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limit switch
« on: September 20, 2013, 02:21:51 PM »
Hi All
As two of my stepper motors are mounted on their slides and move with them, is the attached limit switch arrangement possible and will Mach 3 know which way too move off when it contacts them.
Also can I use one of the rollers as a home position?
Graham

Offline Hood

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Re: limit switch
« Reply #1 on: September 20, 2013, 04:33:49 PM »
Not really sure what you are meaning regards your steppers but the limit arrangement you have shown above  will work fine and yes you can set the Home up to the same input as the limit. What will determine which way you home is the setting for Home Negative on Homing and Limits page.

Hood

Offline ger21

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Re: limit switch
« Reply #2 on: September 20, 2013, 05:30:36 PM »
Mach3 won't move off a limit switch. You need to do that manually.
Gerry

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http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
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Re: limit switch
« Reply #3 on: September 21, 2013, 05:56:28 AM »
Thanks for your replies, will press on.
Graham
Re: limit switch
« Reply #4 on: September 27, 2013, 02:46:49 PM »
Hi All
Have a new problem.
Have done two axis, Y first and then Z.
When I finished the Y the limit switch tripped out on overun as it should and homed perfectly backing off a small amount and setting zero.
When I finished the Z the limit switch tripped out on overun as it should but when I tried to home it hit the limit switch set zero but did not back off thereby triggering a limit switch overide.
If I switch off the Z axis limit switch in ports and pins but leave the home ticked it wiil home both perfectly even though the Z axis limit switch still does not back off.
I have tried altering the home away but it still does not back off but shows the amount on the DRO
Anyone have any ideas on how to get the Z AXIS TO BACK OFF AFTER HOMING.
I have tried a differant limit switch.
Graham
Re: limit switch
« Reply #5 on: September 29, 2013, 06:23:26 AM »
Hi All
After a lot of research the problem was solved by simply increasing the "debounce" parameter.
Graham

Offline Fastest1

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Re: limit switch
« Reply #6 on: September 29, 2013, 12:59:53 PM »
Just out of curiosity, what is your debounce set to?
I want to die in my sleep like my grandfather, not like the passengers in the car! :-)

Offline ger21

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Re: limit switch
« Reply #7 on: September 29, 2013, 09:04:56 PM »
The "problem" is that noise is triggering your switches. Debounce doesn't really solve the problem, is just hides it. But, as long as the debounce is only a few thousand or less, you should be fine.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: limit switch
« Reply #8 on: September 30, 2013, 01:16:14 PM »
Hi Fastest1
Its set at 1000 (debounce), but still do not know if there are any bad effects on this number, it was my best guess!!!!
Graham

Offline Fastest1

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Re: limit switch
« Reply #9 on: September 30, 2013, 02:04:53 PM »
Hi Fastest1
Its set at 1000 (debounce), but still do not know if there are any bad effects on this number, it was my best guess!!!!
Graham

   The debounce setting is a measurement of time (40 microseconds per unit). A setting of 1000 means the signal has to be present for 1000 x 40us (.0399999 seconds).

   Some noise is very short in duration and it is acceptable to remedy the problem with the debounce. A problem where much higher numbers are needed indicates a wiring problem, generally ground issues.

   I come from a hobby machinist background. .03999 seconds is not long to me and nothing will be damaged if my machine over travels at a rapid speed for that period of time. Now that might not be the case for those with commercial machines that are capable extremely high rapids (700-1200ipm possibly?)

   This also brings up another point. The length of time of this setting will influence where the home or limit switch is seen. It will move farther away from the status change the longer the signal is required. Again these are concerns, but most likely arent serious for hobbyists and our machines. 2 different settings would result in 2 different home and or limit locations, minutely different if that was critical.
  
  Anyway that is how I understand it. Hope it helps.
« Last Edit: September 30, 2013, 02:10:25 PM by Fastest1 »
I want to die in my sleep like my grandfather, not like the passengers in the car! :-)