Hello everyone
I'm building a flatbed plasma cutting machine, and i want to be able to cut holes on a tube, also.
The tube will be parallel to the Y axis and rotated probably from axis A with an extra servo driver/motor.
My question is how to configure mach3 to use either axis A or X depending if i want to cut a hole on a tube surface or just a normal sheet metal X,Y plane.
Also i need somehow to give the information to mach3 of the diameter of the tube in order to calculate the right feedrate and the steps per inch/mm for every different tube diameter i will cut.
Any help will be appreciated.
 

I think Terry may have messed around with something similar to this, hopefully he will chime in if he did, but in the mean time have a look here http://www.machsupport.com/forum/index.php/topic,16411.0.html and see if Terry is talking about what you are wanting.
Hood

I just need for start a simple gcode in order to cut for example a 50mm diameter hole.
The rotating axis will be the A and will be parallel to Y axis. the X axis want move.

HIYA guys what I worked on was a way to COPE fit pipe joints on the plasma.

Cutting holes in a pipe is fairly simple with a 4th axis.  BUT you will have to convert the code to use it . The 4th is normally set up as degs/min and to cut it needs to be converted to compensate for the pipe diameter

 One way is to create a drawing then let the CAM do the conversion to the 4th axis. SHEET CAM can do this.

Another way is to use a utility like WRAPPER to convert your Gcode.

It also may be possible to set up a WIZARD to do the Gcode based on parameters

Make sure your 4th is set up accuately as to steps/deg.

(;-) TP

We saw a cool coping plasma at FabTech.  It was 5 axis and made the cut angle on the tube match where it mated up.  It worked on square tubing also.  I could barely afford to walk by their booth, but it was a cool machine.  It used a rotary axis to turn the tube and a robotic arm to move the torch in 5 axes.  I guess it was really a 6 axis.  A 5 axis robotic arm plus a rotary.

I manage to do some holes on the tube by simply substitute "electrically"  the axis X servo drive with the axis A servo drive. So i dont have to do any changes at all at the g code.
Is there any way to tell the mach to substitute software wise the output of the X axis to the output of the A axis?

You can use swappaxis() in a macro to do the physical swap. BUT you will need to scale A axis to get the hole size corrected. you will always have to do some correction depending on the tube size and the motor settings. Best to set the motor settings correctly then adjust through scale.

We have the tubing coping workin fine with mach. It is avaliable from the  Mach Toolbox in the download section.

I will look to see IF we can create a version for basic holes as well.

(;-) TP

The thing you need to determene is how will you drive the A axis.

From the centerline via a chuck     

OR

From a set of drive rollers


IF you set up with drive rollers THEN you can set it up as a linear drive and set you steps per inch directly.

Just a thought, (;-) TP

I manage to do some holes on the tube by simply substitute "electrically"  the axis X servo drive with the axis A servo drive. So i dont have to do any changes at all at the g code.
Is there any way to tell the mach to substitute software wise the output of the X axis to the output of the A axis?

Since you likely won't be cutting sheet and tube on the same job, couldn't you just build a second mach profile for tube cutting? Then it would be as simple as loading the correct "version" of Mach for the job, and you could continue to use your standard g code.

Thank  BR549 i try to use the swappaxis() command, but i couldn't fine the mach toolbox witch you mention.