Homing & Limit Switch UNSOLVED MYSTERY! <solved>

[cncsnw]

There is no need to have a custom macro for M6, if you are just doing manual tool changes.

The built-in default behavior for M6 is to move Z to home (or rather, to the G28 position); stop the spindle and coolant; prompt the operator to insert the tool; and wait for Cycle Start.

[ShawnM]

There is no need to have a custom macro for M6, if you are just doing manual tool changes.

The built-in default behavior for M6 is to move Z to home (or rather, the G28 position); stop the spindle and coolant; prompt the operator to insert the tool; and wait for Cycle Start.

Good to know there's a default behavior, thanks Marc.

[johannes]

I have rec'd several suggestions that this means that the software travel limits are setup incorrectly. Section 7.5 of the manual describes the software travel limits as preventing the machine from crashing into a hard stop or LIMIT SWITCH, not a homing switch.

This is perhaps not what's causing your issue, but it caused some pain for me:
When you set your soft travel limits, the machine should never move beyond those, whether by G-code or manual jogging. However, those travel limit settings are easily reset or nullified when you make changes in the Wizard.
I don't have the machine nearby so I cannot screenshot it exactly, but I believe anything related to the axis configuration, such as axis pairing, jog/rapid speed, turns/rev, etc. results in soft travel limit being reset. Perhaps other settings as well.
I crashed my machine at least once because of inadvertently resetting the soft travel limits...

So, make sure you check that your soft travel limits haven't been accidentally reset... Again, I know it's a very minor suggestion, but I ran into the issue once myself, so thought I'd mention it..

[RJS100]

Thanks for the suggestion. I will certainly check this out.

[CNCMaryland]

Here is why (you have your limits programmed incorrectly):

=========================================================================
CNC12 v. 4.80 coordinates file
Axis Minus Plus Return Return Return Return
Limit Limit #1(G28) #2(G30) #3 #4
X -0.1000 17.5000 0.00000 0.00000 0.00000 0.00000
Y -0.1000 8.5000 0.00000 0.00000 0.00000 0.00000
Z -14.0000 0.1000 0.00000 0.00000 0.00000 0.00000

One of the limits either the minus or plus should be 0 - Zero (on each axis). You're telling the machine to pass the X Y Z limit by -/+ 0.1 inches. Make those zero and I think you will be fixed.

[RJS100]

Thanks for your thoughts. For what it is worth, when I originally crashed the z-axis homing switch, the Wizard settings had zeros where you are recommending. I re-read section 7.5 of the install manual to learn that the settings you are referencing help to stop the machine from crashing into the limit switches, not homing switches. There were lots of different opinions on this topic and frankly I still am not sure what the correct answer is.

Per Shawn's suggestions, I reworked all my limit switches last night, tested the limits by jogging from home to the soft limit on all axes. All appear to be working great! I ended up reversing the direction of my y-axis to have it home to the front of the machine.

I then entered a few MDI commands issuing an M6 T2 (the command that used to crash the z-axis homing sensor) followed by something like G1 F120 Z2 to return the z-axis back down. I repeated this about 10 times, and all is working great.

I am going to write a few lines of code to exercise the limits of all the axis just to do a final test. From what I can see, I think the problem is solved!

Thanks to everyone for all your suggestions. This forum rocks!

Thanks... Richard

[ShawnM]

This is great Richard, hopefully the new mounting and flags will trip every time and this is no longer an issue. You don't really need to write any code to test it unless you want to. Just manually jogging with the keyboard or the wireless pendant will exercise the switches and test them. If you can't jog past any of the switches manually then it'll work when you have a program running.

Please get in the habit of "graphing" your files once you load them if you don't do this already. After you load any g code simply press F8 and the software will show you any errors and will tell you if you will exceed any travel limits.

Per a previous post about the soft limits disappearing or resetting, this only happens on routers with axis paring and auto squaring and it's not a bug. This wont be an issue for your mill.

Let us know how it goes moving forward.

[RJS100]

Bad News! I did run some code to zip the Z-axis up and down for a while and all looked good.

Then I started setting some tool heights. I ran into two problems. When tried to measure a tool, I got and error 907 indicating I had exceeded the Z travel. This was not true. I noticed that when I measured two tools that were about 1/2" difference in height, the tool off set showed 1.04". I looked again at the z-axis homing sensor and found that it was not stopping in the same place each time. See attached images. This appears to be the cause of the 1/2" discrepancy of the tool heights and also the 907 error.

I attached the present homing settings screen shot. I am confused as to what to modify. The software says that figures must be either positive or negative (not both), but if I try to enter .1 for Travel Limit (-) for axis 1 for example, an error pops up saying please enter a number less than 0.

Any ideas.

Richard

[RJS100]

To add to the confusion.... I ran my little test code, a simple tool change command followed by G1 F120 Z2 a dozen or more times. I watched the z-axis homing switch stop in the exact same place each time!

[ShawnM]

This is a tool height offset issue not a homing or travel issue. We now know the travel and the home switches are working correctly. Leave your travel limits at zero and whatever your travel positive or negative limits are.

For your tool offsets, are you using a reference tool since this is a mill or are you using Z home as your reference? There's a setting in the parameters you need to change depending on what your tool reference is. Look at the user manual for parameter 3 and change it according to the method you are using.