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5 Axis calibration


squirrel_41
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Mastercam X7 Mach3 Home made mill router can machine steel Yaskawa AC Servos

Retired Mechanic

Hi Guys  I am in need of some help I have made  a 5 Axis attachment for my machine and I have been trying to fix an alignment problem  on Axis rotations

This is a Table Table  using  the Generic Fanuc  5X Mill post non-nutating

This is a simple cube

first operation machine a step contour Top Top Top  

second operation machine side faces Top Front Front  Transform rotate 90

All operations perform as expected the top contour is stepped  in and down .5mm so I can check the Alignment  after the side faces are machined

now looking at the part from the top the left and right side faces are off  center to the left  X- b y about .25mm

I have probed a ball on the C axis  table to check the  alignment and done the same with A axis rotated 90 degrees I have used the intersection of the of the probe points for the rotation center  I have done this at least a dozen times with no improvement  there is obviously an alignment problem but I cannot work it out  I have thought about it a lot and I cannot point the finger  at the axis that is causing  the problem .

This a a home made unit and I not looking for micron accuracy  I am just trying to get my head around what axis is  creating the error

saxisx       :0               #The axis offset direction?  using mtype 0 does NOT effect the code using mtype 1 or more does effect the code
saxisy       : 0              #The axis offset direction?  using mtype  0 a value here DOES effect the code 
saxisz       : -9.023     #The axis offset direction?   

I would really appreciate it if some one could point me in the right direction

Thanks. 
 

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Almost all 5-Axis machines will have some misalignment between Center of the Rotary Platter, and the Center of the tilt axis.

In your "shift" variables, you are only use the Z Axis shift, so I suspect you'll either need + or - .125 mm (+- .005 inch) in either 'saxisx' or 'saxisy'. Which variable you need to adjust will depend on the kinematic layout of your Trunnion Table. Is this C on A, or C on B? (Is "A" the Tilt Axis, or is "B" the Tilt Axis?)

What are the rotary limits of your Trunnion? Will the Tilt Axis do +- 90 degrees? If you have at least +-90 on the Tilt Axis, it is fairly easy to rotate the Tilt Axis to either +90 or -90, and touch off with a test indicator (.0001 resolution). Then find the "high spot" of the side of the Rotary Platter, and also test at 0 and 180 (rotate the platter through 360 degrees, just to test, and record each value at C0, C90, C180, and C270. Then, rotate the Tilt Axis to the opposite side (if you start at -90, then rotate to +90), and repeat the same test.

At each test position, write down the Machine Z Position, of where the "high spot" is with the test indicator.

I believe what you will find is approximately a .010 (inch) difference between the measurement at +90 and -90 degrees. Then you just need to determine (based on trunnion mounting and layout, versus the machine's axes), which axis to put the shift value in. (It will either be 'saxisx' or 'saxisy', and you'll need to determine the correct signing of the value.)

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Hi Collin I appreciate the response

The A axis is parallel to X axis

C axis which I have renamed to B axis rotates about Z and is unlimited

 My machine it set up the same as 5_5AXGEN_VMVTTAB in the simulator

The 'A' tilt access can rotate -+120 I had already done all as you suggested but the improvement was not great ? However I have since redone all the above checks and I am now happy with the results  it seems I may have been a bit sloppy with my tests the biggest improvement was from using  the center point of the ball rotating  on the  c axis as the rotation center.

This machine is at best able to machine to 0.1mm in 5 axis I can get to about .05mm in 2d 

Now as for  saxisx  saxisy   it seems only saxisy and saxisz has any effect on the code using mtype = 0  , I  have tested this using 2d and 5axis toolpaths

If I use mtype = 1 I get really strange results with mtype = 2 the results are more predictable but now saxisy has no effect but saxisx does  so it seems if i need to use saxisx I will need to reconfigure  and adjust  below

rotaxis1$ = vecy  #Zero      yx works here for the four tool plane directions   using mtype = 0
rotdir1$  = vecx  #Direction  This is the A Axis  change vecy to -vecy to change the axis direction

