Contouring problems Heidenhain 155

[praest]

I have been milling a kontour on stainless plate 75x12 (all measures are mm)
It’s been working fine, but when the mill is about to finish the arc, it’s not completly round.
It’s not a problem for anyone but me. Any suggestion to a solution.
My machine is a abene VHF 40 CNC and Heidenhain 155,
I also suspect that the radius compensation is calculating a bit wrong, had to move center 1mm to get the measurement correct.

[bborb]

Could you post the program (g-code)?
What dia. tool are you using?
What is in your offsets for this tool?

[praest]

Code used Heidenhain plain lauguage programming
Tool def 1 L=0 R=6
Tool Call S=70 (ca. 700 rpm)
L X 500 Y-85 Z 1 F3000
L Z -13 F3000 M13
L X 485 RR F3000
L Y-65,784 RR F100
CC X 495 Y-37,5
C X 485 Y-9,2157 DR- RR F100
L Y 2 RR F100
L X 500 R0 F3000
L Y 50 F3000
the dia. of the tool is 12mm, I'm doing the countour once at full depth.
There's no funny noises, chips looking fine

[bborb]

Your
CC X 495 Y-37,5
is probably not accurite, its supposed to be the coordinates of the center of your circle/arc your trying to achieve.

[praest]

from the end of the piece to the buttom of the arc, there should be 20 mm, and the radius of the circle is 30mm, so I think the CC is allrigth, but
I had to program it CC X496 Y-37,5 to get the measument ok
The attached file is the drawing

[bborb]

Ah, my bad.
Program looks ok dimension-wise.
For grins and giggles, change R=6 to R=6.5 and cut a fresh piece, then change back to R=6 and recut same piece. This should make your recut a "skim cut" with minimal tool pressure. If you get the same results then the problem isn't in your program.

[praest]

Thanks for the help and inputs. Apreciate any contact, cos I'm CNC department at the shop
I'll try next time to cut it twice using 2 R-values

[JohnA]

If it helps, after changing the R6 to R+6 and running it on my Cutviewer programme ( www.cutviewer.co.uk ) the file looks ok. See attached.
Where is it looking wrong?

0 BEGIN PGM 123 MM
1 TOOL DEF 1 L=+0 R=+6
2 TOOL CALL S=70
12 L Z+2,000 R F9999 M08
3 L X 500 Y-85 Z 1 F3000
4 L Z -13 F3000 M13
5 L X 485 RR F3000
6 L Y-65,784 RR F100
7 CC X 495 Y-37,5
8 C X 485 Y-9,2157 DR- RR F100



9 L Y 2 RR F100
10 L X 500 R0 F3000
11 L Y 50 F3000
96 STOP M02
97 END PGM 123 MM

[praest]

It's just at the end of the arc (about 14-15 degrees before the end), just when the mill is commimg free of material, overlength is 1mm.
I suspect that you'r solution will work out fine
I'll guess my next problem is translation off words off the trade from danish to english *lol*
By the way, how do you get the pictures in the text??

Thanks again
Jens Præst

[JohnA]

Good, hope it works.

To get the pictures in the text use attach & upload them first and then click on the file to insert, in this case attach.bmp

[praest]

Could I use Heidenhain plain launguages in the cutviewer program that you use John??

[JohnA]

Yes you can.