Forest Scientific CNC Router
- 1 Forest Scientific MakerFab 4x8 CNC
- 1.1 GENERAL WARNINGS
- 1.2 CNC-specific WARNINGS
- 1.3 General Notes
- 1.4 Checklists
- 1.5 Expanded Major Steps
- 1.5.1 Create and Export Your Design
- 1.5.2 SAFETY GEAR; Safety Glasses and Hearing Protectors
- 1.5.3 Pre-Flight the CNC
- 1.5.4 Reset Home
- 1.5.5 Install Bit
- 1.5.6 Install spoilboard and work piece
- 1.5.7 Zero the Work Piece
- 1.5.8 Pre-flight the job
- 1.5.9 Run the job
- 1.5.10 Park, Shutdown, Unplug and Clean CNC
- 1.6 Background, Inventory, Capabilities and Maintenance
- 1.6.1 CNC Basics
- 1.6.2 Inventory
- 1.6.3 Capabilities
- 1.6.4 Spindle Speed and Feed
- 1.6.5 Collets and Bits
- 1.6.6 Dust Hood
- 1.6.7 Controller Physical Switch
- 1.6.8 E-STOP
- 1.6.9 Spoilboard
- 1.6.10 Axes, Home aka Datum aka X,Y Zero
- 1.6.11 Maintenance
- 1.6.12 Z Zero Block aka TTO
- 2 Previous Draft
- 3 Notes Not Yet Integrated Into The Above
- 4 TODO/check on these things
Forest Scientific MakerFab 4x8 CNC
This first section is focused on using the Forest Scientific MakerFab 4x8 CNC. At the end are several sections on background material under the heading "Background, Inventory, Capabilities and Maintenance".
Especially, if you are new to CNC operation, review the "Anatomy of a CNC" section.
Note: All directions in this document are given as if facing the front of the CNC.
This reminder page is NOT a substitute for being trained on the CNC by a qualified HackPgh member.
This reminder page is NOT a substitute for using your brain and taking appropriate precautions.
ALWAYS wear SAFETY GLASSES when operating the CNC.
ALWAYS wear HEARING PROTECTION when operating the CNC.
NEVER more than one operator at a time in proximity (24") to the CNC.
NEVER put anything on the bed you NOT willing to see machined.
NEVER put drinks or anything else inappropriate on the laptop stand.
NEVER touch the rails, skin oils cause problems.
ONLY use the E-STOP for actual emergencies when the CNC is running.
ALWAYS closely monitor the CNC when cutting and be prepared to pause or E-STOP in an emergency.
ALWAYS check the air filter on controller before each job.
ALWAYS reset home when you first turn on the machine.
ALWAYS use a spoilboard.
ALWAYS first move the spindle up several inches before moving the spindle.
ALWAYS zero the spindle before each job.
ALWAYS turn on the dust control when cutting.
ALWAYS park the machine when you are done using it.
When using the CNC 12 Mill software, all instructions below assume you're starting from the home screen. Press the ESC key a few times to make sure you're at the home screen of CNC 12 Mill. You'll know you're at the home screen if the shortcut keys menu at the bottom of the screen does NOT have an "ESC" icon at the lower left corner.
All directions are given as standing at the laptop stand looking at the laptop, i.e. "back, left corner" is the corner diagonally opposite the laptop stand.
On the Makerfab, datum, aka the machine home, aka the origin point, aka (0,0,0), is at the back, left corner as seen from standing at the laptop.
The work piece home is set in the CNC file generated by the design software and can be literally anywhere, but it is typically the front, left corner of the work piece and this is the recommended work piece home.
The 4' dimension is the X axis.
The 8' dimension is the Y axis.
The Z axis travel is 8.5".
Major Steps Checklist
- create and export your design
- SAFETY GEAR; safety glasses and hearing protectors
- Pre-Flight the CNC
- Reset Home on the CNC
- Install spoilboard and work piece
- Install bit
- Zero Work Piece
- Pre-flight the job
- Run the job
- Park, Shutdown, Unplug and Clean CNC
Running A Job Checklist
Note: This is a short checklist, see below for detailed steps for running a job.
- Do "CNC Pre-Flight Checklist" before running your first job of the day.
- Do "Job Pre-Flight Checklist" before each job.
- Export design from VCarve to gcode type Centroid (i.e. using the Centroid postprocessor), and take note of home position you specified in VCarve.
- Install spoilboard and work piece
- Do "Reset Home Checklist"
- Do "Install Bit Checklist"
- Do "Zero Work Piece Checklist"
- Load job file exported from VCarve
- Simulate job and check for holddown clearance
- Turn on dust collector
- Click green "cycle start" GUI button
- Monitor job until complete.
- Press any keyboard key to pause; click green GUI button to resume.
- Hit E-STOP in case of emergency.
CNC Pre-Flight Checklist
- Make sure the controller dust filter is clean (metal box on bottom, left of machine)
- Plug the CNC into the wall outlet.
- Turn on the controller (green physical button)
- Make sure the E-STOP on the controller is pulled out (red and yellow button)
- Turn on CNC laptop
- Start CNC 12 Mill
Job Pre-Flight Checklist
- controller filter is clear
- Power plugged in
- controller on (green button)
- E-STOP off
- spindle power on
- "Auto" button on GUI on
- dust control is turned on
Jog Button Use Checklist
- Always Raise before jogging X or Y
- Tortoise/Hare GUI button controls jog speed
Reset Home Checklist
- Do "CNC Pre-Flight Checklist" before doing Reset Home
- manual jog spindle up several inches
- manual jog spindle to near park/reset home posistion, at back, left corner of CNC bed.
