3/4 Axis Routers: Onsrud, Shopbot, Intelitek, Prototrak, Modelas
We have an Onsrud 3-axis router in N51-160, with a 48x96" table, 6" Z clearance
The Onsrud has a 12-tool carousel and a vacuum table.
We also have a Shopbot Buddy 3/4 axis router in 3-410, with a 24x48" bed, 6" Z clearance.
The Shopbot tools must be installed entirely manually. It does not have a vacuum table.
The Shopbot does have a (rotary) 4th axis attachment that can be switched out with the 3-axis spoilboard. Its Z clearance from the A axis is limited to about 3".
The Prototrak knee mill is in N51-160 - good for aluminum, wax, plastic.
The Intelitek is a small, low-speed 3/4 axis machine with about 12"x6" of working area and a set of steel fixturing tools /MDF spoilboard.
It has tool holders set up, which must be installed manually.
The Modelas are two small low-speed 3 axis machines designated for PCB copper circuit board milling.
Mastercam will be used to set up jobs on the Onsrud, Shopbot, and Intelitek. Mods are used for the Modelas. Please see their tutorial pages
for more detail.
Material and file prep (and time) necessary for router work:
Our machines have limited Z height - any project for material over 6" thick needs to looked at very carefully. XY areas are listed above.
All material must be very securely fixed to machine tables so they will not move at all during cutting. The Onsrud's vacuum table works well with very flat,
relatively non-porous material. Smaller pieces, warped pieces, and textured/porous materials will require extra fixturing consideration.
Weak vacuum or no vacuum (Shopbot, Intelitek, Prototrak) tables require tools of some kind to hold material down - screws for hard material like wood/MDF on MDF
spoilboards, hot glue for rigid foam/wax on MDF spoilboards, and vises & clamps on metal machine table.
The tools cannot be allowed to get too close to these
fixturing tools, so extra material margins must be designed into the project and cut setup must not be allowed to cut parts completely loose.
CAD file prep for router work will take time.
CAM file prep using sufficiently completed CAD file will also take time.
CAD editing - adding/deleting objects and arranging them to prep a CAD drawing for router setup is always necessary and can take a few minutes to an hour depending on the geometry. Please expect that some time will
need to go into this - file prep for router work is not like file prep for printing, which has its own requirements.
Once a file is at least mostly set up for router work, CAM setup can take anywhere from 20 to 120 minutes, depending on geometry details and complexity. Some objects
are much more conducive to simple CAM setup than others. Some will require a few toolpaths, some will require many separate toolpaths.
Drawing must be scaled correctly, at XYZ 0,0,0, and material dimensions must be exact. This means you need to have material ready to go and measured for accurate setup.
3-axis machines cannot rotate to reach under things - those are called 'undercuts' and we cannot produce them on our machines. The machines can only reach what
they can see from above.
Solids are not necessary or particularly useful for 3-axis milling - delete bottoms and vertical side walls.
Please avoid STLs/meshes whenever possible - a plain old 3dm NURBS file from Rhino is good.
If the object has any interior corners at the edges of surfaces, please draw curves on those edges. Sometimes they will be closed, sometimes open. No duplicate
curves, please.
No partial spheres - deform surfaces defined by arcs just slightly. The deformity can be invisibly small but it must exist.
Interior corners (corners of a rectangular pocket, for example) that will be cut by the sides of a tool will be rounded, necessary mill marks left by the shape
of the sides of the tool. Sharp interior corners would need to be finished by hand afterward.
Our tool diameters are generally 1/8", 1/4", 3/8", and 1/2". They can have flat ends or round 'ball' ends. Tools smaller than 1/8" are too short to reach into
cavities unless the entire piece is very shallow - they will not usually be possible to use. Specialty sizes/shapes are possible but require custom setup - we can
get into those on a case by case basis.
Once file setup is completed, a general cut time estimate can be generated in Mastercam. Many typical files take at least an hour - some are quicker, but some can take several
hours. Geometry from project to project varies wildly, and so 3-axis setup and cut time do as well.