CNC: Rhinocam - School of the Art Institute of Chicago

Transcription

CNC: Rhinocam
Sullivan Fabrication Studio | Version 5.1 (beta)
TABLE OF CONTENTS
Develop a CNC Rhino File. . . . . . . . . . . . . . 6
1. Import Model. . . . . . . . . . . . . . . . . . . . . . 6 –7 2
instructional fabrication
2. Define Stock. . . . . . . . . . . . . . . . . . . . . . . 8 –9 3. Fit Parts On Stock. . . . . . . . . . . . . . . . . 10–11 4.Develop Machining Regions. . . . . . . . . 12–13 1. Import Your Model.
2. Create Stock Size. . .
3. Fit Parts Within Mar
4.Develop Curve Regio
5. Generate Tool Paths. . . . . . . . . . . . . . . . 14–19 5. Generate Tol Paths.
Kinds of Machinig Operations . . . . . . . . .
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File Review . . . . . . . . . . . . . . . . . . . . . . . . . .
22
Material Prep . . . . . . . . . . . . . . . . . . . . . . . .
23
Stock Approval . . . . . . . . . . . . . . . . . . . . . .
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CNC Appointment Reservation . . . . . . . .
25
Glossary....... . . . . . . . . . . . . . . . . . . . . . . . .
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school of the art institute of chicago
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What is the CNC Router?
How to Use This Guide
The CNC (Computer Numerically Controlled) Router is a digitally driven, coordinate
based prototyping and production machine. The CNC mills materials utilizing a
cutting bit fixed in a rotary spindle which traverses along an overhead gantry
system. The gantry delivers the bit along the X, Y, and Z axis’ based on coordinates
developed in relation to a 3D Model in the form of a tool path. Unlike a rapid
prototyper, which prints a part layer by layer, the CNC will incrementally remove
waste material revealing the part from within solid stock. A wide array of materials
may be milled with the CNC when paired with the appropriate cutting bits
including: wood, wood composites, cork, plastics, plastic composites, foam, casting
wax, and non-ferrous metals. Though generally reductive in its nature, the CNC
can also be implemented in augmented additive processes (ie. drawing, marking,
scoring).
Refer to the panel on page () for a indexed reference to the order of operations for
developing a CNC file. Each operational step is explained in more detail throughout
the RhinoCAM section. The reverse section refers specifically to interfacing with the
CNC machine during your machining appointment.
3D Model
CNC File Review Times
While Rhino is our primary 3D model interface for CNC output, 2D and 3D files may
be imported from other programs such as: AutoCAD, Maya, 3D Studio Max, Reveit,
Solidworks, Blender, Adobe Illustrator, etc.
About SFS + CNC
The Sullivan Fabrication Studio Staff are here to assist you in all of your CNC
projects. SFS staff are happy to consult with you regarding CNC file setup strategies
and identify areas of potential exploration and development to improve the quality
of the output.
Monday– Thursday: 10:00a–1:00p & 4:30p–8:00p
Friday: 10:00a–1:00p
Saturday: 10:00a–4:00p
Working Envelope
The CNC machine is primarily suited for working within its relatively large work bed
but with a relatively low head clearance. The Techno CNC has an XY work bed of 48”
x 96” (a full sheet of plywood) and a prefered Z thickness of 2” or less (the thickness
of a sheet of insulation foam). While the CNC gantry has a maximum clearance of
5.5”, cutting deeper than 2” puts undue stress on the machine, and limits the range
of milling tools available for use. Whenever possible, models thicker than 2” should
be split into slices 2” thick or less to be assembled after milling.
Kinds of Milling
Loosely speaking all milling operations are divided into 2 categories; 2-D and 3-D.
2-D milling (aka 2.5 axis) works, very much like the laser cutter, cutting only in
profile lines and flat planes while 3-D milling (aka 3 axis, 4 axis, 5 axis) allows for
the creation of form and topography through 3-Dimensional machine gestures.
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In order to schedule a milling time you will be required to have at least one review
session with an SFS staff member during which an appointment time will be set.
About the Knowledge Base
A set of Knowledge Base files is provided by the Sullivan Fabrication Studio (SFS)
which preloads baseline toolpath settings. All Toolpaths should be generated from
this knowledge base in order to simplify toolpath creation. Select the machining
operation(s) you want to perform and generate your Toolpath. Updates are
periodically available to include new additions to the Knowledge Base. The most
up to date Knowledge Base file can be found at artic.edu/webspaces/portal/irfm/
CNCKnowledge.zip
A Note on using RhinoCAM Off-Campus
If you are working with Rhino off-campus, or with an inconsistent wireless
connection to the server, you should not launch RhinoCam. Files that are open
when network connectivity is lost may also loose all RhinoCam data.
