — that’s mostly acrylic and is just really low quality in general.

Manufacturers of SAE Wool Felt: McMaster-Carr, Aetna Felt, National Nonwovens, Sutherland Felt Company
100% Wool Craft Felt: The Felt People, Weir Dolls and Crafts, A Child’s Dream Comes True

HOW TO: Make an Engraved Felt Pouch with the Laser Cutter

1. Draw your pattern in Illustrator with any engraved lines or cutouts. Outlines work best — large filled shapes result in a lot of burnt smell. The pattern should look something like the image at left. The two edge flaps will be stitched together, right-side facing in, and the whole thing will be turned inside out. The area with the whale outline becomes the closing flap of the pouch.

2. Tape the felt down into the bed and properly focus it. The felt will stay pretty flat because of the friction between the fabric and the honeycomb table. However, the edges will fly up if not taped.

3. Set the line weights and color order properly. This will vary from laser cutter to laser cutter, but the black text should be raster engraved first. Next, the whale can be vector engraved or cut, and, finally, the outside edge should be a vector cut.

4. The settings I use for felt are as follows:
Raster Engraving: Power: 15%, Speed: 80%, PPI: 200
Vector Engraving: Power: 1%, Speed: 8%, PPI: 150
Vector Cutting (2-3 passes, less burning): Power: 3%, Speed: 5%, PPI: 350
Vector Cutting (1 pass, singed edge): Power: 8%, Speed: 3%, PPI: 200
The multi-pass vector cutting option just cuts through, which leaves the cutouts still connected to the surrounding material by friction. This is safer for the laser and makes material removal from the bed easier.

4. Once the felt has been cut, sew the edges together and flip inside out for your pouch!

Process Photos

taping the felt to the bed

felt in the process of being cut

felt after cutting

wallet before sewing

wallet after sewing

optional applique

Felty the Felt Octopus – Cute Laser-Cut Toy Made with F10 1/8″ Felt

Felty is cut from 1/8″ F10 grade wool felt. We chose the F10 grade because it contains 95% wool. We operate our laser cutter in a confined office environment, so we are extra-careful about cutting potentially-toxic materials, especially some of the synthetics contained in certain felt materials.

There are other grades of felt with the same wool content, but F10 is the least dense out of all of them, making it easier to cut at low powers. Cutting felt produces a smell likened to that of a burning dog, and it’s quite pungent. The less laser power we have to apply to the material, the less burning, and therefore the less stench produced.

We’re using a Universal X-660 60W laser cutter with a compressed-air assist. Here are the settings I used for cutting 1/8″ F10 wool felt:

• Raster Engraving: 18% Power, 80% Speed, 200PPI, Single Pass, Low Gas
• Vector Engraving: 10% Power, 8% Speed, 200PPI, Single Pass, High Gas
• Vector Cutting: 11% Power, 3% Speed, 200PPI, Single Pass, High Gas

As with any material, be sure to have adequate ventilation when laser cutting. Felt especially creates some strong odors.

The files:

• felty_the_octopus.ai Adobe Illustrator CS2 file
• felty_laser_settings.las laser settings profile for Universal X660 laser cutter

I’ve found this technique to be really useful for making quick, cheap mock-ups of 3D models, as well as getting some really interesting visual results for artmaking.

The first of the two main techniques I’ve been using is ’slicing’ models in Rhino using the Contour command, then exporting the curves to Illustrator. The curves are cut out of flat material (usually cardboard or acrylic) on the laser cutter, then re-assembled with glue into a mock-up of the 3D model.

This technique results in an economical model relatively quickly, and allows you a lot of flexibility compared to ‘unfolding’ techniques such as those used with Pepakura. It can, however, be quite tedious to re-assemble all the slices in the proper order/orientation. It is also not the most accurate method, as the shape of the model depends on the orientation of our curves in Rhino matching the orientation of the cut slices.

I’ve written a couple of scripts that take a lot of the grunt-work out of processing files. They are free for you [and everyone] to use. Also, keep in mind that the laser cutter part of the equation is optional. The contours can be cut by hand, although it will be a much bigger pain in the ass.

Here is the basic technique:

In Rhino:

• Create a 3D model in Rhino. It helps if the model is solid (aka a joined polysurface, aka watertight)
• Create topological contour curves of the model using the Contour command. The contours can go in any direction, and the spacing should be equal to the depth of the material you’ll be using.
• Group the curves: use the PlanarSrf command to create surfaces from each ‘level’ of slices. This accounts for contours which are donut-shaped, such as those that would come from a tube or bowl shape. These concentric curves must be grouped together to maintian the profile of the 3D model.
• Flatten the surfaces: use the UnrollSrf command to align each surface to the top viewport. This will prevent the curves from being distorted upon export.
• Convert back to curves: use the Make2D command to transform each surface back into the original curves. This prevents the need for extra editing once the curves are brought into Illustrator.
• Export the curves as Illustrator files (*.ai). Preserve the scale, but since Illustrator does everything in points, convert to points (1 inch = 72 points). This will ensure the scale of the 3D model is preserved.

In Illustrator:

• Open each curve file that we just exported from Rhino.
• Move each curve or set of curves into its own layer in a file that has been templated for the laser cutter.
• Arrange and format the curves, then send them to the laser cutter.

On the laser cutter:

• Use the least amount of material possible.
• Keep track of the pieces you’re cutting out. Numbers can be engraved by the laser cutter, or the cutouts can be kept in their original position and compared to the files.

In real life:

• Assemble the slices, using numbers and/or Illustrator files and/or the Rhino model.
• Bask in the glory.

The Scripts:

These scripts are distributed under a Creative Commons Attribution Noncommercial Share Alike 3.0 License. You must follow the terms of this license if you wish to use these scripts.

Please see http://creativecommons.org/licenses/by-nc-sa/3.0/ for details.

These scripts are not intended to do anything malicious, however I take no responsibility for any ill effects caused by these scripts. If you have any questions about the way these scripts work, please feel free to ask prior to running them.

• Rhino: gen_conts_flat_export_WORKING.rvb
• Illustrator: curve_arranger_working.js

Resources:

• Scripting Adobe Applications – User to User Forums
• Illustrator CS Scripting – Getting Started With Javascript [pdf]
• Rhino Scripting [pdf]
• Rhino Scripting Tutorials