So not a Guru

Approach after unwind problem

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We've got a troubling problem, that just came up for the 1st time on our Mazak i800 Variaxis post.

I have a morph path that is crossing the singularity at several places, so it is performing unwinds. The post has the tool retract to G53 Z0, then it re-positions the table and is supposed to restart the path. But when the tool moves to the new start, it going to crash into the part.

Here is a snippet of the code at the 1st rewind

N11
(UPPER SURFS)
(OPERATION NO - 11)
G0 G20 G40 G80 G90
T12 T17 M6 (1/2" BALL 2 FLUTE 1.25"LOC 3"OAL)
G0 G53 Z0.
G53 X-14.37 Y-15.75
G0 G90 G54 G17
A-30.1328 C359.9789
M46 M43
G65 P9544 H1 (CALCULATE G54.4 DYNAMIC OFFSET)
G54.1 P300 (CENTER OF ROTATION WPC)
G54.4 P1
S9168 M3
G43.4 H12 X4.0192 Y1.9357 Z6. A-30.1328 C359.9789
M8
G61.1 P1
Z6.9553
X4.0191 Y1.6847 Z6.5228
G94 G1 X4.019 Y1.4337 Z6.0904 F25.
X3.9986 Y1.4209 Z6.0973 F78.41
X3.9612 Y1.3982 Z6.1066
...                                                <removed for brevity
X.476 Y.8018 Z5.6481 A24.7395 C.0027
X.489 Y.7984 Z5.6442 A26.5794 C.0017
X.4988 Y.7961 Z5.6412 A28.4193 C.0008
(ROTARY/TILT AXIS UNWIND)
G49
G54.4 P0
G0 G53 Z0.
A-30.2591 C180.
M46 M43
G65 P9544 H1 (CALCULATE G54.4 DYNAMIC OFFSET)
G54.1 P300 (CENTER OF ROTATION WPC)
G54.4 P1
S9168 M3
G43.4 H12 X.5056 Y-1.1891 Z9.0398 A-30.2591 C180.
G1 Y.7948 Z5.6392                                   <the tool will crash into the part
X.5051 Y.7945 Z5.6368 A-30.239

I'm attaching a file with the toolpath.

I'm wondering if anyone has a Variaxis that puts out good code for this. If so could you share a snippet with me, so that I can modify our post to work correctly.

Thanks

Zeke

 

MORPH_TEST.mcam

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Just to clarify, I'm just looking for the proper syntax and sequence of the code required, on a Mazak, for safe exit and re-entrance of 5-axis toolpaths, when there is an unwind.

I had no problem creating a path that worked, without crossing the singularity, although it meant cutting more air than I care for.

 

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3 hours ago, So not a Guru said:

Just to clarify, I'm just looking for the proper syntax and sequence of the code required, on a Mazak, for safe exit and re-entrance of 5-axis toolpaths, when there is an unwind.

I had no problem creating a path that worked, without crossing the singularity, although it meant cutting more air than I care for.

 

That is the issue there is not safe process in one toolpath that I am ware of. You have to break it up and create you own when faced with this. The other option is do what you did get around it and deal with the air cuts. I have sepnt days on some parts sorting stuff like this out when it mattered. When it didn't I just dealt with the air cuts.

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Hi Zeke,

 

Our variaxis post is generating code that is fairly similar so I am having a difficult time picturing how the crash it actually occurring and how the machine is moving when this happens.

To start the transition, the tool lifts up to the home position and the trunnion rotates to the other side.

On the G43.4 line the machine activates TCP and calls all 5 axes. I would expect the machine to move in XYZ to the other side of the machine where the part now is, ending with the tool tip roughly 4 inches directly above the next point. This would move all three linear axis at the same time, with the tool moving down in Z and from one side of the machine to the other along Y. This is the move that I would be most cautious of, but the post is adding in a clearance of about 4 inches, and this line was not flagged as the issue, so it should be behaving as expected. If this is the issue we could correct it with an XY position call before activating TCP to bring the tool closer to the front of the machine before this move.

On the G1 line after with the Y and Z values,  the TCP will result in the tool moving straight down in Z to cut at the next point. This is where you indicated the crash was happening, but based how I am expecting the machine to have already moved, this would not be the case.

 

Can you please help me understand how the machine is moving prior to and during the crash so I can understand the reason for it and make suggestions based off of that.

 

 

Thanks,

 

Alex

 

Here is the code we are generating. The main difference is that we are returning the tool to the same point before the solution flip (A-28.4193), while your post is moving to the next point (A-30.2591) . But the move itself is very small, so I would not expect this to be the issue either.

