Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: ottervalley on March 13, 2013, 08:01:21 PM
-
I recently replaced the ball screw on the Z axis of my CNC router. The new one is about 2 inches longer than the original. Now my spindle can move downward to the point the bearing block will run off the rail.
I want to set Mach3 to prevent that. Any help is always appreciated.
-
Do you have a home switch on your Z axis?
Brett
-
I don't think so Brett, although I'm a novice and it may be that I'm wrong.
-
You can set soft limits without home or limit switches, just better if you have a home switch because that is what the work off of. Do you have a certain spot you always jog the z to when you refrence the machine?
Brett
-
I do have a home switch on the z axis Brett. I set the position of z to various points depending on the piece I am cutting. I hit the Goto switch after each cut. What I am trying to prevent is operator error and what I want to do to set a limit that under any circumstance, won't allow the the spindle to travel down to the point where it will not allow the bit to damage the bed of the machine or for the spindle to travel downward to the point where the bearing block moves beyond the rail causing loss of bearings.
-
OK, you can set up softlimits either way but if your just jogging to a point and setting the MACHINE 0, softlimits sucess will depend entirely on the operator. Home (refrence) your machine and jog the z down to where you want it to stop. click on the machine coords. button and write down the value in the z dro. Go to config., homing/limits and put that number in for your z min. Set your slow zone big (several inches) at first to test with. Go to the run screen and enable softlimits by clicking the softlimits button. Should turn green around it then. Test it slow by jogging the z down. When it gets in the slow zone it will start slowing down and eventually stop at the machine coords you entered. As always, test it slow and with caution and hand on estop........... i dont want you hollering at me if you run z off the rails. Eventually you can tune it to run as you want with a smaller slow zone etc. but for now just get it working and tested
Brett
-
Thanks Brett...I'll give it a go.
-
Hey Brett,
No luck so far. Before I started with your instructions, I took a photo (attached) of the screen and activated the soft limit switch. It stopped travel up to a limit and stopped but not down. When I tried to enter a z value I get a message saying Machine out of limits for soft limit activation.
I must be missing something and thought the photo might help in identifying my problem.
-
In that screen shot your machine has not been referenced so no telling where the machine z is at. Disable your softlimits, reference the machine and then enable your soft limits and see if that works.
Brett
-
I think where I'm losing you is referncing the machine...I don't understand what to do to accomplish that.
Bob
-
My bad, jog the machine to where you want to call home. Z up all the way on a router and click the Ref. all home button on the run screen right beside your zero dro buttons. The leds around the zero buttons will turn green once your machine is refrenced.
Brett
-
I may be way off target here, but if it was me I would also fit a short sleeve (clamp ring) over the ball-screw so it mechanically cannot move the axis far enough to loose the bearings etc. just in case the set limits are accidentally overridden. ;)
Tweakie.
-
Spot on as usual Tweakie. Thanks!
Brett
-
There is an over travel software limit that you can set in Mach3 so that it will not travel past that point going down.
(;-) TP
-
Thanks for the input guys!
Brett, thanks for your patience with my lack of knowledge. I watched the tutorial on Homing last night and learned two things...first is that my table has not been set up properly, and secondly, to do so is simply beyond my current capabilities! I do plan to mess with it again today.
Tweakie, thanks for suggesting this option. Considering my statement above, it may be the way to go.
TP, this looks to me like my best simple option to achieve what I want to do. Would you, or someone explain the steps required?
Thanks to all. I have another question but I'll wait until I get my z axis issue sorted out.
Happy St. Paddy's Day!
Bob
-
Go to PORTS and PINS, Mill option .
Left side near top , Z inhibit, check the box and set the lower limit for Z.
Mach3 will now stop at the lower limit you defined. I believe there is also a button on the main mach3 screen lower center above error line.
NOTE: I JUST looked and on the main screen lower center just above the status line is the Zinh on/off button AND the DRO to set it
It works here OK, (;-) TP
-
Thanks TP!