CNC Machines Available to Stamps and Taubman Students

This post is a look at some of the CNC technology available to students at the Stamps School of Art & Design and the Taubman College at the University of Michigan.

CNC Machines

Computer Numeric Control (CNC) machines can be broadly categorized as follows:

1. Additive 
2. Subtractive
3. Shaping / Molding

Some of the machines fall into one category only - for example 3D printers are additive. Others, such as robots can handle many different processes and can accomplish work of all three types.

3D Printers

Between the UM 3D Lab and Taubman College there are several types of printers available.

• The Dimension Elite FDM (Fused Deposition Modeling) machine works by selectively applying ABS plastic in thin cross sectional layers until the entire part is printed. The resulting parts are relatively strong. For more information on this process see Dimension Elite FDM Details.
  
• The ZCorp machine uses a gypsum based powder with multi-colored binder/glue. It can print one vertical inch per hour, in full color, and cures with salt water. Models are usually heavier than the FDM’s models, and are more delicate. For more details see ZCorp 510 Details.
  
• The Cube printers are also available. These machines are open access and very easy to use. You purchase your own print cartridge and can run these machines on your own. The details on getting set up to print with these machines is available here.
  
  

Laser Cutters

Students at Stamps and Taubman have access to two laser cutter machines, named L1 and L2. This is L1, L2 is right behind it.

These machines use a laser to cut at 10,000 degrees Fahrenheit. L1 can cut in an area up to 36"x21". L2 supports 35"x20". These machines have a more powerful laser and larger cutting area than the three Universal Laser Systems machines available only to Taubman students:

The machines can cut wood, paper and plastic. The maximum material thickness is 1/4". You cannot cut plated plastic, PVC, or corrugated cardboard.

Depending on how well tuned the machines are the kerf (width of the material removed during the cut) varies from 0.004" to 0.015".

There are some videos available on using the machines.

3-Axis Routers

There are two 3-Axis Routers available. Both have 4' x 8' vacuum tables to hold the work. This one is operated by the Taubman staff. 

Its neighbor is used by the Art & Design staff. It is also available for Taubman students to use at any time provided they have been trained in its use.

Each router has a 10 tool changer. The Tabuman router can use both conventional and shrink fit collets. The Stamps school router must only use the conventional collets. See below for more information on collets types. 

Here's an example of one of the 3-axis routers cutting the side of a sleigh bed. Full details on this project are available here - Wolfe Sleigh Bed Fabrication. In the video most of the roughing has been done. A 3/4" diameter tool is making the edge cuts. 

In the video below a 1" ball end bit is used for the final finish passes. It steps 0.07" with each pass until the entire surface has been smoothed. 

4-Axis Router

Stamps students have access to a Roland MDX-540A 4-Axis Router. The 4th axis allows the part to be rotated during the cut which can greatly simplify the making of certain types of parts. The table dimensions are 18" x 18". The work piece must be clamped down. Despite the small size this is a very high quality router.

Roland video on the MDX-540:

5-Axis Routers

Taubman has a 5-Axis Router available. The machine has a large enclosure surrounding it. This limits the spread of debris while cutting. That's an important consideration given this tool doesn't have a dust collection system like the 3-axis routers do. That's because the head of the tool can rotate so much it makes it impractical to surround it with a dust extraction hood.

The machine has a 5'x10' vacuum table. Parts as small as 12"x6" can be held securely with vacuum pressure. Smaller parts require mechanical clamping or more sophisticated fixturing.

The machine has a tool changer which holds 10 tools.

A touch screen control panel is available for loading programs and controlling the operation during the cuts.

This video shows part of the process of creating a table using the 5-axis router. Full details on the table production are available here: Torus Knot Table Fabrication. 

This video shows the router cutting foam - see Pedestal Fabrication for details:

Abrasive Water Jet Cutter

The 3 axis water jet is designed for cutting two dimensional profiles or shapes out of flat sheet materials, ranging from sheet metal to metal plate and plastics. In all but a few cases, water jet systems cut completely through a part, and do not have control over depth, like routers or milling machines.

The lab's Flow IFB4800 has a working range of 4'x 8' with 8" of vertical range. This machine is equipped with state of the art dynamic head technology, which eliminates the kerf taper common with waterjets, and can reliably produce parts with .005" tolerances.

Parts are clamped to the ribs over the water tank. Larger parts, which span multiple ribs can be completely cut out. Smaller parts (which would fall between the ribs if cut loose) require tabs to hold them in place. These tabs are then cut manually to release the part.

This video shows the water jet cutting 1/8" stainless steel to make some bed hardware. This is another part of the Wolfe Sleight Bed project. You can see the tiny tabs on the edges of the parts. 

Zund Cutter

The Zund is a knife cutting machine capable of cutting thin materials at very high speed. It has a 5' x 10' table. It can cut paper, cardboard, plastic and wood veneer up to 1/16" thick.

