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This Web site is dedicated to the thousands of "users" of my programs, those who have helped test my programs over the last 23 or so years, and especially those who shared their experiences with me.

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SECTION: 7.10 is for some "general" information about CAM, CNC, or NC type automated machine tools, see also the program files in the current distribution of my programs, the other parts of this HTML documentation, and the current On- Line version of this Web site for information more specifically about my programs. Any comparisons of my programs or methods to some others is only given as a vague generality of my opinion and is not intended as a recommendation or reference to any particular products, always make your own evaluations and comparisons before taking any action.

The tool path that the CAM machine's computer software will read in order to operate the CAM machine tool via the drive electronics is a set of coordinates. If you remember the "connect the dots" coloring books of your childhood that is basically what the tool path is, a set of dots or points, the CAM machine's computer and software use to figure out how to draw a line between the points, and send signals to the drive electronics to have the CAM machine follow those motions. The motion is carried out in very small steps that are counted off one by one at high speed, so that the motions of the machine seem almost continuous. The size of the motion steps used would generally be from 0.01 inch to 0.0001 inch for typical machine tools and might be much smaller for working on very tiny parts. Each movement between the coordinates of the points is made by having the motors move so many small steps left or right versus how many steps up or down and so on. In three dimensional CAM operations, such as when using my program DANCAM.EXE (tm), the points in the tool path to connect can be anywhere in a three dimensional volume of space, and my program can connect the points by going along a line using linear motion through the volume of space between those points. In some other CAM systems the motion might only be in flat planes, and so even though those other CAM systems can input points located in 3D space their movements to go from one point to another are only 2D, i.e. only two of the axis can move at the same time.

Today computers use many different data formats to store line drawings, i.e. tables of coordinates. My CAD and CAM software programs have several drawing file data formats which are used for different purposes. In the early days of "Numerical Control," or NC, the codes used in the tool path "punch tape" needed to be very simple and brief because the tool path "program" was punched as holes into a paper tape like the ones used for teletypes of that time. The codes used on those paper tapes were generally "G" plus two numbers or "M" plus two numbers, e.g. G01 or M06 and so on. So these codes are sometimes called "G codes" even though today some other codes have been added.

Because many of the early NC type CAM machines used G codes many of the CAM machines and software programs used for CAM have some way to share tool path data in this format. Sometimes plotter languages such as HPGL are also used to operate CAM machines that work like a pen plotter.

My CAD programs DANCAD3D.COM (tm) v2.7 and DANCAD87.COM (tm) v2.7 can read and write files that use a sub- set of G codes for the interchange of tool path data. G code tool path data loaded into my CAD programs can be edited and converted into the ASCII tool path file type that my CAM programs normally use.

The G code command set has special commands for "arcs" generally segments of a "quasi circle." I put quasi circle in quotation marks, since all shapes are of limited resolution on NC machines and "true" circle motion is not made by the incremental motion. The motion to make a shape on a CAM machine is actually produced by, and limited by, the stepwise motion of the motors or encoders on the motors. If you make a set of points very close together, say 0.0001 inch (0.0025 mm), you can get something close enough to the curve that you want. All tool path movements in my programs are made up of line segments, but these line segments can be very short which lets you alter or edit odd shapes, and irregular quasi curves, to be cut in ways that could difficult using the simple "arc" G02 and G03 commands. It is possible to use G01, linear motion, to make arcs if the individual points are spaced close together, you just get a larger tool path file, which is not necessarily a problem since computers today generally have large harddisks capable of storing larger files, i.e. in the old days you could probably not make a paper tape long enough to machine detailed surfaces made of irregular quasi curves by using millions of G01 movements. Some of my programs can work with disk files up to about fifty million line segments when about 2.1GB of disk space is available on the workspace drive and on the drive the programs are in.

