finecut - perform finecut machining operation
finecut [-cdbsqiprnvk2][-ttrvs][-kpitch] tooldia
| -c | Climb cutting mode. |
| -d | Dig (conventional) cutting mode. |
| -b | Bidirectional cutting mode (default). |
| -s | Slow cut mode (reduced feedrate). |
| -q | Quick cut mode (normal feedrate) (default). |
| -i | Mirror image cut mode (mirror x axis). |
| -p | High precision cutting mode. |
| -r | Rectangular (cartesian) cut mode. |
| -n | No cut mode, display cutting parameters only. |
| -v | Void skipping cut mode. |
| -k | Reverse longitudinal feed cutting mode. |
| -2 | Two spindle cutting mode. |
| -ttrvs | Skip ahead to traverse number trvs. |
| -kpitch | The pitch or modulus of finecut traverses. Cut every nth traverse commencing with traverse 0, where n is pitch. |
| tooldia | Actual tool face diameter in microns (mandatory). |
The default cutting regime is bidirectional at normal (quick) feedrate. No X-axis mirroring occurs and tool commands involving radial travel of the spindle are expressed to normal precision. Cylindrical coordinates are assumed, voids are fatal (no void skipping), longitudinal feed is clockwise as viewed along the positive sense of the cylindrical axis (positive X-axis) and 1 spindle operation is assumed.
The beginning traverse for the default case is on longitude 0 and all longitudes within the current longitude range are traversed.
Specification of the tool face diameter, in microns, is mandatory. It should be noted that some options may not be supported on certain types of CNC milling equipment.
When adding the optional arguments and switches, selections from the cutting mode group must be joined together, the traverse selection must be joined with its argument, and each group must be separated by a space and preceded by a dash. The mandatory tool face diameter argument must be last, and must be separated from optional arguments if they are present.
Roughcut and finecut are the two commands which control the machining of Echo scanned images under computer direct numerical control. Although the two commands have many similarities and control somewhat similar machining processes, they have marked differences as well. Both commands have relatively complex argument structures, and a thorough understanding of that structure as well as the arguments themselves is essential for ensuring desirable machining results.
Both commands require a valid image consisting of nonnegative radius values, and the current radius range must not exceed available spindle travel. Voids are normally filled prior to machining but the void-skipping option may be employed with caution.
The finecut command structure is easier to understand and utilize when its structure is studied one option group at a time. The string of arguments shown in the first set of square brackets designates optional modes of proceeding through the fine cut machining process. Five of these arguments fall naturally into 2 modal subgroups: the direction of tool advance into the material and the speed of the tool relative to the stock.
| -cdb | These options refer to the motion of the workpiece relative to the cutting surfaces of the tool. During full diameter slotting cuts, fully one half of the cutting surfaces are in contact with uncut portions of the approaching workpiece. As a particular portion of the cutter rotates through the semicircle where the tools leading edge is in contact with the workpiece, it first cuts in opposition to the advance of the workpiece then across the advance and finally sympathetic with the workpiece advance. For such full diameter cuts both the dig (opposition or splitting) mode and the climb (assistance or hacking) mode of tool/workpiece interaction take place. |
Once the initial slotting cut is completed, there will be a strong tendency for characteristics of one or the other of the tool/workpiece interactions to dominate during subsequent finecut traverses, depending upon the direction of the traverse. As the succession of traverses advances laterally with increasing longitude, the uncut portions of the workpiece will tend to be either pulled toward the tool's path (dig cutting) or pushed away from the tool's path.
The effectiveness of a given tool in forming and clearing optimal chips in certain materials may be heavily influenced by the predominance of one or the other of these quite different tool/workpiece behaviors. Furthermore, the quality of the cut surface may be quite different due to one mode or the other tending to induce undesirable effects such as chattering or perhaps tearing and splitting.
For many materials of interest, structural foam and some waxes for example, the differences in cutter performance are sufficiently masked by relative lack of cutter resistance that bidirectional cutting can be used without jeopardizing results. On the other hand, many materials, e.g., various hardwoods, metals, brittle plastics, etc. exhibit behavior which strongly recommend the preferential use of one mode or the other.
| -sq | These options modify feedrate. It is assumed that the machine control provides a manual feedrate control of some type for fine adjustments. |
| -i | This switch modifies positive X axis orientation, i.e., i = mirror or reverse the sign of X axis coordinates. |
| -p | This switch forces tool radius values to be output to the milling machine to one addition significant digit where high precision is desired, e.g., machining images at severely reduced scale. |
| -r | This option modifies the coordinate system to be rectangular (cartesian) coordinates, rather than the default cylindrical coordinates. |
| -n | This option produces a summary display of the machining parameters
pertinent to the current state of the resident image without transmitting the
normal sequence of actual ìG codeî instructions to the controller for the
machining device. This display enables you to review the various parameters for
possible oversights and also provides a convenient compilation of machine setup
parameters such as the actual ranges along the machine axes which will be
involved in machining the current image.
