Cutter comp above the part

[Jeremy Grigsby Excelsior Marking]

I am machining an aluminum plate with many small parts arranged in rows and columns. I am having a problem with profile violation because it is applying the cutter comp, (G41, G42) at depth. In other words it is plunging in with centerline of the tool on the profile and then moving over for the compensation. How can i make it apply cutter comp above the part. I can't put much of a lead in/out in to compensate, because of the small distance between parts.

 

[ 01-14-2003, 12:06 PM: Message edited by: JeremyG ]

[chris m]

I don't know the post stuff but one easy way to eliminate this problem is to use centerline programming with comp in the computer & wear comp in the control or comp in the computer only (depending on tool size variation and part tolerance). It can take a little while to get used to from an operator standpoint but the machine will do what you think it should do; not what it wants when it reads the comp commands

 

C

 

[ 01-14-2003, 12:09 PM: Message edited by: chris m ]

[Elad]

If I understand you right,There is no control that knows to calculate the cutter comp. in control before getting to the depth cut.

G41 G42 must be open on a line,and i have no idea why the control programmers didn't fix that untill today.anyway,it is ok to open the G41 G42 on a line length of 0.01 mm,in other words,as far as i know,you must add lead in/out when using cutter comp. in control.

 

Hope this helps.

[Jeremy Grigsby Excelsior Marking]

i would use centerline programming, but these are long run parts and we may have tool wear eventually

There has to be a way to have it apply before its at depth. I'm just trying to figure out how.

[chris m]

Jeremy

 

You can still use centerline programming by selecting Comp in Computer "On" and Comp in Control "Wear" or "Reverse Wear" depending on whether the control will take negative tool radius offset values. Although we NEVER used this type of programming before we got Mastercam it works very nicely for us now and allows you to be more confident that you are sure where the machine is going to go.

 

I know it is possible to turn cutter comp on above the part with some controls (the Fanuc 18M on one of my machining centers will do it) but it can really be more of a hassle to do things this way.

 

C

[godzillia_dude]

I'm with chris m! As a newer user, we never programed this way, but now it has proven to be pretty easy and the guys on the machines like having "0" cutter comp. I would encourage you to give it a try. Good Luck.

[Trevor Bailey]

In your lead in/out, you may want to try the RAMP feature. Extend the length of the lead in line and all should be fine for you. It is a very nice feature to get into small spaces when CC is needed.

[Jeremy Grigsby Excelsior Marking]

Well, we decided to use the wear comp and it seems to work good. I have however been informed that in release 9.1 you will be able to apply cutter comp and take it off above the part. That will be nice. Thanks for your suggestions

[Jim Whipple]

I also use wear comp almost exclusivly...I interpolate a lot of bores, and may not have room for the comp move if I didn't use wear. I've used as little as .005 for lead in and out lines....

Jim

[Brian Ulrick]

I had my Fadal POST modified to turn comp on above the part and also use comp on in computer and machine in MASTERCAM and zero tool dia. at machine offsets. Then I adjust only the small amounts I need for tool wear. No jumps in tool movment when comp comes on.

[Greg Williams]

quote:

---

If I understand you right,There is no control that knows to calculate the cutter comp. in control before getting to the depth cut.

---

Elad,

 

All fanuc controllers form at least 15M can set the cutter comp above the job and then go to depth

 

However I am not sure if Mastercam has this function

 

[Andy]

Another BIG advantage to wear comp is:

You put zero's in for all your offset diameters in the machine!! You no longer have to input the dia of the cutters. This means no more data entry errors. And it also means you wont have to change the diameter in the offset table if you decide to use a different size EM. i.e. just change the EM in Mastercam, regen, send to machine and run. A lot less complicated!!

Good luck,

Andy

[cadcam]

Just hang in there all what you want is coming.

[chris m]

quote:

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it also means you wont have to change the diameter in the offset table if you decide to use a different size EM. i.e. just change the EM in Mastercam, regen, send to machine and run. A lot less complicated!!

---

That's less complicated than changing an offset from .500 to .4375?

 

Each type of comp has its advantages!

 

C

[Guest CNC Apps Guy 1]

quote:

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...Each type of comp has its advantages...

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and Disadvantages.

[Mgrenier]

quote:

---

And it also means you wont have to change the diameter in the offset table if you decide to use a different size EM. i.e. just change the EM in Mastercam, regen, send to machine and run. A lot less complicated!!

---

Or you can use comp in computer and have the value of the compensation write itself within the program which is a very safe way of doing it since the tool comp will write itself to the correct value the next time you run the job. And the machinist doesn't need the programmer to change a tool in the program.

 

The command line for fanuc is: G90G10L12P___R___. Where P is the offset number and R is the value of the cutter comp.

[chris m]

quote:

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The command line for fanuc is: G90G10L12P___R___. Where P is the offset number and R is the value of the cutter comp.

---

In the spirit of this; the Okuma line is:

 

VTOFD[XX]=.YYY

 

where "XX" is the diameter offset number and ".YYY" is the cutter radius value.

 

VERY nice!

 

C

[P_Scott]

Andy and All,

 

quote:

---

And it also means you wont have to change the diameter in the offset table if you decide to use a different size EM. i.e. just change the EM in Mastercam, regen, send to machine and run. A lot less complicated!!

---

The advantage to Wear comp is the fact that you DON'T have to go back to Mcam to program a compensation value if the tool is different from what was programmed in Mcam. That's really what the Wear comp is for. It's the "best of both worlds". If the cutter WEARS down during machining, simply adjust the dia. at the control and re-cut the necessary toolpath. Besides that everything Andy stated in the first part of his post is correct. V9.1 (soon to be released) will have Lead In/Out switches that will allow the user to turn comp on and off above the start point. HTH

 

[ 01-20-2003, 11:11 AM: Message edited by: Peter Scott ]

[Kenneth Potter]

in those sticky tight places for a comp move.......Create some geometery that blends into your contour

above your part....use that as your comp on geo....then use the toolpath editer to force the tool down after comp is on to your X,Y,Z positions.

 

the tool path editer can get in out of a lot of Jams..

[steve f]

Jeremy, until v 9.1 comes out try adding a vertical move, using the graphical toolpath editor, between the first line of lead in where the cutter comps and the arc move of lead in. Same applies for lead out move. If your control can handle it this will accomplish the exact same thing as what v9.1 will do.

 

Steve