Hello Guest it is October 20, 2019, 05:56:43 AM

Author Topic: Limit switch issues  (Read 19390 times)

0 Members and 1 Guest are viewing this topic.

Offline Tweakie.CNC

*
  • *
  •  7,951 7,951
  • Super Kitty
    • View Profile
    • Tweakie.CNC
Re: Limit switch issues
« Reply #120 on: December 28, 2015, 01:50:22 AM »
just one more thing: my pins should be set to active high.....by doing this will I cause any "magic smoke" lol to come out of my electronics?

Because I can't see the switches being normally open, that would defeat the purpose wouldn't it? meaning they would SUPPLY power to the axis when triggered instead of cutting power to the axis......

According to your .xml your switch input pins are set to Active High.

Maybe a good idea to connect a multimeter (set to ohms) across each switch to see if they are N.O. or N.C.  ?

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Davek0974

*
  •  2,580 2,580
    • View Profile
    • DD Metal Products Ltd
Re: Limit switch issues
« Reply #121 on: December 28, 2015, 03:54:53 AM »
Ok, looked through the manual, watched the video on homing and can't find where I tell mach3 to back off from the homing switches by x amount...

Anyone have any ideas?

You don't, this feature is programmed in.
When you have a home/limit switch set correctly and issue a home command on that axis, the axis should move towards that switch at a rate you set on homing/limits, when it hits the switch the switch opens and mach stops movement, reverses and moves away until the switch closes again, thats it as far as i understand things.

When you said earlier your axis was hitting the frame before the switch does seem to indicate a very poor build/design as that should never happen, glad you got that sorted.

As for positioning the work, at switch on I home my table to set machine co-ords to zero on x/y as z is not homed on a plasma. Then I place my material wherever and align the cutter with the corner of it and zero my work co-ords, now my machine knows where its axes end and also where my material lies. In my Cam software I have an image of that sheet and I place the parts to cut exactly where I want them, as the sheet gets used up, I just remove the cut operation from previous parts but leave the part on the sheet so i can see where material has been removed previously.

It sounds long-winded but in reality it means I can use my material more effectively by keeping part-used sheets for smaller jobs and fill in the gaps when needed later, all the sheets are numbered as are the cut files to match, all the jobs are placed relative to the corner of the sheet which i use to set my work zero - 0/0.

I have no idea what cam solution you run but with your fixed strips of wood this method might work nicely for you too probably. I can take a part-used sheet off and reset the entire machine, replace the sheet and continue using it very easily as long as i set the work co-ords accurately.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline bfgstew

*
  •  105 105
  • DOH!!!!!!!
    • View Profile
Re: Limit switch issues
« Reply #122 on: December 28, 2015, 05:24:50 AM »
Glad you are making progress Mike.

OK , you remember the little diagram I posted about limit switches, put one probe of your multimeter on one cable and the other probe on the other end of the cable and press each switch in turn, each time you press a switch it should read zero, and therefore it should beep or read 100% when no switch is pressed indicating a complete circuit. Is that how you have it???? If not check each limit switch, it should be moulded into the casing what each leg is - COM = common, N/C = normally closed and N/O = normally open.
Lets make sure this circuit is working correctly before we jump into settings.

Offline stirling

*
  • *
  •  2,188 2,188
  • UK
    • View Profile
    • www.razordance.co.uk
Re: Limit switch issues
« Reply #123 on: December 28, 2015, 05:44:30 AM »
LOL: a few thousand posts back our man posted a data sheet with a clear as day picture of the switch terminal layout. Just look at which freakin' terminal the wire's connected to and compare it to the pic.

Offline Tweakie.CNC

*
  • *
  •  7,951 7,951
  • Super Kitty
    • View Profile
    • Tweakie.CNC
Re: Limit switch issues
« Reply #124 on: December 28, 2015, 06:53:45 AM »
LOL: a few thousand posts back our man posted a data sheet with a clear as day picture of the switch terminal layout. Just look at which freakin' terminal the wire's connected to and compare it to the pic.

Come on, that makes it far too simple.  ;D

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline bfgstew

*
  •  105 105
  • DOH!!!!!!!
    • View Profile
Re: Limit switch issues
« Reply #125 on: December 28, 2015, 07:10:24 AM »
It suprising how often the smallesr simplest things get over looked and cause hours of untold grief. The amount of times i get called to breakdowns (maintenance technician) were, after asking the machine op is it switched or the likes, i find that it was not plugged in,  or switched on or the e stop was in, after showing the op the error you get replies like, well it was plugged in yesterday, or i didnt think to look...............ARGHHHHHHH
Never overlook the simplest of things. Thats all i ask.

