KSA FAB LAB > CNC Routers

OVERVIEW

The ShopBot is a 3-axis CNC router. It is essentially an armature for moving a standard router through the normal 3 spatial axes (X, Y, and Z). It is capable of working with materials up to 4' x 8' x 6" in size. The router we have is capable of speeds ranging from 10,000 to 21,000 RPM.

The ShopBot is can function as both a cutting tool as well as a 3D object scanner. Cutting operations happen in two general modes - templating and milling. This page provides an overview of each type, and also describes the process of using the ShopBot.

Cutting Operations

Templating Jobs

A template cut is a cut along a profile, or template - typically done all the way through a material. Template cuts are vector operations similar to vector cutting or engraving operations done on the laser cutter. Templates are usually laid out in AutoCAD, and saved in DXF format. The ShopBot 3 software will then convert the file to SBP format using its built-in file converter. The resulting SBP file will then be executed by the ShopBot 3 software to produce the cut.

It should be noted that template cutting is typically - but not always - used to cut all the way through a material. Cuts can also be done to different depths in the same project by assigning different colors to each line; the conversion process will ask you to specify a depth for each color found in the source DXF.

A second option for template cutting is the ability to cut wider swaths of material. For example, an irregular area can be excavated evenly by the following process:

1. Draw a shape of the size you wish to excavate.
2. Offset that shape inwards by the radius of the router bit you will be using, and delete the first shape. This will leave a toolpath that will leave the perimeter of the shape intact (except for any sharp inside corners).
3. Offset this new shape inwards about 90% of the diameter of your router bit - some overlap between inner paths is beneficial to avoid narrow fins of material being left untouched. Continue offsetting these inner shapes until no space remains.

To read more about producing a template cut file, click here.

Milling Jobs

Where templating is essentially a vector operation, milling is a raster operation - tracing regular lines over a surface as the tool varies the depth of its cut. Milling can be used to produce terrain models and undulating surfaces such as piece pictured at right.

Milling jobs can either be processed via the MillWizard software, or the 3D toolpaths can be generated directly from the 3D modeler of your choice. Beginning users are recommended to use the MillWizard software.

Jobs in this format are best exported from the 3D modeler of your choice in STL format - although 3DS and DXF are also options. This source file is then read in to the MillWizard software for translation into SBP format. The MillWizard software will walk you through the process of generating the SBP format, including the creation of roughing passes and a finishing pass where desired to produce the finished piece. You will be asked to orient your piece in space and within the material you'll be milling, as well as to specify certain information about the drill bit(s) you will be using.

To read more about using MillWizard to produce a milling cut file, click here.

Executing A Part File

When you have produced an SBP file and purchased your material(s) and router bit(s), you are ready to execute your file. The basic steps in this process are as follows:

1. Place your router bit in the router, and make sure that the dust collector is securely attached.
2. Place your material on the cutting table, and affix it securely in place.
3. Orient the ShopBot tool by defining the origin point.
4. Set your Move and Jog speeds according to the type of material you are cutting.
5. Telling the ShopBot that it has control over the router by setting output channel 1 to On.
6. Executing your part file and, when prompted, pushing the Start buttons on the ShopBot control box and dust collector.
7. When your part is finished, removing all debris from the room and taking any scrap pieces and your router bit with you.

To read more about executing your part file, click here.

Moving the ShopBot Manually

Scanning Operations

In addition to using the ShopBot to cut material, you can also perform scanning operations by fitting the ShopBot with a special digitizing probe.

To learn how to use the ShopBot as a copy machine, click here.

Troubleshooting the ShopBot

As much as we would like the equipment to work perfectly, eventually you will have to troubleshoot a problem. This is a compilation of steps to resolve some common problems with the ShopBot, as well as actions you should avoid taking.

Connecting to the ShopBot

To read more about common problems and their resolutions, click here.

Error messages, and how to recover from them

Links

There are a number of resources on the Internet which can help you as you use the ShopBot:

• ShopBot Tools
  The manufacturer of our ShopBot maintains a fairly useful website with some good basic information.
• Talk ShopBot Forums
  This is the official user forum for all ShopBotters - the folks here can be very helpful in a pinch.
• Because We Can
  This is a design-build firm in the Oakland area that does some amazing work with a ShopBot and other tools. They're of particular interest to anyone who wants to tackle furniture projects.

Questions?

If you have any questions about anything contained in these documents, please contact Matt Bernhardt at bernhardt.7@osu.edu, or 614.292.7595.