Frequent use of this option is strongly encouraged as a "filter" to verify the consistency of roughcut commands with the current state of the image and with the current working coordinate setup on the mill. Unfilled images, excessive radius ranges and other inconsistencies are readily identified with this option. |
| -v | This option causes voids to be skipped thus allowing the machining of images which have not been filled. Interior voids are "bridged" by linear tool path vectors joining the valid data points on either side of the void point (interval). Exterior voids are "bridged" by tool path vectors projecting to the latitude range boundary at constant radius. |
| Note: Some releases incorporating this feature may not be usable in your applications due to the fact that exterior void skipping was implemented in a manner such that the tool path projection from the terminal non-void data points to the latitude range boundary was at zero radius. In recent releases, the radius of the terminal non-void data point is used for the radius of the projected tool path vector. | |
| -k | The option enables reversal of the normal direction of longitudinal feed at one "special" milling facility. |
| -2 | This option enables two-spindle milling operations at the above unique facility. |
Multiple switches from the cutting mode group of options may be selected and entered on the command line immediately following the leading dash (-). Each letter option entered must be joined with its predecessor, the last of which must be followed by a blank space.
The -ttrvs argument for this command designates the intended beginning longitudinal traverse number if other than zero.
The -kpitch argument defines the skipping of an integral number of traverses between successive traverses as might be desirable on cylindrical finecuts on relatively low radius images where tool paths would normally result in considerable overlap. The argument for this command is the pitch of successive traverses, e.g. 2, rather than the number skipped (1) to achieve that pitch. The integer tool face diameter argument indicated in the finecut usage is the only mandatory argument and it specifies the face diameter, in microns, of the milling cutter.
By default, the initial bed travel, rotary table and spindle positioning moves assume bidirectional cutting mode commencing with the first latitude interval (0) on the first longitude traverse (0). Accordingly, the horizontal bed is positioned at the current X0.Y0. position, the rotary table remains at its initial or indexed position (0), and the spindle positions the cutter face to a level just clearing the maximum feature radius.
In view of the foregoing discussion, about the only restrictions regarding the use of optional switch arguments are that each category, if chosen, be separated by a space, that each category be immediately preceded by a dash(-), that selections from the cutting mode group be joined together and that, if chosen, the -t and -k designators are joined to their numerical arguments. The mandatory tool diameter argument must follow optional switch arguments and be separated from them by a space.
The simplest and most often used form of the finecut command is illustrated by the following command:
| fin 1600 |
This might be used to finish cut an image, in structural foam for example, for which the radius range of image features is well within the constraints of both the available spindle travel as well as the effective cutter length. The range of latitudes to be cut as well as the range of longitudes to be cut, if other than their respective maximums, need to be set prior to entering the finecut command. If it is desirable to restrict the minimum or the maximum radius for some reason, the appropriate radius range should be set in advance. There are no provisions for altering the machining parameters "on the fly" other than those normally available to the machine operator, e.g., perhaps spindle speed and feed rate override.
A somewhat more involved example illustrates the next most common finecut command usage scenario involving restarts following an interruption of the machining operation for whatever reason. One would like to proceed directly to the point at which the interruption occurred and resume the process there rather than retrace the work already done.
Fortunately, the finecut command structure allows you to do exactly that upon entering the appropriate command. The appropriate form of such a command would typically be something like:
| fin -t271 1500 |
Assuming everything has been restored to the initial conditions, the system will seek directly the configuration that will result in resumption of machining along traverse 271 as if no interruption had occurred.
Going on to an example of intermediate complexity, let's assume we're to machine the mirror image (X-axis) of a subject of relatively large size in a material offering considerable resistance to the advance of a slender, tapered fine cutting tool, e.g., machinable wax. Let's say for example that we observe a tendency for the tool to deflect into the uncut wax in the dig cutting mode. We might consider trying the command:
| fin -ci 1800 |
which will result in unidirectional climb cutting with a rapid traverse "carry" at max radius back to the appropriate end of the work piece prior to commencing the next traverse.
Let's now assume that we experience a power outage half way through the finecut and wish to restart at the traverse where the interruption occurred. An appropriate command would be:
| fin -ci -t241 1800 |
This should get you back on track provided you re-indexed the rotating table and didn't lose your working coordinate references.
As a final, perhaps extreme example, let's cut a finish pass for the mirror image of an injection mold that we've just roughed out in aluminum. We hope to use a 1 mm diameter tool and elect to invoke the dig, slow, mirror, precision and rectangular coordinate cutting mode options.
