Failed Z axis brake maybe?
I have a 2014 "Industrial Brand" CNC router. It runs Mach3. Its just started to do this weird thing where when I shut it down for the day, the Z axis and spindle slowly descend until the tool touches the spoil board or I now put a piece of MDF to keep the Spindle from touching? What on Earth is causing this? It did not do this before.
Any constructive suggestions will be appreciated.
Cismontguy
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Failed Z axis brake maybe?
Jim Dawson
Sandy, Oregon, USA
There have been a few large mills and lathes that have done this, I recall one lathe had a very heavy tool changer on the X axis which was mounted vertically, it had a hydraulically operated pin the operated when the power was cut, release the E-stop and re-power the servo's and the pin released.
Otherwise it sank into the bed.
IOW, there is often some kind of method to prevent back feeding of the ball screw.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Hello Al_The_Man, Thanks. No tool changer of Z axis break on my machine. I have a Tormach 1100 PCNC too and it has a break, so I do know what that is.
Cismontguy
Sounds basically as already stated, the axis is back feeding and as Jim said either the brake is no longer working, or if it never had one, then friction conditions have changed that allows it to happen.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Thanks, anyone have any suggestions for possible repairs, solutions? This just started happening today. I apologize for my poor typing above.
Also I did notice I can move the X axis as well by hand when the machine is turned off. You could never do that either... Just thought of that, right now.
Thanks,
Cismontguy
Repair does not apply if it never had back feeding prevention on it before.
You may have to devise some kind of fix yourself.
First find out if it has counterbalance etc, if not you may have to come up with a brake of some kind, if it persists.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Hello Al, No I am afraid there is no counter balance. I am beginning to think it may have to do with the way I shut down Mach3? I was reading on line about that. My machine does not have a real, functioning E stop. There is one but it is not connected to a proper relay and the instructions manual says to use mach3. On my Tormach, you use the E stop before turning Pathpilot controller off, and then turn the power off the CNC machine.
Here is a quote from else where in the forums,
Normal shutdown procedure is to E-stop the mill with the big red button, then close mach3, then shutdown the PC, then power off with the disconnect switch on the side of the cabinet. This ensures that the motion controls are disabled before Mach3/PC is turned off, so the parallel port is never left 'floating' with the motor controllers enabled. It's unlikely, but possible for noise on the port to manifest as motor movement otherwise. Incidentally, the start up procedure should be the reverse, so power switch>PC power (this is normally configured to come on automatically when power is switched on)>Mach3>Green button>mach3 reset button.
Seems like I need to install a better Break Out Board that has a real accommodation for a real working e-Stop. I just do not use the CNC router that much for all the time it would take to install a new BOB.
Cismontguy
Your hard wired e-stop should also input to the PC-Mach to advise that an Estop has taken place, The built in watch dog timer should advise the system if mach ever goes down.
There is a preferred sequence to implementing E-stop, that covers all bases if possible..
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Yes, I agree. The CNC router I use to have was properly connected with a working E-Stop to Mach3. For some reason, "Industrial Brand" chose not to do this. It even states in their very limited manual not to press the mechanical E stop on the machine, but rely on Mach3 for stopping the router. Not a good situation. I have purchased a PoKeys57 BOB with the intention of getting it installed and then I will not have to use a SmoothStepper controller card, either. Time has just not been available but this new situation may require that I find the time. Appreciate your help. Cismontguy
I think this contains the essence of the problem.With the machine powered down,the Z axis ballscrew has now worn enough that gravity takes over and brings the head down.A really proffessional solution would be to add something like a truck brake that needs an energy input to release a brake-maybe pneumatic or using a solenoid to disengage the lock.The less professional way would be to keep a piece of wood by the machine to lodge beneath the Z axis backplate.It isn't a surprise to learn that with power off the X axis can be moved and I expect the Y axis would be the same.All of which illustrates the need to use a homing routine each time the machine is used to establish the correct machine datum.
Hello Forum, I just run two new parts on my "Industrial" Brand CNC router this AM. I reset the Machine Coordinates per Mach3 manual and then I loaded and ran my G-code program, making two examples of the same part. I then followed the outlined shut down procedure described earlier in this thread. My E-Stop button does nothing. But I pushed it in anyway and then followed the steps. The Z axis did not move an inch and you cannot move the X axis by hand, as I could last night. So it all has to do with the shut down procedure. Hopefully this problem is solves but I am going to change the BOB so the E-Stop really works. Thanks for all of your input Cismontguy
Hello Mactec54, The power to the entire machine is completely off at the end of my work day. I live in a rural area and in the summer we have massive thunderstorms.
I disconnect the power to my CNC Mill and Router and Lathe as routine. Unplugged.
I believe my issue was with the steps I took this one time turning things off. I must have done something out of order. There is no break on the Z axis of this Router.
Will report back if it happens again or something changes. Thank you. Cismontguy