Feed rate control is controlled by the "F" variable in G code files. When using v2.7 of my software to draw tool path files, the drawing line color can be used to control various machine operations, such as feed rate, dwell, relay on or off, and pause for operator intervention. When G codes are loaded into my CAD programs the feed rates set by the "F" variable are converted into various line colors according to the way the configuration was set up in the Files Load Industry G code command. When G code files are saved from my CAD programs the feed rates are converted from line colors into commands using the "F" variable in the G code file according to the configuration that was set up in the Files Save Industry G code command.

Sometimes it is desirable to mark out points along the final shape of the part you wish to cut out, and then use radius compensation to offset the coordinates of the points in the tool path file so that the size of the radius of the tool is used to have the tool follow along side the line marked out. In G code files the G code commands G41, G42, and G40 are used to select the radius compensation mode, follow left side or follow right side, and to turn off the compensation. My CAD programs offer support for these radius compensation modes, with the extension that the compensation can be used on arcs and free form quasi curves made of short line segments.

Although there is a standard for G codes the controller or control software used for various CAM machines may interpret the G codes somewhat differently, so conversion of a G code tool path from use on one machine to use on another machine may require some editing. In my programs the tool path is converted from G code into a drawing file, so you can view the tool path file in my drawing editor, and use the various editing commands to make various changes as needed, before saving the edited tool path file for use with my CAM programs, or perhaps as a G code sub-set file for use with another CAM system. G code files saved from my programs may not work with any particular CAM system, but you may be able to write a computer program to "process" the file to make the needed corrections. For use with my CAM programs the needed changes would be made in the drawing editor before the ASCII tool path file is saved.

Below are some example G code type codes for a tool path to make a pocket using an end mill. The tool path starts and ends on the same point, which would be the home point generally. My CAD programs have a Files Save Industry G code command in a revision of v2.7B that can automatically create this sort of G code file from tool path lines drawn in the CAD program's drawing editor. My CAD programs can also load this sort of G code file and convert the tool path lines into ASCII format for use with my CAM programs, see the example converted tool path data below.

%
O0001
N0001M03
N0002G90
N0003G01X-6.Y6.Z-3.F10.
N0004G01X-3.Y4.
N0005G01Z-2.
N0006G01Z1.F2.
N0007G01Y1.
N0008G01X-2.
N0009G01Y5.
N0010G01X-4.
N0011G01Y0.
N0012G01X-1.
N0013G01Y5.
N0014G01X-3.
N0015G01Z-2.
N0016G01Z-3.F10.
N0017G01X-6.Y6.
N0018M02
%

See also the information about using G codes with my programs in Section: 3.1.35.0, and Section: 3.1.50.0.

The formatting and production of the G code files may be different in the version or revision you have, the examples here may have been made by a different version or revision from the one you have.

In this example tool path file you see the G code file from the example above converted into my ASCII tool path file for use with my CAM program DANCAM.EXE (tm). The conversion from G code into ASCII was done by loading the G code sub-set file into a revision of DANCAD3D.COM (tm) v2.7 and saving the converted lines back out as an ASCII file.

When you make such conversions you should examine the converted lines that represent the tool motions in a graphic display, such as the graphic display in the Preview command or the drawing editor in my CAD programs.

After saving the element loaded with the Files Load Industry G code command by using the Files Save ASCII command the Files Utilities ASCII Squeeze command was used to reformat the ASCII file to make it take less disk space.

VERSION v2.7A { CAD SQUEEZE } ENTER
-6 -6 -3 -3 -4 -3   3   1   0   0
-3 -4 -3 -3 -4 -2   3   1   0   0
-3 -4 -2 -3 -4  1   4   1   0   0
-3 -4  1 -3 -1  1   4   1   0   0
-3 -1  1 -2 -1  1   4   1   0   0
-2 -1  1 -2 -5  1   4   1   0   0
-2 -5  1 -4 -5  1   4   1   0   0
-4 -5  1 -4  0  1   4   1   0   0
-4  0  1 -1  0  1   4   1   0   0
-1  0  1 -1 -5  1   4   1   0   0
-1 -5  1 -3 -5  1   4   1   0   0
-3 -5  1 -3 -5 -2   4   1   0   0
-3 -5 -2 -3 -5 -3   3   1   0   0
-3 -5 -3 -6 -6 -3   3   1   0   0
 0  0  0  0  0  0   0   0   0   0

