Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Bill CNC on December 16, 2007, 04:27:36 PM
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hello All,
I am still in the middle of trying to set this thing up with the home and limit switches but I think I need to get the machine coordinates done first!
I have a problem, When I have my all my axis all set to zero in my machine coordinates all three axis are in the middle of their travel, how do I fix this? I cant seem to be able to set the machine coordinates to zero on the limit switches.
Thanks
Bill
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Look under Config/Motor Softlimits and see what the G28 home positions are set to.
Also under Config/General bottom right of window un-check copy G59.253 to G54
Graham.
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Hello Graham,
I think what you are wanting to know looks fine. Here is a few screen shots of those menus. Does it look ok?
My homing is not working properly. The limits stop the machine but the homing does not back off the switch. BTW I am running Mach3 and I have six switches limits and 3 of the six I want to use as homing switches. Hobby CNC Pro board.
Thanks
Bill
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So you do a home move, the axis moves, hits the home switch then stops? Does the LED around the "Zero Axis" button turn green? If yes it means Mach has homed. Do you see the switch still active on the Diagnostic page? If yes then sounds like your switches may be noisy so try setting the debounce level to 2000. If that helps then try reducing it until it no longer works.
Hood
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Hello Hood,
When I tell the machine to Ref All Home, the z axis moves to its home switch, the machine stops and All the switches turn yellow on the diagnostics page, nothing is green.
Here is a diagnostics screen shot of what I get when I hit Ref All Home or from the diagnostics screen I hit Ref Z.
Thanks
Bill
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OK , how do you have all of your limits connected? Are they all (limits and homing) connected in series and using only 1 pin on the parallel port? Have you tried increasing the debounce to 2000 (on General Config page) ?
Hood
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Hood,
Yes they are connected in series and I am using 3 of the six as homing switches. I did try the debounce at 2000 ... No Change.
Here is another thread that I started to get the switches working so a quick re-read might help with this problem. http://www.machsupport.com/forum/index.php/topic,5160.0.html
I think that this problem needs to be corrected for the other to fall in place.
Many thanks guy's
Bill
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I have never wired all limts and homes to one pin, so can't be certain. In the homing routine, all of the switches will change state if they are all on one pin as your screen shoot indicates I think. The homing routine should then jog your z back to a point that the limit/home isn't made. On your settings page, is Auto limit override enabled?
Brett
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Chaoticone,
yes the auto limit override is on.
If you have never wired all the switches in series, how is this done? I have limit switches at the end of all three axis, and the top Z and the left X and the farthest away from the user on Y are the ones I want to use as home switches.
I just want limits and homes to work, I don't care how but I need to get them working and get the machine coordinates set at the 0's so I can get her going. As of now, it just looks good and is pretty much useless otherwise.
Anything will help!
Thanks
Bill
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Quick win? - I'd consider splitting your switches (2 per axis) accross 3 input pins. Bet that'll work just fine.
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Stiriling is right. I can't test the issue as I have seperate homes. I wonder if the VB in the ref. all home button could/should be modified for your application. Do you get a limit switch error when it tries to home? What kind of hardware are you using? A BOB, Grex, etc. ?
Brett
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I dont see why it would make any difference where or how the switches were connected. On my Lathe I have all the limits into one pin, I do however have seperate homing switches but that is because I am using the Index homing feature on Eds board and its best to have seperate homes.
As far as Mach is concerned it starts the homing process, it knows which axis is moving and as soon as it sees a limit switch that is configured for that axis it stops then reverses until the switch again shuts. So if all the switches are in series and set up to one Pin it will just look to Mach as if one switch has opened and then shut again.
I may be wrong, I often am ;)
Hood
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Do you get a limit switch error when it tries to home?
Yes I do!
What kind of hardware are you using? A BOB, Grex, etc. ?
Hobby CNC ... 4 Axis HCNCPRO Driver Board Kit
Thanks
Bill
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Do you get a message saying Home Switch active or something like that? Is it only after your Z Axis has hit the switch? If yes to both then that is what I would expect if your switch was doing what I think its doing.
Hood
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Hood,
1. Yes
2. Yes
Whats should I do?
Thanks
Bill
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Sounds like noise to me or a bouncing switch. The test Hood described will help narrow this down.
Brett
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Throw your switches away ;)
Seriously though its either noise (which I doubt) or your switches dont open very well. What is happeneing is Mach homes, the switch opens and Mach reverses. But because the switch isnt opening correctly Mach sees it closing again and stops the reversing but then it opens again and Mach sees that limits are active so wont continue withthe homing.
Best thing to do is wire up an on/Off toggle switch and keep your Ports and Pins set up the same way, have the toggle closed, do a home, open the toggle and Mach should reverse. Close the toggle and Mach should start the next axis etc etc.
If this works correctly then you need to look either at just thaat one switch or all of them and see if either your trigger is not opening them enough or if they are just poor switches.
Hood
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BTW the reason I am thinking it wont be noise is that you are not getting erroneous triggers apart from when a switch is actually hit, if it was noise I would think you would get limits going off at all different times.
Hood
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The switches are good I have testes them and the are very tight and accurate in nature. I don't know that on a millisecond scale but the are repeatable with the DRO down to .0006 so I think they are fine they are a good quality blade with a roller on them.
I don't think its noise because as Hood pointed out they are not erratic in behavior.
Bill
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As I said in the previous post I would test with a toggle switch (On/off) and if that works then you can go onto using one of your limits. If that works then add to the series and see where it fails. It could just be that your Z switch is dodgy. Testing with Mach to see when they open is not really the best test, granted it will show they are opening at the same repeatable point each time but if the switches are bouncing Mach will see that where you might not.
Hood
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Hood,
Gotcha, I will test it with a SPST switch and see if I can get it working. I will post the results when I get done after work tonight.
Thanks Guy's, you have been very helpful!!!!!
Bill