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Develop a CNC Rhino File
1. Import Your Model
Develop a CNC-specific Rhino Model by importing from your project model.
A.
THIS IS A PROJECT MODEL
Most Rhino models can be milled on the CNC
but some may demand very different setups than
others.
B.
Import geometry from project model and arrange
it according to the CNC parameters. All geometry
should exist in the positive X,Y Quadrants and
below the Z PLANE.
THIS IS A CNC MODEL
C.
Duplicate important geometry onto a locked layer
D.
Model must be sized to fit on the CNC machine.
as a backup.
The CNC has a recommended working envelope of
48” x 96” x 2”.Your CNC parts must fit within this
volume, if they do not, parts should be split into
pieces and/or layers and arranged accordingly.
Z-PLANE
96”
2”
48”
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DEVELOP A CNC RHINO FILE
2. Create Stock Size
Y
X
Z
2
A.
The top southwest corner of the stock should be positioned at 0,0,0 within
B.
Be sure to have a good understanding of what stock is available from Resale
C.
Actual stock may not correspond to its labeled thickness. Be sure to verify
your rhino model.
or other suppliers.
material thicknes s with calipers.
3.72
*Material thickness is not always consistent
with its labeled thickness.
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3. Fit Parts Within Margin
A.
Fit all parts to be milled within a 1–1/2” margin of actual stock. Multiple parts
B.
This margin accounts for the position of screws and other fasteners which
should at least have 1–1/2” of support material in between.
can damage CNC bits if collisions occur. The margin ensures that no cutting
C.
If this margin presents complications due to unique project requirements,
D.
If your milling part(s) are thinner than your stock, your parts should be
please confer with SFS before proceeding.
oriented to the bottom of the stock in order to ensure proper final thickness.
occurs near your fasteners and provides perimeter support material.
STOCK
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4. Develop Curve Regions
Develop Curve Regions that describe the geometry of parts and/or the areas to cut within
B.
All region curves should be projected to the Z, 0 plane.
C.
If you are making any modifications to the position of a part on this model,
D.
Some 3-axis machining operations will require that region curves be offset in
or around. These curve regions will serve as selection areas for generating tool paths.
A.
Dupedge, Dupborder, Dupfaceborder, and Silhouette are common commands
for this procedure. Mesh Outline can be useful, but vtroublesome.
Dupedge
Dupborder
Dupface Border
Silhouette
Mesh Outline
be sure to move these region curves simultaneously.
order to allow milling of an entire part. Generally, this offset amount is ½”, but
can vary depending on the type of tool path and the requirements of the part
to be milled.
OFFSET
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5. Generate Tool Paths
A.
All machining operations should derive from the Knowledge Base, a set of predetermined machining parameters, and be generated only with tools from the
B.
Load predefined TOOLSET (2012 KB.vkb).
SFS Toolset. Loading from the Knowledge Base will load SFS established settings
like feed speed, cut direction, and some of the advanced parameters for you,
limiting complications in creating toolpaths. BOTH THE MACHINING OPERATIONS BROWSER
AND THE MACHINING OBJECTS BROWSER SHOULD BE SELECTED FROM THE RHINOCAM MENU.
A
B
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5. Generate Tool Paths continued
C.
Load predefined KNOWLEDGE BASE.
D.
DRAG & DROP appropriate tool path into the Machining Operations Browser area.
C
D
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develop settings for the tool path.
5. Generate Tool Paths continued
E.
DEFINE TOOL PATH PARAMETERS. Double click on the toolpath name in the machining
operations browser. Scroll through each of the tabs in the machining operation
F.
When all settings have been developed, select GENERATE to create tool path.
G.
Tool Paths Generated.
to develop settings for the tool path.
E
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Kinds of Machining Operations
2 1/2 AXIS MACHINING
3-AXIS MACHINING
3-Axis Machining creates toolpaths that follow 3d surfaces to carve objects.
2 1/2 Axis Machining creates toolpaths that follow 2D lines, or flat
Cuts are determined by the X,Y and Z coordinates for each point along the
surface geometry, to cut to a programed depth. Cuts are determined by the X and
surface of your 3D Model.
Y coordinates at each point along the surface edge or line. Cuts are made in depth
increments to fit the tool’s cutting capacity. 2 1/2 axis milling is used primarily for
cutting sheet materials.
