5-axis axis post question

[Guayaco]

I hate to admit I'm a post greenhorn, but I'm tweaking the generic Fanuc 5 axis post and need to know the difference between the "primary" and "secondary axis". Comments or references?

[Guest SAIPEM]

The Primary or "Master" Rotary Axis is the driving Rotary Axis and the Secondary or "Slave" Rotary Axis is the driven Rotary axis.

 

This means that the position of the secondary axis is dependent on the position of the primary axis.

 

The math for calculating the angles for each from the tool vectors is different depending on the rotary axis configuration.

 

I Vector = 0.1227878

J Vector = 0.1227878

K Vector = 0.98480775

 

Mighty USA B-5000 5BC

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Master - Angle C = 45.0

Slave - Angle B = 10.0

 

Haas VR-11

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Master - Angle B = 7.1070759

Slave - Angle A = -7.0530219

 

SNK PC-60V

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Master - Angle A = -7.1070759

Slave - Angle B = 7.0530219

[John Summers]

Here's the non-mathematical explanation. Most 5-axis machines can take either of two positions to satisfy the tool axis vector. The postprocessor is biased so that it will not switch back and forth between them during a cut. Often the primary position faces the work towards the operator more than the secondary.