Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: mrpizzaman09 on February 12, 2011, 12:48:26 PM
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Hello all
This is my first post on this forum and I have some issues with my mach 3 setup. I recently bought a small cnc 4 axis mill with a Geckodrive 540 controller. I have had some success moving the axis but they are moving at a much slower rate than Mach 3 says they are moving. I have the steps per calculated correctly because the mill does travel the correct distance when I run a simple program but I am not getting anywhere close to the correct velocity. Mach 3 says I should be moving 37.5 inch per min but I would be surprised if the drives are even moving 1/100 th of that speed.
The second issue I am having is that I can only moving the axis with a written G code program. I am not able to jog the axis with the buttons on the screen or my keyboard directional keys.
Any help would be greatly appreciated. :)
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Can you please attach your xml file.
Hood
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...Mach 3 says I should be moving 37.5 inch per min but I would be surprised if the drives are even moving 1/100 th of that speed.
...I am not able to jog the axis with the buttons on the screen or my keyboard directional keys.
You don't have feed rate override enabled do you?
Is the speed problem the same with both G01 and G0?
You don't have jog disabled do you?
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Thank you for the replies. I have the same slow problem with G01 and G00, I also tried with G02 to cut an arc and of course it was still slow. I was able to get the axis jogging, it turned out I had an absurd number in for the acceleration. I tried feed override but it did not seem to change anything.
Hood, I will attach my xml file as soon as I find time to go get it.
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Hood, I have attached the xml file, sorry for the wait.
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You are not likely going to have much luck with the motor tuning you have, steps per may be correct at 40,000 and likewise for Velocity but I think your steppers will instantly stall as you have an acceleration on X Y and Z of 4000
I would think a more likely value for that would be in single figures.
Hood
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Changing the acceleration to very low values, below 1000 has a very noticeable decrease in acceleration. With the acceleration set to 4,000 the motors accelerate to their top speed in about 1 to 2 seconds but yet again the top speed is still very, very slow. It almost seems like the clock that tells the program what the duration of a minute is, is off. I think this because both acceleration and velocity are considerably slower than they would be if measured.
The steppers do not stall, they accelerate very slowly when I use an acceleration in the single digits. The steppers take over 1 minuet to get up top speed with an acceleration value of 4.
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Well that sounds like something is way out of whack in motor tuning or with your drive setup
What micro stepping are your drives set to?
Is there gearing between motors and screw?
What pitch are the screws?
Hood
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the micro stepping is 10
there is no gearing between the motor and the screw
the screw is 20 tpi.
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Your steps per are correct then, something very weird going on as no way in the world will you manage an accel of 4,000 I/s/s and from what you are saying its definitely not going anywhere near that anyway. Your vel is if I recal about 70IPM so with an accel of 4000 i/s/s you would get to top speed before you pressed the jog key ;D
Have you tried increase the pulse settings on the motor tuning page? try 5 for both and see if that helps
Hood
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Changing the pulse settings did not do anything.
There just seems to be some scaling factor wrong for the velocity once it is sent to the drive controller.
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If you zero the X DRO and then in MDI command a G0X1 does it move 1 inch?
What type of drives do you have?
On the diagnostics page what does the frequency say and also the Time in Int?
Hood
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Changing the pulse settings did not do anything.
There just seems to be some scaling factor wrong for the velocity once it is sent to the drive controller.
If it helps any the controller is the Geckodrive G540 and the steppers I am using are the ones listed on this website: http://geckodrive.net/g723-280-p-45.html
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The drive does move 1 inch on all 3 axis correctly, I will get back to you on the frequency, Time and Int.
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The time and int is between +19 and +20 when moving and when not jogging it is between +9 and +10.
I am not sure if I was looking at the correct number but the pulse frequency was everywhere between 650 and 800.
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I would say that is your problem then, your computer is not pulsing correctly. Drop the kernel down to 25KHz and obviously you will have to drop the velocity to suit and see hwo that goes.
Hood
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I have tried it at 25KHz and all the other settings up to 100KHz. The speed is identical at all settings. I will try again later but right now I have some other work that needs to be accomplished.
Do you suppose that the problem could be related to running Mach 3 off of a laptop?
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You will either need to get another computer or try and clean that one out.
What are the specs of the computer?
Hood
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It is an IBM thinkpad T43. I have it on a separate port replicator so I may try plugging directly into the port on the computer.
It has a 1.83 ghz single core processor, 1gb of memory. The OS is loaded with crap though so I will try doing a fresh install of XP and start over. It will be a Saturday project.
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Laptops are not supported by ArtSoft unless using external pulsing devices and for good reason. That reason is the vast majority are very difficult to get Mach running right due to the power saving features in them, seems the more modern your laptop is the worse of a problem you are likely to have.
Disable all power saving features especially if you can find any in the BIOS but to be honest you will save yourself a lot of grief by going and buying a cheap second hand desktop and using that.
To give you an idea what you are fighting think about this, the time in int you reported is 20uS, when running at 45KHz the computer interupts at 22.2uS so your computer is using 20uS for pulsing and that is only leaving 2uS for everything else that is going on in Windows and Mach itself, I am amazed you have not had constant crashes.
Hood
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Sorry, I have misrepresented a number there. The 20uS number is when running at 100KHz.
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Well I am even more amazed then that you have not had constant crashes of the computer, when running at 100KHz the interupt is 10uS and your Time in Int, ie the time it takes Mach driver to do its stuff is twice the time it has. The Time in Int will vary a bit with the kernel speed, but it would, I think, go up the lower your kernel is set.
Hood
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The computer is barely using any of it's processing power. I will test to see if lowering the kernel speed lowers the time and int number.
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I've had Mach on numerous PC's and anything about 35Khz has crashed all of them. My shop PC's are probably crashing as we speak just thinking about running at 100Khz. :)
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Well I finally got it running! I decided to install Mach 3 on windows 2003 server edition and now the drives move very fast. Though now they do not run very smooth. I am currently running with a kernel speed of 45 khz which was smoother than 35khz and 25khz.
Surprisingly they run amazingly smooth is using the Axis calibration. Any thoughts?