This color perspective drawing was saved from DANCAD3D.COM (tm)'s macro DISPLAY command as a BMP file and then converted into a GIF file in another program. The colored lines in this drawing represent the tool motions for a tool path file for an automated CAM vertical milling machine. The two line colors represent the two feed rates, i.e. from F10 and F2 in the G code, used in this tool path file.

This is a view of the example tool path file whose codes are shown in G code and ASCII above.

The tool path lines are superimposed over a "solid" shape rendered in DANCAD3D (tm) showing how the pocket would be made if an end mill with a radius of one unit was used with this tool path. The cyan lines show rapid linear feed across and down to a point above the work-piece, then the feed rate changes to the red lines for the cutting feed rate and the tool drops down to the bottom of the pocket, moves around in a spiral motion with some overlap at the end, then moves up, switches back to rapid feed, finishes moving up, and then goes back to the starting point.

This example tool path is somewhat over simplified, since in normal practice smaller cuts would normally be made, taking several layers off one at a time, and the tool would go around the outside taking a small finish cut, see the illustration of the typical tool path drawing below for an example showing some of these details.

This illustration shows what a typical 3D tool path looks like when displayed by the Preview command in DANCAD3D (tm) or DANCAD87 (tm). The different line colors are used to control the feed rates or speed of the cutting tool. In DANCAM.EXE (tm) there is a feed rate table that is used to translate the line colors used in the tool path into various speeds. The feed rate table and configuration in DANCAM.EXE (tm) can also be set to have certain line colors in the tool path select rapid motion or linear motion, as well as activating a programed pause and switching on and off auxiliary relays to control such things as coolant and spindle speed. The Files Save Industry G-code command can be used to save this sort of tool path as a G-code file for use with other compatible CNC controllers. In the case of making a G-code file, there is also a translation table in the Files Save Industry G-code command to regulate the feed rate values output by the various line colors used in the tool path. Tool paths in existing compatible G-code files might also be loaded and displayed using the Preview command or the Drawing Editor. Note that in a practical tool path such as this one, the tool makes many repetitive motions, cutting a little deeper on each pass around the shape to be cut, with a somewhat larger pass around when the tool reaches the bottom of the cut to clean up the walls of the opening. Click on the links above to view this tool path at higher resolutions. You may need to use a browser that does not shrink-to-fit illustrations larger than your screen size to view the small details in the higher resolution illustrations.

This color perspective drawing was saved from DANCAD3D.COM (tm)'s main menu Preview command as a BMP file and then converted into a GIF file in another program. The lines in this drawing represent the tool motions for a tool path file for an automated CAM vertical milling machine. The various line colors represent the various feed rates used in this tool path file.

This tool path file makes two counter sunk holes and a slot between them. The radius of the holes and slot are larger than the radius of the cutter used.

Notice the slightly larger tool path outlines lines in magenta at the bottom of each stack of roughing cuts, that is the finish cut path that uses the "full" side of the end mill to smooth out the finish to the final dimension. The blue lines extending above the cutting lines are the return extensions I might some times refer to as the "telephone poles" that bring the tool up above the work-piece so that the tool can safely move to the top of the next starting point in another part of the tool path file. Under the blue extensions moving up, are the starting lines that move part of the way down for the first plunge of the end mill into the work- piece. The final radius would be about the distance of the final cut lines from the starting center line plus the radius of the end mill, plus or minus a little for the flex of the tool.

See also the video segment about making the Synchro mounting plate to see how this type of tool path was used to make the parts out of aluminum.