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I am going to guess that you are using the 'haas with a-axis.cps' post processor. If this is the case, then it is quite easy to disable inverse time feedrates (G93) and output DPM/IPM feedrates (G94) instead. Just modify the following line in the post.
/** Calculate the multi-axis feedrate number. */
function getMultiaxisFeed(_x, _y, _z, _a, _b, _c, feed) {
var f = {frn:0, fmode:0};
if (feed <= 0) {
error(localize("Feedrate is less than or equal to 0."));
return f;
}
var length = getMoveLength(_x, _y, _z, _a, _b, _c);
if (false) { // inverse time (Change 'true' to 'false')
f.frn = inverseTimeOutput.format(getInverseTime(length[0], feed));
f.fmode = 93;
feedOutput.reset();
} else { // degrees per minute
f.frn = feedOutput.format(getFeedDPM(length, feed));
f.fmode = 94;
}
return f;
}
This will output feedrates using G94 mode. You can read the following Forum post to learn a bit more about feedrate calculations for multi-axis moves.
Bob Schultz
Sr. Post Processor Developer
There is a problem with the rotary axes delta calculations. You will need to make the following changes to the getMoveLength function to get the correct feedrate numbers.
/** Calculate tooltip, XYZ, and rotary move lengths. */
function getMoveLength(_x, _y, _z, _a, _b, _c) {
...
moveLength[0] = linearLength + radialLength;
moveLength[1] = Vector.diff(endXYZ, startXYZ).length;
moveLength[2] = 0;
var start = new Array(startABC.x, startABC.y, startABC.z); // add these lines
var end = new Array(endABC.x, endABC.y, endABC.z);
for (var i = 0; i < 3; ++i) {
var delta = Math.abs(end[i] - start[i]); // modify this line
if (delta > Math.PI) {
delta = 2 * Math.PI - delta;
}
moveLength[2] += Math.pow(delta, 2.0);
}
We will make these required changes in the stock Haas posts.
Bob Schultz
Sr. Post Processor Developer
The Haas controls use a unique calculation for feed rates with rotary axis moves. They use a fixed part diameter (Setting 34) and then require FPM rates based on this diameter. The Haas post by default was using a combination FPM/DPM calculation that is common in the industry.
I am attaching an updated version of the modified 'haas with a-axis.cps' post that has this calculation implemented (it will be officially released shortly). It should eliminate the choppy moves. Please let me know if it is working on the machine as expected so we can place it into the Post Library. You will have to enable the Rotary moves use IPM feeds property to output IPM feed rates with rotary axes moves The G94 code should not be output when this property is set. You will also have to make sure that the Feed rate calculation diameter property is the same as Setting 34 on your control.
Bob Schultz
Sr. Post Processor Developer
The diameters just have to be the same. The post will adjust the feed rates based on the actual diameter being cut and the value stored in Setting 34.
Bob Schultz
Sr. Post Processor Developer
If Setting 34=2 and the diameter property is set to 2, then this is OK. The post will adjust the feed rate so that it reflects a 2" diameter part in the output even if the actual part diameter is 6". The post actually uses the tool position at the given cut to determine the "floating" diameter and is adjusted for every tool position.
You should notice that the feed rates remain the same when cutting at a fixed diameter, and then changing as the tool moves in and out from the center of the table.
Bob Schultz
Sr. Post Processor Developer
Thanks for taking the time to test the post and providing feedback. It is much appreciated!
Bob Schultz
Sr. Post Processor Developer
The feedrate displayed on the screen shows the tool tip feedrate as if it was setting34/2 (the part radius) from the center of the table. Since the tool is actually 3.5" away from the center of the table the actual cutting feedrate will be 3.5 times the feedrate displayed on the control. So you should be seeing a feedrate of 2.14 (15 / (Setting_34 / Actual_Cutting_Diameter)), but the tool should be moving across the part at the programmed feedrate of 15.
Of course, when Setting 34 is closer to the actual diameter of the part being cut, then the feedrate number on the screen will more closely match the cutting feedrate. In either case, the actual cutting feedrate across the part should be the same on the machine.
Bob Schultz
Sr. Post Processor Developer
Hi Bob, sorry to dig up an old post, but I am grateful they are still around. This helped me solve the same issue. Was simply the difference between my Parameter 34 and Feed rate calculation diameter.
I seem to be missing something though.
I now have to enter my "cutting feed rate", for example, is 4000m/min and usually run a built-in high feed rate of 12,700 m/min, so now the feed rate is jumping between the two of them. Feed at 4000, X move (my step over on rotary toolpath) and then immediately feed at 12700 which is now my cutting feed rate. So does this mean that my "built in high feed rate" is actually a "cutting feed rate"?
If you have defined Setting 34 in the control to 1" and set 1" in the Feed rate calculation diameter property, then these high feed rates can be expected. The X position in your sample code is approximately 2", which defines a cutting diameter of 4". This means that the feed rate values will be 4x the programmed feed rate, or 16,000. The post processor will not output a cutting feed rate higher than the High Feedrate value, so it is truncated to 12,700.
This means that the machine should be cutting a bit slower than your programmed feed rate. If you change Setting 34 and the property to more closely match the diameter of the part you are cutting, then you should see feed rate numbers that are similar to your programmed feed rate.
Bob Schultz
Sr. Post Processor Developer
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