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erratic uncontrolled cycle starts
« on: October 18, 2012, 09:54:44 AM »
I am a couple of weeks into the CNC and things are coming pretty good with everyone's help
I do have a problem trying to figure why the cnc starts off crazy when I hit cycle start
to begin a run

After I zero the axis to the surface of the material and then send it home
I hit cycle start....Sometimes the z axis will go straight down and crash if I don't stop it
sometimes Z will raise a bit and head off in the opposite direction
but, after I go through and do everything again it will do just fine....

I am learning to be very very cautious and carefully but it is taking a great deal of time
having to run a trial run without the tool before I can start with the tool
something is set wrong somewhere

for example
last night I ran a Gcode from VCarve Pro that I have run a couple times aleardy
I load the program hit cycle start the Z axis it heads to the project (looks good) makes its descent
but, it doesn't stop... before I can hit the stop it bores through the material and into my sacrificial bed....

I reload the program reset all the axis to the material again
start completely all over
and it runs perfect.....

what do I need to check

thanks ahead for all the help

Offline Tweakie.CNC

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Re: erratic uncontrolled cycle starts
« Reply #1 on: October 18, 2012, 12:43:00 PM »
It would be extremely unusual for Mach3 to ‘throw a wobbly’ so I am assuming that your machine is not correctly obeying the commands it has been given. Check the Mach3 DRO’s, when it all goes wrong and if they do not agree with your machine position then it is a machine problem.

Often, electrical noise can cause strange things but I would suspect that your Direction signals are not being picked up correctly so a minus direction is continuing after a plus direction has been commanded (or visa-versa).

Perhaps checking all your machine wiring for bad connectors or poor connections etc. may be the way forward.


Offline BR549

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Re: erratic uncontrolled cycle starts
« Reply #2 on: October 18, 2012, 03:35:05 PM »
Could be a tool offset or a fixture offset is left modal from a previous run and it gets reset when you hit Estop after the crash then it runs ok .

Just a thought, (;-) TP
Re: erratic uncontrolled cycle starts
« Reply #3 on: October 18, 2012, 04:06:15 PM »
yes, I agree figured it's a machine problem.....

I am still confused to why all of sudden last week I couldn't reference home and
m1 limit and home led lights were on....

end up having to change all my home and limit switch settings to ways that even make
sense in order to get the lights out and so that it would reference home again...

something just isn't right about all that
I dont know what it was that caused that
I don't enough to figure it out....
Re: erratic uncontrolled cycle starts
« Reply #4 on: October 18, 2012, 04:57:35 PM »
I had a ongoing problem with the Z axis not stopping sometimes, not sure if this is relevant but i checked everything and could not find a problem. However one day when using my CNC machine my screen showed that zone alarm was asking for permission to allow my computer to accept a program at the same time the z axis was not stopping, luckily it was a z + command so it just hit the overtravel switch. I had a thought that my broadband connection was sending signals down the printer line which was now my Mach3 connection, I was not using the internet at the time but the computer was linked via my wireless connection. Since then I disconnect broadband whenever i use my CNC machine. This was 4 months ago and the z axis has behaved it self since. Just a thought, maybe totally wrong but worth thinking about. Also some of the security software does background checks of you software, this could also send signals to Mach3 via your connection to your machine.   Jim
Re: erratic uncontrolled cycle starts
« Reply #5 on: October 18, 2012, 07:14:01 PM »
hey jim that is good thinking...
I use a wireless router in the home
but, the computer running Mach 3 doesn't have wireless
Re: erratic uncontrolled cycle starts
« Reply #6 on: October 19, 2012, 05:56:07 AM »
good info there from Jim

All you should have on the computer running the machine is the operating system and mach3, anything more and you're asking for trouble.
Re: erratic uncontrolled cycle starts
« Reply #7 on: October 20, 2012, 05:57:06 AM »
Just a quick update. Been telling you all I haven't had any problems with erratic moves since. WELL accidentally left the internet connection plugged in yesterday but didn't go online and guess what, Z went off without stopping, Z + thank God. I did not go on the net all day. Disconnected it and carried on working all day with no problems, however when I came to turn off my computer there were 3 windows update to install. Just thought I would have a look at my computer actions and found out the machine had been doing a scan at the time of the Z axis fault. Moral of this story set your schedule scan (if you have a virus checker) for when your not CNCing and unplug your internet connection even if do not intend to use it. Just for reference I only use the internet for downloading my CNC Mach programs, which I do in the warm in the house, watching the football.
Re: erratic uncontrolled cycle starts
« Reply #8 on: October 20, 2012, 07:18:24 AM »
Jim, you could drop the file onto a memory stick and copy it onto your work computer.
Re: erratic uncontrolled cycle starts
« Reply #9 on: October 20, 2012, 02:19:14 PM »
[img]Hi AngleTec. I do that now, I have a couple of memory sticks with all the files on, only problem is they are always in the wrong place, (keep leaving them in the workshop) as you can see I keep a tidy workshop. I don't use the internet except for windows updates and other program updates, just forgot to disconnect it last time.