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Author Topic: Need help on homing machine  (Read 1069 times)

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Need help on homing machine
« on: May 30, 2018, 12:07:52 AM »
Hi, this may sound stupid but I really need help,
Whenenver I press refer to home, it will home the z first and when it comes to x and y ,
when it touches the homing switch on Y it will back down, but unlike the Z axis it won't stop backing until it reach the end of the table , same thing will happen with the x axis
so in order for it to stop , I'm manually lighting up the switches by using a metal.
I can still use the machine , I'm not able to figure out how I can remedy this.
Thanks for any help.
Re: Need help on homing machine
« Reply #1 on: May 30, 2018, 05:17:28 AM »
Hi.
the usual sequence of events when referencing (also called homing) an axis is:

1) The axis is driven in the nominated direction at the nominated percentage of traverse speed
2) The axis stops when home switch is activated.
3) The axis backs off the switch until it de-activates
4) The machine co-ordinate for that axis is zeroed (referenced) or set to the axis offset if so programmed.

It rather sounds like your switches are activating at step 2 but not de-activating as in step3.
Can you tell us more about the switches and how you have them wired? Do you try to make them double as limit switches as well? It is a common,
but in my opinion misguided, practice. Are your switches active low or active high? Do you have pull-up resistors (or pull-downs) to ensure reliable
switch de-activation?

Craig
My wife left with my best friend...
     and I miss him!
Re: Need help on homing machine
« Reply #2 on: May 30, 2018, 06:41:07 AM »
Also, have you set the pull-off distance?
With my setup, it is a setting in the motion controller plug-in config, not Mach config.
Re: Need help on homing machine
« Reply #3 on: May 31, 2018, 12:04:05 AM »
I believed it is also double as limit switches. I dont know about the wiring , this is a China CNC machine, switches are low active.

How can I set the pull of distance ? and where should I set it up ? can you guide me on this, I've been trying to contact the manufacturer  but to no avail.
I was being told that they will coordinate this with their engineer, I purchase  the cnc machine and comes with a pc and software needed.
Thank you for helping Craig.
Re: Need help on homing machine
« Reply #4 on: May 31, 2018, 03:03:48 AM »
cHi,
a pull-off distance is where at the conclusion of step 4 above the axis will then drive some nominated distance from the switch and zero it machine co-ordinate
for that axis.

Note that this is not standard Mach behavior but is offered as a functional feature of some motion controllers. To my knowledge PoKeys 57CNC certainly offers
this feature and believe that Warp9's ESS has recently had this feature added. There may well be other controllers which have it but I'm not familiar with them.
It is not a feature I've ever used or required. Even if I did a simple motion script could enact it even if your controller can't.

Mach's  parallel port controller does not have this feature.

In absence of manufacturers support you are going to have to inspect even disassemble your machine to find out the wiring details and disposition of the switches.
You will also need to know the capabilities and connection details of your controller or breakout board.

Quote
I've been trying to contact the manufacturer  but to no avail.
This is normal for Chinese manufacturers. If you spend a couple of hours reading posts on this forum you'll find hundreds of similar complaints. It is pretty clear you didn't do
any reading prior to your purchase and now the consequences of buying cheap will come home to roost.

Find out how the switches are wired, how the switches are arranged and the IO connections of your controller. Without that basic information I can't help much.

Craig
My wife left with my best friend...
     and I miss him!