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### Author Topic: Major/ minor arcs in turn  (Read 13488 times)

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#### DAlgie

• 314
##### Major/ minor arcs in turn
« on: May 29, 2009, 12:11:09 AM »
It was suggested to override a feed speed problem in Turn that you use the R value instead of using I and K arc centers. I like the R value because it is faster to hand code, as I do that a lot. However, with the R value I don't seem to be able to control the arc Major or minor and seem to always end up with the major arcs. I looked through it all and I bet I'm missing something simple, but how do you force Mach Turn to differentiate between major and minor arcs? Thanks.
DaveA.

#### DAlgie

• 314
##### Re: Major/ minor arcs in turn
« Reply #1 on: May 30, 2009, 03:20:02 PM »
Anyone? Surely this is a problem that someone else has had to deal with.

#### SteinarN

• 155
##### Re: Major/ minor arcs in turn
« Reply #2 on: May 30, 2009, 03:36:40 PM »
What is major and minor arcs?

#### Hood

• 25,835
• Carnoustie, Scotland
##### Re: Major/ minor arcs in turn
« Reply #3 on: May 30, 2009, 05:27:05 PM »
Not sure what you are meaning as well, wondering though if it is the Reversed Arcs in Front Toolpost setting you need to change, its on Ports and Pins , Turn Options page.
Hood

#### DAlgie

• 314
##### Re: Major/ minor arcs in turn
« Reply #4 on: May 30, 2009, 07:22:06 PM »
Sorry, I should have been more descriptive. If you fit an arc between two points without a signed centre, it can go two different paths and still be a G2 clockwise or G3 counterclockwise. One path is a minor arc, the shorter of the two, and the other is the major, the longer path of the two. One will blend in smoothly with the rest of the geometry, and the other will be abrupt, but the control will still agree with it. An Accurite CNC mill I use has a soft key to let you choose between the two. Mach turn seems to always go for the major, the longer arc if you use an R value instead of a signed centre point.

#### SteinarN

• 155
##### Re: Major/ minor arcs in turn
« Reply #5 on: May 31, 2009, 01:55:33 AM »
I'm going out on a limb here.
Have you tried to use a negative value for the R? What happens then?

#### Hood

• 25,835
• Carnoustie, Scotland
##### Re: Major/ minor arcs in turn
« Reply #6 on: May 31, 2009, 02:42:47 AM »
Can you attach a screenshot of ewhat you are meaning please.
Hood

#### Hood

• 25,835
• Carnoustie, Scotland
##### Re: Major/ minor arcs in turn
« Reply #7 on: May 31, 2009, 03:00:42 AM »
If its like this then it is the Reverse Arcs in Front Post that you want to change as mentioned earlier.
Hood

#### SteinarN

• 155
##### Re: Major/ minor arcs in turn
« Reply #8 on: May 31, 2009, 04:23:40 AM »
Hood, just out of curiosity, if you want one major arc and one minor arc on the same work piece, how do you do it then?

#### Hood

• 25,835
• Carnoustie, Scotland
##### Re: Major/ minor arcs in turn
« Reply #9 on: May 31, 2009, 04:42:48 AM »
I am atrocious at G Code but would imagine you would code your arc in two segments.
Hood

Edit
Is it something like this you are meaning?
G1X100.4Z-209.85F0.3
G3X103.6Z-206.65R1.6
G3X102Z-211.45R1.6
« Last Edit: May 31, 2009, 05:44:50 AM by Hood »