Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: B.E.N. on September 03, 2008, 02:13:20 PM
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Hello,
I am back to the frustration level. I thought everything was going well. I have been spending the past several weeks trying to get a lathe (2-axis) ready for production use. I was able to make about 200 parts ( I need to make about 2500/week) during which time the both the spindle motor and the servo motors had "seizures". Re-zeroing the servos seemed to take care of the control part but the spindle motor, I have no idea. I have put a surge protector on the computer power. The lathe power is 220V single phase I will put a sola there as well.
I went back at trying to run the lathe again this week after the holiday and I can't make a single good part. I loaded the same program I was using, I zeroed everything the way I have been I checked calibration and motor tuning settings. No luck.
Is there a way to write the program in encoder counts rather than inches or millimeters? I assume zero on the encoder is at same location all the time? Maybe I am really not getting everthing back to the correct offsets? It seems everytime I use the machine I have to tweak the program to get good parts. What am I missing?
We have an Applied Motion system that is about 5 or 6 years old now and the program is bullet proof. You can shut it off in the middle, pull the plug anything and when it powers up it is back and ready to go. Since it is getting old we are setting the Mach up as a back up/ replacement if the Applied Motion does quit.
B.E.N.
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How do you home? Do you have turret if not how do you change tools? Got any pics of the lathe to let us know what we are dealing with?
Hood
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I am not using home switches. I zero on gauge pins then tell the drivers to go a dimension as a home. Find attach some photos.
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Two more pictures.
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Your repeating after a shutdown will only be as accurate as your homing. If you tell the machine to move to a point then set up a dial gauge then move away and go back to that point again does it go there time after time? If yes then your repeatability is ok and it has to be your homing that is at fault. If the repeatability is not there then you will have to find out why, if that is the case then tell us a bit more about the motors, drives, gearing etc and also attach your xml.
Hood
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Hello,
I have done the repeatability test. I wrote a simple program to cycle between two points on y-axis 0.120 apart. The dial indicator always came to the same spot. I did this with G01 about 50 times repeat every time. Then I went to G00 and I ran about 15 cycles and the axis quit. The program kept going. I will try this again with a slower velocity on the motor tuning.
Sounds like I have a homing issue. The manual I have talks about pressing "Set Home" is that a keyboard input or a screen icon or a drop down menu or the REF ALL HOME? Or, would I use the gauge pin zero points as the G28 settings?
Obviously, I am a little confused about the homing issue. Do you still need my XML file?
B.E.N.
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B.E.N.
What you need to do is move your axis to a predeterminined point and then press the Ref All button. Another way is, for the Z axis on a lathe you can often do away with referencing it as normally your zero position will be the end of the stock, you can just move to very slightly beyond the face of the stock and zero the axis then take a faceing cut. You can do similar to the X axis, just take a cut and measure then enter that dimension into the X DRO. However its not the best idea especially if you have multiple tools that you can place in a repeatable manner, what I mean by that is if you have a turret or a quick change toolpost.
Its not a difficult thing to add home/limit switches and the optical ones I use on my mill are fairly cheap and very accurate so it might be an idea to think about adding some home switches.
Hood
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Thanks for info about REF ALL HOME. I still can't seem to get back to making parts. I had the machine running today to tweak it in and after about 20 cycles the Y axis just quit. The DRO continued to run for Y but no movement. Can't even get it to go with the jog function. I have shut the drive down still nothing. Is there some kind of error log that might indicate what happened? I will restart Mach 3 and see what happens. I don't have the Sola on the drive supply yet.
B.E.N.
Do you have servos or steppers? what make of drives do you have, sounds like your problem is a hardware issue and your drive is playing up or there are loose connections. Mach will continue to run if a drive faults unless you have an input to Input 1 to tell Mach the drive has faulted.
Hood
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Hood,
I have stepper motors with Gecko drives and a Sound Logic control. I will look into the Input 1 setup.
B.E.N.
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OK but if your axis will not move then you need to find the problem, check for loose connections on both your breakout and your drive, if you have a voltmeter check the power supply is putting the correct voltage to the drive when you try and jog. You can also check at the Step and Direction Inputs on the breakout to make sure the signals are getting to it, if they are then check on the drivewhile trying to jog. When checking on the Step pin you will need the meter in mili volt range , voltage is not important as long as you see something when you jog and zero when you stop. For the Direction pin you should see 5V when you jog one way and zero the other.
Hood
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BEN
Are you using MACH Mill to run your lathe?
RICH
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Hood,
I did restart Mach. Axis still would not run. Restarted computer and the axis is working again. Nothing else was checked, moved, adjusted. It is hard to believe it is hardware if it will run for hours sometimes weeks and then just quit. I have other things that come at work so sometimes the lathe sits for a couple days and the drives will work. Then I go to use it and it stops. A couple weeks back I ran it 2 or 3 days in a row no problem. Since then I have plugged in an ethernet network connection would that cause intermittent problems?