You should model flat surfaces. To convert 2D lines to surfaces, use the Planar
Surface tool in Rhino.
HORIZONTAL ROUGHING
Roughing operations are needed when cutting deep into hard materials
such as woods, plastics, and metals. Incremental cuts are made in a series
of depths that are within the tools cutting capacity. Roughing operations are
time consuming but neccessary parts of machining solid geometry in hard
FACING
materials like wood.
Facing toolpaths machine the entire surface to flatten or dimension the material.
FINISHING
PROFILING
Finishing operations are created to accurately carve your geometry.
The toolpath is created to follow the surface of your model precisely.
Profiling toolpaths follow the edges of surfaces to create profiles.
POCKETING
Pocketing toolpaths cut away all of the material inside of a selected
PARALLEL FINISHING
Parallel Finishing make cuts in line with each other, at
a consistent step over.
HORIZONTAL FINISHING
contours of your model at a consistent Z stepdown.
region to create pockets.
ENGRAVING
Engraving toolpaths follow lines on the center to apply text or
engrave a design.
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Horizontal Finishing will create toolpaths that follow the school of the art institute of chicago
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File Reivew
SFS will conduct a file review consultation and may ask you to repair elements within your file and
return at a later time or date (repair & repeat). Arrive at the SFS during reccomended File Review
times
Material Prep
1.
Purchase Material from Resale with ArtiCASH only
2.
Any externally sourced materials(home depot etc.) should be verified with SFS staff before
purchase to assure that these materials comply with SFS usage regulations
Monday– Thursday: 10:00a–1:00p & 4:30p–8:00p
Friday: 10:00a–1:00p
Saturday: 10:00a–4:00p
3.
Cut material to the size described in your RhinoCAM Stock or to SFS recommendation
4.
Laminate material as needed. Allow 24hrs prior to milling
for any glue to cure.
When laminating material be sure to use an adequate
number of clamps and enough glue such that it squeezes
out from all sides of the lamination.
Be sure to test your clamping strategy without glue first to
ensure you have enough clamps for the glue up.
Glue should be spread evenly on all surfaces to be glued.
Use a spreader or an old paint roller to do this.
Be sure there is craft paper down on any surface on which
you are gluing on to keep glue off of tables and floor.
If glue has not fully cured (24hrs) there is a risk of the
material delamination during milling be sure to allow 24
hours for glue to dry
When laminating yellow foam use only super 78 spray
adhesive which is specifically formulated for polystyrene
foam. other forms of spray adhesive will melt polystyrene
foam damaging the materials contact surface as well
releasing dangerous fumes.
For other laminating questions please refer to SFS staff.
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Stock Approval
CNC Appoinitment Reservation
1.
1.
ARRIVE 15 MINUTES BEFORE APPOINTMENT. Appointees more than 5 minutes late
for their appointment risk cancellation.
2.
CHECK IN and check out CNC tool kit.
3.
Be sure to bring your PREPARED STOCK AND CNC-PREPPED RHINO MODEL (do not
come with post files only).
SFS will verify your stock according to your model. If your physical stock does
not correspond with your Stock in RhinoCAM, it may be necessary to make
modifications to your file and/or re-create your stock to fit the constraints of
your model. Such modifications can cause un-necessary time over runs or other
complications so it is best practice to verify this as you go.
2.
Establish a time estimate for machining your file by Posting / Viewing Information
3.
Add 15-45 minutes to your time estimate to allow for machine setup, bit changes
etc.
4.
OPEN RHINO FILE for shop staff on the computer adjacent the CNC machine.
Shop staff will look the file over to verify all information.
4.
SFS will work with you to establish a suitable appointment time
5.
Shop Staff will guide you on how to MOUNT YOUR MATERIAL to the machine and
prepare the machine for your run.
6.
During your CNC run, PAY ATTENTION TO THE MACHINE. Phones, books and
internet browsing are prohibited. Be prepared to pause the machine at any
sign of trouble. If you need to leave the machine unattended for any reason,
you must pause the run.
7.
When the machine comes to a stop notify Shop Staff. A bit change may be
necessary.
8.
SFS Staff reserve the right to end your appointment at its scheduled end time
regardless of file completion.
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Glossary of CNC Terms
CLIMB CUT (AKA DOWNCUT):
In a climb cut, the cutter motion is downriver, opposite its
rotation—the cutter rotates clockwise but is fed conter-clockwise and away from the rotation.
GANTRY: The horizontal support member of the CNC, on which the Spindle is mounted. The
gantry moves along the X-axis. The router moves laterally along the gantry to describe the Y-axis.
