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Author Topic: CV G64 and Exact Stop G61  (Read 4970 times)

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Offline Mauri

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CV G64 and Exact Stop G61
« on: December 26, 2016, 09:12:57 PM »
Hi,
Has something changed with CV G64 and Full Stop G61 on the Mach4 program?
Using Road Runner example.
Earlier versions of Mach4 you could run Exact Stop G61 and it would follow the line precisely in Simulation Mode.
Now on the latest versions of Mach4 it goes faster around on the lines (using the same Road Runner example) but does not track them?
It is like it is in some sort of CV Mode even though it is G61?
When trying out the CV Mode G64 I cannot get it to track the lines?
Has anyone tested what Speed settings on the Degrees in the CV Wizards would be required to track the Road Runner lines precisely or close?
When preforming 2.5D/3D engraving/carvings there are many thousands of varying cutting angles, similar to Road Runner so there must be some sort of settings that would do the task.
Can anyone help?
Regards,
Mauri.
Re: CV G64 and Exact Stop G61
« Reply #1 on: December 27, 2016, 03:30:34 AM »
Hi Mauri,

I can't help you but that are good questions. I played around with the CV-Wizard with the Simulator and I can't figure out the mystery behind it. How do I have to use the settings for the angles? There must be something wrong in my thoughts. In one test all angles were set to the same number - 500 and I expected this would be the maximum feed rate but the feed rate went up to the max velocity set in Mach-Config. But now the tracking is perfect as far as I can see on the monitor. I have no idea what's going on. ???

Can anyone explain the usage of the the CV-Wizard?

regards from Germany
Klaus

Offline Mauri

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Re: CV G64 and Exact Stop G61
« Reply #2 on: December 27, 2016, 10:00:34 PM »
Hi,
I performed some more tests using a G-Code file that I made up.
This file performs much better than the Road Runner example?
I used Mach4 V3233.
G64 CV with 0 Degrees at 100 performed better than G61 Exact Stop, you have to enlarge each angled corner to see the differences.
Although the Exact Stop should be true to the G-Code profile in this case it does not.
Both performed better than Mach3.
Test File below.
I will have to see how it performs with 2.5D profiles and will comment further after I have made some tests.
Regards,
Mauri.

Offline dude1

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Re: CV G64 and Exact Stop G61
« Reply #3 on: December 27, 2016, 11:32:30 PM »
Mauri Try a Vcarve, M3 struggles with V carving, It was better in the M4 2.0 versions than what M3 could do at the same feed, velocity and file I have not tried the new version.

Offline Mauri

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Re: CV G64 and Exact Stop G61
« Reply #4 on: December 28, 2016, 06:07:14 AM »
Dude1,
I have performed many 2.5D and 3D 4 Axis Carvings using Aspire and madCAM with Mach3 and have been able for Carve in Brass and Timber for many years with reasonable results.
On the Brass we finish the output using a stereo microscope and fine needles as well a special stones that you can make into a fine point.
On Timber we use fine paper to improve the 2.5D and 3D carved shapes.
We are perfectionists and we were hoping Mach4 was going to make the finish that much better than Mach3 thus reducing the microscope work.
I tried an example medallion that uses a .1mm Tip cutter with CV and found that it did not follow the same path as the G-Code, I may need to make some adjustments to the 0 to 179 Degrees in the CV settings.
Have you tried doing this with Mach4
Regards,
Mauri.

Offline Chaoticone

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Re: CV G64 and Exact Stop G61
« Reply #5 on: December 28, 2016, 09:30:22 AM »
In regards to the tool path view, the only reason a machine can not follow the toolpath accurately in exact stop mode is if the step resolution is so poor that it can not possibly go to the requested position. Of course the display does not take into account machine flex or backlash....... which in the real world actually running parts can make huge differences.

What speeds you can set for different angles in the CV wizard is entirely dependant on 2 things. Your axis ability to accelerate and the tolerance you have to hold your tool path to. Its simple physics. Does your machine run like a pro-mod drag car, an Indy car or a bus? No mater how it performs, CV is a trade off. Nothing happens instantaneously. No matter how much accel and rigidity a machine has it cannot go around any corner (angle) without rounding it unless it stops at the end of one line and starts back in the direction of the next. End of story.

Now, what the CV wizard does is limit the feed rate to whatever you set it to for any given angle. It does not limit the feed rate in straight lines, only in corners (direction changes). So say your machine can take a 90 degree corner and only rounds it by about .010. If the tolerance you have to hold in that corner is .005 the .010 is not acceptable. So how fast your machine can take that 90 degree corner and still hold the .005 tolerance is the question. Unfortunately, your the only one that can answer that question. So, you have to do some testing to find out. When you do your testing I would do so in the worst case scenario (biggest tool, deepest cut in hardest material etc.). All of these considerations are trade offs as well. Maybe you use a 1.000 2 flute end mill to surface your aluminum table but most of your cutting will be with a .250 v cutter in styrofoam. So do you optimize the CV wizard to surface the table, do some v-carving in foam or somewhere in between? Lots of things to think about. This is why predefined (before the build begins) specifications are not optional if you hope to end up with a machine that will meet the end users demands.
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline Mauri

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Re: CV G64 and Exact Stop G61
« Reply #6 on: December 28, 2016, 02:36:18 PM »
Chaoticone,
Thanks for your reply.
Before I do machining I would like to see that the Tool in Toolpath G-Code displayed in Mach4 actually cuts on the same path.
Having produced many detailed cravings/engravings in 2.5D and 3D in Brass, we have optimized our milling machine as best we can and with Mach3 the results are not perfect but acceptable.
When running Mach4 and viewing the "Toolpath display" which is machine independent and has no short falls it should follow the path precisely if in "Exact Stop" and very close in CV mode if the CV settings are optimal.
That is what I am trying to accomplish, so until I can get a good path it is not much use in cutting actual maternal.
Any other assistance would be appreciated.
Regards,
Mauri.

Offline Chaoticone

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Re: CV G64 and Exact Stop G61
« Reply #7 on: December 28, 2016, 02:44:29 PM »
What are your steps per set to for each axis? This will make a difference even if only in simulation mode.

Post up a picture of your whole Mach4 screen when it does not follow the path and a close up of a section that is off. Show us what your seeing.
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline Mauri

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Re: CV G64 and Exact Stop G61
« Reply #8 on: December 28, 2016, 02:56:24 PM »
Chaoticone,
I use a metric setup. 25.4mm to 1"
Counts per unit = 800 in mm or if in inches = 20320
Velocity Units/Minute = 1000 in mm or if in inches = 39.37
Acceleration Units/Sec^2 = 150 in mm or if in inches = 5.905512
As cutting brass in dry mode (continual Air Blast to cool) it does not require fast velocity or acceleration.
Give some time to set one up and I will today.
Regards,
Mauri.

Offline dude1

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Re: CV G64 and Exact Stop G61
« Reply #9 on: December 28, 2016, 03:41:22 PM »
Mauri I have not use M4 sinces the cv stuff was added, I am weighting to my pendent can be used with M4 before I move over, When that is working I will be as M4 is faster than M3 and works just that much better it's worth moving over, with the same trajectory engine M4 is better.

I got M4 to 0.001 +- .001 M3 is .002 +-002 after 1000 moves on any axis doing a Vcarve