What Is A Chain
A chain is series of objects (lines and arcs) linked together to make one unit (a chain). The chain has a start point and an end point it also has a side and a direction for a cutter to follow. It knows what layer it is in and how many objects it has.
Chain Defined
A connected series of objects.
Objects in a chain are treated as a group. If the objects are points (or a series of circles) for drilling holes, etc, then they of course are not connected, but are treated as a group.
Creating geometry to chain
Create one rectangle three by three inches starting at X0 Y0. Go to Transform, Relative (incremental), click on the ‘Everything’ button in the action buttons. This will prompt you to an “XYZ” dialog box, enter four 4 inches in the X field and click “OK”. Now it will prompt you for number of copies, enter 4, then it will prompt to leave originals click “Yes”. AutoFit your screen and five rectangles should be visible. These rectangles will be used to create chains and then modify them. Your screen should look like the one below.
Now go to the action buttons on the left and click save.
Chaining While Cutting
Chains are created in two ways, one way to create a chain is to create a new cut and then select the geometry to cut and assign a side for the cutter. Most of the cuts that you have generated up to now have been this way. And that is just fine. However, if you have geometry that is not correct, you may have to cancel the cut in order to modify the geometry then come back to re-cut it.
However, if you create the geometry then create the chains, when it’s time to cut your geometry the cuts will be done faster and more efficiently because you will have resolved any problems with your geometry and chains.
Chaining Without A Cut
Do not start chaining until you reach the instruction on the next paragraph. To create a chain go to Modify, Edit Chain, Create New Chain (Link), then select the start of your chain and either select the geometry around the part or click ‘AutoChain’ on the action buttons. Selecting geometry for your new chain is simple, just keep in mind that if your first object is a line, you will have to click the line on the end where you want the beginning of the chain to be. If you make a mistake, go to the action buttons on the left and click on “UnDo”.
Instructions: Go to Modify, Edit Chain, Create New Chain (Link), the prompt now says “[Link] Select first object”. You will now create a chain on the first rectangle; starting point will be the bottom of the vertical line on the left. This will make the chain start at X0Y0. Follow the instructions as illustrated in the next two pictures.
Notice that the cursor is at the bottom of the vertical line; this will be the beginning of the chain, if your screen display looks the same click once. The chain will now follow the direction to the top and around to the right as illustrated on the next picture
Notice that the start of the chain is now marked with an “X” and the cursor is at the top of the rectangle guiding the direction of the chain. This will ensure that the cut goes up and around making this a climb cut as the cutter follows the outside of the rectangle. Chain the rest of the rectangle and click DONE.
IMPORTANT: WHENEVER YOU FINISH SELECTING GEOMETRY WHEN CHAINING EITHER IN THE MIDDLE OF A CUT OR JUST CREATING A CHAIN, YOU CLICK DONE IN THE ACTION BUTTONS WHEN YOU ARE FINISHED SELECTION YOUR GEOMETRY. THIS ENSURES THAT GEOPATH PROMPTS YOU TO THE NEXT STEP.
Before you continue, go to View, AutoFit. Then go to View, Half this will make the graphics half the size. This is important because when you are ready to review the chain data, you will be able to see the chain viewer window on the left and the chain in your screen.
Chain Info
When modifying cuts the chain information is very important because you will want to review the chain data to make sure that it’s the right chain to modify. When there are other chains overlapping the one that you want to change, you will not be certain the chain selected is the correct one unless you examine the properties.
Chain Viewer Explained
Select Info, Chain Data, notice that the action buttons changed and now the “By Number” and “Preview” buttons are active. Click on the chain that you just created, a window will appear on the left side of the screen. That is the Chain Viewer window.
Chain #: This is the number given to the chain for identification. Each chain has a number. It is usually created in sequence; all tool paths are also created in chains, so if you create tool paths they will also be assigned a number in the sequence that they were created.