The resulting cut can produce a finer surface edge but climb cutting is extremely hard on bits
and can be easily overdone. Climb cuts should only be made with extreme caution and in special
situations.
G-CODE:
A system of numeric code and machine instructions. When you Post a file, Rhinocam
will produce G-Code. Once the file is posted a plain text file will open in a new notepad window.
This is the G-Code. Do not alter this code! You will notice the file type is .nc, this stands for
CNC: Computer Numerically Controlled
numeric code.
COLLET: The holder that locks cutting tools into the spindle of the CNC router.
GENERATE: The command in Rhinocam which tells Rhinocam to interpret the information you
have provided in the MOp and develop toolpaths.
CONVENTIONAL CUT (AKA UPCUT):
In a conventional cut, the cutter rotation and tool motion
are in parody, the cutter is fed upstream into the material, producing a robust cut but with a
HOME:
tendency to tearout. Conventional cutting is the standard cutting direction and should be used in
machine Home you are sending it to this absolute coordinate position. If you are running many
most situations.
files with a consistent origin, it is useful to know where that origin is in relation to the Home
An absolute coordinate position programmed into the CNC machine. When you send the
coordinates. In the event of a CNC shutdown or some other loss of your origin coordinates, the
coordinates can always be reproduced from this Home position.
CUTTING EDGE: The sharpened edge of the tool used for cutting.
KNOWLEDGE BASE:
DOWNCUT BIT: The flutes and cutting edge of a downcutting bit are spiraled downward
pushing chips and grain down into the material.
FEED RATE: The rate at which the cutter moves from point A to point B. Expressed in inches/
minute.
FLUTE:
The grooves cut into the tool to allow chip removal during cutting.
A group of basic tool-paths with speeds and other parameters already
defined. Most often, when a student begins developing a toolpath they should start with one of
the toolpaths found in the Knowledge Base file so that some options are already established.
MACHINING OPERATIONS (MOPS): The term used to describe the tool path and settings
created for machining.
ORIGIN:
In Rhino, this is the world 0,0,0 coordinate. On the CNC machine you establish this
point when you zero out the bit on the material. When you do this you must zero out all three
coordinates. Once you have established this origin, the CNC will interpret that origin to be the
FIXTURE:
position of the 0,0,0 origin in your Rino file.
A template or clamping device which helps to either locate or affix your material to
the machine. If, for example, a student is milling many parts from identical sized stock, it would
make the process go faster to affix a location template on the spoil board so each new piece of
stock would not need to be re-zeroed and could instead use the same origin point as the last
POST (OR POSTPROCESS): The process by which Rhinocam converts tool paths into numeric
code which are interpretable by the CNC machine.
milled piece.
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POST PROCESSOR:
In the Rhinocam setup tab, there is an option to define the Post processor.
When you define this you are telling Rhinocam what kind of CNC machine you are using. Every
CNC speaks a slightly different form of numeric code (.nc) so it is necessary to tell Rhinocam what
kind of machine it is going to be communicating with so that it posts the .nc file in the correct
format. In SFS, we only have two machines, TechoIsel and Onsrud TM3. If your post processor is
setup for any other machine, your file will not run correctly.
REGION: The area in Rhinocam you use to designate a milling area. Generally, regions are
closed curves on or around the geometry you wish to mill. Think of a region as a way to tell
Rhinocam where to look for milling geometry.
SPINDLE: The rotating motor that spins the cutting tool.
SPOIL BOARD:
Sheet of underlying material, beneath your working stock, which serves as both
a place to affix your stock as well as a sacrificial cutting surface. While it is allowable to set your
toolpaths such that they cut into the spoil board, be sure they do not cut through it!
STOCK: The material that will be machined on the CNC Router.
STRAIGHT FLUTE:
Straight flute bits are used in applications where the material may flex or lift
during cutting, when for instance the material is thin and light.
SUPPORT MATERIAL: The material outside of the part you are milling. When you are milling,
there must generally be some sort of support material in addition to the part being milled so as to
secure the parts to the machine as they are being milled.
TOOL: The rotary cutter used in the CNC machine to cut the material. Tools are made from a
variety of materials and in a wide range of sizes and geometry.
TOOLPATH:
A definition of the motion of the tool as it makes a given cut. In Rhinocam, the
toolpath itself is expressed by a light green line. Each green line represents one linear motion of
the tool and defines the center location of the bit at any one time.
UPCUT BIT: The flutes and cutting edge are spiraled upward pulling chips and
grain up out of the material.
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CNC: Rhinocam - School of the Art Institute of Chicago

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