- Click "Reset Home" GUI button.
- Wait for CNC to finish moving on its own.
Install Bit Checklist
- move carriage to convenient working location
- make sure red physical button on spindle is in "off" position
- remove dust hood brushes for easier access
- select and install bit in collet
- insert bit and collet into spindle
- tighten collet using two flat wrenches
- reinsert dust hood brushes (optionally wait until after Zeroing to do this)
- make sure red physical button on spindle is in "on" position
- turn on "auto" GUI button
Zero Work Piece Checklist
- Prepare to Zero
- use manual jog to raise the spindle several inches
- use manual jog to near park
- park the CNC
- use manual jog to move spindle to the workpiece home point as designated in gcode file
- Zero the spindle X and Y axes
- use manual jog to raise the spindle several inches
- use manual jog to move spindle to above work piece
- position center of bit at front, left corner of work piece
- from home screen, press F1 "Setup" then F1 again "Part"
- confirm that X axis is highlighted in yellow at center of GUI
- press F10 to set current position as X axis zerom
- press F1 to yellow highlighted section to Y axis
- confirm that Y axis is highlighted in yellow at center of GUI
- press F10 to set current position as Y axis zerom
- Zero the spindle Z axis using aluminum Zero block
- use manual jog to raise spindle several inches
- use manual jog to move spindle inward towards center of work piee
- check that Zero Block cable is plugged in to both block and controller
- place Zero block on work piece, under bit
- press F1 for "Auto", click green "Start Cycle" GUI button
- watch spindle lower to touch Zero block, then rise
- DO NOT press F10 to set the Z axis, Auto did that for you.
- use manual jog to raise spindle several inches
- remove Zero Block and place back on controller
- reinsert dust hood brushes if not already reinserted
Expanded Major Steps
Create and Export Your Design
Detailed description of this is outside the scope of this document. Hopefully at some point in the future we will add tutorials for creating the design.
The jobs run on the MakerFab CNC are in gcode.
Centroid.cnc is the dialect of gcode used by the MakerFab. When exporting the job from your design program, select Centroid.cnc. In some CAM software, this may be referred to as "Centroid postprocessor".
Also, when exporting the job from your design program, make note of where the work piece home is set to, i.e. front, left corner; front right corner; back, left corner; back, right corner of the design's bounding box.
It's a wise idea to use a filename that includes details of the job, such as scale, metric/imperial, etc.
See the section on VCarve and Fusion360 below.
SAFETY GEAR; Safety Glasses and Hearing Protectors
You MUST wear safety glasses at all times when using the CNC.
It is highly recommended to wear hearing protectors. The CNC spindle is fairly quiet, but the bit cutting wood or other materials can be quite loud, for a prolonged period of time.
Pre-Flight the CNC
Make sure the controller dust filter is clean. This is a plastic frame and foam filter on the metal box on the bottom, left of the CNC.
Pull it off, check it, clean it if necessary, then reinsert it.
When reinserting the filter, be careful that the foam dust filter doesn't fold over or otherwise leave a gap that will allow dust into the controller.
Plug in the CNC to the wall outlet.
Turn on the controller by pressing the green physical button on the front.
Make sure the E-STOP (the red and yellow physical button) on the controller is pulled out.
Turn on the CNC laptop. Do not turn on the CNC laptop before turning on the controller, or the CNC softare
Start CNC 12 Mill on the laptop.
Every time you power down or E-STOP the machine you will need to reset home when you try to use it again.
The previous CNC operator should have parked the CNC, leaving the spindle near the back, left corner of the machine, about 1 inch from the hard limit switches.
If they did not, first use the manual jog GUI buttons on the CNC 12 Mill GUI to move the spindle to the back, left corner the bed before clicking the "Reset Home" GUI button.
ALWAYS start any manual jog by moving the spindle upward several inches, to avoid any possibility of hitting anything else when moving the spindle.
The reason for using the manual jog GUI buttons to move the spindle to near the back, left corner before clicking the "Reset Home" GUI button because the reset home process moves the spindle very slowly (20 inches per minute) and it will take quite a long time to finish resetting home if the spindle is not already near the back, left corner.
When you click "Reset Home" the CNC will slowly move the spindle to the back, left corner, until each of the Y, X and Z carriages activates their respective hard limit switches. The CNC will use this to determine the precise location of the spindle and then will set soft limits so that operating the CNC will not hit the hard limits.
The CNC will back off about a quarter of an inch from the hard limit switches after resetting home.
Use the manual jog UI buttons to move the spindle to a convenient working location, usually near the front of the bed.
Make sure red physical button on the spindle is in "off" position
Select a bit and a collet.
The Forest Scientific trainer said the most frequent cause of injuries is cuts to your fingers from handling the bits, which have very sharp edges. He recommends the following procedure for installing the bit in the collet.
Insert the sharp end of the bit into the collet from the back (threaded end) of the collet.
Holding it all by the collet, press the back end of the bit against the bed and use that to push the bit through the collet until all of the flutes are exposed.
IMPORTANT: The bit flutes (cutting edges) should never be inside the collet when you install the collet in the spindle.
Give the yellow knobs on the dust hood plate a quarter turn to release the dush hood brushes, so you can more easily see what you're doing. Set the dust hood brushes aside.
