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Author Topic: MACH3 Soft limits problem  (Read 6990 times)
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mrpeja
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« on: April 14, 2009, 04:30:06 PM »

Hi,
I use Mach3 and THC300. My machine has X axis 3500 mm, Y axis 1600 mm, Z axis 100 mm.
Have common switches on all axes for limits and home and separate switch for floating head. When I do Homing, X and Y axes go left and down, respectively. Z axis goes up. Should I zero all DROs?
But Soft limits led won't go On (I have soft limits set) and don't work.
How to set those parameters?
Should I set Auto zero?
How Mach3 knows where is top of material when it goes to safe Z?
Should Z DRO shows negative numbers?
I'm confused and need detailled explanation how to set all parameters.
mrpeja
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Hood
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« Reply #1 on: April 14, 2009, 04:42:27 PM »

For softlimits setup if your tool in relation to your X and Y axis is at the lower left (imagine a X/Y graph on a sheet of paper) when homed then you set X and Y min as Zero and Y and Y max as there respective travels. If your tool is in a position other than that then you need to set a home off value which will be the distance it takes to get to the above position but the Max and min will remain the same. For the Z you have the Z Max as zero and Min as your axis travel but as a negative number.
 Most likely you will want Auto zero checked, that will mean when you home it will zero the axis for machine coords.
 Safe Z can be set up in three ways, the safest is to set as a machine coordinate value and if you set that as zero then the axis will (or should be) well clear of any obstructions.

Hood
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mrpeja
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« Reply #2 on: April 15, 2009, 01:20:21 AM »

Hi Hood,
Let's check if I understood:
For X axis (3500 mm travel) I would have Soft min as 10 mm and Soft max as 3490 mm
For Y axis (1600 mm travel) I would have Soft min as 10 mm and Soft max as 1590 mm
For Z axis (100 mm travel) I would have Soft min as -95 mm and Soft max as -5 mm
I would have Safe Z as -50 mm.
Is this OK?
What about Reversed, Home off. and Home Neg. columns?

BTW, is the improper Soft limits settings reason why Soft limits led on Run screen wont go ON and Soft limits are inactive?
mrpeja
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Hood
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« Reply #3 on: April 15, 2009, 01:41:23 AM »

No you MUST have the Soft Min for X and Y and Soft Max for Z ALL set to zero, if you have anything greater than zero then you will have to disable softlimits to Home and then you will not be able to enable the softlimits until you have jogged further than the values you have set.
 Here is why it should be zero, when you home Mach moves to the switch, it opens the switch, Mach reverses until the switch has again closed and this is now your machine zero. This means you can go to zero without fear of hitting the limit switch. If you had 5 for  the min instead of 0 then when you homed the axis would go to the switch, back off, machine coords would be set to 0 but you would have an illegal softlimit situation as you have your softlimits as 5 but you are at 0.
 You can set up a slow zone so that if you are moving at full rapids towards a softlimit Mach has time to decelerate before it hits the limit, this value will be individual for each machine as decel will vary.

Reversed is for you to reverse an axis direction instead of having to reverse motor wiring.
Home Off is if you have a home switch at a position other than true axis zero position.
Home Neg is if you want your homing direction to be in a negative direction.

Hood
« Last Edit: April 15, 2009, 02:38:46 AM by Hood » Logged

mrpeja
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« Reply #4 on: April 15, 2009, 02:21:31 AM »

Hi Hood,
Very clear, better than manual explanations !!!
Please again to comment Safe Z.
At the moment I am not near to the machine and please explain to me where is the place to set it as  a "machine coordinate value."
And, is it -50 mm (minus 50) possible value?
Should I check Home neg. for Z axis?
Regards,
mrpeja
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Hood
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« Reply #5 on: April 15, 2009, 02:28:35 AM »

You can set Safe Z to whatever you think will be a true safe Z in all situations, on a machine such as a mill the safest position woiuld be Zero but as you have a plasma then you may well be safe at -50. However if axis velocity on the Z is reasonable I would suggest you have closer to zero as the safe z, at least until you have gained some experience in your new machine.

No Home Neg should only be checked if you had the home switch at the lowest point on the Z axis and it is unlikely that you have that as it would mean you were homing towards your work. If your axis travel is moving down when the DRO says it is moving in a positive direction then you need to use the Axis Reverse option.
Hood
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sefsarim
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« Reply #6 on: April 24, 2009, 02:29:09 AM »

Hi firends,
I'm the new user of Mach 3 with 4 axis cnc step driver TA8435.
I need the limit switch connection diagram of the driver.
And how can I adjust the soft limit on Mach3 ?
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