#Secondary axis angle description (in machine base terms)
#With nutating (mtype 3-5) the nutating axis and this plane normal
#are aligned to calculate the secondary angle 
rotaxis2$ =  vecz  #Zero       zy works here for non nutating axis the four tool plane directions     xz works for nutrating axis
rotdir2$  =  vecy  #Direction   #this flips the Y axis direction but also flips the B Axis Direction -vecy only seems to work with m type 0

 

#Machine base matrix (Base matrix to map positions into)
matb1$       : 1    # was 1 Make X axis neg
matb2$       : 0
matb3$       : 0

matb4$       : 0
matb5$       : 1   # was 1  -1 make B axis flip 180
matb6$       : 0

matb7$       : 0
matb8$       : 0
matb9$       : 1   # was 1 -1 changes y sign but wrong value

I have tried many combo's using Matrix base to reconfigure to use mtype = 2 but as yet have not got it to produce the correct code I will keep working on so I can use saxisx and perhaps saxisy together

So to cut a long story short it would appear that the bulk of my problems come from a incorrect rotation center

Thanks again Collin.

 

 

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I'd first separate issues between machine calibration and futzing with the post. If you can rotate to multiple compound angles and the ball is where it is predicted to be, within the desired accuracy, only them move on to the post processor.

 have no idea what kind of 5ax calibration routine is available in Mach3. A colleague made one by probing the corner of a just-cut part and it works amazing.

 another way, rather than messing with those post settings is to create a point in CAM that represents the COR, and have that as all your coordinate system;s origin,

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On 7/25/2019 at 10:06 PM, squirrel_41 said:

Hi Collin I appreciate the response

The A axis is parallel to X axis

C axis which I have renamed to B axis rotates about Z and is unlimited

 My machine it set up the same as 5_5AXGEN_VMVTTAB in the simulator

The 'A' tilt access can rotate -+120 I had already done all as you suggested but the improvement was not great ? However I have since redone all the above checks and I am now happy with the results  it seems I may have been a bit sloppy with my tests the biggest improvement was from using  the center point of the ball rotating  on the  c axis as the rotation center.

This machine is at best able to machine to 0.1mm in 5 axis I can get to about .05mm in 2d 

Now as for  saxisx  saxisy   it seems only saxisy and saxisz has any effect on the code using mtype = 0  , I  have tested this using 2d and 5axis toolpaths

If I use mtype = 1 I get really strange results with mtype = 2 the results are more predictable but now saxisy has no effect but saxisx does  so it seems if i need to use saxisx I will need to reconfigure  and adjust  below

rotaxis1$ = vecy  #Zero      yx works here for the four tool plane directions   using mtype = 0
rotdir1$  = vecx  #Direction  This is the A Axis  change vecy to -vecy to change the axis direction

#Secondary axis angle description (in machine base terms)
#With nutating (mtype 3-5) the nutating axis and this plane normal
#are aligned to calculate the secondary angle 
rotaxis2$ =  vecz  #Zero       zy works here for non nutating axis the four tool plane directions     xz works for nutrating axis
rotdir2$  =  vecy  #Direction   #this flips the Y axis direction but also flips the B Axis Direction -vecy only seems to work with m type 0

 

#Machine base matrix (Base matrix to map positions into)
matb1$       : 1    # was 1 Make X axis neg
matb2$       : 0
matb3$       : 0

matb4$       : 0
matb5$       : 1   # was 1  -1 make B axis flip 180
matb6$       : 0

matb7$       : 0
matb8$       : 0
matb9$       : 1   # was 1 -1 changes y sign but wrong value

I have tried many combo's using Matrix base to reconfigure to use mtype = 2 but as yet have not got it to produce the correct code I will keep working on so I can use saxisx and perhaps saxisy together

So to cut a long story short it would appear that the bulk of my problems come from a incorrect rotation center

Thanks again Collin.

 

 

Simulation is not tied into the Post in any way, unless you purchase integration from your Reseller. 

 

Do not mess with 'mtype'. You set 'mtype' to 0 for a Trunnion, 2 for a Gantry, and 1 for mixed-mode (1 rotary on tool, 1 rotary on table).

The primary and secondary are configured solely with the rotaxis and rotdir variables. 

The Machine Base Matrix is defined as a Vertical machine, by default. Only Vertical and Horizontal machine configurations are supported. (Do not flip signs or change values, unless you have a good understanding of 'why' you are flipping those values.)

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