Cutting into area that ruins the part question

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Cutting into area that ruins the part question

Postby Hivoltage » Mon Jun 17, 2019 3:16 am

I have my rotary axis set up and going well.
The only issue is that the rotary axis does a combination A and Z move that causes the bit to hit part of the geometry and cut part of the model its not supposed to cut. The finished look in V-Carve does not look like what I get as a final result.
I have attached an image to show where the error happens. The red arrow shows where its cutting into the original model and it does this on both sides. I used a model I got from thingiverse as a test.
Any ideas on what causes this?
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err.jpg
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Re: Cutting into area that ruins the part question

Postby Rcnewcomb » Mon Jun 17, 2019 4:27 am

The finished look in V-Carve does not look like what I get as a final result.

If the results don't match the preview then you are dealing with a controller or machine issue. What does X-Carve support say?
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Re: Cutting into area that ruins the part question

Postby 4DThinker » Mon Jun 17, 2019 1:42 pm

You should check the Clearance (Z1) value on the Material SETup page of the toolpath menu. You can set it to a higher value to be sure the bit lifts higher up between paths/passes to clear parts it might rotate into. Yes, this is a slight "bug" in how rotary toolpaths are calculated. What would be easily cleared when the material is uwrapped flat can often end up in the way once the toolpaths are bent around the actual cylindrical model.
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Re: Cutting into area that ruins the part question

Postby TReischl » Mon Jun 17, 2019 9:21 pm

4DThinker wrote:You should check the Clearance (Z1) value on the Material SETup page of the toolpath menu. You can set it to a higher value to be sure the bit lifts higher up between paths/passes to clear parts it might rotate into. Yes, this is a slight "bug" in how rotary toolpaths are calculated. What would be easily cleared when the material is uwrapped flat can often end up in the way once the toolpaths are bent around the actual cylindrical model.


Really?

Have you reported this bug?

Seems a bit odd to me since all calculations are done in the flat and then wrapped around X or Y. Do you have an example program of the bug?

That part has a lot more gouges on it than what he pointed to. They are all over the place on it which is indicative of lost steps, bit slipping in collet, etc.
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Re: Cutting into area that ruins the part question

Postby Greolt » Tue Jun 18, 2019 12:23 am

I have never seen this.

Is it possible to upload the code used in this example.

"What would be easily cleared when the material is uwrapped flat can often end up in the way once the toolpaths are bent around the actual cylindrical model."

This is a misunderstanding of the wrapping of a toolpath. The toolpath is basically the same, just which axis moves is changed.
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Re: Cutting into area that ruins the part question

Postby IslaWW » Tue Jun 18, 2019 12:39 am

I'm with Ted and Greolt on this one. Never saw this before and would be interested in seeing the code that produced it. More likely to be a machine issue that a "forgotten" retract.
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Re: Cutting into area that ruins the part question

Postby TReischl » Tue Jun 18, 2019 1:17 am

OK, some of the folks here know that I wrote this sort of software in my past life, that does not make me "the expert" by any means since I had my share of "bugs" lemme tell ya!

The usual way that a rotary post processor is written is to use the CL file (cutter location file, which is an intermediary file not specific to a particular machine). The diameter the user has input is multiplied times Pi. For example, a 2 inch diameter yields a length of 2 X Pi = 6.28. . . . (I am keeping it simple here so only using a couple of decimal places). So, if the cutter needs to move from 0,0 to 0,3 then (3/6.28) * 360 = degrees required. In this case about 171.89 degrees.

That is all there is to it. During the process there is no reason to change any of the values in the other two axis.

There is no "bending" of anything. The motion is simply converted to degrees based on the input diameter.

So the point of this is that if the flat preview looks correct then the wrapped output will also be correct. There is no fiddling with Z axis during wrapping because there is no reason to fiddle with it.

Now, where there is a "wee bug" in the rotary stuff (at least in the version I am running) is in the preview. Run a simple test in which you define a pocket exactly one half the length of the wrapped distance. Let part of the pocket hang off one end so you can see the cut easily. Cut the pocket then preview it. The software will show a perfectly nice flat surface that passes exactly through the centerline that looks like this:

c1.JPG


The reason it is wrong is because of this:

c2.JPG


Notice those little areas in yellow. Most folks who run the wrapped software understand why this exists and the reason is obvious, the cutter has to run on the centerline. But the preview does not show the material removed.

The only way I know of to produce what is shown in the preview is through modeling, not pocketing.
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Re: Cutting into area that ruins the part question

Postby Hivoltage » Tue Jun 18, 2019 8:12 am

1st I cannot contact the manufacture of my system. I have modified it.
They do not use Mach3. They do not use a gecko 540 controller.