...
X.489 Y.7984 Z5.6442 A26.5794 C360.0017
X.4988 Y.7961 Z5.6412 A28.4193 C360.0008
(WARNING 2002: TILT AXIS LIMIT REACHED - RETRACT/REPOSITION MOTION WILL BE ADDED)
X.4988 Y-1.0362 Z9.0272 F100.
G64
G49
G00 G91 G28 Z0.
G90
A-28.4193 C540.0008
G43.4 H#3020 X.4988 Y-1.0362 Z9.0273
G01 X.4988 Y.7961 Z5.6413 F25.
X.5056 Y.7948 Z5.6392 A-30.2591 C540. F78.41
...

 

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1 hour ago, Alex Dales said:

Hi Zeke,

 

Our variaxis post is generating code that is fairly similar so I am having a difficult time picturing how the crash it actually occurring and how the machine is moving when this happens.

To start the transition, the tool lifts up to the home position and the trunnion rotates to the other side.

On the G43.4 line the machine activates TCP and calls all 5 axes. I would expect the machine to move in XYZ to the other side of the machine where the part now is, ending with the tool tip roughly 4 inches directly above the next point. This would move all three linear axis at the same time, with the tool moving down in Z and from one side of the machine to the other along Y. This is the move that I would be most cautious of, but the post is adding in a clearance of about 4 inches, and this line was not flagged as the issue, so it should be behaving as expected. If this is the issue we could correct it with an XY position call before activating TCP to bring the tool closer to the front of the machine before this move.

On the G1 line after with the Y and Z values,  the TCP will result in the tool moving straight down in Z to cut at the next point. This is where you indicated the crash was happening, but based how I am expecting the machine to have already moved, this would not be the case.

 

Can you please help me understand how the machine is moving prior to and during the crash so I can understand the reason for it and make suggestions based off of that.

 

 

Thanks,

 

Alex

 

Here is the code we are generating. The main difference is that we are returning the tool to the same point before the solution flip (A-28.4193), while your post is moving to the next point (A-30.2591) . But the move itself is very small, so I would not expect this to be the issue either.

...
X.489 Y.7984 Z5.6442 A26.5794 C360.0017
X.4988 Y.7961 Z5.6412 A28.4193 C360.0008
(WARNING 2002: TILT AXIS LIMIT REACHED - RETRACT/REPOSITION MOTION WILL BE ADDED)
X.4988 Y-1.0362 Z9.0272 F100.
G64
G49
G00 G91 G28 Z0.
G90
A-28.4193 C540.0008
G43.4 H#3020 X.4988 Y-1.0362 Z9.0273
G01 X.4988 Y.7961 Z5.6413 F25.
X.5056 Y.7948 Z5.6392 A-30.2591 C540. F78.41
...

 

Alew the 1st index is close to 360 and the other is 180. The crash can be something where the C Axis is spinning that 180 like a web, rib or feature.

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3 hours ago, Alex Dales said:

Can you please help me understand how the machine is moving prior to and during the crash so I can understand the reason for it and make suggestions based off of that.

I am slammed at the moment, but I will get back to you as soon as possible.

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I always turn off motion on G43, G43.4 and G49 in Mazaks.  I don't know if this is your issue or not but I hate motion on tool length comp activation.

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17 hours ago, 5th Axis CGI said:

Alew the 1st index is close to 360 and the other is 180. The crash can be something where the C Axis is spinning that 180 like a web, rib or feature.

That is not what is occurring in this case. If the A was much closer to zero and we were going from C0 to C180 then we would have that issue. The C0 and C180 are not the issue in this case. Here we are hitting the machine's limit at A30 and changing solutions to A-30. I have heard of machines in vector mode will run into this limit and move the machine from A30 C0 to A-30 C180 with the tool down, which does not end well. We are avoiding that here by send the machine home in Z before calling the new A and C.

 

16 hours ago, So not a Guru said:

I am slammed at the moment, but I will get back to you as soon as possible.

Thanks, keep me updated.

3 minutes ago, jlw™ said:

I always turn off motion on G43, G43.4 and G49 in Mazaks.  I don't know if this is your issue or not but I hate motion on tool length comp activation.

I agree, I am not a big fan of the motion either. I doubt this is the issue, as the start of the tool path is using G43.4 and not crashing. Always a good thing to check though, as it could have enough clearance on the first but not the second.

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