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Author Topic: Home ref all stepper stop when hit home/limit switch  (Read 3292 times)

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Home ref all stepper stop when hit home/limit switch
« on: July 23, 2013, 06:57:06 AM »
Hello  

I have been using Mach3 for a while and my CNC router seams to work well.  

The only thing i have not been able to figure out through looking on the help forumns is why when i do a REF ALL the steppers move to the combined home/limit switch hits it and the stepper stops, all 3 axis do this, to get it to start i reset and the y axis will do the same and then the x.  I have tried various values in debounse upto 2000 but nothin has changed, as surgessted by HOOD.

So what this mean is that i do not ref all after turning on my table and i do not use soft limits.

I make sure that when cutting i use a working cord of 0,0 well within the table area.

The limits switches stop all axis if hit but i have no safety control if the axis run off the table area ( the reason of having soft limits set)

I have checked and all the DRO count up/down in the correct direction

I have the limit/home switches at the  bottom left front corner of my router table and on top of the z axis

i have tried changing motor acc and vel setting and my motors run smooth

I am using a USB controlled board.

Any help would be welcome
« Last Edit: July 23, 2013, 07:04:45 AM by handyandy »

Offline Hood

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Re: Home ref all stepper stop when hit home/limit switch
« Reply #1 on: July 23, 2013, 08:09:17 AM »
As you are using an external controller then Debounce Interval will have no effect as that is only used by the Parallel Port. Some external devices such as the Smootstepper have filtering options in their plugin, if yours doesnt then you will have to contact the vendor to see if a noise filtering function could be added to the device.
However the best and recommended solution is to get rid of the noise if possible, if you have properly shielded and grounded wiring on the limit switches noise should not be a problem. Notice I said "should" as if your environment is extremely noisy eve that may not be a 100%  cure.

Hood
Re: Home ref all stepper stop when hit home/limit switch
« Reply #2 on: July 23, 2013, 09:03:12 AM »
Thanks Hood for the quick reply

No i have not got shielded wires on the limit switches so a job for the weekend if i can find some. Would i be able to use Cat 6 network cabel for them, as i have load of that.

The stepper motors also have Non shelided cabel, should that cencern me.

many thanks

Andy

Offline Hood

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Re: Home ref all stepper stop when hit home/limit switch
« Reply #3 on: July 23, 2013, 01:50:54 PM »
When dealing with low voltage signalling it is best to shield everything if possible. It is important however that you ground the shields correctly as not doing so may cause more problems than they solve. The current thinking is the shield connected only at one end and all shields connecting to a central, single point.

Cat 6 should be fine if its shielded.

Industrial machines use 24v for the signalling, this is much more noise immune and  thus shielding usually isnt needed unless it is extremely noisy. I wire all my machines with 24v, in the past this meant I had to do the 24v to 5v conversion myself with relays etc, as close to the computer as possible, now however there are external controllers that are 24v I/O and that makes things much easier for me :)

Hood
Re: Home ref all stepper stop when hit home/limit switch
« Reply #4 on: August 02, 2013, 09:49:29 AM »
Hi again

My system is a 24v system.  I have seperated all AC wires from DC wires


I have just tried a NPN limit switch on the Z axis but i still have the same issue the motors not reversing off the combined home and limit switch

I am using a USB control board

I have orderd some sheilding singal and motor wires, but i am not sure this will help

I have tried setiing the motors to various speeds and acceleration valves but nothing changed.

So i am out of ideas and have found no other things to try from the web :'(

Offline Hood

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Re: Home ref all stepper stop when hit home/limit switch
« Reply #5 on: August 02, 2013, 10:12:01 AM »
I suspect it may be your controller, 24v I/O should not really have an issue with noise whether shielded or not.
 As a test can you just have a wire that you can touch to the input to simulate a switch.
Hood

Offline Chaoticone

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Re: Home ref all stepper stop when hit home/limit switch
« Reply #6 on: August 02, 2013, 10:18:52 AM »
What USB Controller are you using Andy?

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

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Offline Chaoticone

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Re: Home ref all stepper stop when hit home/limit switch
« Reply #7 on: August 02, 2013, 10:23:48 AM »
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!