Insert the threaded end of the collet into the spindle.
The spindle does not have a button to lock it in place to allow one-handed tightening of the collet.
Use the two flat wrenches included in the bit kit to tighten the collet.
Leave the dust hood brushes off for now, until you finish zeroing the bit to work piece.
Turn the red physical button on the spindle back to the "on" position.
Make sure the "Auto" GUI button is enabled.
Install spoilboard and work piece
Before cutting a design on the big CNC, set up an auxiliary "spoil board", a sacrificial sheet of wood to protect the CNC bed. Fasten the spoil board down to the bed with 1/4 x 20 Brass Machine Screws at the perimeter. Then attach your project to the auxiliary spoil board.
Note: Members should ONLY use brass screws to anchor things to the auxiliary spoil board. Members should ALWAYS do the following:
- ALWAYS use brass screws and brass screws ONLY.
- NEVER use steel screws or anything harder than brass.
- ALWAYS use an auxiliary spoilboard.
- ALWAYS use 1/4 x 20 brass machine screws to anchor the auxiliary spoilboard to the main bed.
- ALWAYS use brass screws and ALWAYS with a pilot hole, to anchor the work piece to the auxiliary spoilboard.
CNC Bed: The CNC bed or main spoil board is the MDF board that is permanently attached to the CNC frame.
Auxiliary spoil board: An auxiliary spoil board is an additional board, secured to the main spoil board. This is often described as a "sacrificial spoil board". The purpose of the auxiliary spoil board is to avoid damage to the CNC bed.
The accuracy of the machine is affected by any unevenness in the surface of the CNC bed, so avoiding damage to the CNC bed is important. The CNC bed can be resurfaced and even replaced, but it takes extensive time and effort and members should take the above steps to make replacement infrequent.
Brass screws: The reason to use brass instead of steel screws is that the brass is soft and the router bit will cut the brass, rather than vice versa. If you break a steel bit off in MDF, we will be unable to resurface the MDF using the fly bit.
Pilot holes: When attaching anything to the CNC bed, always use an existing pilot hole or drill a new pilot hole, rather than simply screwing into the CNC bed. Screwing into the CNC bed without a pilot hole causes the MDF to bump out, which makes it impossible to properly fasten an auxiliary spoil board to the CNC bed.
Always use a spoil board to protect the CNC bed.
Zero the Work Piece
Generally you will find it easier to do these next steps with the dust hood brushes removed, to make it easier to see the bit in the spindle. The dust brushes should have been removed and left off when inserting the bit and collet into the spindle.
The work piece home, or origin point of your design, as mentioned in the "Create and Export Your Design" section, will be set in the software you use to create the design and you should have made a note of it.
Most commonly the work piece home will be the front, left corner of the design and the rest of this section will assume that. Correct the directions below to match your design's work piece home.
ALWAYS first park the head. This ensures that you're starting the work piece zeroing from a known starting position.
From the home screen of CNC 12 Mill, press F10 for the Shutdown menu, then F1 for "Park", then click the green "Start Cycle" GUI button.
Next use the manual jog GUI buttons to move the spindle so the center point of the bit is above the work piece home, which is usually near the front, left corner of the design.
Use the tortoise/hare GUI button to change to fine control for fine adjustments to the bit's location until the bit is properly positioned.
Note: If you prefer, you can break this X, Y zeroing process into two steps, first centering the bit over the front edge and setting the X axis zero, and then centering the bit over the the left edge and setting the Y axis zero. This description assumes you're positioning the bit for both the X and Y axis zero at the same time.
From the home screen of CNC 12 Mill, press F1 for the "Setup" menu, then F1 again for the "Part" menu.
At the center of the GUI it should have the coordinates of the X axis highlighted in yellow, with the name of the axis ("X") to the left.
Press F10 to set the current position as the work piece X axis zero.
Press F1 to move to the Y axis, the coordinates will change and the name of the axis ("Y") will appear to the left.
Press F10 to set the current position as the work piece Y axis zero.
Press F1 again to move to the Z axis; DO NOT press F10, you will use the Z axis Zero Block (aka TTO, Tool Touch Off) for that.
Also, DO NOT press the ESC key, the following instructions assume you're at the same place in the GUI where you finished seting the work piece Y axis zero.
Use the manual jog GUI buttons to first raise the spindle up a few inches, then move it inward, towards the center of the work piece.
Check that the Z Zero Block cable is plugged into both the block and the controller.
Place the Z Zero Block on top of the work piece and center it under the bit.
Press F4 for "Auto" and click the green "Start Cycle" GUI button.
The CNC will lower the spindle until the bit touches the Z Zero Block, then raise it back up.
DO NOT press F10 to set the Z axis, the Auto process already did that for you.
Use the manual jog UI buttons to raise the spindle a few more inches, then remove the Z Zero Block and place it back on top of the controller.
Pre-flight the job
Repeat these steps before each job that you run.
Check that the controller filter is still clear. Clean it if necessary.
Check that the CNC is plugged in.
Check that the green physical button on the controller is on.
Check that the E-STOP on the controller is off (pulled out).
Check that the red, physical button on the spindle is set to on.
Turn on the Dust Control system, located behind and to the right of the CNC.
Run the job
Make sure you have proper safety gear (safety glasses required, hearing protection recommended).
Make sure the "Auto" GUI button is enabled.
Load the job file exported from VCarve.
