Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Thorpydo on September 24, 2008, 01:56:09 AM
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Hey,
I just got my new build up and am having a couple problems. The first being that the computer I'm running Mach3 from (and only mach3. . . it's a fresh windows install) will tend to sit in the "Windows is shutting down" screen indefinitely. I have a feeling its trying to do something with the parallel port pins but I really have know idea. I'm using a PCI card to get the parallel cable and I'm confident that the drivers are up to date. Any ideas on what is going on?
And the second problem that I am having is everything I do is scaled down. ie 1 inch is .2 inches. Mach3 is set to inches. The ball screws I am running are 5 rot/in and the steppers are 200 steps/rev. Under motor tuning, I've got mach3 set to 1000 steps/unit. I don't know what the difference is between full stepping/halfstepping/microstepping. Can someone please explain? I am running G203v drivers.
While I'm here, I'd also like to ask. . . what's the right way to change directions on an axis. For instance, my Y goes in when I want it to go out.
Thanks and I apologize for the basic questions,
Adam
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Your first problem certainly sounds like a windows issue, it can happen with lots of different things, a google might help but there are so many things that cause this it may be a long search. Has it happened from day 1 or has it just started happening?
Motors 200 steps per rev, microstepping on your drives is 10 so thats 2000 per rev. Your screws turn 5 times to move 1 inch so if you have no gearing between motors and screws you need 5 x 2000 - 10,000 steps per unit.
Direction change is done in Homing and Limits, motor reversals, it can also be done by changing the active state of the direction pin but some drives prefer it one way or the other and I seem to remember someone saying the G203 prefer active High.
Hood
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As Hood said - change direction by using the active high/low facility on Config/Ports and Pins - dir pin.
If however, you have to set up your motors in a particular direction, butwith dir in the wrong active state for your drives, you can physically change the way the motors turn by reversing the wires to them - they are DC windings. Change either A with A+ OR B with B+ (but not both) and the motor will rotate the opposite way.
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If you haven't already, check out these recommendations (a text file) for setting up Windows XP for Mach at http://www.machsupport.com/downloads/XP_Optimization.txt. This may not help with your shutdown problem (or maybe it will!), but it won't hurt for running Mach.
Oh! I'm assuming you're using XP.
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I will play with the computer more to see how it behaves. I believe that it only hangs up when I've been using mach3. As I believe I mentioned, its a fresh install with nothing on it except mach3. SP3. . . I'll trouble shoot it some more and verify if this is the case or not.
Changing the steps/unit to 10,000 got me to .960 in for g1 x1. Could the other 40 thou be backlash? I've got the ball screws from the deluxe CNC fusion and was under the impression that I shouldn't see any backlash.
Reversed the Y without trouble. Thanks,
Adam
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Ah ok could possibly be Mach is not shutting down for some reason, possibly some VB code getting hung. When you have shut Mach down press Ctrl Alt Del and under the processes see if Mach is still there, if it is try and end it. If it wont end then go to the Mach3 folder and run the driver test, that should kill it. Now see if the computer shuts down properly.
Backlash can be from many places such as loose bearings, flexing brackets or even loose pulleys so give everything the once over. To know whether it is backlash move in one direction, zero the DRO and then command a further move in that direction, if its backlash you wont see it as you only see backlash in axis reversals.
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Ok,
did this:
g1 x-1
g1 x0
Zeroed dial indicator
g1 x1
indicator reads 973 thou
I did the same thing twice and got 973 both times.
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Could your screws be metric rather than imperial? 5mm pitch would move 0.98425 inch for 5 turns.
Hood
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Yeah. . . your good.
Looked at the site I bought them from. 5mm pitch
Leaves me at 10160 steps/in I believe. About to go check it.
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And now I'm at 988 thou. . . Again, tried it twice.
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I'm also curious why my velocity seems to be capped as a function of steps/unit I used to not be able to go above 150. Now I can't go above 147.13431
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Upon further inspection it looks like all three axis are almost there. . . 995 tho on x and 996 tho on y and z. Still not sure what the deal is.
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Try over a greater distance (2 inch) and see if the error doubles
Hood
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I only have 1" indicators... but I do have a couple of them. I think I might be able to put one on each side and get 2". Or I could compare .5" to 1".
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Th greater the distance you can measure the best chance you have of getting things accurate, however going smaller may give you an indication of whether the error seems to be cumulative.
Hood
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After playing around with the machine more tonight, I've definitely noticed a correlation. The more you move the axis the more it is off. I've experimented in both + x and - x. Maybe the math is off somewhere or I am supplying the wrong information. . .
5mm pitch on the ball screws, evidence here (deluxe kit):
http://www.cncfusion.com/smallmill1.html
I think the 200 steps/rev on the steppers is typical. I bought Nema 23's 370 from novakon.
Steppers are directly attached to the ball screws.
Gecko drives should be 10 microstepping.
25.4mm to an inch. I thought this was exact but maybe some units are left off?
I suppose I could try setting the mill up in mm and see how it reacts then. I can still use imperial from the DRO by switching the units with the gcode, right?
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Tried the units in metric with the same results.
I then played with the steps per inch and it seems to be 10182 gives me 1.000"
22 more steps then calculated. Not sure what's wrong but I've verified it using 2 indicators at the same time. . .