Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: copperwrap on August 31, 2011, 03:30:10 PM
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My issue is quite madding. I will calibrate z axis and Mach doesn't seem to be saving the calibration and it seems to be increasing the "Steps per".
Steps to reenact issue:
Open mach version R3.043.022 CNC Plasma
Pop window stating "kernel speed set over 25000"
Config - Motor tuning - Z axis - Steps set at 9387.437181 (all other y and x are set around 1900), velocity 159.788019997191, Acceleration 60, g's 0.155411424, Step pulse and dir pulse 0.
Set Z axis to around 2000 and save
Calibration:
settings - Axis calibration(steps per Unit) - Z axis - Start gap of torch head is 2.296"- In the prompt I move Z 1.5"- Z now only moves .298" - Next prompt states "Z axis will be now set at 10067.114 steps per unit" Accept? - yes.
Then when I try to recalibrate Z axis It is sill off by .338 Mach wants to save the steps at 12552.511.
Then if I try to recalibrate Mach wants to increase the steps yet again to 15554.536.
Ran Drive test and it came back System Normal.
Any feed back would be greatly appreciated.
Thank you
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Are you remembering to press the 'Enter' key after each entry?
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Yes enter was pressed and was that appropriate? How would one get through the prompts with out pressing enter?
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You will find that some entries are with an enter press and some are without an enter press SO yes it was an appropriate question to ask. You have no idea how many times that was the problem.
(;-) TP
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Can you attach your xml please.
Hood
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Did anyone solve this? Mine is doing the same thing. I calibrate and then it sets the new steps/per, but it doesn't even come close when I run a new calibration to check how far it moved. It just keeps coming up short and increasing steps until it maxes out then complains it's too high for 25000 kernel.
What's going on??
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Make sure you save settings and then go out and back into Mach after the calibration is done.
Double check that the steps per are correct / were changed when you open Mach.
Frankly you should calculate the steps per unit. If the mechanics of the machine is good then when runnning the calibration check you should be spot on. Since the mechanics may not be exact the calibration check can be used to refine
the steps per but use common sense and know why your changing from the calculated number. The Kernel speed can limit the velocity, so lower the velocity setting.
RICH
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Ok Rich I'll look into that, thanks. I did adjust my X axis drive under the table as it was binding. Now that is fixed it works better of course but I can't get it close to cutting a proper pattern since the dimensions are way off. I knew this would involve a lot of learning but not this much!! LOL..
I'll try and get back here to reply.
Andrew
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If you're only setting the steps per to 9387, why on earth do you WANT to set the kernel speed above 25K? There is absolutely no benefit whatsoever to doing so....
Regards,
Ray L.
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I meant to ask as well, what do you do if you calculate the steps per unit and it doesn't work? Then what? Or is that not normally a problem?? I have a 13 TPI threaded rod, a regular 1.8 deg stepper. So at 16 microstepping 3200 steps per revolution. I set my units to MM when I setup Mach3. So 13 tpi is 13 turns for 25.4 MM or 1.95 MM per turn. so.....3200 / 1.95= 1637.79 or 1637. Is that right?? My kernel speed is 25000.
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Ok so I was trying to calibrate again. I tell it to move 30 "units" which should be mm as I set that up in the config. So it moved about 26 not bad but not close enough. So it asked and I put in 26 and it calculated a new steps and I accepted it. Then I closed down and re started Mach3. Checked that it was in there and it was. Did a calibration, for 30 again. It moved less than it did before. Then it wants to set it higher and higher each time as it moves less.
What am I missing?? It moves but not enough. I even set it really low to 600 steps and it still didn't work or go far enough. WTF??
Please anyone with ideas?? If you need more info simply ask as I am not sure what you might need.
Thanks.
Andrew
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Sounds like your axis is losing steps, could be due to binding or maybe even the pulse width not enough. Try with Sherline Mode enabled and see if that helps.
Hood
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Ok so I used the Sherline mode and it got a lot better. But I still couldn't get consistent distances. SOunds like the steps are being missed. It is a cheap Ebay TB6560 board. But is there any other settings that could be doing it as well?? (I think a Gecko is looking better everyday..)
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Might be worth trying 8 microstepping if its available.
Hood
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Ok further developments. I upped the kernel speed to 65000 and it seems to really like it and it seems to give consistent distances. Should I just go to the max kernel speed??
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What does the frequency and Time in Int read on Diagnostics page when running at both 25KHz and 65KHz, you must restart Mach after you change the kernel for that to read correctly.
Hood
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I checked it at both 65000 and 100000 as well and it reads between 5.2 and 4.5 or so each time. So now it's at 100000 and seems to work really well. I calibrated again and it does it right on, well as far as a ruler can tell but good for now until I do it better.
Thanks for your help!
Andrew
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If your system is happy then go for it but be aware that you may have issues due to the high kernel.
Your Time in Int is reasonably low so you may be OK but it is still 50% or so of the the interrupt when at 100KHz so you are getting close to the edge.
Hood