Simulate the job and check that the bit's path will not hit any of the holddown clamps.
Turn on the dust collector.
Click the green "Cycle Start" GUI button.
Monitor the job until complete.
Press any keyboard key to pause the job if necessary. Click the green "Start Cycle" GUI button to resume the job.
Hit the E-STOP in case of emergency.
Note: Do not hit the E-STOP button for non-emergency reasons. Usign the E-STOP will require starting the entire job over again, and it's possible that hitting the E-STOP can damage the machine due to inertia.
Park, Shutdown, Unplug and Clean CNC
When you are done using the CNC, Park the CNC.
From the home screen of the GUI, Hit F10 for for "Shutdown", then F1 for "Park", then the green "Cycle Start" GUI button.
If nobody is using the CNC after you, shutdown the laptop, turn off the CNC using the red physical button on the controller, and unplug the CNC from the wall outlet (behind and to the right of the CNC -- remember all directions are as seen facing the front of the CNC).
The dust collector should have got the majority of the sawdust created using the CNC, but clean up the remainder using either a shopvac or the dust brush from the sawstop.
Background, Inventory, Capabilities and Maintenance
Here's a basic terminology/anatomy-of-a-CNC.
- aluminum T-slot channel
- linear guide rails
- linear guide bearings
- gantry aka Y axis carriage (rides on the rails)
- X axis carriage (rides on the gantry)
- Z axis carriage (rides on the X axis carriage, carries the spindle)
- hard stop switch AKA hard limit switch
- dust hood
- dust hood plate
- dust hood brushes
- work piece
- holddown clamps
- dust collector
TODO: Add definitions/photos/diagrams of CNC parts
There are a lot of parts and it's hard to describe any one part without mentioning how it relates to the other parts, so I'll try to give a quick overview here. Someday soon we'll add a diagram and/or phot with labels.
There are several other styles of CNC. This is a router CNC aka a gantry CNC. You may also hear the term "mill" used. Generally speaking "router" seems to come from the woodworking world and "mill" seems to come from the metalworking world. Router CNCs carry a strong connotation of working on flat materials while mills are more for 3-dimensional work. The MakerFab has 8 1/2" of travel in the Z axis but I'm going to generally refer to it as a router CNC in this document.
Routers use router bits, mills use endmills. In this document I'll generally use "bit".
The whole point of all of this is to move the cutting bit in the X, Y and Z dimensions according to a preprogrammed path, to cut wood or other materials.
Everybody Has Axes To Grind
The CNC has 3 axes, the Y (96" horizontal), X (48" horizontal) and Z (8 1/2" vertical) axes. There are Y, X and Z carriages that move along these axes, and electric motors to make them move.
The metal tube steel frame holds the wood MDF bed which holds the piece you're working on.
The frame also holds the Y rails that the Y carriage rides on.
The Y carriage in turn holds the X rails that the X carriage rides on.
The X carriage holds the Z rails that the Z carriage rides on.
The Z carriage holds the spindle, the motor that makes the bit spin.
Note: the Y carriage is sometimes called the gantry.
Spindle and Bit
The spindle is mounted in a metal tube, and a dust hood plate is bolted around that metal tube. The dust hood plate and the dust hood brushes attached to it keep the wood dust mostly confined to a small space so the dust collector vacuum can suck it away.
The bit is a spinning, cutting blade, like a regular woodworking router bit. The bit is similar to a drill bit, but both the bit and the motor that spins it are designed to cut sideways, i.e. to cut and endure lateral force, force in a direction that's perpendicular to the axis that the bit is spinning on. It can also plunge, cutting in a vertical direction.
The bit is held in a small piece of metal called a collet, which is then installed into the spindle.
Linear Guide Rails
The Y axis linear guide rails run along either side of the bed, along the long dimension of the CNC, the Y axis. The Y carriage rides along the grooved top of the linear guide rails to keep it on track, while there is a rack and pinion along the bottom of the rails that controls the motion. Do not touch the linear guide rails, as skin oils can cause problems. See "Rails Maintenance".
The part of the Y carriage that makes physical contact with the linear guide rails are called the linear guide bearings. They are protected from dust and other contaminants by black rubber seals on either side of them, which conform to the shape of the linear guide rails. They are lubricated internally by grease, which occasionally needs to be refilled via the grease ports on the carriages. See "Grease Ports".
Each set of rails is also equipped with "hard limit switches" aka "hard stop switches". These are literally hardware switches that the different carriages will make physical contact with if they go to far. The CNC uses these when you do the "Reset Home" command to figure out the physical relationship between the carriages and the rails. Then it sets "soft limits" or "soft stops", meaning it makes a not in software of where the hard limits are and stops before getting to that point.
Limit switches AKA stops are important to know about because you'll be using them when you "Reset Home" at the beginning of each use of the CNC, and because they're sometimes a source of errors when the design you load into the CNC requires the CNC to travel past those "soft limits".
The bed is what you fasten your spoilboard and work piece to. The work piece is the piece of material that you're cutting. The spoilboard is a sacrificial board that you fasten to the bed, then fasten the work piece to the spoilboard. The spoilboard is there to give you a margin of error when cutting all the way through some material, so the bit doesn't cut into the bed itself. The bed can be replaced and is to a certain degree considered a consumable, but it's a significant amount of work and expense to replace the bed. It's much easier and cheaper to replace a spoilboard.
