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Soft Limits
« on: November 18, 2008, 07:23:51 PM »
OK, I totally don't understand the soft limit setup. If I define my XY work space as a 22" x 44" area that has limit switches 2" outside of that, and the Y axis has a 7" height with 1" to the limit switches above and below that, and I want to have soft limits 1" outside my XY work area and 1/2" above and below my Y, with a slow down setting of 1/2", shouldn't my Soft Limits settings be:
X Soft Max: 45
X Soft Min: -1
X Slow Zone: .5
Y Soft Max: 23
Y Soft Min: -1
Y Slow Zone: .5
Z Soft Max: -7-1/2
Z Soft Min: +.5
Z Slow Zone: .5
When I do this, I can still jog right past all of the soft limits. And, what is Home Off.? And also the manual says, "the defined limits only apply when switched on using the Soft Limits toggle button -- see Limits and Miscellaneous control family for details." Where the heck is that??? Anybody?
Thanks again, Bob
Re: Soft Limits
« Reply #1 on: November 18, 2008, 07:44:09 PM »
So your limits are at      0 and 26 for the Y............  0 and 48 for the X     ? ? ?
Soft limits should be      1 and 23     "                     1 and 45      "

This button toggles the soft limits on/off...Green border when ON.

RC

"Home Off" is where you enter the value that you would like for the DRO to display after the homing routine is completed.
« Last Edit: November 18, 2008, 07:46:17 PM by Overloaded »
Re: Soft Limits
« Reply #2 on: November 18, 2008, 08:48:27 PM »
No, what I think I want is that the work space is defined by the X being from 0 to 44, the Y being from 0 to 22, and Z being from 0 at the top and -7 at the bottom. If the soft limits and slow down are going to be outside of that area, then they would be, I think, at the locations I listed. Part of the problem, I just discovered, is that my manual doesn't have the soft limits section that was copied in the other post. I will go play with that, but if you would let me know if the way I'm thinking about it as referenced in the previous sentence, I would appreciate it.
Re: Home Off., in my case, that would be 000, wouldn't it?
Thanks again, Bob
Re: Soft Limits
« Reply #3 on: November 18, 2008, 08:50:54 PM »
Sorry, that should read, ...." but if you would let me know if the way I'm thinking about it as referenced in the previous sentence is correct...."

Offline ger21

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Re: Soft Limits
« Reply #4 on: November 18, 2008, 08:53:50 PM »
Limit switches are at 0 in machine coordinates, and can't be at -2. I think the soft limits need to be in machine coordinates as well. Also, your Z min needs to be less than Z max. you have them backwards.
Gerry

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Re: Soft Limits
« Reply #5 on: November 19, 2008, 07:53:53 AM »
Bob,
  1 axis at a time...X.
Do you have + and - limits and a seperate HOME sw. ? If so, soft limits can be a - and a +.
Or does one of the X limits double as the home ? Then both soft limits are +.
Soft limits are relative to the HOME pos in Mach Coords.

Home the axis, then jog to where you want the soft limits to be in Mach coords, copy the DRO values into the Soft limits table.
RC

Offline Hood

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Re: Soft Limits
« Reply #6 on: November 19, 2008, 08:53:59 AM »
Tell us a bit more about your setup such as limits and home switches like RC has asked, also which position relative to the tool that your home switches are.
 I dont really know what RC is meaning but Softlimits should always be Zero for X and Y min and Z Max and the axis travel for X and Y Max and Z min (X and Y being a positive number and Z being a negative number). If your switches are other than at the Machines Zero position (see diag below) then you set a Home Off value to tell Mach that. In the drawing the quill is fully up and that is Z zero, the table is fully right for X zero and fully towards you for Y zero.
 If you dont have.zero  for  the X, Y min and Z max then you will need to disable softlimits each time you home.


Hood
« Last Edit: November 19, 2008, 08:55:32 AM by Hood »
Re: Soft Limits
« Reply #7 on: November 19, 2008, 09:12:38 AM »
Hi Hood,
  I was referring to the original post. Looked like he wanted the Soft Limit 1" before the switches.
SoftLimits +1 and +45 .... Switches at 0 and +46.
Really need to know how he is configured.
RC

Also, I agree with Hoods procedure. I have this clip saved in my "Pertinent Notes" folder.
« Last Edit: November 19, 2008, 09:39:21 AM by Overloaded »

Offline Hood

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Re: Soft Limits
« Reply #8 on: November 19, 2008, 09:50:54 AM »
Has ha RC you could have edited my typo for me ;D
In the situation above I would set a Slow zone to be 1 inch and that way the axis would start to slow down 1 inch before the axis extent however its probably not needed to be that large but that will depend on axis Accel/Decel.

Hood
Re: Soft Limits
« Reply #9 on: November 24, 2008, 06:05:39 PM »
Okay, I'm back after a computer meltdown. If it isn't one thing it's another....
I have reread all the posts re: this subject several times now, and I still need some clarity. Firstly, unless I have completely misunderstood some of the posts, it seems that there is some disagreement about the Z axis and whether it is standard for the Z zero to be set at the high part of its range, and everything below that (closer to the table) is negative. Others seem to think that Z zero should be set at the work surface, and everything above that should be positive. In the case of the Z zero at the top, a soft limit above the Z zero position would be positive, but it would be negative if it is set below the low position. In the latter case (the Z zero is at the work surface), the soft limit would have to be negative if it is below the work surface. The problem as I see it with the first configuration is that you have to work with negatives, measuring down from your tool bit and then adding another negative number to that to get the cut depth you want. The problem with the second method is that if you want your tool to go home after doing a procedure, or to get ready for another procedure, it would travel at the height of, and/or end up at, the work surface, making it hard to remove the work and possibly damaging the surface of the material.
So, let's solve that first.
As to Hood's question about my machine orientation, the lower left corner of the XY axes is near the operator and on his left. As of yet, there are no limit or home switches -- this is why I want to get this soft limit thing correct.
Is it possible to avoid some of the issues mentioned above by having the soft limits be the home and positions away from home beyond which you don't want to go (that is, what I would consider the usable work surface), and the slow down 1/4 inch, say, before that? The only problem that I can see is that the machine slows down when it is working near the limits...is that a problem?
Thanks again, Bob