Beginner and Pre-Purchase FAQ |
Q: What is a CNC machine?
A: CNC stands for Computer Numerically Controlled and basically means a robotic tool which is controlled by commands sent from a computer. In the Buddys case it can move in 3 directions (axis) simultaneously. These are referred to as the X, Y and Z axis and correspond to the standard system of specifying 3D space using Cartesian co-ordinates. This means that be sending the machine a set of 3 co-ordinates it can be moved to a position that corresponds to those. In reality a CNC machine will process many of these commands each second and the movement will appear to be seamless. The file which contains the co-ordinates is typically known as a Toolpath and for a ShopBot this will have a .sbp file extension. This is generated from the Design software (PartWorks or PartWorks 3D) and is processed and sent to the machine by the Control Software. |
Q: How does the machine know how to cut my part?
A: A 2D CAD/CAM software, PartWorks, comes with a ShopBot machine. You will draw your parts in this software, then from this geometry you will use the software to create a “toolpath” for them. You do this by choosing a cutting tool and the type of cutting strategy you wish to use (profile, pocket, drill etc.) – you will also need to specify depths of cut and other parameters for the cut. Once you have calculated this you can preview it within PartWorks to make sure it looks correct (3D shaded preview lets you see exactly what you will get). Once verified you will save this file as a ShopBot Part File (.sbp) which is loaded into the Control Software and this is the co-ordinate information that is automatically communicated to the machine and tells it exactly what to cut. |
Q: What is meant by 2D, 2.5D (2 ½D) and 3D cutting – what is the difference?
A: Typically a 2D cut refers to a toolpath which moves first to a specified Z depth (vertical move) and then moves only in X and Y (horizontally) to cut a shape or area. A 2.5D move typically refers to something like V-Carving which when finished will have created a 3D shape but does this using 2D outlines combined with a tool of a specific shape rather than actually cutting a 3D computer model. A 3D toolpath typically refers to something which is actually a bas-relief when finished (rather than a completely 3D object), it uses a dimensional computer model to define the toolpath which runs back and forward over the model to create the final part normally with a Ball-nosed cutter. A lot more can be read about this subject on this page on the SB main site: http://www.shopbottools.com/3-d_work_v2.htm |
Q: Can I get the Buddy into my basement?
A: It will fit through a standard 36” door, provided there are no walls in close proximity because you need to angle it to get it through the door. Also, it weighs 600 lbs. so getting it safely down stairs is a big consideration too. If you plan on doing this you should take careful measurements and contact ShopBot for specific size information |
Q: How do you hold your parts in place while they are being cut?
A: There are many ways to hold a part in place on a ShopBot and often it will depend on the particular job requirements, the material and what options you have available (such as if you have a Vacuum hold-down). The most basic method is just to screw your work-piece down or clamp it to the sacrifice sheet (spoil-board) which is attached to your work table (or PowerStick). Some customers also develop specialized jigs and clamping methods for particular parts. You need to make sure whatever mechanical method you use that it will not get in the way of the toolpath and that if you are cutting your part out that something will be holding it in place when its cut out. This might be a screw through the part itself (although this would mean damaging the part) or it may be leaving small tabs (a function of the PartWorks toolpath) which hold the finished part to the waste material and can be easily manually trimmed off once the part is finished cutting. Other than manual hold-down methods the other main way to hold a part down is a Vacuum hold down. When setup correctly a Vacuum hold-down is surprisingly powerful and has the benefit of being quick to release (and activate) and not having anything to get in the way of the toolpath. It will also when used correctly hold the finished part in place when it is cut-out. There is a wealth of information on Vacuum systems in the ShopBot forum http://www.talkshopbot.com/forum and also here on the main ShopBot site: http://www.shopbottools.com/vacuumholddown.htm |
Q: Is the aluminum table on the Buddy considered the zero distance in the Z Axis' 5" total travel range, or did you still have 5" of total travel after you added a spoil board?
A: The 5" travel takes into account a 3/4" top added onto the aluminum bed. From this, one could calculate that anything over 3/4" would reduce the 5" total Z travel by the same amount. |
| Troubleshooting for Buddy Owners |
Q: What does Runtime error 91 mean in the ShopBot control software?
A: Check the regional settings on the computer. It must be set to English US to read commas and decimals correctly. |
Q: Why is my tool moving the wrong distance?
A: Check the unit values. The wrong default file may have been loaded for your tool so it is set to metric rather than inch or vice-versa. Type UR to reset this. |
Q: Tool doesn’t stop at the proximity switches.
A: PRS tools have a normally closed proximity switch. Type VN and verify that inputs 2 (X) and 3 (Y) are set to normally closed. If not, type UR and select the correct default file for your tool. |
Q: What are the power requirements for my HSD spindle? What gauge wire to I need.