The bed has slots cut into it and metal T-slot channel embedded in those slots. You can slip holddown clamps into the T-slot and slide them to where you need them to be, and then tighten them to hold a spoilboard or a work piece.
The CNC itself was used to cut the slots in the bed for the T-slot channel, so you can count on the T-slot channel being aligned with the Y axis movement of the CNC and use the channel for reference when lining up work pieces.
Controller and Laptop
The motors that move the spindle around are mounted on the Y, X and Z carriages, but they're all controlled from the controller, the metal box bolted to the front, left, bottom of the frame.
The controller in turn gets its commands from software running on the laptop that's on the laptop stand at the front, right, top of the frame.
- grease gun & GADUS grease tube
- Z Zero Block aka TTO (Tool Touch Off) and cable
- 1/4" collet
- 1/2" collet
- 3/8" collet
- 1/2", 2 flute, up spiral carbide bit (24-102-0885P)
- 1/4", double-ended 60/90 degree conical carbide bit (24-132-9002)
- 1/4", 10 degree, flat-bottom carbide bit (49-SLIN062)
- 1/4", down spiral carbide bit (49-SRD218)
- 1/4" allen wrench
- 2 collet wrenches
- holddown clamps (4 large, 4 small) 400px
- Spindle (basically a router)
- controller (big bare metal box in base of CNC)
- laptop (front right of CNC)
- VCarve by Vectric (on laptop)
- CNC 12 Mill aka Centroid (on laptop)
To order replacements: 1-800-956-4056
TODO: Add photos of all of the above.
HackPGH's large CNC is a Forest Scientific MakerFab 4x8, with a cutting area of 48" x 96". The front and back are open to allow feeding longer pieces through. The MakerFab uses a Port Cable spindle, model #75182. It uses the Porter Cable collet system and comes with collets for 1/4", 1/2" and 3/8" shank bits. The MakerFab uses Centroid controller software. The MakerFab 4x8 is capable of cutting wood, aluminum (at very slow feed rates) and foam and composites.
- X axis range 48"
- Y axis range 96"
- Z axis range 8.5"
- Maximum feed rate 160"/minute
- depending on material;
- 50" to 80" for wood is typical
- 2" is recommended for aluminum
- depending on material;
- Spindle Motor Model#: 75182 (Porter Cable)
The spindle uses Porter Cable proprietary collets. The machine comes with collets for 1/4", 1/2" and 3/8" shank bits.
Spindle Speed and Feed
The spindle speed is fixed in this CNC, that is it cannot be automatically changed by the CNC 12 Mill software.
You can change spindle speed manually by adjusting the setting on the spindle hardware itself. Obviously you must do this while the CNC is NOT operating.
Changing the spindle speed is not generally recommended.
The feed rate (how fast the spindle moves in relation to the work piece) is set in VCarve when you design the job.
The maximum feed rate of this CNC is 160". It is not generally recommended to go that fast.
40" to 50" is a conservatively safe rate for wood.
2" is a conservatively safe rate for aluminum.
As a rule of thumb, if you are hearing any sound come from the cutting itself, i.e. from the physical interaction between the bit and the material, then you're doing something wrong.
Collets and Bits
The CNC comes with 3 collets, a 1/4", 1/2", and 3/8".
The collet is the piece that holds the router bit and is in turn inserted into the router.
The collets are a Porter Cable proprietary collet type, ER.
The CNC comes with 4 carbide router bits, but router bits are considered consumables; members who want to use the Forest Scientific CNC are expected to purchase and bring their own router bits. The 4 router bits that came with the CNC are:
- 1/2", 2 flute, up spiral bit
- 1/4", double-ended 60/90 degree conical bit
- 1/4", 10 degree, flat-bottom bit
- 1/4", down spiral bit
IMPORTANT: The bits are very sharp and you will quite likely cut yourself if you're not careful when handling the bits.
IMPORTANT: The bits are shipped sealed in wax to protect them. Peel the wax off with your fingers before using the bits.
The trainer said the 10 degree, flat-bottom bit is not often that useful.
The down spiral bit results in cleaner edges on the top side of the cutting surface.
To clean up the rough edges from an up spiral bit, re-run the program with the same bit.
The CNC comes with a 1/4" allen wrench for tightening/loosening the allen bolt at the back left corner of the dust hood.
The dust hood holds brushes around the cutting area to keep dust confined until it's sucked away by the dust control vacuum.
The dust hood consists of a flat aluminum dust plate with black brushes, bolted to the bottom of the spindle.
There is a 1/4" allen nut on the left side, back corner of the dust plate. The CNC comes with a 1/4" allen wrench for adjusting it. This allen nut loosens the dust plate.
Generally speaking you should not need to adjust the dust hood. The dust plate should be tight (no wobble) and it should be high enough not to contact the work piece when the bit is cutting.
The yellow knobs on the dust plate allow you to easily remove the brushes to make it easier to see what you're doing when swapping out bits and zeroing the CNC. Just turn the knobs 1/4 turn to remove the brushes.
Controller Physical Switch
The front of the controller has 3 physical controls: a green "on" button, a red "off" button, and a red and yellow E-STOP button.
If the E-STOP has been used at any point prior to this, or the CNC has been unplugged, you will have to click the Reset Home GUI button before Start Cycle will work.
The E-STOP cuts power to all the things that move on the CNC (e.g. servo motors, spindle, tc). It does not power down the controller or laptop.