In this case, the command below would be appropriate and might eventually get the job done.
| fin -dsipr 1000 |
flagset -iorcbuCNRL
The header of an Echo image contains some flags which indicate to the software functions certain properties of the image data. Most Echo images are created by processes that explicitly and automatically assign the proper flag states reflecting the appropriate geometry and properties for the image. Certain procedures may require these flags to be manually changed.
Flagset enables you to change these flag states:
| -i | Set the image type to inside-out |
| -o | Set the image type to outside-out |
| -r | Set the image type to rectangular |
| -c | Set the image type to cylindrical |
| -b | If image is rectangular, interpret in the special bilateral mode |
| -u | If image is rectangular, interpret in the normal unilateral mode |
| -R | Set the geometry to a Right-Hand coordinate system |
| -L | Set the geometry to a Left-Hand coordinate system |
| -C | Set the image type to color |
| -N | Set the image type to no-color, range only. |
For example, if you need to transform image data from cylindrical to cartesian coordinates and you want to perform some operation on this data which requires explicit knowledge of the intended geometry, you can simply set the image flag to cartesian.
Flagset does not change the image data in any way. Only the attributes are changed. Setting the -r flag on a cylindrical dataset will not convert it to a rectangular data set. However the display commands will project it into cartesian space, interpreting the radius values as Z values.
Use the status command to verify the current value of lgincr. The value is usually 12272 for 512 longitude cylindrical images. Typical values for 512 longitude cartesian images would be 417 for linear table scans and 781 for relief images transformed from cylindrical to cartesian.
Some scanners produce images in a left-handed cylindrical coordinate system. If your left thumb is extended to indicate the positive Y axis (usually upwards), your curved fingers will point in the direction of increasing longitude.
Color scanners will produce images with the color flag set. This indicates that a companion color file exists. If the color file is un-needed or deleted use flag -N to prevent error messages.
Setting the color flag can enable some special effects. Any SGI type image file with the proper dimensions may be used to map color onto the range vertices. Name the file the same as the range image file with the extension .color. Give the command flagset -C to set the color flag. When you display, Echo will map the "color" file onto the range file.
The color flag applies only to existing images. To set scans to range-only before scanning, use the command set ECHO_RGB_MODE false. This may be desirable to save disk space and process time, if the color map is not necessary for your application.
getvar - get environment variable value
getvar [variable]
The program uses a large set of environment variables to control its behavior. These are initialized when the program is first started, but can be changed temporarily by the setvar command. Variables are stored in several configuration files, or in some cases they are set internally.
getvar displays the current value of variable. If the variable argument is omitted, getvar displays the entire environment, including system variables. The variable argument is case-sensitive.
| get ECHO_RGB_MODE |
The system may return:
| true |
For more information on using environment variables, see Configuration Files. For a listing of standard variables and their default values, see the Environment Variables section of this manual.
If the requested variable has not been defined by setvar, or in the echo, optic, graphic or mill configuration files, getvar will give an error message. Some variables have been defined internally by the Echo program. The internal default value is listed in the Environment Variables section.
If you want to see a certain section of variables, you may wish to try the source script pget. It uses the IRIX fgrep utility to find matches for a given string of characters. This is a useful shortcut.
| pget LT |
The system may return:
| ECHO_NLT=450 ECHO_LTINCR=700 ECHO_OPTICALTABLE=/usr/local/echo/optic.tab |
gradlim - pre-processing for milling steep slopes
gradlim x y
| x | tool tip diameter in microns |
| y | tool taper (included angle) in degrees |
During milling pre-processing, gradlim provides a way for the tool to pass steep slopes where it might otherwise interfere with or destroy material during its route to the lower point. For example, this precaution is particularly helpful in the steep areas around the nose, chin, and ears. The tool tip diameter and the tool taper can strongly affect the severity of the interference.
The gradlim command allows the image data to be preprocessed with a specified tool tip diameter and taper angle in order to detect and correct the surface where an interference might occur. This results in a buttressing effect along the flanks of some higher elevations, by sacrificing some definition at the base of the adjusted slopes.
To see the effect of the gradlim command on a particular image, use the paste -d command to compare the "before and after" differences. Apply the gradlim command to an existing image, and use paste -d with the unprocessed image as an argument to compare the effects with the original image.
With cylindrical images, you can use the rincr command to create a large cylindrical radius (perhaps 75000 to 100000 microns), forcing the differences to be displayed relative to a cylindrical background surface.
Or, you may change the image to cartesian coordinates using flag -r and use the stat and lgincr commands to set the lgincr=ltincr. This way, you will be able to display the entire pattern of gradlim effects in a single view.
help
Help provides a summary of the commands available in the present version of the Echo software. Some commands may be undocumented features.