KSA FAB LAB > CNC Routers

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. Tell the ShopBot that it has control over the router.
6. Executing your part file.
7. Removing all debris from the room, taking any scrap pieces and your router bit with you.

Let's look at these steps in more detail.

1. Place your router bit in the router, and make sure that the dust collector is securely attached.

Router bits can cost anywhere from $20 to $60, depending on what qualities you're after. The most important characteristics to look for include:

• Shank diameter: The router we have can accept shank diameters of 1/4" or 1/2", which covers the majority of bits available on the market today. If you cannot find a suitable bit that matches these diameters, you will need to buy an adapter to interface between your bit and one of our collets.
• Cutting diameter: This is entirely up to you - although it is important to remember that while smaller-diameter bits will allow for more detail, they are more fragile. This is especially true if you need a bit that can reach great depths.
• Cutting length: Like the cutting diameter, this is up to you although longer bits are usually only available in wider diameters.
• Fluting style: Bits come in one of three general fluting styles: straight fluted, down-spiral, and up-spiral. Generally speaking, you want an up-spiral bit, which will throw the milled material upwards and towards the router. Down-spiral bits will try to throw debris away from the router, which is great if you are cutting all the way through material with no sub-surface. Unfortunately, we have a sub-surface. A straight-fluted bit can be a good compromise, but they can be problematic on an initial plunge into your material.
• End Mill or Ball Nose: This refers to the tip condition of the bit; end mill bits have a square profile, and are good for producing extremely flat surfaces. Ball nose bits, on the other hand, will leave scallops on your surface - which can work to your advantage when producing undulating surfaces.

There are many other characteristics of bits available - please ask Matt or Ryan if you have specific questions.

When placing your bit in the router, use the wrenches that are in the ShopBot room to tighten the collet. Be sure that you do not push your bit so far into the router that you feel it bottom out in the router - this can damage the router.

2. Place your material on the cutting table, and affix it securely in place.

What method you use will depend on the density of your material - building insulation foam can usually be held in place with masking tape, while wood and its derivatives will usually require several large clamps. Use caution when placing clamps - students in the past have inadvertently run the ShopBot through the metal clamps, usually causing damage to their bit, the clamp, and the ShopBot itself. It is a good idea to have already viewed your cut in preview mode before clamping the material down, so you have a better idea of which areas to avoid.

In extreme cases, it is also possible to pause the ShopBot in the middle of a cut to allow you to move clamps, but this is generally not recommended.

3. Orient the ShopBot tool by zeroing it in all three axes.

Typically this is done by placing the Z-axis origin at the top surface of your material, and defining the X-axis and Y-axis origins at the back right corner of your material. Zeroing the X and Y axes can be done at the same time, while the Z-axis can be tackled separately.

To zero the X and Y axes, you will need to manually move the ShopBot using keyboard commands until the center of your router bit is located above the back right corner of your material. When this is done, open the Zero menu, and select "zero [2] axes (X & Y)". This will define the X and Y axis origins at the tool's current location.

Zeroing the Z axis is now significantly easier than it has been, thanks to the presence of the Z plate. The Z plate assembly consists of an metal plate and a clamp that are attached to the ShopBot control box. To use the Z plate, place the metal plate on your material directly below the router bit and place the clamp either on your bit or on the router collet. You may need to manually move the ShopBot to get the bit positioned over the metal plate.

When you have positioned the plate, and placed the clamp on your bit, open the Cuts menu in the ShopBot interface, and select "C2 - Zero Z Axis". This is a pre-made SBP file that will slowly lower the ShopBot until the bit comes in contact with the metal plate. The ShopBot will drop only until it reaches -5" in the Z axis - so you will need to be relatively close to the plate when you begin the process.

After contacting the metal plate, the ShopBot will repeat the touching process 3 times to verify it's position, and then set the Z-axis origin at the bottom of the metal plate - and thus the top surface of your material.

4. Set your Move and Jog speeds according to the type of material you are cutting.

The Move and Jog speeds can be set by typing the desired speeds directly into the fields in the Shopbot Control Console. Jog speeds, because the ShopBot will not be cutting any material when they are performed, can usually be set very high - the default is 12 inches per second in X&Y, and 3 inches per second in Z.

Move speeds will vary greatly depending on several factors. The biggest of these is the type of material you are cutting; dense materials like wood will require slower speeds than a porous material like foam. Other factors to consider are the diameter of your bit (larger-diameter bits will be stronger, and thus more able to survive fast move speeds) and the depth of cut (a cut which is 1" deep will require slower speeds than a pass which is only 1/32" deep).

In general, it is better to err on the side of cutting too slow - although you should be careful not to cut too slowly, as this can cause your material to heat up and catch fire.

5. Telling the ShopBot that it has control over the router by setting output channel 1 to On.

This step is new, and very important. Beginning in 2005, the ShopBot now has control over starting and stopping the router - but it needs to be told this each time you load the software. This is accomplished by setting output channel 1 to the On position.

The keyboard command to do this is "SO,1,1" - for Set Output channel 1 to position 1 (on). Using the Control Console, open the Settings menu and select "set [O]utput".

At this point, you will see the screen at right. Enter "1" in the Output Number field, set the Setting dropdown box to "1 - On", and click OK.

With this step completed, the ShopBot now knows that it has control over the router, and it will prompt you to press the "Start" button on the control box each time you manually move it or execute a part file.

6. Execute your part file.

At this point, you have a part file that is ready to be executed, material securely in place on the router table, and the ShopBot is oriented in space and knows it has control over the router. Ensure that you are in "Move/Cut" mode rather than Preview mode, and you are ready to proceed.

To execute your file, open the File menu and select "[P]art file execute". This will call up the dialog box pictured at right. Generally speaking, you shouldn't have to adjust any of the settings listed in this dialog box.

Click the Start button, and you will be asked to press Start on the control box before proceeding. When you do this, also remember to turn on the dust collector in the ShopBot room to ensure that the ShopBot stays as clean as possible while executing your file. This may seem a minor point, but the process of milling material can generate a staggering mess - which can (and has) caused the ShopBot to skip off the tracks in the past.

While the ShopBot is running, you are expected to remain in the control room at all times - it is extremely dangerous to leave the ShopBot running while you go to the bathroom, etc.

7. Remove all debris from the room, taking any scrap pieces and your router bit with you.

When the ShopBot has finished executing the part file, the router will turn itself off. You are then free to move the ShopBot off your part and remove your material and your router bit. Don't forget to clean up any mess that remains, and you are officially done using the ShopBot.

ShopBot Overview