[rcs9250]

I am learning about programming. Some people program by using the drawing dimensions and then using an offset to allow the end mill to step aside by the amount of the radius. As the tool wears you use the wear file to compensate for the size.
And then some programmers program to the centerline of the spindle and add the radius of the endmill to the programmed numbers.
To me the second method is odd in that wouldn't you have to change all your program numbers ? How would you compensate for a size problem with the part size ?

Which method is better ? Why would I want to program to tool centerline ?

[Shakylx]

I think I know what your asking here. Say if doing a .750 hole from centerline to edge would be .375 when using a cutter comp programming method you would use this number and would be able to adjust for wear such as
G1 G41 x.375
G3 x-.375 r.375
G3 x.375 r.375
We use this typically for large runs using endmills with tight tolerances

Or for the same without cutter comp you wou just subtract half the cutter like you said so if using a 1/2 endmill replace the .375 #'s with .125 you would lose the g41 or g42 to feed into comp as well.

We use this with not so tight of tolerances with inserted type tooling that gets replaced before wear becomes an issue with size hope this helps.

[txcncman]

Can't really explain why one method is better for some things versus the other. This is another one of those things that you learn by doing (multiple times over several years).

[rcs9250]

A cnc trainer I know says the only way (his opinion) is to program to the part drawing. That way you don't have to worry about the endmill size if the one you are using wears out or breaks. All you have to do is enter the new endmill size in the geometry page. The obvious advantage is the endmill size doesn't matter at all because the controll automatically compensates for the size.

Does his opinion hold water ?

[Shakylx]

You are programming to the drawing either way just one compensates for wear or correction of size where as the other is you got what you got unless you change the numbers in program. Also when programming without the use of compensation you are writing for a certain size cutter where as with compensation you could use several sizes given their is space for tool.

[rcs9250]

Thanks guys.

[txcncman]

A cnc trainer I know says the only way (his opinion) is to program to the part drawing. That way you don't have to worry about the endmill size if the one you are using wears out or breaks. All you have to do is enter the new endmill size in the geometry page. The obvious advantage is the endmill size doesn't matter at all because the controll automatically compensates for the size.

Does his opinion hold water ?

You can still use the "program to center line of desired tool size method" and use a different tool size. You just have to input the proper additional offset in the tool geometry data, instead of 0.000. Be sure to include enough lead in and lead out to account for various size tools (which would also be needed in the "program to part dimensions" method).

[rcs9250]

Thanks tx. That's a good and important point when making a size change of endmills.

[dak1]

Same subject matter.

question about G41/G42 - Page 2 - CNCzone.com-The Largest Machinist Community on the net!

[txcncman]

Same subject matter.

question about G41/G42 - Page 2 - CNCzone.com-The Largest Machinist Community on the net!

Yeah. People jump right into posting a question without searching for the answer first. Would be interesting to see someone develop a pop up window that searches forums and gives links as they type their question.

[dak1]

Yeah. People jump right into posting a question without searching for the answer first. Would be interesting to see someone develop a pop up window that searches forums and gives links as they type their question.

That would be nice.

[rcs9250]

Often in forums of a technical there are members with highly varied knowlrdge of the subject matter. sometimes the OP does not have the knowledge to understand some of the replies because they are short on some background. So, to tailor their question very specific to their needs it saves time in searching out new information learned in replies.
I taught repair of specialized mechanical devices and ALWAYS was empathetic
to the person that was still in the learning process and did not, would not publicly chastize them for asking a question that was asked before and they just weren't satisfied with the answer.
To ask a question with specific focus and intent and hoping for a clear concise specific answer is always beneficial to learning. My students expected it, desired it and got it.

Sorry if you are offended.

[txcncman]

Often in forums of a technical there are members with highly varied knowlrdge of the subject matter. sometimes the OP does not have the knowledge to understand some of the replies because they are short on some background. So, to tailor their question very specific to their needs it saves time in searching out new information learned in replies.
I taught repair of specialized mechanical devices and ALWAYS was empathetic
to the person that was still in the learning process and did not, would not publicly chastize them for asking a question that was asked before and they just weren't satisfied with the answer.
To ask a question with specific focus and intent and hoping for a clear concise specific answer is always beneficial to learning. My students expected it, desired it and got it.

Sorry if you are offended.

It is not only a matter of readers of a question taking offense. It is also a matter of the questioner being worthy of the time it takes others to answer. One way to show that worthiness it to make a reasonable attempt at researching a topic on ones own before asking the questions that have been answered multiple times in public forums such as these.

[uperez]

it's a matter of convenience is all i can say.. for profiles that only needs side cutting you would normally program it to part size then use the g41/g42 compensation, but on features that needs center cutting you would normally compensate the tool radius in your program. in my case i always program to center on roughing process and facing operations, then use g41/g42 on finishing (side cutting) to control the size. this is of course with manual programming.