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  #1  
Old Sun 26 September 2010, 12:17
giggler
Just call me: giggler
 
na
United Kingdom
Home switches?

I was thinking about using home switches or at least fitting them but have a few questions since I've got a small cnc router already before considering mechmate and I have to admit I've not really used them; they are fixed in middle axis.

1). Should they be movable? if so what suggestions do you have about mounting them or rather the pick up stud. Specifically the X axis channel steel isn't light stuff and I can't see me drilling and tapping enough holes for every situation (holes for proximity pickup studs).

2). Are they worth the effort since I don't really use them on my little machine? Limits sure but the homes while setup in turbocnc, just ain't used.

thanks in advance,

dc
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  #2  
Old Sun 26 September 2010, 13:00
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
If I understand correctly, your questions is "do you need home switches" and "do they need to be adjustable from a known location"?

1) The switches do not need to move, just mounted in a reliable and repeatable location.
2) Once the switches are located in the location, then the machine will automatically find "home" each time you request it. Nice feature for repeated setups.

3) You don't NEED home switches really. Often folks will manually jog the machine to a known location each morning, set 0,0 as a "soft home" and work from there for the entire time the machine is powered on.

Heck - I think MM #1 and all her sisters run without home and limits. Just hard stops on the machine frame and "setting home" in Mach each day. The "soft limits" in the parameters inside Mach will govern the table limits most of the time.

So, in summary, you don't need them....but once you have them, you get really comfortable with them.

Sean
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  #3  
Old Sun 26 September 2010, 13:35
giggler
Just call me: giggler
 
na
United Kingdom
smreish,

thanks. Ok another question, how does the control software know where the home switch is? I mean know to move +steps or -steps on any given axis? as when I turn my machine off, it's not stored and starts up at some unknown position?

turbocnc doesn't seem to remember, at least it doesn't for me, but even so I could of rolled the gantry to some other position by hand (rack based) in order to get to where the tool was or move the head out the way, then the direction of travel isn't know in order to home. It will end up hitting a limit, phyiscal or otherwise.

sorry to add to this thread but it is all about home switches

dc
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  #4  
Old Sun 26 September 2010, 13:49
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Your correct in the fact the software does NOT know where the home switch is unless on is present and active. Home is a relative term. You can "set" home anywhere on the table surface at most any time with Mach - it's the 0,0,0 position.

THe questions you really are asking is if the home is an ABSOLUTE or RELATIVE. Mach does both.

If you machine has home switches, then you can have both....if you machine doesn't have switches, then you emulate Absolute, but you really only have relative.

For a complete understanding, I recommend you visit artsoft.com and download the manual or visit the MACH3 wiki for a very indepth explanation of how they work. It takes a while to grasp in just text form...the manual and wiki have pictures to back up the dialogue for clarity.

Sean
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  #5  
Old Sun 26 September 2010, 17:17
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Giggler,
Thanks for the question
and
Sean
Thanks for the response. It makes sense now.

Red
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