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### Author Topic: Softlimits - Message  (Read 8582 times)

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#### Chaoticone

• 5,634
• Precision Chaos
##### Re: Softlimits - Message
« Reply #10 on: February 15, 2008, 08:23:33 PM »
Hey RC, they way it should work is this, I can leave my softlimits on, do a ref all home, and my soft limits will never let me hit a limit switch. Sometimes when I do a power up, I will have to disable my softlimits, ref all home the first time, enable softlimits. After this, it is good to go. The reason you can set your softlimit min to 0 is this, when you home the axis it goes till it sees the switch then reverses untill it isn't made. This is Machine 0. Softmin 0 will work here to because remember, it is not making your limit at this point. I don't understand why you get the warning if it is within the limits unless you have not done a ref. all before setting your coord. zeros.

Brett
If you could see the things I have in my head, you would be laughing too.

My guard dog is not what you need to worry about!

• 4,902
##### Re: Softlimits - Message
« Reply #11 on: February 15, 2008, 08:41:39 PM »
Thanks Brett, I've got a pretty good grip on that and understand the internal mechanism of a "Snap Action" limit switch. The Slow Zone prevents the overtravel that might trip the switch AFTER the DRO reaches 0.0000. But I don't think that is affecting my problem.
Is Soft Limit Min. the Mach. coord in the NEGATIVE most direction of travel ? Beit a + or - value ?
And    "      MAX             "                    POSITIVE                                  ?           "

For instance...A lathe with Z 0.0000 at the right end, 10" to the chuck.
Z MIN = -10      Z MAX = 0    or vice versa ?

Thanks Brett,
RC

« Last Edit: February 16, 2008, 09:08:46 AM by Overloaded »

#### Hood

• 25,856
• Carnoustie, Scotland
##### Re: Softlimits - Message
« Reply #12 on: February 16, 2008, 02:59:09 AM »
Well I dont know where that is in the manual but if it is I disagree. The screenshot you have mentions the slow zone and not to have that too small in case the limits are hit.
Heres how I see things, when you home the machine trips the switch, Mach reverses the axis until the switch is again closed then stops, you are now referenced and your position is machine zero. If you set your min to zero it will be when the switch is closed. Now on to what I think the manual says, if you set a slow zone that is too close to the switch and you are moving towards the switch at full rapid Mach does not have enough time to  decel the axis before it can reaches the limit switch and overshoots, thus tripping your switch.
This may wel be nothing to do with your problem but it is as well to get this sorted out as it will take one problem  out of the equation and we can then move on to other possible causes.
Can you post the code and I will load the same version and see if I can replicate it.

Hood

EDIT
Sorry didnt notice this went on to page 2 and Brett has already described what I have said.

• 4,902
##### Re: Softlimits - Message
« Reply #13 on: February 16, 2008, 09:25:29 AM »
Thanks Hood,
Can you find what I may be doing wrong in this example............?

Set Home,  X and Z ,  Machine Coords DRO's  are 0.0000

Jog X in the POS. direction to 6.0 +/-     (remember, my switch is at the X NEG. end of travel) Max travel is 12 in Dia. mode.

Jog Z in the NEG. direction to -6.0 +/-    (Z-8.0 will hit the chuck)

Now, Zero  the DRO's......Part Zero      Verify by selecting Program coords. All are 0.0

Set Soft limits...X   Max 12       Min 0.0
Z   Max 0.0      Min -8.0

Hit Cycle Start and see what you get.
Thanks for helping Hood,
RC
« Last Edit: February 16, 2008, 09:27:58 AM by Overloaded »

#### Hood

• 25,856
• Carnoustie, Scotland
##### Re: Softlimits - Message
« Reply #14 on: February 16, 2008, 11:32:40 AM »
RC,
Things are fine for me, I tried it just setting up a new profile and dont get any errors. Could you attach your xml and I can load that and see what happens.
Hood