Kind: There are four main types of chains.
a. Point Chain - This type of chain is used for drilling,tapping, mill c-bore.
b. Mill Chain - In the picture on the left it identifies the chain as “Chain”. This is a Mill Chain; this type of chain is used for milling.
c. Surface Chain – This type of chain is used when cutting 3D surfaces.
d. ToolPath Chain– And finally a tool path chain. This is the chain that is generated with your toolpath
# in chain: This tells you how many objects are in your chain. A square is made of four lines, but this rectangle has 5 objects. That is because when a rectangle from the Shapes menu is created it automatically splits the horizontal line of the first XY coordinate entered.
Layer #: This tells you what layer this chain is in, this will help when you are trying to find the chains that were created in separate layers. You can also move a chain to a layer of your choice so that you can work on the modifications without other geometry using the same space.
Lft/Rt,NoComp: This tells you what side the cutter is on. If the cutter is on the left side the field will display “1,0”. If the cutter is on the right side the field will display “-1,0”. And if the cutter is on the center-line the field will display “0,0”.
Used by tools: This field shows you what tools are using this chain and also what cuts in that tool are assigned to this chain. You may have multiple tools using this chain along with many different types of cuts.
Finally, at the bottom of this window you will see the Previous, Next, and Done buttons. If you have more than one chain you may go sequentially back and forth from one chain to another revealing the properties.
Now create a chain on rectangle number 3, the start point will be the top horizontal line as shown in the following illustration. Chain the rest of the rectangle and click DONE.
Chain Colors
After creating the chain, go to Info, Chain Data, click on the action button “By Number”. Notice that the chain you have just created is Cyan/light blue. This color means that this is the current chain, the last chain used, the chain that is assigned to the number in the “Enter Chain Number” window, and the chain that will be displayed on the Chain Viewer. Click O.K.; notice the “Previous” button at the bottom. Click it and notice that the color changed on the rectangle and that the first rectangle is now cyan and the third rectangle is now red.
Red means that the chain is not the active one in use but the geometry has been linked. It also means that this chain maybe in use but not by the current tool. Let’s say that you have three tools, each tool has three cuts. The current tool is tool #3. The last chain used is cyan. At this point all chains used by a different tool will be Red along with any chains that are not in use.
So, what about the two chains used by the current tool that is not either Red or Cyan? Well, they are Magenta this is the color used to show a chain that is not the current chain but is in use by the current tool.
See color chart below:
Color Function
RED Linked into a chain.
YELLOW Unlinked, unused objects.
DASHED Currently selected objects about to be operated upon.
MAGENTA (purple) Chains used by current tool.
Light BLUE Temporarily used to show the current chain you are working on.
Dark BLUE Temporarily used to show that Geopath is calculating a tool-path for those objects.
WHITE Used to show objects that are currently being created but not completed yet.
Now go to rectangle number 5 and make a chain starting from the top right vertical line.
Now chain the remainder of the rectangle keeping in mind that you are chaining clockwise and the starting point is the top Right, click DONE when finish selecting the geometry. Go to Info, Chain Data and click on the action button “Preview”, notice that two other buttons appear. This will allow you to select the chain that you want without having to figure out which number chain you want to work on or with out having to click on any chain. Click on “Previous” and you will see that the last chain is now Red and the previous chain is now the current chain (light blue). Now click “Done" and the information of the current chain is now in the Chain Viewer.
Play with these functions on your own and get good feel for what they do.
Closed Chains
A Closed Chain is a chain that would be created when cutting a circle for milling on the inside or outside. This would also apply when cutting around a rectangle. So when the start of a chain is the same as the end of the chain it is considered a closed chain.
Open Chains
An Open Chain is a chain that would be created when cutting an arc that is not 360 degrees or a rectangle that would only have three sides cut. In other words the start of the chain is not the end of the chain.
http://www.cadfamily.com/html/Article/Chains%20step-by-step%20example_1013_1.htm
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