CAD files are exported to the Adobe Illustrator format (.AI) and are loaded into the machine.

The knives are mounted in rotating holders which automatically align tangent to the cut.

Here is a short video of the machine in operation cutting thin plastic: 

7-Axis Robots

There are two large 7-axis Kuka Robots, each with a 10' x 8' reach. They are placed on tracks, one 30' the other 20'. The machines are accurate to about 1mm. The robots can load a variety of tools including a milling head for cutting wood and foam, and a water jet cutting nozzle for full 3D cutting of any material.

The robots can work individually or in tandem.

Toolpath programming is done using MasterCAM or Super Matter Tools.

This video shows a robot cutting foam using a hot-wire. Full details on this project are available here: Robotic Fabrication of Parametric Chairs. 

The lab also has two smaller robots. These are Kuka model KR 6 R900 SIXX. These are used mainly for training.

Vertical Milling Machines

A Haas vertical milling machine is available to Taubman students wishing to work in metal. 

The machine is a Haas VF-2 SSYT. 

A smaller bed mill is also available- on this machine cooling is accomplished by spraying a mist:

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Guitar Stands

I was commissioned to design and build a multiple guitar stand. I made it for my friend who wanted to give it to his friend for his 50th birthday.

 Here's my friend's friend receiving it!

Here are some details of the development:
The initial idea was to hold five guitars with one facing forward, the others facing sideways.

After reviewing the 3D model for the large stand I was asked to make a smaller one as well. Here's the 3D model of the prototype.

Here's the prototype, filled with my guitars, built of African and Philippine Mahogany I had on hand:

These photos don't capture the amazing chatoyance of the African Mahogany.

After looking at and testing out the prototype for a while I decided to make some changes. I wanted to alter the way the guitars are angled as they rest, and to eliminate the tendency of the top to twist too easily. Here's the revised computer model:

This uses two vertical supports to provide greater resistance to twist at the top. It also provides some little(!) shelves for picks, capo, tuner, etc.

I hand picked some pretty amazing tiger maple for the final stands.

Some of the pieces, those with the highest curl, are also spalted. These will be used for top, and supports and top rail of the bases.

Here's are some progress pictures...
No top or stain yet, followed by a stained top. You can see what an incredible difference staining the wood made! I used Minwax Golden Oak wiping stain.

The top was cut on a 5-axis CNC router. That was simply an easy way to get the 15 degree slope to the guitar neck cut outs in the top.

The area where the guitar neck rests is sloped. This was first cut straight down, then a few passes with the bit tipped were made to slope it.

Here's the cut piece. Held to a spoil board of MDF with vacuum pressure:

I also designed a Stand for Five Guitars, which is wider allowing for a front facing guitar in the middle.

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Pedestal Fabrication

I did some fabrication work for artist Lily Cox-Richards on some sculpture pedestals. Here's a summary of these (and earlier) pieces:

The Stand consists of carved plasters depicting tree stumps, wheat sheaves, and massive quartz crystals, all props that were once used structurally and allegorically in American Neo-Classical figure sculpture. The works in The Stand are all based on marble sculptures by Hiram Powers (1805-1873), once known as The Father of American Sculpture, whose works depicted idealized female figures that symbolized allegorical themes. By shifting the focus to the supporting elements and the contact points, Cox-Richard hopes to show a different allegory: I aim to create a new whole, not a fragment or ruin. In condensing these sculptures down to their supports, figure and ground conflate into new forms, revealing latent content.

Greek Slave by Hiram Powers

Here's a link to a video where Lily discusses a bit of her work.

These were modeled on the computer,  CNC cut from high density Styrofoam, then covered in a thin layer of plaster.

Here are a few of the CAD renderings, modeled in Rhino. They are all surface of revolution or one rail sweeps:

In order to get the plaster onto the pedestals we needed some templates that were 1/4" offset from the foam surface. Each template has two parts that ride against the foam. In between is the gap for the plaster.
They are cut on a old but functional laser cutter in the Taubman College woodshop. The kerf on this tool is 0.004".

The templates are made of 0.18" thick acrylic.

The foam used is 3#, C bead. That's the densest we could get. We ordered it from Arvron in Grand Rapids, Michigan. The foam is held in place using vacuum pressure from the table below.

Let the cutting begin. All the roughing is done from above. The bit is 1" diameter spherical tip that's about 10" long.

Two finish passes are done. Each at 45 degrees, one from each side.

Um, ah, errr... lots-o-stuff to clean up. That blizzard is after 3 pieces have been cut.

Here are three pieces, still covered in dust. All the templates are visible on the table.

Here's a YouTube video of the Cutting Process:

Here's a close-up of a template. A "key" slips in to a notch in the template. This lets the template slide over the molding and lock into place in a groove routed into the top and bottom of each pedestal.

These have been exhibited at the Vox Populi Gallery in Philadelphia. The exhibition is called The Stand (Possessing Powers)

More photos of the finished pieces:

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