IMPORTANT: While the CNC is running a job, ONLY use the E-STOP button in an emergency. The E-Stop stops the CNC abruptly and that has a chance of causing damage to the CNC due to inertia, etc. It will definitely lose your zeroing and home position and make it impossible to resume the job.
Even if the CNC is not running a job, you should avoid using the E-STOP unless necessary, because doing so will lose your home position and zeroing.
IMPORTANT: Always, always, always use a spoilboard. This is essentially a sacrificial board, ideal of MDF, clamped to the machine's main bed and then the working piece board is secured to the spoilboard. CNCs often cut all the way through the work piece and then some extra. The spoilboard's purpose is to take the extra cut, so the main bed does not have to.
Axes, Home aka Datum aka X,Y Zero
The CNC needs reference points or starting points. Two of those reference points are the "machine home" and the "work piece home". In addition, most CNCs have a "park" command that sends the carriage to a particular location for shutdown.
The machine home is usually set permanently and is a starting point that the machine uses as a reference to figure out where the cutting head is after moving.
The work piece home is usually something you set for each job. You need to know where the work piece home to make sure the work piece is arranged properly where the cutting edge needs to go.
IMPORTANT: The controller has a vent and the vent has a plastic foam dust filter that must be cleaned when it's dirty. Pull off the black, plastic frame, remove the foam and clean it with a vacuum cleaner.
IMPORTANT: Be careful when reinserting the filter, make sure that the foam is smooth and covering the entire area of the vent. The Forest Scientific trainer (Tyler Blair) said this is a problem that occurs frequently.
IMPORTANT: Do not lean on or otherwise touch the rails with your hands. Skin oil on the rails will cause problems.
If the rails get any rust (e.g. due to humidity, etc), clean them with WD-40 and a green Scotch Brite pad.
IMPORTANT: Make sure it's a GREEN Scotch Brite pad only, the other colors are harder and more likely to cause damage to the rails.
Z Zero Block aka TTO
The CNC comes with a Z Zero Block aka TTO (Tool Touch Off).
This is an aluminum block with a cable connecting it to the processor in the bottom of the CNC.
The CNC has been pre-programmed with the height of the TTO.
Always leave the TTO plugged in.
IMPORTANT: ALWAYS start each job by zeroing the X, Y and Z axes. See below.
The CNC comes with a grease gun and a tube of Shell brand GADUS grease.
The CNC has 10 grease ports; 4 on the Y carriage, 4 on the X carriage, and 2 on teh Z carriage. They need to be refilled occasionally, approximately every 40 hours of continuous use or roughly once a month.
Use ONLY Shell GADUS grease, mixing grease types leads to problems.
To refill the grease just give it 1, at most 2 pumps.
More than that will cause the grease to leak out.
If grease leaks out, clean it up, otherwise sawdust will stick to it and it will cause problems.
The grease is used to lubricate the rails and make the machine move more smoothly.
Kept here for notes and additional information. The content below might be merged into the above version at a later date.
CNC 12 Mill Software
1) Turn on the controller before starting the CNC 12 Mill software, or the CNC 12 Mill software won't be able to find the controller.
2) Start CNC 12 Mill, aka Centroid, on the laptop.
TODO: Insert photo of CNC 12 Mill UI with labels.
The CNC 12 Mill UI is a bit old-fashioned. Some key details:
The green button on the right side, middle of the UI is the "Start Cycle" button.
The "auto" button is "Auto Spindle". When turned on it allows CNC 12 Mill to automatically turn on the spindle.
IMPORTANT: There is a red hardware on/off button on the spindle. When set to off it is impossible for the spindle to power up.
Make sure this is turned off when you are changing bits or otherwise working directly with the spindle.
Make sure this is turned on when you want to use the spindle.
3) If the previous user failed to properly park the CNC, use the "manual jog" buttons on the CNC 12 Mill UI to move the head of the CNC near to the home position, which is the back, left corner.
TODO: "reset home" notes "home" is when it contacts all 3 of the physical limit switches. home is the back, left corner, where the hard stop aka soft limit, aka where the gantry hits the physical limit switch soft stop (aka soft limits) is a quarter of an inch before the hard stop "parked" is near home, an inch or two back from the physical limit switches
Prior to shutting the machine down, F10 for shutdown menu, F1 for Park, Green Cycle Start
ALWAYS reset home when you first turn on the machine.
IMPORTANT: Always first move the spindle up so you have a few inches clearance between the end of the bit and anything on the bed of the CNC before using the manual jog buttons to move the spindle in the X and Y axes.
The "reset home" GUI button moves extremely slowly, so you want to move the head near the home position before running the automatic home.
The CNC 12 Mill motor speed buttons do not work on this spindle. There are manual controls directly on the spindle to adjust spindle speed, but for the most part the defaults should be fine.
CNC 12 Mill is currently set to imperial units, i.e. English units, i.e. feet and inches.
Preparing Your Design for the CNC
TODO: This section is very sketchy and needs to be fleshed out or more likely link to a more in-depth resource.
VCarve or Fusion360 are popular programs for preparing a CNC design.
HackPgh has licenses for both.
TODO: Check on licensing.
You export your design from the program (VCarve or Fusion360) to gcode. Different machines take subtly different dialects of gcode. When you export, you choose the gcode dialect that matches your machine, in this case Centroid.cnc.
It's also important to make note of where the home or origin point of the design is. I.e. when you set the home on the work piece, is that going to be at the lower, left corner of the design, lower right corner, upper left corner, back corner?
