Machine Operation
Putting everything together to make parts and projects
Ideally everything for operating a machine would be covered at: https://my.carbide3d.com/ as well as: https://shapeokoenthusiasts.gitbook.io/shapeoko-cnc-a-to-z/ with the specifics of Carbide Create covered in 2D Drawing, Toolpaths, and (for folks with Pro licenses) 3D Modeling from 2D Geometry, and Carbide Motion covered in Machine Motion. This chapter will function as an overview of the entire process of making a part or project, making no assumptions.
The Shapeoko is a 3-axis CNC router made by Carbide 3D. https://carbide3d.com/
Design
Design will be done in either a 2D (e.g, Carbide Create as shown in 2D Drawing), or 3D program (such as Alibre Atom 3D, FreeCAD, &c.). Design elements may describe the geometry of the part/project, or may define the perimeter/structure of the part/project, or even describe the toolpath which will cut out some aspect of the part/project. Once a final appearance is arrived at, Toolpaths may be set up.
Toolpaths
Toolpaths will be created or assigned in a suitable CAM program (or by directly creating toolpaths by hand-coding G-code or directly programming), and like the design, will be either 2D or 3D. Note that it is possible to assign 3D toolpaths to 2D elements and vice-versa (cutting a 3D part free with a 2D perimeter cut). Toolpaths should be added/adjusted until the 3D preview of the toolpaths is correct.
Stock
The raw material is referred to as the stock. Depending on the nature of the cut, it may be necessary to have the stock precisely measured and entered accurately into the design file, or not. It will be necessary that the stock is securely clamped in place (see Workholding below) and the zero set relative to the stock so as to match how this is set in the G-code file.
Workholding
The stock must be securely held in place in the working area of the machine so that the origin may be set relative to it. There are myriad products and approaches. Considerations include:
access of the tool to the work and the ability of the tool to clear the workholding if need be
efficient usage of the stock
distorting the stock due to clamping pressure or cutting forces, or having it collapse in on the part as material is removed
how securely the piece is secured --- it must be fastened so as to not be displaced by cumulative cutting forces and vibration
When securing stock, options include:
mechanically clamping from above/outside the part
mechanically clamping from the sides
mechanically clamping using through holes (this can include the use of polymer nails)
using adhesives to secure the stock (a popular option is painter's tape on both the bed of the machine and the stock, fastened together using cyanoacrylate glue)
vacuum
It is possible for a single part/project to use multiple techniques (a typical one would be clamping from the side initially so as to drill through holes, then using those holes to fasten a part in place for the balance of the operations). When fastening it is important to consider leverage and the attendant principles. See: https://community.carbide3d.com/t/work-part-clamping-many-of-you-are-doing-it-wrong/3396
Machine Operating Checklist
Be safe — wear appropriate safety equipment (esp. eyes (safety glasses/goggles), and ears (hearing protection — at least foam ear plugs)), ensure clothing, hair and jewelry cannot become caught up in the machine. If necessary, arrange for dust collection and proper ventilation (if necessary, use respiratory gear suitable to the dust particles of the material being milled). Consider the possibility of the spindle starting a fire by friction and take suitable precautions (having a fire extinguisher handy, and planning for evacuation, or removal of the machine).
Check the machine (all bolts and set screws tight, V-rails/linear rails in good condition with no nicks or other damage, belts tight and in good shape, couplers and other hardware secure, linear rails and ballscrews well lubricated, wiring in good condition with continuity and securely fastened, and nothing frayed or broken, everything clear and safe). The bolted down, inverted belts which result when using the belt anchor clips make this somewhat difficult — use a mirror to examine the belts while moving the machine along its full range of movement. Note that it is especially important to check the machine after a crash or a failed cut or one which induces chatter or excessive vibration.
Secure the workpiece (right-side up and in the desired orientation) to the worksurface using a technique appropriate to the material (see Workholding). After securing the workpiece, be certain that the machine is still able to move — this is especially important on the Nomad where the through holes on the table create the possibility of a too-long bolt locking the table to the machine base.