• 4,902
##### Re: Softlimits - Message
« Reply #15 on: February 16, 2008, 05:41:32 PM »
Here you go.....Thanks Hood,
RC

My Lord....what a mess of chicken scratch. Good luck !
« Last Edit: February 16, 2008, 05:45:47 PM by Overloaded »

#### Hood

• 25,856
• Carnoustie, Scotland
##### Re: Softlimits - Message
« Reply #16 on: February 16, 2008, 06:35:12 PM »
I just looked at your xml, you dont have any home switches defined in the Ports and Pins , Inputs. Is that the correct xml?
Quote
Jog X in the POS. direction to 6.0 +/-     (remember, my switch is at the X NEG. end of travel) Max travel is 12 in Dia. mode.

Jog Z in the NEG. direction to -6.0 +/-    (Z-8.0 will hit the chuck)

Now, Zero  the DRO's......Part Zero      Verify by selecting Program coords. All are 0.0
Dont think you should be zeroing your X, your x axis should be at zero when the tool is exactly in line with the spindle centre. So it will depend on how you are setting your tools up how set this. If you dont have a way of accurately swapping tools (QC toolpost, Indexable  ToolPost etc) then what you will need to do is take a skim cut on the dia of your stock, keep the X axis on this dia and measure the stock then enter this Dia  into the DRO. What you are doing at the moment is saying that the zero position of the X axis is on the outside of the stock and you are turning it down into minus nimbers. Or am I reading this totally wrong?

Think I need to get a grip on where your limits are, which direction you are calling X plus and minus and Z plus and minus.
Is the following correct?
Your X axis is going negative as it moves towards the spindle centre.
Your X axis home is beyond the spindle centre in the X Negative direction.

Your Z axis is going negative when it is moving towards the chuck .
Your Z axis home is towards the tailstock.
Also do you have a way of accurately swapping tools such as a QC post or are you going to just set up each tool as you go into a programme?

Hood

PS out of curiosity what kind of motors are you using, it seems to be a fast beast, nearly 19M/min rapids
« Last Edit: February 16, 2008, 06:37:01 PM by Hood »

• 4,902
##### Re: Softlimits - Message
« Reply #17 on: February 16, 2008, 07:25:15 PM »

Think I need to get a grip on where your limits are, which direction you are calling X plus and minus and Z plus and minus.
Is the following correct?
Your X axis is going negative as it moves towards the spindle centre.    YES
Your X axis home is beyond the spindle centre in the X Negative direction.  YES   "X Home Neg."

Your Z axis is going negative when it is moving towards the chuck .  YES
Your Z axis home is towards the tailstock.  YES  "Z Home Pos."

I am simulating this for you from my home PC, that's why you don't see the switches.
There is a single 3/16" square HSS tool mounted on the tool plate in a block.
I typically do the skim cut on the OD then measure the stock to set the Part X 0.0000 on center line of spindle. Also skim the face for Z 0.0000.
I have to set the tool up each time...that's OK for now.

For this example, moving x to anywhere near 6 and zeroing, puts Part X0.000 nearly in the center of the axis travel and near center of the set Soft limits for X which is 0.0 to +12.
Likewise for Z but Part Z 0.00 is about 2" from the chuck and the Z- soft limit.

The part is quite small and the program run doesn't come NEAR the Soft limits. So... why the warning ?
Could RADIUS/DIAMETER mode maybe have something to do with it ?
Thanks for taking the time Hood.

The simulating explains the motor speed.
RC

#### Hood

• 25,856
• Carnoustie, Scotland
##### Re: Softlimits - Message
« Reply #18 on: February 16, 2008, 07:32:07 PM »
OK I just set up the pins for the homes and set up a emulated key so I can simulate a home ( I too am on the home comp )
Funny thing is I am getting a Soft warning on Z min.
It quite hard trying to work out whats happeneing when you dont have the machine hooked up but I will see if I can work out why.
Strange that we are getting different axis warnings
Hood