[reg.miller]

Why would I want to stop the job and how would that prevent the tool cutting speed from being several times the feedrate in arcs?

[jreynolds5]

In the good old days we could simply use G09 or similar if available.

Actually G09 is liie a precision stop, not a physical stop. It makes the program pause for a moment to 'catch up' to itself before starting the next move. It really helps with precision machining of very tight tolerances, not what you are really looking for here.


So since so no one here seems to want to actually answer your original, very simple question, I will. So yes, more expensive CAM software does allow you to select a corner slow down. Take this screen shot from Esprit.


Attachment 492676

[reg.miller]

Thanks for adressing to the question.

What is PM,PT ?
Does "const removal rate" option provide for a near constant tool tip cutting speed between straight lines and corners?

[jreynolds5]

Thanks for adressing to the question.

What is PM,PT ?
Does "const removal rate" option provide for a near constant tool tip cutting speed between straight lines and corners?

PM= Per Minute
PT= Per Tooth

And yes that is what const removal rate does. Now mind you this is probably about $15k or so just for the standard milling package. But you can do things like Trichodial milling and what not. It is very powerfull stuff.

[reg.miller]

thanks. So that looks like surface feet per minute and thou per tooth.

For top flight software I'd have thought a speed would be marked in coherent, physically meaningful units, not "per minute" which if anything is a frequency, but I guess for that money you get a nice glossy user manual if you can be bothered to read it

Actually G09 is li[k]e a precision stop, not a physical stop.

Haas tells me it is a physical stop:

Machine moves decelerate to the programmed point before the control processes the next command.

Deceleration and then acceleration to continue implies lots of change to physical load, chip load etc., it is not obvious to me how this necessarily improves precision. It sounds like a recipe for some rather arbitrary changes in precision and accuracy.

[jreynolds5]

thanks. So that looks like surface feet per minute and thou per tooth.

For top flight software I'd have thought a speed would be marked in coherent, physically meaningful units, not "per minute" which if anything is a frequency, but I guess for that money you get a nice glossy user manual if you can be bothered to read it





Haas tells me it is a physical stop:


Deceleration and then acceleration to continue implies lots of change to physical load, chip load etc., it is not obvious to me how this necessarily improves precision. It sounds like a recipe for some rather arbitrary changes in precision and accuracy.

I mean what other way would you calculate feedrate for milling??

So most modern CNC machines have a look ahead function. Sometimes when running through extensive code it will not slow down and miss a precise corner. I have used this a few times on Swiss machines and it has greatly increased the accuracy of the feature.

[reg.miller]

Thanks, that makes sense. Forcing a stop is a crude way of reducing the cutting speed for that part of the path, meaning smaller chips and in general a finer finish. So long as that does not harden the material or result in rubbing on harder materials, I can see that would work. Maybe reducing feedrate around that feature would be a more controlled way but just throwing in a G09 is quick and easy.

Thanks for the insights.

[LuciaPeter]

Feature that changes the way complicated patterns are made. Allows for accurate cuts and makes mistakes less likely.

Strongly suggest if you want to be more precise and accurate in tight areas.

[jreynolds5]

Thanks, that makes sense. Forcing a stop is a crude way of reducing the cutting speed for that part of the path, meaning smaller chips and in general a finer finish. So long as that does not harden the material or result in rubbing on harder materials, I can see that would work. Maybe reducing feedrate around that feature would be a more controlled way but just throwing in a G09 is quick and easy.

Thanks for the insights.

The G09 doesn't cause a hard stop, it is a split second stop if it actually stops at all.

I have also included some more screen shots of the other option tabs for rouging. There are even more options when you are using a solid model to program too.

Attachment 492736

[Dwalin]

Controlling feedrates on G2/G3 arcs when the tool radius is more than half the arc radius requires careful consideration.