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Author Topic: Cutting inside or outside the line??  (Read 4830 times)

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Cutting inside or outside the line??
« on: January 25, 2011, 09:27:29 PM »
I'm sure this question has been answered before but I haven't been able to find the answer.
I'm trying to designate which side of the line my cutter follows.  Example, a 1" x 1" square.  I want to be able to have the cutter stay outside the lines so once the square is cut, The measured part still reads 1.000 and not .875 using a .250 cutter.  I'm running a licensed copy of Mach3 and I'm trying to use the old version of Lazy cam to generate my G-code, (it was free!)  I'm beginning to think I need to purchase a g-code generating software as I'm just not having any luck figuring out the old version of Lazy cam.
Any help would really be great.
Thanks.
Re: Cutting inside or outside the line??
« Reply #1 on: January 25, 2011, 10:42:21 PM »
This will mainly depend on the direction of machining:

This is called conventional milling or climb milling.

Conventional milling is where the lips of the tool is pushing the material where climb milling is when the tool lips is trying to grab or pull the material.

Conventional milling is more often associated with non CNC machine and climb milling is associated with CNC machine because the finish is better.

Thia is associated with G41 (climb) and G42 (conventional) for tool compensation also  call left or right machining.

http://www.innovativetoolsales.com/ITS%20Techpage-Conventional%20v%20Climb%20Milling.pdf

http://www.youtube.com/watch?v=4EMryFADwMk   ( look at the direction of the cutter)



 
Re: Cutting inside or outside the line??
« Reply #2 on: January 25, 2011, 11:13:38 PM »
Think your labeling is backwards on the 2nd drawing, if I understand your logic.
Re: Cutting inside or outside the line??
« Reply #3 on: January 25, 2011, 11:52:03 PM »
That second drawing has all the climb/conventional directions backwards....
Regards,
Ray L.
Re: Cutting inside or outside the line??
« Reply #4 on: January 26, 2011, 12:16:45 AM »
Looks like the arrows are  depicting the direction of table movement, not the cutter.
In that sense, it's right.
A good illustration for a manual machinist ?
Re: Cutting inside or outside the line??
« Reply #5 on: January 26, 2011, 12:22:25 AM »
Looks like the arrows are  depicting the direction of table movement, not the cutter.
In that sense, it's right.
A good illustration for a manual machinist ?

That would make sense, except it's more conventional to think in terms of tool movement....

Regards,
Ray L.
Regards,
Ray L.
Re: Cutting inside or outside the line??
« Reply #6 on: January 26, 2011, 01:14:20 AM »
That illustration is not from me, it came from Wiki if I remember well.

Did not even took time to get a good look at it.

Hope that it did not created confusion.

Jeff

Offline RICH

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Re: Cutting inside or outside the line??
« Reply #7 on: January 26, 2011, 05:50:57 AM »
Quote
I'm beginning to think I need to purchase a g-code generating software as I'm just not having any luck figuring out the old version of Lazy cam.

Never used the old version of LC so don't know how that behaves, what works and what does not. Cutter compensation was upgraded in Mach to follow programing per Peter Smid's  explainations in his book and i would suggest to anyone interested in learning to do Gcode they buy the book.

You can learn a lot by looking at the code generated from a program and quickly do a comparison ie. cutting along the line, to the left or right, maybe more importantly
how to apply more complex things like different lead ins / outs and the rules  associated with them and the G41 & G42 commands. As soon as the profile gets more complex a program is worth it's weight in time saved.

You may want to try using the wizards to generate the code for your square....... and look at the code differences.  
Graham posted an excellant example of using compensation ....do a search.

Some suggestions to consider,
RICH