Material Preparation

  1. Select Material
  2. Select Tools
  3. Cut material to size
  4. Glue/mount material
  5. Clamp/weight material

 

Material Selection

cut_materialThere are a wide variety of millable materials, however, some are better suited to particular jobs than others.

Extruded polystyrene s inexpensive, cuts easily, and is recommended for most surface milling jobs.

High density polyurethane is designed to be milled and so is able to achieve better results than extruded polystyrene.

Specialty plywood can be suitable for surface milling. Sheathing grade plywood, as it contains many knots and pulpy layers, is not recommended.

MDF is more durable and has a uniform consistency, but exposure to dust is not recommended.

Please see the material tab for more information on materials.

 

 

Select Tool(s)

Cutting tools come in a range of sizes, materials, and geometry types. Some tools are not appropriate for certain milling operations.
It is generally more efficient to use a combination of different toolpaths and tools to achieve a detailed model rather than assuming that a small tool with a smaller stepover is the only way. Oftentimes, a larger tool can achieve better finish results.

Carbide tools are expensive and unnecessary for use in foam; high speed steel is recommended for those applications.
The GSD has a number of common cutting tools available for use. Additional tools can be purchased if required, and are available through Onsrud or McMaster-Carr.

 

Cut Material to Size

Allow for extra material around your milled project when cutting your material, when mounting the material to size, and when setting up the stock in RhinoCAM.

Depending on which machine is used and the geometry of the part, it may be necessary to secure the material to the router table with screws. It is best to plan for extra material around the area that is to be milled. The finished product can be later removed with an additional milling operation or with another method in the shop.
As many of the shop machines are limited in the depth they can cut, cut the material before gluing.

 

Glue/mount Material

Gorilla glue (used for blue foam) requires 24 hours to cure. Both surfaces to be glued must also be misted with water to aid the curing process.

Gluing must be done at least 24 hours in advance of your routing appointment, as glue that has not cured may result in a damaged model and/or cutting tool. Gorilla glue expands as it cures, so be are to sufficiently clamp/weight your material. Gorilla glue can also be used to mount a single layer of foam to a more rigid material such as MDF or plywood to prevent warping. If mounting to another material is undesirable, the bottom face of the blue foam can be sanded to relieve the surface tension. This reduces warping, but some warping is still likely.

Wood glue is sufficient for gluing layers of wood together. Be sure to clamp the material.

Follow the directions on the glue bottle!

 

Clamp/weight Material

clampTo ensure a clean-looking and continuous bond between materials, it is necessary to adequately clamp and/or weight your work while the glue is drying/curing.
Pressure must be applied to edges as well as the center of the work. To accomplish this, sandbags may be placed in the center of the work or long pieces of wood may be laid on their narrow face across the material and clamped on either end to more evenly distribute the load.