This is configurable in the program you use to create the design.
VCarve, by Vectric is the drawing program you use to compopose your CNC design.
Contact the board for a license for VCarve.
Tabs: VCarve can be set to include tabs in the design. These are small connections between the pieces, to keep the pieces from moving once they're entirely cut free. This is generally an important detail for safe operation of the machine, as loose chunks of wood can cause problems.
The Forest Scientific trainer said that 0.3mm x 0.3mm tabs seem to work best.
I believe that for Fusion360, you can download and use the free version, then bring your design in and use the licensed version on the HackPGH computer cluster to export your design to gcode.
FIRST DRAFT Running a Job
This assumes you have already designed your job in VCarve and exported it to the proper gcode dialog for use in the CNC (Centroid.cnc).
0) Install a spoilboard and fasten the work piece to the spoilboard. A common approach is to screw the work piece to the spoilboard using drywall screws short enough that they won't go through the spoilboard, into the CNC bed.
Recommended fasteners are drywall screws, brass screws, plastic nails, or double-sided tape. The key point is to use less durable fasteners that will be less likely to cause damage to the CNC or bit.
1) Make sure the controller is on, then open CNC 12 Mill on the laptop.
2) Use the "manual jog" buttons to move the spindle to a convenient spot so you can work on it.
IMPORTANT: Always first move the spindle up so you have a few inches clearance between the end of the bit and anything on the bed of the CNC before using the manual jog buttons around in the X and Y axes.
3) Use the physical red button on the spindle to turn off the spindle, so it's safe to change the bit.
IMPORTANT: Do not press the yellow and red E-STOP button when adjusting the bit. With the E-STOP activated, the spindle willmove freely and it can throw off settings.
4) Take off the brushes so you can see what you're doing with the bit and collet.
Reminder: The yellow knobs on the dust hood allow you to easily remove the brushes to make it easier to see what you're doing when swapping out bits and zeroing the CNC. Just turn the knobs 1/4 turn to remove the brushes.
IMPORTANT: The bits are very sharp, you are likely to cut yourself if you don't handle them properly.
IMPORTANT: The bits are shipped sealed in wax to protect them. Peel the wax off with your fingers before using the bits.
5) Insert the bit into the collet.
The recommended way to insert the bits into the collet is to position the end of the bit in the collet, then carefully turn the collet and bit over, hold everything by the collet, press the working end of the bit against a piece of wood (e.g. the spoilboard) and apply moderate pressure to push the bit into the collet.
To remove the bit when done (or when removing the bit still in the spindle) use a similar motion, hold everything by the collet and press the working end of the bit against a piece of wood and apply moderate pressure to push the bit all the way through the collet.
TODO: Add photos of collet & bit, bit insertion process, bit removal process, collet tightening process.
6) Insert the collet-and-bit into the spindle and tighten it using the two collet wrenches. This spindle does not have a mechanism to lock the spindle's rotation, so you will need to use both wrenches when inserting or removing the collet. Use one wrench to hold the spindle from rotating and the other wrench to tighten or loosen the collet in the spindle.
7) Use the "manual jog" buttons on the CNC 12 Mill UI to move the spindle to the "home" position, at the back, left corner of the CNC bed.
TODO: Add screen shots to all of these steps.
8) Zero the X and Y axe by pressing "F10 Shutdown" and "F1 Park", then press the green "Start Cycle" button.
IMPORTANT: ALWAYS zero the axes before starting ANY job. The Spindle can and is quite likely to be moved freely when the system is powered down, and that throws off the homing.
Note: Pressing F3 at the main screen of the CNC 12 Mill brings up the manual gcode prompt. If you're knowledgable with gcode you can then use gcode commands to move the spindle. However, this is generally an advanced topic.
9) Use the "manual jog" buttons to move the spindle to the zero point on the work piece, i.e. the front, left corner of the work piece.
10) Use the CNC 12 Mill UI to adjust the amount that the jog buttons move the bit to finer control, and then adjust the bit's location so that the center point of the bit is right over the front, left corner of the work piece.
11) Press the ESC key a few times to make sure you're back at the first/main screen of the CNC 12 Mill UI.
Note: If you prefer, you can break this X, Y zeroing process into two steps, first centering the bit over the front edge and setting the X axis zero, and then centering the bit over the the left edge and setting the Y axis zero.
12) Zero the X and Y axes to the work piece.
Press F1 for "Setup" menu and then F1 again for "Part" menu.
This should cause the X axis to be highlighted in yellow on the UI.
Press F10 to set the current position as the X axis zero.
Press F1 to highlight the next axis, the Y axis.
Press F10 to set the current position as the Y axis zero.
Press F1 again to highlight the next axis, the Z axis.
13) Zero the Z axis.
IMPORTANT: Always first move the spindle up so you have a few inches clearance between the end of the bit and anything on the bed of the CNC before using the manual jog buttons to move the spindle around in the X and Y axes.
Use the "manual jog" buttons to raise the spindle up a few inches, then in towards the center of the work piece.
14) Place the TTO block under the bit, on top of the work piece.
15) Press F4 (Auto) and click the green "Start Cycle" button.
The CNC will lower the spindle until the bit touches the TTO block, then raise it back up.
DO NOT PRESS F10 to set the Z axis, the Auto process already did that for you.
16) Remove the TTO block from the work piece and set it back on top of the controller.
