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softlimits question
« on: September 24, 2008, 01:36:31 PM »
I setup softlimits on my mill. I have the autozero option enabled on XYZ. X homes negative, and Y and Z home positive, so I set the - limit in x and + limit in y and z to 0, then kept the machine in machine coords, jogged to pretty damn close to the limits of the opposite end of the respective axes, noted the machine coords, and configured those softlimits appropriately. I tested by turning on soft limits, then jogging to the axes limits. I found the safe zone to be a bit limiting travel-wise, so I backed it off a bit, and the servos have no problem slowing the axes well in advance of the soft limits. When I run a program after doing a REF ALL, it immediately warns me about soft limits, even though I specify a work offset, then a G0 move that is away from the limits. Is this because the axes are still in the safe zone immediately after referencing? I think it's pretty annoying.

Joe

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Re: softlimits question
« Reply #1 on: September 24, 2008, 05:09:22 PM »
You say the slow zone is limiting travelwise, what do you mean by that? The axis will still move right up to your soft limits even though you have a slow zone, its just the axis will get progressively slower in the zone when jogging into it.
 You need the home switches to be zero for machine coords, you then set up the slow zone distance which you find out by trial and error, Basically the slow zone is the distance it will take for your motors to decelerate from rapid speed.
Hood
Re: softlimits question
« Reply #2 on: September 24, 2008, 05:53:00 PM »
 
You need the home switches to be zero for machine coords, you then set up the slow zone distance which you find out by trial and error, Basically the slow zone is the distance it will take for your motors to decelerate from rapid speed.
Hood

Isn't that what I just described doing?
My question is, why do I keep getting a softlimit exceeded warning when the next move is away from the softlimits? If I start the same program an inch away from machine coords x0y0z0 I do not get a softlimit warning. Am I getting the warning because the axes are within the slow zone?

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Re: softlimits question
« Reply #3 on: September 24, 2008, 06:00:39 PM »
My apologies, I thought you were meaning you entered a number greater than zero for the X and Y min.
 Ok, to answer your question, No it is not that you are in your slow zone, that will make no difference.
 If you have X min and Y min and ZMax as zero and X Max, Y Max and Z Min as your axis travels (z a negative number) then it should work fine.
 What position is the tool in relation to the workpiece when you are homed ?


Hood
Re: softlimits question
« Reply #4 on: September 24, 2008, 07:17:25 PM »
I set the slow zone to .7 x and y, any less and it's cutting it too close. Z is set to .8, never get anywhere near the limits jogging the Z.
I am using work offset 3 for this experiment.
machine coords
X0 is -
Z0 is +
Y0 is +
After a G56, my first G0 moves (in machine coords) approx -4". Definitely not going anywhere near the Z+ softlimit, but that's the warning I get.
It definitely makes a difference if, before executing the programs, I jog several inches away from the home positions.
I really want to use the softlimits but if I can't rely on them to not erroneously report softlimit violations, then it's no use having them toggled on.
Joe

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Re: softlimits question
« Reply #5 on: September 24, 2008, 07:21:44 PM »
Please attach your xml and also tell me where your home switches are in relation to  the tool. eg if when you are at the home position is  your tool is at the lower left corner of your table ( table fully right and away from you)
 getting late here so will probably be the morning before I look back.

Hood
Re: softlimits question
« Reply #6 on: September 24, 2008, 07:52:27 PM »
X home is at the left end of the table, or X-
Z home is at the top of the column, or Z+
Y home is at the far edge of the table, or Y+

Joe

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Re: softlimits question
« Reply #7 on: September 25, 2008, 05:57:52 AM »
Does your machine look like the pic when in the home position? If so then that means that you need a Home Off distance for the Y axis. You need to set Y min as 0,  Y Max as 6.47 and have a Home Off Distance set to  6.47. That will mean when you home X and Z will be at zero and the Y will be set to 6.47, confirm by looking at machine coordinates.
 At the moment you seem to have all movements in the Y as negative numbers, the Z should really be the only axis that is negative.
Hood
« Last Edit: September 25, 2008, 06:01:13 AM by Hood »
Re: softlimits question
« Reply #8 on: September 25, 2008, 06:50:34 AM »
Although I understand your logic, I fail to see where it has anything to do with the error that I'm getting. Right now all machine Y coords within the working envelope of the machine are negative. When I'm done, they'll be positive. I can't see where it will fix the softlimit issue, since the errors I'm getting are on the Z axis. I do see that the Mach3 setup guide suggests that both X and Y home negative and that this would be a workaround but seems like I could just as easily change the y to home negative and change the softlimits to suit. I think I will go that route instead, which will have the side benefit of not "tugging" the x servo lead wire when I REF ALL. I'll let you know how it turns out.
Joe

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Re: softlimits question
« Reply #9 on: September 25, 2008, 06:56:03 AM »
Joe, yes it may not be the cause of your problem but I am just trying to get your machine set up so that it knows where the zero position is then we can look into why you have the softlimts issue. I have a SmoothStepper on my mill at the moment and it is busy working but as soon as I have finished the current milling I will put it back to the parallel port and see if I can replicate your problem. BTW what revision of Mach are you using.

Hood