A: We will provide you with the power requirements, but a qualified electrician will have to supply the correct gauge wire based on the amperage and the length of the cable run. The electrician will also know the local code requirements. |
Q: I can’t see the PartWorks file that I saved in the ShopBot control software.
A: If you only saved the file with the .crv extension then you only saved the vector data and can only open the file again in PartWorks. After calculating your toolpath, you must save the toolpath under toolpath operations. That will create the file with the .sbp extension that will open the control software. |
Q: I am running Windows Vista and I’m getting errors when I try to run my files.
A: Many problems with Vista can be solved by turning User Account Control off. |
| Glossary of Terminology |
The Machine |
PRSstandard
Stands for Personal Robotic System – Standard.
ShopBot PRSstandard is the basic control system that comes with a standard Shopbot machine. These tools use "open loop" stepper motors with low-backlash gearheads. These are the motors that were used in all our products until the introduction of our PRSalpha systems. The PRSstandard control system now utilizes the acclaimed Geckodrive stepper drivers and provides higher speeds, higher step resolution, and smoother cutting than our previous PRTstandard ShopBots.
The mechanical components of these PRS tools are the same as those shipped with our current PRSalpha CNC tools. If you later decide you would like the performance of a PRTalpha, you will be able to easily upgrade by adding PRSalpha Control System, drives, and motors. |
PRSalpha
Stands for Personal Robotic System – Alpha
ShopBot's new PRSalpha is an upgraded control system for customers with needs for very high speeds or a production environment. The Alpha control represents the next generation of CNC technology. With rapid transit speed of 1,500 inches per minute and cutting speed of up to 600 inches per minute (depending on cutter and material), ShopBot PRSalpha CNC tools give you performance and affordability. Where production speed is important, a PRSalpha is the tool. These ShopBots utilize the advanced technology of Vexta, alpha step motors, which combine the power and speed advantages of stepper motors with the feedback advantages of servos - providing high-performance CNC cutting, drilling, carving, and machining. |
Gantry
The mechanicals of the ShopBot. (PRT, PRS, Buddy) |
Proximity switch (prox switch, limit switch)
The X and Y axis of the ShopBot each have a switch and two targets. The switch is triggered when the target and the switch line up and the machine stops. The most common use of the prox switch is in the ShopBot homing routine. The homing routine [C3] is a program that uses the switch to keep up with your working zero. |
Z zero plate
A devise used as a switch in the z zero routine to locate a surface, reference it as zero/home position (for vertical movement). Once the routine touches off the plate it will pull the cutter up to a safe parking height. [C2] |
VFD
Variable frequency drive, or spindle controller. |
Operation |
Chip load
(or how you measure it) the size of the chip the tool is making. Correct chip load gives efficient machining and the best edge quality on your parts. |
Tolerance
This denotes the cumulative error which is built up when using a number of mechanical sources. This value is a measurement of how close to the actual defined co-ordinate/size of the part the machine will operate within. Example a Tolerance of 0.003 inches would mean that all parts cut should be within 0.003 of the size/shape specified within the software. |
Hold Down
Any device or method being used to hold a part (or spoil material). |
Plenum
The layer of your vacuum table with the grid of channels cut into it, typically the second layer on top of the base plate. |
Spoil Board
Any board under the material you are cutting that you might cut into (slightly). Also known as a “Sacrifice Sheet”. |
Software |
CAD
Computer aided drawing or design – typically denoted the software you use to layout your design in 2D or 3D. Example = PartWorks, VCarve Pro, Rhino, TurboCAD etc. |
CAM
Computer aided machining. Your CAM software looks at the drawing/model and calculates tool offsets and generates an offset path (Toolpath) for the cutter to follow. Your CAM software takes you toolpath and converts it into ShopBot code with a post processor. Example = PartWorks 3D, MillWizard, Vector Art 3D Machinist, VisualMill etc. |
CAD/CAM software
Has the ability to do both the design and the machining functions in one software package. PartWorks is both a CAD and CAM software package as it allows you to create the layout and also assign and save toolpaths. |
Toolpath
The path that the center of the bit will follow on the ShopBot. Your CAM software looks at the drawing calculates tool offsets and generates an offset path for the cutter to follow which is the toolpath. This is saved in an SBP format for transfer to the Control Software. |
Post processor
A software routine that converts virtual toolpaths from the CAD/CAM software into machine code for the ShopBot Control software to read. Save as an .sbp file. NOTE if you pick the wrong one you will get the wrong file!!!!! |
Cut File
A list of commands (the machine code that is your part). Has a file extension in .sbp (ShopBot Part) |
Control software (SB3)
The software the runs the ShopBot, executes part files, reads the code and moves the machine. |