I did see a reply asking about if I run Mach Mill to run the lathe. No, I run a program that the lathe supplier provided (XML file).
B.E.N.
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I dont think it is a software problem if the DRO move when you jog. It copuld be the parallel port that is a problem so next time it happens test that the pulse is coming out on that axis Step pin with your voltmeter set to milivolt range.
Hood
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Hood,
I set up to do the repeatability test again on the Y-axis. It ran 6 minutes with a variation of about .0006 inches. I was cycling .350 inches. Just past the 6 minute mark the stepper motor did its twiching and pushed the dial indicator out of the way. I ran a drive test right away all the displays looked normal but there was no line on the graph. 23731 to 23733, 547 and, 4192. The motor tuning settings are 23.94 in/min. 2.98 in/sec2. FRO is at 6. I have G17, G61, G90 and , G94 on the first line of the program. I am using G01 to go to the dimensions.
I stopped it when it hit the dial indicator. When I hit the start again all that would run is the elapsed time.
I will hook up a millivolt meter on the drive and run the experiment again.
B.E.N.
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Did you have Mach shut down when you run the drivertest, if not you will not get a line, Mach needs to be shut down.
Hood
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Lathe ? Y axis?
Ed
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Yes,
The vendor of the lathe provided me with an additional stepper and drive to run the tailstock. I do have occasion where I will use the other axis.
That gives me an idea though, I will run the tailstock off the Z-axis drive and see if anything bizarre happens. Maybe it is the extra stuff for that stepper that is the problem?
B.E.N.
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Hood,
I moved the y-axis cable to the Z-axis, replaced the y's with z's in the repeatability program and ran 15 minutes without even a hesitation. Tweaking the velocity and accel I was able to improve repeatabilty to about .0003 in. I would get an occasional .0005/6. I am going to move my tooling back in place and try to make some parts. If all goes well I will contact the lathe vendor and ask about the XML file and the Y-axis settings.
Thanks for the support and have a great weekend. Hopefully you won't here from me on Monday.
I did shut MACH down and got the graph on driver test.
B.E.N.
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B.E.N.
Was the line in the drivetest nice and straight?
Hood
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B.E.N
Hopefully you will have things sorted out by Monday and the following becomes mute.
It seems intemittent and when that is the case it's nice to try and duplicate what is happening. If you can.
So if some particular combination makes it occur keep things the same. That at least allows you to do some logical
checking / disciplined checkout. The checkout should be at a high level and try to pinpoint to major section / component of the system.
Follow the signal path at the start and at the receiving end. If the program keeps running and no steps are going out the PC that's one thing, but if the steps are going to the Geco drive and not the steppers that points to something else ( like maybe a voltage problem).
But since you swapped the drives and seemed like some success, i would ask what if any difference exists in the
MACH tuning & settings for the Z axis as compared to the y axis and also any difference in the current limiting resistors?
Any difference in motor temperature after running?
One thing at a time and evaluate. Don't go jumping around or you won't be able to put some intelligence against
the problem. This way you scratch your head instead of pulling hair from it!
RICH
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Hello again,
I did shut everything down on Friday after getting everything set at a point I could make a part. I started everything back up Monday, loaded the G code I used on Friday, loaded a part and hit start. The part did not come out at all like on Friday. After checking things out carefully still no success. I did go to the single step mode to see what is happening line by line.
I did load the tuning & settings from the Y into the Z. I don't have information on the current limiting resistors at this point. The motor temperature did not seem to change, it just remained barely warm to the touch. I haven't put a thermocouple on it yet.
As far as the line in the drivetest being straight, I am not sure I understand. The stepper is just spinning the drive screw back and forth and line on the screen graphic was straight.
Needless to say I have run more than 50 parts this week and not made a single one even close to acceptable. From the pictures you can see I am taking an aluminum ring .006 thick by .176 wide. The lathe and tooling is then suppose to form flanges on each side of the ring. I have during the past three months been able to make about 400 parts so I have some confidence the system will work.
I have been reading other posts to get some ideas. Thanks.
B.E.N.
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OK the drive test needs Mach shut down, you then look in the Mach3 folder and you will see Drivertest.exe, double click on that and it will do a countdown, take over the system and run the test, after a while it will stop. If the line is smooth you are OK if its full of huge spikes then you have problems.
Sounds however like there are other problems with your system but do the driver test and see what its like.
Hood
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BEN
You still do not seem to be getting anywhere.
I think your problem is that you have no idea what the problem is - and this makes it difficult to find a solution.
1 - The problem appears intermittent.
2 - As far as you can see, where is the problem - is it always on one axis, or does this affect both ??
3 - Your set up appears compact so it seems unlikely that any stray signals are getting in there.
