Cutter comp to the center or edge

[westerfieldcct]

I have always been a center person thould I would get other peoples input.

[o1dakota440]

i'm just getting into the cnc hobby and am new to all of it, but so far i use the center of the tool.

[307startup]

Originally Posted by westerfieldcct I have always been a center person thould I would get other peoples input.

What the hell are you talking about?

Cutter compensation by definition is an offset either to the LEFT or the RIGHT of the center line, to compensate for the difference between the measured OD of a cutting tool and the dimensions of a cut surface, whether it's due to incorrect coding of a tool path, mismeasured tool, excessive runout, or a cutting edge wearing out or being replaced.

How exactly would you compensate ON CENTER?

A tool isn't going to get any more centered by adjusting cutter compensation , nor is a line on a tool path going to become more centered than it was programmed...if your tool is off-center, you have a bad tool-holder and it should be replaced, if a cut on your workpiece isn't where it should be in relation to a dimensioned drawing, your program should be checked for errors.

[Torsten]

Been a bit confused by the terminology.
1) Do you mean to the Center of the Tool by using the Toolradius as compensation Value?
2) And to the Edge of the Tool by compensating for the difference of the actual Toolradius from nominal Toolradius only?

Tough choice
For the short Programs I manually enter into the controller I often use the 1st option it is far easier to drive the drawing dimension directly without having to do the math and i can decide on the tool size later.
It also helps with macro cycles where the actual size of the tool is known to the program.

Cam generated Programs are a different story to avoid problems with verification and the different ways compensation is invoked by varying Controllers I usually use the 2nd methode.

[307startup]

Originally Posted by o1dakota440 i'm just getting into the cnc hobby and am new to all of it, but so far i use the center of the tool.

I will excuse you for being a newbie, but nobody cuts with the center of the tool, everybody cuts with the periphery of the tool.

A tool rotates about it's axis...at the center, there is no rotation. Even with a center-cutting endmill, this is a misnomer, as the center isn't cutting anything, there is a gap between the webs of the tool, like on a split-point drillbit.

[glovebox20]

When I use the "Dumb Thumb" programing method, I program to the edge of the tool. That way you can program to the print demotions and be done with it.

But when using a Cam system I use the "Center" like Torsten dose to avoid cutter comp issues.

I only program mills, so lathes maybe another story.

[westerfieldcct]

Originally Posted by 307startup What the hell are you talking about? Cutter compensation by definition is an offset either to the LEFT or the RIGHT of the center line, to compensate for the difference between the measured OD of a cutting tool and the dimensions of a cut surface, whether it's due to incorrect coding of a tool path, mismeasured tool, excessive runout, or a cutting edge wearing out or being replaced. How exactly would you compensate ON CENTER? A tool isn't going to get any more centered by adjusting cutter compensation , nor is a line on a tool path going to become more centered than it was programmed...if your tool is off-center, you have a bad tool-holder and it should be replaced, if a cut on your workpiece isn't where it should be in relation to a dimensioned drawing, your program should be checked for errors.

All you need to do is ask for more information. I am amazed that others can read and understand but you don't. The questions could be stated by saying do you program to the print without using the radius of the tool, or do you program computing in the radius of the tool you wish to use. Others have answered with out issue, why can't you?

[307startup]

Originally Posted by westerfieldcct All you need to do is ask for more information. I am amazed that others can read and understand but you don't. The questions could be stated by saying do you program to the print without using the radius of the tool, or do you program computing in the radius of the tool you wish to use. Others have answered with out issue, why can't you?

Because this: I have always been a center person thould I would get other peoples input. doesn't mean anything in English or any other language.

If someone else wants to communicate a point, it is their responsibility to write intelligibly and effectively, it isn't my responsibility to guess at what they are trying to say and interpret gibberish. Especially when they are conducting a poll. Otherwise what bearing would the results have on anything?

That's the problem with the world today, no one has or maintains any standards, it's just a free-for-all, do-whatever-I-wanna-do kinda world, where criticism is bad and justifications & excuses are ok.

Being a "center person" doesn't have jack-squat to do with actually USING cutter compensation, now does it? Your program is either correct, your tool was indicated properly and your workpiece hit it's target dimensions, or it didn't. And that is why cutter compensation would be used...to alleviate one of these conditions.

Again...you can't use cutter compensation ON center, because it's an offset FROM center. That whole communication thing, where words have definitive meanings and thus a common understanding can be achieved...

[Geof]

Originally Posted by 307startup ........That's the problem with the world today, no one has or maintains any standards, it's just a free-for-all, do-whatever-I-wanna-do kinda world, where criticism is bad and justifications & excuses are ok..........

Down boy down. You are encroaching on the territory of crotchety old farts like me. But I guess it is good you encroach because this old fart gave up trying to get young twits to use correct spelling and grammar years back.

[fizzissist]

Originally Posted by Geof Down boy down. You are encroaching on the territory of crotchety old farts like me. But I guess it is good you encroach because this old fart gave up trying to get young twits to use correct spelling and grammar years back.

....and old farts like me as well

I was taken aback by the tone of the response to what was a simple and innocent question....and an answer that to me at least was inaccurate.

Cutter comp on a lathe for a tool with a radius tip takes into account the theoretical tip location. That takes into account the X AND the Z compensation needed to give accurate contours, correct?

Least that's the way I have to program my cutter comp on my lathe.....

....but wait, we're talking about milling comp, where the tool rotates?? A rather different nature to the compensation?? Ok, like the ability to compensate to the edge OR center of the tool for wear?

My Fadal Format 1 allows not just zero compensation, but negative compensation so you compensate for a tool that is undersize, right on the mean, or oversize. Regardless, you program the toolpath according to the part's dimensions directly, and invoke either left or right cutter comp with G41 or G42 so the control has to suffer the calculations of the actual path.

I always (with RARE exception) program the toolpath using dimensions right off the print, input the tool's diameter into the control, and use the appropriate comp. It makes reading the program feasible for the inevitable editing .....

[holbieone]

307startup , WHAT ?

[fizzissist]

Maybe to simplify.....

You really need to program to the part, NOT the tool....and use the part dimensions as your toolpath (all this presumes you have the ability on your control to use cutter comp??), so you're free to change the tool to a different diameter if need be.

For example.....a simple part that is 3"tall in Y by 5"long in X....with origin at lower left corner 0,0 and you want to go clockwise from the origin (we'll ignore approach here for simplicity)

You've called G41, left offset, in the approach move, then you have; (we'll program in absolute)

G1 X0 Y0 (tool starts at origin
G1 X0 Y3 (tool goes to upper left corner
G1 X5 Y3 (tool moves right to upper right corner
G1 X5 Y0 (tool moves down to lower right corner
G1 X0 Y0 (tool moves left back to origin

Now, if you don't use cutter comp, you'll have to change the values of the X and Y coordinates in each and every move to allow for the radius of the tool, and you'll have to change the entire program if you break your precious and only 1/2" dia endmill, the customer is screaming for his part, and the only tool you've got is a 7/16".....

To people who've been doing this for awhile, the poll could seem silly. But if you're like me and at one time had absolutely NO clue (arguably still the case), there's no stupid questions.

When I teach Aikido, I always remember the frustration of wondering where the hell are my feet supposed to go when I first started. The beginner before me is going through that very same experience, and I am bound to get him past that as quickly as I can. I don't need to beat him up, he'll do enough of that on his own.

Same thing with this skill. We don't need to be discouraging newbies while a skilled labor force is so crucial to our future.