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Re: Mach3 logic help
« Reply #10 on: September 01, 2016, 04:02:19 AM »
Well, I need it to be perfect.
Machine mechanicly has the precision of 0.0015 per step, as I designed it to make pressure mold for plastics on it.
Now the software are limitations.
Also, when making JIGs, it has to be perfect due the each side macining.

Offline Davek0974

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Re: Mach3 logic help
« Reply #11 on: September 01, 2016, 04:11:01 AM »
I can fully understand your issues but maybe Mach3 was not the correct choice?

I don't know, i'm only guessing as i  only use it on plasma cutting - not very precise, engraving - machine only has 0.01mm and seems ok and a Bridgeport so not mould-making.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives
Re: Mach3 logic help
« Reply #12 on: September 01, 2016, 04:44:44 AM »
Now I am thinking it too. Well, 0.01 would be acceptable, if it was proper 0.01 and not like this. Cutting corners and low tolerance on makog jigs is very bad, as my parts dont fit anymore when I flip them.
This is just simple milling, nad mach3 by deafult fails in that direction.

Offline Hood

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Re: Mach3 logic help
« Reply #13 on: September 01, 2016, 05:58:52 AM »
What is the following error when running code at  1500mm/min ?
Hood

Offline Stuart

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Re: Mach3 logic help
« Reply #14 on: September 01, 2016, 06:50:40 AM »
Lopata

To get that kind of accuracy none of the controller software you have mentioned will do it

Mach 3 or 4 are budget end and Linux CNC is a freeby

You will need to spend some big bucks to get that degree of accuracy you desire
Is your Machine rigid enough to take the g forces that your acceleration of the machine mass is subjecting it to?

What happens if you put a 0.0001 dti on the spindle to work piece and push on the gantry with o out 100 pounds force?

IMHO the controller software that you or using is not up to it
And remember no part is ever 'perfect' there will be some tolerance variation ,it's if that is within your expectation

Regards
Stuart

Sorry to down play Mach software but mach4 works for me and will hold the tolerances for my parts repeatedly over tens of runs.

Offline Davek0974

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Re: Mach3 logic help
« Reply #15 on: September 01, 2016, 07:22:57 AM »
Have you tried running exact-stop instead of CV ??
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives
Re: Mach3 logic help
« Reply #16 on: September 01, 2016, 10:36:26 AM »
Hello Davek,

I havent tried exact stop, as that was not the problem, problem was rounding up on higher speeds.

I am on to something now, as I have been playing with setups today, and here are my current machine setup.

Velocity 6000 mm/s
Accleration 1000/s/s (was set to 300 mm/s/s)

In the video, I was engraving with 35 mm/s feedrate.

CV is set to 0.0001 (0.1) units, and Lookahead is 120 (Old value was 20).

The finish move is clearly slowing down and there is slight jerky feeling, but it was due the configuration of the spline.

In pictures you will see much higher precision, and all the corners are pretty correct.





<a href="https://www.youtube.com/watch?v=XYTflFqMk0g&amp;feature=youtu.be" target="_blank" class="new_win">https://www.youtube.com/watch?v=XYTflFqMk0g&amp;feature=youtu.be</a>

Youtube Video on this address: https://youtu.be/XYTflFqMk0g
« Last Edit: September 01, 2016, 10:39:17 AM by lopata »

Offline Davek0974

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Re: Mach3 logic help
« Reply #17 on: September 01, 2016, 10:54:36 AM »
That looks nice to me :)

What tool was that running?

I think my lookahead is on 1000 at the moment, velocity 5000 and acc is 500, these may need tweaking though.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline stirling

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Re: Mach3 logic help
« Reply #18 on: September 02, 2016, 04:48:01 AM »
I am on to something now, as I have been playing with setups today, and here are my current machine setup.

Velocity 6000 mm/s
Accleration 1000/s/s (was set to 300 mm/s/s)

 ??? Throughout the thread you've said your accel was 2000mm/s/s.

If you actually have been using 300mm/s/s then that explains everything you've been seeing. 300mm/s/s is hopelessly low for CV to produce the accuracy you're trying to achieve.

When using CV mode, the accuracy of the actual path, i.e. how close it is to the programmed path, is directly proportional to acceleration. This I'm afraid is true of every machine and every controller on the planet - blame it on the laws of physics.

Acc: 2000mm/s/s goes up to 4000 mm/s/s without problems, but that is insane acceleration.

What's insane about it? 4000mm/s/s is not particularly high for a truly rigid machine. if your machine is capable of 4000mm/s/s then that is what you should be using. The ONLY reason you would turn DOWN accel. is when the jerk your drive system is capable of creating exceeds the rigitity of your machine.

A word about Mach3's CV settings like dist. tolerance etc.

ALL CV settings are there to try to help when a machine's acceleration is not good enough for the job expected of it. i.e. they ALL stop CV from working to its fullest extent one way or another i.e. they all take CV closer and closer towards exact stop. On a machine with accel. good enough for the job expected of it - they should ALL be completely OFF.

Finally a note for Dave. A Lookahead of 1000 is at best nearly always pointless and at worst counter productive. I don't really care about the hair-pin at john o'groats before I've left the car park at land's end. Well unless I'm travelling at the speed of light and my brakes are really crap - then I might. ;D
« Last Edit: September 02, 2016, 04:51:13 AM by stirling »

Offline Davek0974

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Re: Mach3 logic help
« Reply #19 on: September 02, 2016, 05:05:57 AM »
Thanks Stirling, it was a value offered as "normal" somewhere, i will wind it back to 200 or so :)

BTW on a servo machine like my Bridgeport conversion, how is it best to arrive at an acceleration figure?
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives