CNC Router Training
The Fablab has one Techno LC4896 computer numerically controlled (CNC) Router. The CNC router is managed by trained teaching assistants. Once the technician gets your part started, you are required to observe the router while it is in operation. Only trained teaching assistants or technicians may start the CNC router.
Training Resources
Overview
The CNC router can be used for cutting 2d part files and 3d surfacing. The CNC router has a 4’x8’ bed with a 5 ½”gantry clearance (Z height). A 4” maximum Z height is a good rule of thumb, but the maximum Z height depends on other factors including tool length, steepness of surface, and tool clearance . For 2d cutting, there should be a 1” margin no cut zone around the perimeter of your material stock to screw into the router spoil board. The router is a 3-axis router, therefore it cannot make undercuts and bevel cuts.
Materials you can use are:
- Wood, including plywood and hardwood
- Rigid Insulation Foam
- Other materials subject to testing and discussions with TA and Faculty.
Preparing Your Files For CNC
See RhinoCAM video tutorials and Rhinocam Manuals for detailed information.
Step 1. The first step involves preparing your part geometry. This can be done in Rhino. 2d cutting requires only 2d line drawings. 2d cut parts should have all parts joined as a closed region. Be sure your lines meet exactly at endpoints, and there are no duplicate, intersection, or overlapping lines. 3d surfacing uses a surface or solid model. These files should be at actual scale of the part you are making.
Step 2. Tool-paths need to be generated to program the machine to cut your part. We use RhinoCAM which is a plug-in that works within Rhino. We have five seats of RhinoCAM located in the FAC 444. Rhino will import geometry from most software programs. The three basic operations of RhinoCAM are profiling (cutting), horizontal roughing (rough cutting of surfaces), and parallel finishing (finish cutting of 3d surfaces).
Depending on the material you will be using and the complexity of the project, you will load the UMass Tool Library into RhinoCAM or use preset Knowledge Bases listed below .
We stock four standard tools:
- ¼” endmill for profile cutting
- ¼” ball endmill for surfacing
- ½” endmill for roughing
- some 1/8″ mills for engraving
You may wish to purchase a bit particular to your project.
Step 3. Before your part can be scheduled, you need to review your RhinoCAM file with the teaching assistant. They will preview your RhinoCAM file for errors and correct settings. TA’s are not to program your part, but review for common errors and settings particular to this machine and the tools we use. If your RhinoCAM file is approved, you will “post” your file and create a machine-readable text file (G-code) which is specific to our Techno machine. You must also supply shop documentation for the TA. Bring this with you so you know what your tool changes will be. Once your file has been posted, the TA will schedule a time for you to run your part on the CNC router. Do not expect that this part can be run immediately. It is advisable to have your RhinoCAM file reviewed several days in advance of your desired cutting time.
Material Preparation
Students must supply their own materials. If your material stock is glued up, be sure that it has had at least 24 hours to dry. Use liberal amounts of glue spread evenly across the material to ensure complete adhesion when laminating materials. Also please note your actual material thickness, as this may effect your RhinoCAM settings. Calipers are located in the Digital Fabrication Laboratory to get the exact thickness of your material. For example, if using ¾” plywood, it is likely the actual thickness is .6875”.
Cost
Students must provide their own materials including their own bits.
Setup and Operation
You are responsible for clamping or screwing your stock down to the router table, working with the TA. Be aware of where you are placing screws to ensure that they are not in the way of a tool path. If a tool path hits a screw, the bit will be destroyed. If bits are broken due to carelessness, students are responsible for the cost of the bit (which is between $20-$50 depending on the bit).
The technician will load your file and set the machine for your part. The technician will instruct you on how to make a tool change, if necessary. You are responsible for observing the machine while in operation. You are responsible for changing out the tool when prompted by the machine. Please note that it is common for parts to take several hours to finish. The estimated time from RhinoCAM should be tripled for actual run time, including material attachment, etc.
You are required to wear eye, ear and dust protection while the machine is in operation. Eye protection, ear muffs, and re-useable dust masks are available in the CNC router room.
Clean-Up
You are responsible for leaving the CNC router room in a clean condition. There is a dust collection system that will pick-up the majority of dust. You are responsible for emptying the dust bag, putting the dust in a black trash bag, and putting the dust bag back onto the dust collector. The floor should be broom swept. You are responsible for putting off-cuts and scraps into the dumpster. Do not leave large scraps in the router room and be particularly courteous to others using the lab for research projects. You will loose your privileges to use the CNC router if you are negligent in your clean-up responsibilities.