Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: dougie329 on October 07, 2006, 12:42:32 PM
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This is really becoming a problem for me :( When im running a program the Z axis will move -ve direction and miss steps on its own + make a horrible sound. Once I left it for a few seconds and it had gradually jumped 10mm down into my vacuum table (not good) but still showed correct depth on readout. This happens nearly every program I run. Dont seem to have problems with X & Y steps jumping! I am running it all from a compaq presario 2100 (could this be the problem) Any help would be most appreciated. Cheers, Mark
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Hi, this could be a bunch of things.
First make sure there is no binding in your z axis travel.
Second slow down your accl and velocity and see if that helps.
Third your z could be just to heavy for the size stepper you are using.
Fourth just for fun try increasing you step and Dir pulse width to 5us and see if that makes any diff.
The dro does not know if the motor stalled so they will always read the correct location. This tells me that mach is doing it's thing and the problem is in the hardware..
Chad
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Also you need to look and see that you don't have a problem with noise :) Do you have shielded wires on the step and direction?
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Not sure if I have shielded wires on step and direction Brian :-\ . How could I tell if I had a problem with noise? Is there a simple test? CNC router was new a few months ago from these guys (www.cnc-step.com) Seems like a well built proffesional piece of kit with CE approval and the like. The software that came with it was awful so I got mach3 which is fantastic to use :). I have tried adjusting the acc/vel & pulse width but to no avail.. Dedicated laptop what I run it from is an intel celeron 2.4 processor with 192Mb of ram. Not sure if this is sufficient or not? Cheers
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As has been said above hardware rather than software is more likely your problem but I am curious to what operating system you have on your computer?
Hood
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It is running windows XP home edition, version 2002. service pack1 :)
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I would say 192megs is a bit small for XP, it could be a problem but if you have been using it when you didnt have the problems then it is unlikely the cause.
Hood
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As for fault finding with the hardware you could try swapping drives round to different axis and seeing if it follows the drive or stays with the axis.
Hood
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You mean reverse the Z axis into the Y axis on the controller? My X axis is driven by 2 stepper motors..I have kinda been having the problem with the Z axis twitching away from the word go.. The people I got the machine from aren`t really much help on technical problems and im not the best at speaking German hehe ::) I figured I could try my new dell desktop as the driver test is perfect (it is not on the laptop) but it doesn`t have a parallel port!! Mark
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Where are you from?
I am not sure how your control harware is set up or what type drives etc you have but there should be a way to swap the wires from one axis to another fairly easily.
Hood
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Im from the UK and its just gone midnight, guess I should really go to bed but it is a Saturday!! Will try swapping the Z & Y over tomorrow, dnt think my neighbours will be too impressed if I light it up now :D Thanks for the help, will let you know how I get on
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I am from Scotland and I could send you pci parallel port for a loan if you want to try the DELL. You would have to open up the case and pop the card in so if the DELL is under warranty that might be a problem as their might be anti tamper stickers.
Let me know.
Hood
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Im defo going to bed in a minute ;D Thanks for the offer hood but it is a slimline dimension 5150c computer and doesn`t take the normal size pci parallel port cards as I have tried to get hold of one before.. Will try a few things with the axis then go from there. Cheers, Mark
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No problem, just try and buy a decent computer next time LOL
Let us know how you get on.
Hood
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Think I solved the Z axis problem. I was reading an old post with kinda the same problem and it suggested switching the Z axis step and direction to low active in ports and pins. So before I took a big sledgehammer to the whole shabangle I gave it a try and hey presto it worked. Not even a twitch now!! It reversed the direction so I went into homing/limits and reversed it in there...I am well chuffed I dont have to buy a new PC just yet :D
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not really sure how that would make a difference but as long as it does who cares :)
Hood
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My X & Y has got the twitches also. Only until I open Mach and hit reset does it stop. I'm going to try this and see if it helps. I have not seen a problem when running. I don't think I have Mach settings wrong. In fact, I think Mach is so good that not only does it run my machine very well, it may be fixing a problem I have created my self somewhere else!!!!!!! :D
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If your motors twitch BEFORE Mach is opened then I think it is something else on your system querying the parallel port. If you have the charge pump support on your breakout board the drives/motors wont get any pulses until the parallel port is getting a steady stream at a certain frequency. Check your breakout to see if its supported and set it up if it is,
Hood