Offline stirling

*
  • *
  •  2,188 2,188
  • UK
    • View Profile
    • www.razordance.co.uk
Re: Limit switch issues
« Reply #126 on: December 28, 2015, 08:05:26 AM »
LOL - you're both right of course - but given the way this thread's gone so far, aren't you both making the rather rash assumption that Mike's view of Ohm's Law is the same as everyone else's?  >:D
Re: Limit switch issues
« Reply #127 on: December 28, 2015, 08:07:22 AM »
yeah, they are wired N/C so 5 vdc is constantly going through them so the x'd out column in the active low settings column makes sense now...

but all is well in Denmark....it works....I do blame myself for a lot of these headaches, I had so many issues with the poor design I should have KNOWN to look for the issue first. I can't tell you how many times wiring has been pinched between axis and or ripped out because it got caught on the gantry. I have numerous bungie cords holding things out of the way.....

What kills me is he wrote to me about a year ago trying to sell me a new gantry for $1000 US ($1400 CAN).....I feel like writing him back and say "why would I pay you $1000 to correct flaws in your machine design when I can personally correct ALL the design flaws myself for under $400 CAN?

 
Re: Limit switch issues
« Reply #128 on: December 28, 2015, 08:21:55 AM »
Ok, looked through the manual, watched the video on homing and can't find where I tell mach3 to back off from the homing switches by x amount...

Anyone have any ideas?

You don't, this feature is programmed in.
When you have a home/limit switch set correctly and issue a home command on that axis, the axis should move towards that switch at a rate you set on homing/limits, when it hits the switch the switch opens and mach stops movement, reverses and moves away until the switch closes again, thats it as far as i understand things.

When you said earlier your axis was hitting the frame before the switch does seem to indicate a very poor build/design as that should never happen, glad you got that sorted.

As for positioning the work, at switch on I home my table to set machine co-ords to zero on x/y as z is not homed on a plasma. Then I place my material wherever and align the cutter with the corner of it and zero my work co-ords, now my machine knows where its axes end and also where my material lies. In my Cam software I have an image of that sheet and I place the parts to cut exactly where I want them, as the sheet gets used up, I just remove the cut operation from previous parts but leave the part on the sheet so i can see where material has been removed previously.

It sounds long-winded but in reality it means I can use my material more effectively by keeping part-used sheets for smaller jobs and fill in the gaps when needed later, all the sheets are numbered as are the cut files to match, all the jobs are placed relative to the corner of the sheet which i use to set my work zero - 0/0.

I have no idea what cam solution you run but with your fixed strips of wood this method might work nicely for you too probably. I can take a part-used sheet off and reset the entire machine, replace the sheet and continue using it very easily as long as i set the work co-ords accurately.

Yeah, I've done that too, (left a sheet on the table, with the workpiece zero'd in via the offsets and then cut pieces out of it). The main reason I wanted to get the homing sorted it is due to power fluctuations which basically erased my home every time it happened, or losing home when an axis skips a tooth for various reasons, or whenever I lost the offset.

Now that I have a constant set point of reference (home), whenever this happens, I can reset and not muck up my work.....that picture of the sign with the eagle and bear on it, the eagle took about 12 hours of machine time, the bear about 6 and the whole sign total about 20...the whole time a big project like that runs my stomach is (was) in knots praying that nothing went wrong......because I'd have to start all over again from scratch because the eagle's head is now 1/8" offset horizontally and 1/8" vertically because of a power blip....

One thing through this whole exercise: now I feel totally (or at least MORE) comfortable pulling out all the electrics when I replace the mechanicals.....

I will say a great big thanks for those who helped....
Re: Limit switch issues
« Reply #129 on: December 28, 2015, 08:27:40 AM »
LOL - you're both right of course - but given the way this thread's gone so far, aren't you both making the rather rash assumption that Mike's view of Ohm's Law is the same as everyone else's?  >:D

Barbossa: ......... and secondly, you must be a pirate an electrician for the pirate's code Ohm's Law to apply and you're he's not. And thirdly, the code Ohm's Law is more what you'd call "guidelines" than actual rules. Welcome aboard the Black Pearl, Miss Turner Mr. Stirling.  :)

 ;D