4 - From what you describe, the problem is the axis ( or both) suddenly seem to do their own thing.
Try and narrow down the problem - BUT - if you have a spare drive I would change it - if this means just switching the four wires and reconfiguring ports and pins, all well and good.
The problem when you are starting up is different, and Hood has already mentioned this. You must, when starting, take some action to "zero" the machine - so it knows where it is. This does not mean that physically it is in the same position as when you left it, it means that all the counters and DRO's have reset on start-up to the correct settings. I am not talking about configuration - since this does stay set. I am thinking of offsets and such, which can easily become altered.
You should really "home" your machine when starting. You do not need switches on it, but you need to put the machine at the same position everytime, on start-up. If you can attach a couple of blocks on the bed, so you can jog the tool holder up to these blocks (slowly) until the motors miss, and then stop, you can then "RefAll Home" or if you are using the lathe screens, "Set Home x" and "Set Home z". This position can be anywhere on the lathe bed, and might be better at the tailstock end, so they do not get in the way of normal operations.
If you check the DRO's, the Machine Co-ordinates should now be 0,0. ( The machine co-ordinates button should be lit - or on the lathe screens - selected) The machine always keeps track of it's position in machine co-ordinates
I must assume that your work is always in exactly the same position - and your tools fit in the toolpost in exactly the same position. If so, then jog to your position 0,0 on your program. This takes a bit of doing on a lathe, particularly finding the lathe centre for the X axis. Press the machine co-ordinates button and the light will go out. The machine is now displaying "program co-ordinates" (Or on the lathe screens these are selectable on their own).
Type in the MDI line G54 ( The default offset ) and zero both DRO's
You will see the display got to zero, but if you have a quick look back at the machine co-ordinates, they will not have changed. This is the "offset" for your program. If you look in the Config/Fixtures you will see that G54 contains these figures. The other offsets should all be zero - if they are not, then clear them all.
Copy the figures from G54 to say G55, or any of the other slots. G54 is prone to change if you are not careful (indeed they all are) so do not zero the program co-ordinates again, or it will change the offset.
You can either add the G55 offset to your program, or type it in manually when you start the day or indeed, at any time after you have homed your machine. It is more professional if you add it to your program. Make a note of it somewhere, because, providing the stop blocks stay in the same place, that is always the offset for that program.
And This is Why.
At the beginning of the day, run your table up to the blocks, and zero the "Machine Co-ordinates" That is the job done - your machine knows exactly where it is.
If you have added the offset to the beginning of the program, there is nothing else to do, when you press cycle start, the offset is entered and the machine then moves to the correct position for that program. You must make sure, of course, that there is a path for the table, and tool to the start point, without hitting anything else.
If you have not added the offset to the program, type it in on the MDI line. The program co-ordinates will change to take account of this, and if you were to type in the MDI line G0X0Z0 then the machine would move to the 0,0 position of your program. As it is you can just jog roughly up to the start position, it doesn't matter exactly where, press the cycle start and the machine will go to the correct start position anyway.
Note: Once you have zeroed the "Program Co-ordinates" when setting up the offsets, you do not need to zero them again at all. You must not zero them while the program is running, or the offset table will alter.
On a lathe the x offset is usually always the same, so only need be fiddled with once. The Z offset might need altering for different program.
Thats a bit of a diatribe - but I hope it helps.
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Hood,
Find attached a sketch of the drive test. The fuzz on the right side only occurs occasionally otherwise a straight line. I will follow procedure outlined by Jim Pinder to see what I am missing there. This is a very good explanation of ref all home, machine coordinates, and G54, etc.
If the drive test shows something I should look at let me know.
Thanks,
B.E.N.
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Yes your drive test is bad, it should be simlilar to the first part of it with maybe an occasional spike. Have a look on the downloads page and right down at the bottom you will see optimisation steps you can do, that may sort out your pulse problem. It still may not cure things but it should at least eliminate one problem if you are getting a nice clean pulse.
Hood
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Hood,
I looked under downloads on the website. I see a couple selections. I went into Mach and found some stuff on XP documentation. I did not find optimization steps. Can you be more specific. I am running windows 2000.
B.E.N.
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B.E.N.
The optimisation is XP specific but a lot of it can be done for W2K, you will find the steps here
http://www.machsupport.com/downloads/XP_Optimization.txt
Hood
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Hello again and Happy New Year.
Things had been going very well with Mach 3 for awhile. I managed to figure out a zeroing technique and I moved the cable for one of the motors that was erratic to a spare driver and life was good. Now I am back to that same motor doing same thing again. I can run for 20 minutes sometimes and others 2 minutes. While the motor is turning it has seizures and looses steps. As a result, the zero position is lost. I have slowed down the drive no help and it was working.
I will verify that I did the optimisation, I think I tried that.
B.E.N.