17) Now that you're finished with zeroing the bit, reattach the dust hood brushes to the spindle.
18) Load the job file you exported from VCarve.
Press F2 to get the load file dialog.
Select the file you exported from VCarve.
Check the job name.
NOTE: It's a good practice to save job files using key details in the file name, like what dialect of gcode you exported as and the dimensions of the piece, and whether the design uses English or metric units.
IMPORTANT: Make sure that the VCarve design and CNC 12 Mill are both set to use the same sort of units, i.e. English or metric. CNC 12 Mill is currently set to imperial units, i.e. English units, i.e. feet and inches.
19) Press F3 to simulate the job on the screen.
Look at the simulation to confirm that it's the job you want.
20) The simulation includes the expected path of the spindle as a red line.
From looking at this red line you can determine where the CNC thinks the spindle is. Check that and confirm that it matches the spindle's actual location and the work piece.
Use the "manual jog" buttons to move the spindle to each of the holddown clamps in use, and check the red line on the simulation to confirm that the Spindle path will not hit any of the holddown clamps.
When you've checked all of the possible collisions, Use the "manual jog" buttons to move the spindle back to near the X and Y zero of the work piece.
21) Make sure the physical red on/off switch on the spindle is set to "on".
22) Make sure the "Auto" button in the CNC 12 Mill UI is on.
23) Turn on the dust collector, which is behind the CNC, against the wall.
TODO: Add photo of dust collector.
24) Click the green "Start Cycle" button to start the job.
Note: If the E-STOP has been used at any point prior to this, you will have to click the Rest GUI button before Start Cycle iwll work.
IMPORTANT: You MUST monitor the CNC while it is in operation, and be prepared to pause the job (see below) or, in an emergency and ONLY in an emergency, hit the big red and yellow E-STOP button.
IMPORTANT: When the job is running, pressing ANY key on the laptop keyboard (spacebar, enter, letter keys, etc) will pause the job and turn off the spindle. You can resume the job by clicking the green "Start Cycle" button in CNC 12 Mill.
IMPORTANT: While the CNC is running a job, ONLY use the E-STOP button in an emergency. The E-Stop stops the CNC abruptly and that can cause damage.
IMPORTANT: Even if the CNC is not running a job, avoid pressing the E-STOP button unless necessary. With the E-STOP activated, the spindle will move freely and it can throw off settings.
Notes Not Yet Integrated Into The Above
This section contains random bits from my notes that don't fit in anywhere else.
They may be redundant or irrelevant.
A usual task with CNCs is zero-ing the three axes, i.e. setting the starting location, the (0,0,0) for the X, Y and Z locations.
The Z (height) axis in particular often needs to be set, and with this CNC, the (X, Y) origin also needs to be set for each job.
TODO: CW recommends zeroing to the top of the spoilboard. Tyler recommends zeroing to the top of the work piece. In reality there is no one-size-fits-all answer, it depends on the job.
TODO: Get some examples of different use cases and describe them here. What is the critical final dimension; in engraving the top surface of the workpiece is the critical depth; in through cutting the bottom surface of the workpiece, aka top surface of the spoilboard is the critical depth.
(X,Y) datum position, aka zero position of the work piece (not the spoilboard or the main board).
additions and corrections
TODO: This section contains new notes that have not yet been integrated into the main body of this page.
Review and normalize use of "reset home", "zero", etc. Pick one and use it consistently, but also explain the variations at some spot.
plug in wall power when starting, unplug when done
brush CNC bed with sawtable brush when done
we have 1mm to 7mm collets (tupperware of yellow blocks)
we have a collet extender
jog GUI buttons, tortoise mode & hare mode, in tortoise mode when lit, click to unlight and switch to hare mode
rapid (hare) motion is 350 inches per minute
slow (tortoise) motion is 20 inches per minute
make sure bit flutes are not actually inside the collet when you tighten collet
important to know where the work zero aka work origin aka work program home is, e.g. bottom left corner, bottom right, etc. This is set vcarve/fusion/etc
There are two sets of cycle stop/start buttons, the ones by the jog GUI buttons are for general CNC operations, the other set is for the spindle only.
cycle start is green containing white line
cycle stop is red containing white circle
cycle stop stops and cancels the program
feed hold pauses the program
to Z zero, position the Z block, click auto, click green cycle start GUI button,
GUI will prompt you to check that the Z block is set up properly
visually confirm that it is and then click the green cycle start GUI button again
after doing auto Z it leaves the bit on the surface of the TTO block so use jog GUI buttons to raise it
our spindle always turns clockwise
our spindle is fixed speed, spindle speed override GUI does nothing
After you hit F8 for simulate you can hit F1 to get a 3D render
incremental mode, when lit the 1X, 10X and 100X control how far the jog GUI buttons move the head, it's 1/1000th, 10/1000th, 100/1000th. When not in incremental mode these buttons do nothing.
auto for spindle is the white button with auto spindle man, top of the screen
when running the job, you hit green once, it renders, you hit green a second time to actually start cutting
simulate is actually "graph mode"
when in graph mode, F8 will toggle between the rendering and the gcode display
to shutdown, F10 and then F1 to park, then green to start
Don't use power off/F2 because that will shutdown the laptop
TODO/check on these things
My first set of notes has a warning to park the CNC before each job, so the CNC is starting from a known good position. Need to confirm whether this should be Park, or is it really supposed to be Reset Home?
I'm keeping links to these photos here until I inline them where appropriate above.