Cavity Mill _ corner control slowdown help!!

[kyleb77]

I wanted to know if anyone has had success with the corner control slowdown on a cavity mill operation. Is there a way to make every pass on walls to slowdown in the corners? So far I have noticed that slowdowns will work randomly in corners. We have a older cnc machine that cannot make 90 degree turns over 40 ipm without keeping material on part. So basically if i want to rough out a square pocket at 200 ipm but want the passes on the wall to slow down to 40 ipm in the corners, I keep seeing a inconsistent feedrate. Any comments would be appreciated. Hopefully I gave enough information.

 

[BobM3]

If you can't get help here, try this forum:

http://www.practicalmachinist.com/cgi-bin/ubbcgi/ultimatebb.cgi

 

[mrainey]

Could you program a short dwell in each corner? This is usually done with a G04 command, followed by a dwell time in seconds or parts of a second - usually expressed as a P or F code.

Software For Metalworking

http://mrainey.freeservers.com

 

[jbel]

Are you using a CAM software package?? Many CAM programs have some feature that will accomplish this for you.

If you are writing your own code by hand you could do something like this:

G1X8.F200.
G1X8.5F40.
G3X9.0Y0.5I8.5Y0.5F40.
G1Y1.0F40.
G1Y8.0F200.
G1Y8.5F40.
G2X8.5Y9.0I8.5J8.5F40.
G1X8.0F40.
G1X0.5F200.
ETC...
ETC...
ETC...

Effectively what you are doing is slowing it down in the corners yourself. Notice that there is a short linear move at the 40 IPM feedrate. This will allow for deceleration of your table and a true 40 IPM feedrate through the corners.

With a G91 incremental Z move and a looping command you could write the entire code to any depth in about a dozen lines.

 

[kyleb77]

Well I know how to write the code by hand but what I am really trying to find out is how to make the Cavity Mill operation do it. I have been trying a few things out like using Circular Feedrate Compensation. It seems to work a bit better but still it is missing some slowdowns. I tried to change the percent of tool dia. slowdown and also the amount of steps. I guess Cavity just isnt perfect but I have to believe there is a way to have more control over it. Thanks for all the input so far though guys.

 

[jbel]

Kyleb77,

What is Cavity Mill? Is it a feature in a CAM software package?? If so, which program.

 

[kyleb77]

Ya I should have mentioned that important fact from the beginning. UG NX2

 

[jbel]

Ya I should have mentioned that important fact from the beginning. UG NX2

Well, in that case I can't help you a bit....

But, here's something to think about. Is UG primarily a CAD package or a CAM package???

Me thinks its a CAD package. That being said, the functionality of any CAM add on should be an interesting proposition indeed.

Good Luck!!!

 

[derekkarp]

UG is a CAx package. It has an integrated CAM application, and its arguably the best out there. Corner slowdowns are sometimes quirky. Its hard to help without seeing your tool path. That being said, can you post your part so I could give it a shot? Plus, you'll get alot more help from the UG forum on this site, plus the UGS BBS.
-Derek

 

[kyleb77]

Well I cannot show you the part I am sure you know why. Nice try though

 

[derekkarp]

I understand, we're kind of in the same boat here as well. Anyways, it looks like there is 2 Problem Reports open that are related to your issue. These can be found at

http://www.uganswer.com

[PR-05539290]
[PR-02074263]

 

[jbel]

UG is a CAx package. It has an integrated CAM application, and its arguably the best out there.

mmmmmmmmKay, if you say so...

 

[jelmerra]

One way of getting around it is to customise your postprocessor. For instance you could write an ude/mom procedure that triggers a different feed when the angle between two linear elements exceeds a certain amount.