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Author Topic: "Limit Switch Triggered"  (Read 26848 times)

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Re: "Limit Switch Triggered"
« Reply #40 on: January 14, 2009, 07:18:13 PM »
You can put a -1 in the Y scale box and that will flip it.

Darek

BClemens

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Re: "Limit Switch Triggered"
« Reply #41 on: January 15, 2009, 05:02:02 AM »
Also setting up X and Y correctly will help too!

Offline Hood

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Re: "Limit Switch Triggered"
« Reply #42 on: January 15, 2009, 05:42:22 AM »
Sorry Bill, actually thought you were just joking as it is sort of upside down normally.
Hood

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Re: "Limit Switch Triggered"
« Reply #43 on: January 15, 2009, 12:33:37 PM »
What!!? I thought you were serious too, so I've hired a lift to mount my mill on the ceiling....

Question: Is the location of HOME a matter of necessity or choice? On this conventional vertical mill, both X and Y are homed negative so the table homes away and to the right - it that correct? I've run CNC machines and presently run a Sciaki Electron Beam Welder that is CNC and I still have this question mark over my head regarding this. I rarely home the welder, only the work positioner but the gun is not - could be, but not.

Thanks,
WAC

Offline Hood

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Re: "Limit Switch Triggered"
« Reply #44 on: January 15, 2009, 01:19:17 PM »
You can basically home any direction you want or even halfway on an axis if you wish. The thing that is proper is that your machine coordinates Zero position is fully X and Y minus. If you had an axis homing the opposite way then all you would do is put a Home Off distance in the Homing and Limits page for the amount of axis travel.
 Example,  if you had 800mm travel then if your home switch was in the positive direction the machine coords for that axis would be set to zero and any move would then be a negative number in machine coords. If however you have a home off set when you home the machine coords DRO would be set to 800 which would be correct in that Mach would now know you are 800mm positive from true machine zero.
 The same would be true if you had a home switch midway on an axis, you would just enter a home off distance equal to the distance from the switch and true machine zero.

 Hope that makes sense as its quite hard to explain.
Hood

Offline simpson36

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Re: "Limit Switch Triggered"
« Reply #45 on: January 15, 2009, 03:52:31 PM »
It helps me to think in terms of the tool moving and not the table, or to imagine I am tiny and standing on the table so that I am 'still' and the tool is moving around.


My suggestion in this particular case is to split the difference and mount the mill on the wall instead of the ceiling. This way when you look at the table,  zero zero is the lower left corner . .  just like in a geometry text book.  :P

Offline Hood

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Re: "Limit Switch Triggered"
« Reply #46 on: January 15, 2009, 03:57:57 PM »
Best yet, just smoke some of that funny tobacco and when you levitate your table will look correct.
Hood

Offline budman68

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Re: "Limit Switch Triggered"
« Reply #47 on: January 15, 2009, 04:12:17 PM »
Best yet, just smoke some of that funny tobacco

I thought that's what simpson was already doing?  :D
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BClemens

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Re: "Limit Switch Triggered"
« Reply #48 on: January 15, 2009, 04:16:19 PM »
OK, I was writing while you guys were adding more tid-bits for great information. I'll let it go as it was written below....

 Simpson 36, The wall mounting leads to some peculiar problems - In actuality, I cannot think of any reason that the machine couldn't be mounted on the wall. Eye height would be good. So, steel toed shoes and a face shield would be a must. There's a benefit! The smoke would linger longer behind the shield - more effect - better machining visualization. YEA!


Thanks Hood, that makes very good sense. Very well explained. The ability to 'zero' at some distance from actual home would require another switch but may be a real time saver at boot-up time. A Mazak CNC at Jefferson Lab does a 'backward' home for Y (I believe) and that machine refuses to run a program at all unless it has been homed. It goes positive Y to 'home', then zeros negative to actual home. The Mazak is the machine that has led to my confusion about this homing business in the first place. X homes as you would expect; negative - table moves left. Y homes with the spindle to the far side of the table or positive......Have I misinterpreted what the machine is doing or is this description correct?

Appreciate it !

WAC

Offline Hood

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Re: "Limit Switch Triggered"
« Reply #49 on: January 15, 2009, 04:34:01 PM »
Machine zero should be like simpson says, if your table was a piece of graph paper the X0 and Y0 would be lower left corner so that is where your tool should be. So in terms of a mill, if yo are in front of it the table moved fully right and fully towards the column is X0Y0 in machine coords. If you have it the opposite way for any axis then you should enter a Home Off value equal to the distance you are away from that position. I have done a quick sketch below which shows the table position for X and Y zero.
Hood
« Last Edit: January 15, 2009, 05:22:27 PM by Hood »