Author Topic: Cutter comp  (Read 4679 times)

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Offline lew

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Cutter comp
« on: July 04, 2007, 03:52:12 PM »
Hi All:
I ran a part this morning. I had run this part before. The program calls for M6 and then T8. T8 is a 1/2" dia. end mill. The first cut started without allowing for the 1/2" end mill tool. So, the path it took had tool zero for comp. and it did scrap the part. I didn't notice this until I saw the cut about half way through it's  path. I wondered what had happened and brought up the tool table. I looked at tool 8 and it was indeed set for 1/2" end mill. Then I hit the "accept" button and exited . I restarted the part program just to see what would happen and it called the correct tool and proceeded to mill the part correctly. I don't have a tool changer but use M6 to signal a tool change.
Anybody experience this?
Is there something I need to do in the way of a script when Mach starts to insure that cutter comp is set?
Thanks
LEW

Offline ger21

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Re: Cutter comp
« Reply #1 on: July 04, 2007, 10:26:41 PM »
When cutter comp is called (G41/G42), you can specify the tool # (G42 D1 for tool #1) or tool radius (G42 P0.25 for a 1/2" diameter tool). If neither is specified, Mach should use the current tool radius for the offset.
Gerry

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Offline lew

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Re: Cutter comp
« Reply #2 on: July 05, 2007, 08:15:00 AM »
Ahh!
I was unaware that the letter "D" was to be used to specify a tool. I was accustomed to using the letter "T" for calling a tool.
I will experiment with using the letter "D" because I would much rather include the tool information that way instead of using M6 and then calling a tool.
Thanks
LEW

Offline ger21

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Re: Cutter comp
« Reply #3 on: July 05, 2007, 05:08:50 PM »
The D is only used with/for G41/G42. You still call the tool with a T for the tool change.
Gerry

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Offline lew

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Re: Cutter comp
« Reply #4 on: July 05, 2007, 07:28:55 PM »
Thanks for the info ger:
I did play a bit with the "D" command but it is not "persistant". If I encounter another g41 command without adding the "D" the software defaults to tool zero with no comp.
I still have the problem where the software does not recognize the m6 t8 command on the first go round. If I stop and restart then it seems to pick it up. I probably have a setting wrong. For the time being I'll just have to be cautious when I first start a program using comp.
Thanks
LEW

Offline Bear

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Re: Cutter comp
« Reply #5 on: July 06, 2007, 06:17:33 PM »
?
Doesnt the tool # call up the offset page,where the offsets are entered ?
Bear
(Mac-2 user)

Offline lew

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Re: Cutter comp
« Reply #6 on: July 06, 2007, 10:52:54 PM »
Hi Bear:
The way I understand it, the M6 command when encountered in a g-code file signifies a tool change. The T command and the integer after it signifies which tool is installed. The tool info comes from the tool table which is entered previously from the config. menu. Once the software goes through these two commands, it knows what tool is in the spindle and subsequently makes offset calculations based on this info. If T8 is a 1/2" end mill then cutter comp takes into consideration the diameter of the tool and either offsets the toolpath to the left with a G41 or to the right with a G42. Left and right correspond to whatever direction the cut is progressing.
That's my understanding. My glitch is that on first startup and running of a program with cutter comp., the tool does not seem to get recognized and consequently no cutter comp. is built in. The toolpath if left alone will create a cut that is wrong. For whatever reason, if I restart the program the tool gets recognized and the toolpath works just fine.
LEW

Offline Bear

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Re: Cutter comp
« Reply #7 on: July 07, 2007, 09:19:52 AM »
 Maybe youre holding an offset ,not calling cancel before ,or after using an offset ?
 
   Bear

Offline kfrey

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Re: Cutter comp
« Reply #8 on: July 07, 2007, 11:13:44 AM »
Please clarify this for me. On all the controls I am used to, (Fanuc), T8 only tells the machine what tool you want, it doesn't register any offsets. G43 Hxx calls the length offset and G41/42 Dxx calls the dia offset. If you don't have a G41/42 Dxx, you won't have any tool dia offset.  Does Mach work differently than this?

Kev

Offline jimpinder

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Re: Cutter comp
« Reply #9 on: July 07, 2007, 01:52:09 PM »
Lew - I am a complete novice at this, but surely if you start a program, without giving the machine the necessary information, i.e. tool no, and diameters or whatever, then it will just cut without any compensation.

Jim Pinder
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