Examine the End mill to ensure that it is sharp and in good condition and not chipped (this is best done with a loupe or magnifying glass), install it per the spindle manufacturer’s directions so that it projects at least as much as the deepest intended cutting depth, check to make certain that everything (including the shaft which the collet is installed in) is clean with no foreign material (which can cause runout or even break endmills), the collet is tight and will not work loose during operation (it needs to be more than hand-tight --- the machine will take no notice or care if it works loose) and the entire assembly is in good condition and spins truly.
Ensure the work area is clear and all cables, hoses, wires, etc. run without interference, and that they will not interfere with the machine motion, esp. when homing. Especially check that there is nothing beneath the rails which might interfere with motion.
Connect the machine to the computer --- power up PC, connect the USB cable, wait until the micro-controller boots up, start the comm/control program, turn on power for the machine, check that once plugged in and switched on there is a steady light on the power supply as well as the control board.
Initialize/home the machine, then jog to where the origin will be set relative to the workpiece and set the zero there, either manually, or using a BitZero (Probe)
If a BitZero (Probe) was used, be certain to remove the ground clip and secure it safely outside of the machine’s working area. Ensure that nothing has been left in the work area. (Optional: Traverse the working boundary of the job as a final check.)
Browse for the file which you will be cutting (note that this may be a .c2d or .nc (G-code) file) and load it, verifying the preview, and that the origin in the file matches where the origin was set relative to the stock. Start the job to send it to the machine, following all prompts for tool changes and starting the spindle as required and setting it to the correct speed and stopping it.
Monitor the machine while it operates, ensuring there is no build-up of dust, debris or fumes, and that nothing works loose, keeping clear of the work area. Do not reach into the machine’s working envelope, nor insert any object into it while the machine is operating. Once the job is complete, turn off the spindle, return the gantry to the home position, or a known offset from home and ensure the end mill has stopped spinning before removing the finished piece and any waste. Store endmills carefully when not in use so as to protect the edges. Collets and accessories should be cleaned between uses — wiped off with a suitable solvent such as isopropyl alcohol, and the machine itself cleaned/dusted/vacuumed and lubricated as necessary, not in particular that the interior shaft of the spindle must be cleaned.
One should keep a log of machine usage and note when adjustments are made, or a fastener is (re)tightened, as well as keeping a tally of usage time, including for specific bits, so as to determine when parts need to be lubricated, or bits should be relegated to rough work or resharpened or recycled and replaced. Similarly, one should record machine settings and the specifics of each tool chain which is used with the machine.
Safety and Precautions
The Shapeoko and Nomad are machine tools, and requires the same caution which should be exercised around any power tool. For the Shapeoko's typical configuration of a trim router cutting wood and plastic, the same sort of safety gear advocated for the trim router is suggested:
Eye protection — safety glasses or goggles which are suitably impact resistant
Hearing protection — ear plugs or muffs, for long jobs doubling these up may be desirable. Hearing damage is cumulative and irreversible, so one should err on the side of caution
Respiratory protection — a filter or respiratory mask suited to the dust generated by the material being cut should be worn, dust collection should if possible include a cyclone and HEPA filtration
Ensure clothing, hair, and/or jewelry cannot become caught in the machine, never reach into the machine’s working envelope while it is running — long sleeved shirts and pants and suitable footwear is suggested, when doing metal-working, gloves and an apron are recommended
Additionally
Use care when handling endmills, both to avoid being cut, and to avoid damaging them. Handling them with suitable gloves, or using a cloth to avoid contaminating them is recommended. Inspect them carefully before each use and ensure that they are securely held by the collet.
Never leave the machine running unattended/unsupervised.
Always inform someone before operating the machine and check in with them after successfully completing work.
Safely dispose of milling debris — recycle or safely dispose of milling debris and dust, keeping in mind flammability, (potential) spontaneous combustion, and chemical considerations. Even natural materials can have surprising implications for disposing of them, e.g., walnut wood dust is allelopathic (inhibits plant growth) and an irritant to the skin and breathing tract and potentially poisonous to some animals in addition to the typical spontaneous combustion hazard which sawdust poses.
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