2nd. I do not think its a bug. Its something that I am not aware of as I am new.
I just need to know how to fix this situation.

I use Vcarve Pro and the post processor I am using is: Mach2/3-WrapY2A ATC(mm)(*.txt)
I have attacted the output from Vcarve to this post.
All I need to do is figure out what setting will remove this problem.

I have tried increasing the height of the safe zone etc... it still cuts into the area of the model it is not supposed to.

The Vcarve visual does not show the cut but the final results do. This shows up in the Rough cut.
Attachments
FlashRing 3D Roughing 5.txt
Job I was running.
(279.82 KiB) Downloaded 17 times
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Re: Cutting into area that ruins the part question

Postby Hivoltage » Tue Jun 18, 2019 8:15 am

I forgot to add that I am using Mach3 and a gecko 540 controller for XYZ and the A is controlled by a TB6600
My issue could be how Mach3 is interpreting the code. Maybe there is some setting that can be changed to fix this. I do not know.
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Re: Cutting into area that ruins the part question

Postby TReischl » Tue Jun 18, 2019 1:32 pm

Hivoltage wrote:I forgot to add that I am using Mach3 and a gecko 540 controller for XYZ and the A is controlled by a TB6600
My issue could be how Mach3 is interpreting the code. Maybe there is some setting that can be changed to fix this. I do not know.


Now we got a clue! You are running a G540 (which CAN run an A axis) and also a TB6600 which is really controlling the A axis.

The other thing I noticed is that it seems you are using the centerline of A axis as Z0. Pretty much everyone who runs an A axis uses the surface of the material to set zero. I don't think that is causing your problem unless your material is much thicker than what you thought it was which can lead to those lost steps due to overloading the cutter.

Now, if it were me. . . . I would disconnect the TB6600. Then unplug the Y and A axis on your G540. Lock the Y axis over the centerline of the A axis. Then plug the A axis motor into the G540 A Axis port. Make sure things are set up right in your software and give it a go. What that will do is isolate the TB6600 from the system. If things go correctly then you know you need to concentrate on the TB6600 and its setup.

Beyond that maybe someone on an Arduino forum can help you out. A really good thing is that you understand it is not a software problem.

It is NOT how Mach3 "interprets" the code, it is what your TB6600 is expecting. You have sort of mixed things together. A G540 which is NOT an arduino device and the TB6600 which from what I read is designed for arduino. If the problem persists I would add another Gecko device in place of the TB6600. I could be wrong about it being an "arduino device".
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Re: Cutting into area that ruins the part question

Postby IslaWW » Tue Jun 18, 2019 2:28 pm

"The other thing I noticed is that it seems you are using the centerline of A axis as Z0. Pretty much everyone who runs an A axis uses the surface of the material to set zero."

I would disagree. From years back all rotary training sessions that I have attended and going forward to the vast majority of todays rotary instructors, including myself, all recommend Z axis referrence as the cylinder axis. In the Vectric software "Help Topics" cylinder axis is also listed as the preferred method. Screen clip of Help contents attached

Z ref.JPG
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Re: Cutting into area that ruins the part question

Postby mtylerfl » Tue Jun 18, 2019 4:20 pm

Yes. Ted surprised me with that comment! Rotary Z axis is typically referenced from the center of the cylinder (aka bottom of material when unwrapped Flat).
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Re: Cutting into area that ruins the part question

Postby Rcnewcomb » Tue Jun 18, 2019 7:27 pm

Hivoltage,
Can you post a link to the actual CRV file? I assume it is over 2MB, so you would need to post it somewhere like drive.google.com or dropbox.com and then share the link here.

That way we can look at tools, feeds, speeds, etc.
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Re: Cutting into area that ruins the part question

Postby TReischl » Tue Jun 18, 2019 9:30 pm

I even surprised myself with that comment!!!!!

What was I thinking??????

I know what happened. . . . . I have a plate on my tailstock that I touch off on and then hidden in the bowels of my computer that dastardly little man automatically sets the Z0 to wait for it. . .wait for it. . . . still waiting? THE CENTERLINE OF THE SPINDLE!!!

Well, if you will all excuse me now, I have to go fall on my sword and be carried back on my shield.

Thanks for pointing that out guys!
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Re: Cutting into area that ruins the part question

Postby Hivoltage » Wed Jun 19, 2019 7:15 am

Ok here is the file for those of you wanting to take a stab at it.
Its small and its for the roughing pass. The detail pass doesn't seem to have any issue.
Attachments
FlashRing 3D Roughing 5.txt
Rough pass
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