Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: nitecreate on August 23, 2011, 08:29:23 PM
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??? ??? ??? Like so many others I'm a real novice with CNC. I've built a 3 axes router (David Steel's plans). Started off with some pretty cheap Chinese electronic and after fighting with them for a few months I purchased a G540 Geckodrive. Well it's been working great for a number of months and then all of a sudden it was like something took over my Mach 3?? What's driving me nuts is the fact that mainly with the Z and Y drive. X drive works just great. The signal sent to the stepper motors ( Z & Y) is very erratic. Whether I'm in Jog or running in MDI when you have it go ( + pos) sometimes it will do that and others it goes (- neg). The next time it will work great and then once again it's like it gets struck in any one direction - or + what ever way it wants to go??? In fact if you use the mouse in jog mode, pressing the button on the mouse will change directions?? The same with MDI. You call out one direction and it a lot of time will go just the opposite. The the next time it work just fine??
I've changed motors, I sent the Geckodrive back and had it check out. It came back "A"OK. I can't help but think it's nothing more than set up? What I need to know is what controls the direction of the motors. Possibly I've got something switched wrong.???? I use the CNC router for 100% volunteer work in the community and being the fact that it's not working is a real bummer. Frustrated and really confused. Dennis
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My guess is a weak parallel port. What you're describing is reported frequently by G540 users, as it tends to require a bit more current to function than other drives.
One thing that may help is to increase the pulse width in motor tuning to around 15 or so.
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If 15 in pulse width doesnt help or totally solve it you may need to enable Sherline mode, it seems some people need that with the G540's while others dont, likely its computer dependant.
Hood
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Let me try to reexplain and tell what's happening now.
Three weeks ago everything with my cnc router was working perfect. In fact for the last 6 months it's run like a clock. Then all of a sudden things went south. Let me try to explain. All the axes XYZ run erratic. Using the jog mood in a positive move, sometimes it will run that direction and then it will run in a negative direction. In MDI when you program a direction it does the same thing, you never know which direction it's going to go??? I've sent back my G540 to the factory (twice) thinking it was a faulty board and it's been returned checked out 100% with no apparent problems. I'm running Mach3, so I dumped the program totally, reloaded it and the drivers, No Change? I changed my parallel cord, No change. I tried another computer, No Change, I've changed motors and rewired, No change. My pulse speed is and has been at 15, and I did enable Sherline mode with no change. Through this whole thing I found out that when for instance I'm running X + and I put pressure on the carriage, it will start to move back in the X - direction??? I am not a technical person, Beyond pressing the "go button" I really don't have a great understanding of electronics. So if you think you can help, please make it simple. Dennis
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Try checking the stepper motor power supply voltage.
Sage
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The most likely cause is that your direction signal wires connections are slack or are picking up noise. It could be a mix up with duplicated config settings so if you attach your xml I will check that out.
Hood
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Assuming that Hood does not find any fault with your .xml configuration...........
As Sage has said - check the voltage from your power supply with a multimeter, both stationary and with the machine axis moving. The voltage should remain constant without any significant voltage drop when any or all axis are moved. If this test is OK............
As you have changed the parallel port lead and as you have changed computers without making any difference plus all the other things you have tried and the fact that the X axis works OK suggests to me that the fault is with the Gecko G540.
I know you have had it checked (twice) but...........
For example, was the G540 tested using 3.3V logic switching ??
Would it be possible for you to try another G540 ??
Tweakie.
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;D ;D Problem solved...... Turns out that there was not one but 3 bad connections plugged into the back of my G540. Rewired new db9 plugs and all my problems went away. I guess it pays to check and double check when problems accrued. Thanks for all your help, it kept me looking, not to say the amount of knowledge I got from this whole situation. Thanks again. Dennis
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If 15 in pulse width doesnt help or totally solve it you may need to enable Sherline mode, it seems some people need that with the G540's while others dont, likely its computer dependant.
Hood
RE: Sherline Mode. This problem described in this thread is very close to what I'm experiencing getting my Taig mill, Mach3, Gecko 540 system unpacked and running again after being packed up for 9 months for a move. Each axis stops for a split second either by jogging or under code - and not always in the same place. Code tells the z axis to go down .01 in. but it comes down about 1/8 in. Strangest of all, I'm sure Ports & Pins/Motor Outputs Dir Low Active were all checked and green for the x,y and z before I moved. Now both the y and z axes have to be unchecked/red to move in the proper direction. No bad connections that I can see. I tried separating the motor cables from power cables. I can't find anywhere in the config sections of Mach3 to change pulse width.
But simply checking Sherline Mode in Port setup and Axis Selection fixed the problem! Anyone know why? What does Sherline Mode do and why didn't I need it before the move? With similar systems, are the Dir Low Active cells checked and green for all axes? The only changes I made were to replace a crashed PC running XP with a faster Vista one, added a parallel port and upgraded to R3.042.020. Strange behavior.
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Sherline mode increases the pulse width to 40uS.
The pulse width is adjusted on Motor Tuning page but if you are in Sherline it is fixed to the 40uS and changing it there has no affect.
Reason you probably need to use a wider pulse now is there is less latency in your new computer so pulse width needs to be increased, you may find you can choose not to use Sherline and can get away with just increasing on the motor tuning page, on there you can increase up to 15uS.
Hood
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Thanks for the explanation. For some reason, I can't find pulse width referring to anything but spindle setup. In Config, Motor Tuning, all I see is the Motor Movement Profile window having to do mostly with acceleration for the axis motors. Below to the right, there is a box for Step Pulse and Dir Pulse, both set at one as the docs recommend. They go from 1 to 5 and 0 to 5 respectively. Where exactly do I set pulse width?
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Below to the right, there is a box for Step Pulse and Dir Pulse, both set at one as the docs recommend. They go from 1 to 5 and 0 to 5 respectively. Where exactly do I set pulse width?
That is the pulse width you are talking about, it can be set as high as 15 if I recall .
Hood
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I am having the same problem with my Z axis it was running just fine for the first month that I had it but today during a cut the z axis motor started going crazy. I am pretty new to this this so please tell me where to change the pulse width? In the motor tuning settings there is a Step pulse and a dir. pulse where do I put the 15? in the step pulse or the dir. pulse? Also how do you enable Sherline mode? Thanks guys.