Homing & Limit Switch UNSOLVED MYSTERY! <solved>

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cncsnw
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Joined: Wed Mar 24, 2010 5:48 pm

Re: Homing & Limit Switch UNSOLVED MYSTERY! <solved>

Post by cncsnw »

Enter a program something like this:

Code: Select all

G53 Z-1
G91 F40
G1 Z-4
G0 Z4
G1 Z-4
G0 Z4
G1 Z-4
G0 Z4
G1 Z-4
G0 Z4
G1 Z-4
G0 Z4
G90 G53 Z0
Home the machine; verify that Z0 in Machine Coordinates is where you expect it to be; then run the program to do multiple slow-down, fast-up cycles. Then check whether Z0 in Machine Coordinates is still where you expect it to be. This may tell you whether you are dropping steps, or slipping, during rapid moves.
RJS100
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Re: Homing & Limit Switch UNSOLVED MYSTERY! <solved>

Post by RJS100 »

Thanks Keith. I will run this today. Very much appreciated.
RJS100
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Re: Homing & Limit Switch UNSOLVED MYSTERY! <solved>

Post by RJS100 »

Ok. I ran Keith's g-code and the machine returned to home position each and every time. I even increased the speed to 80 inches per minute, ran it another 10 times and the machine returned to the same exact position as when I homed the machine upon startup (the correct position).

With this many posts, I thought it may be a good idea of making a video to see what is happening (Probably just user error). Work with me here... I am not the video kind of guy... Here you go (Clearly not YouTube material):

#1: https://www.dropbox.com/s/vu6xtebjk46fb ... 3.mp4?dl=0

#2: https://www.dropbox.com/s/agsxby8c83a9u ... 1.mp4?dl=0

#3: https://www.dropbox.com/s/xcgizkb67h1qy ... 9.mp4?dl=0


Thanks in advance for all your effort in trying to help out here.

Richard
cncsnw
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Re: Homing & Limit Switch UNSOLVED MYSTERY! <solved>

Post by cncsnw »

After you measure a tool, save changes, jog Z up until the software limit stops it, and see that it is ca. 3/8" too high:
1) Press Alt-D to switch to Machine Coordinates on the DRO (the word "Machine" will appear in the top left corner). What is the Z display?
2) What are the tool and height offset displayed in the status window?

Saying that G59 is the same as machine coordinates is based on multiple assumptions. We would rather not make assumptions in troubleshooting.

Next:

Does it behave any differently if you change Machine Parameter 3 to a value of 0, and repeat the whole process?
RJS100
Posts: 380
Joined: Tue Oct 20, 2020 8:41 pm
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Re: Homing & Limit Switch UNSOLVED MYSTERY! <solved>

Post by RJS100 »

Thanks for your feedback. I was not clear on my video, I did check the actual machine coordinates and when the machine was .375 too high, the machine coordinates displayed at that time were z=0.

For what it is worth, Parameter 3 was originally set to "0" when I started having this problem. I am going to uninstall/reinstall CNC12, then repeat the process with Parameter 3 set to "0" and "4". I will also take note of the tool and height offset shown in the status window.

Thanks again for your thoughts... Richard
RJS100
Posts: 380
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Location: Arizona

Re: Homing & Limit Switch UNSOLVED MYSTERY! <solved>

Post by RJS100 »

Ok, I ran the routine again (before and after reinstalling CNC12) and got the same results with the machine returning to the correct Z home height after measuring the master tool height, then returning 3/8" above this datum after measuring the tool off set for tool H2.

Parameter 3=0
-measured the master tool, save changes, jog Z up until the software limit stops it, machine coordinate indicates z=0, machine returned to correct Z home height.
Measured tool T2, jog Z up until the software limit stops it, machine coordinate indicates z=0, machine returned to 3/8" above original homed position.
Z height for reference tool = -12.1287
H2 = -.4273

Repeat procedure again
Parameter 3=4
Z height for reference tool = -12.1290
H2 = -.4258

Reinstall CNC12. repeat procedure again.
Z height for reference tool = -12.1290
H2 = -.4258

In summary, the machine is behaving the same with Parameter 3 set to 0 or 4 and even when the machine coordinates indicate z=0, it over shoots the proximity sensor by 3/8" after measuring the height of H2.

One question. Every time I perform a tool change with my power drawbar, as the drawbar is activated, a relay breaks the E-Stop circuit for safety. Could this be causing a problem?

Lastly, when I reinstalled CNC12, a window popped up asking to assign a static IP to the network adapter. There were only two choices from the dropdown window: None and the Wifi connection. I accidentally clicked on Wifi. I reinstalled CNC12, I was never prompted for the static IP connection again but CNC12 appears to be working correctly. Unfortunately, now the WIFI connection shows no internet. Is there an easy fix to restore my wifi connection?

I know for sure that on my previous CNC12 install the static IP for Acorn was setup correctly.

Thanks... Richard
suntravel
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Re: Homing & Limit Switch UNSOLVED MYSTERY! <solved>

Post by suntravel »

RJS100 wrote: Sun Nov 27, 2022 1:28 am .......

One question. Every time I perform a tool change with my power drawbar, as the drawbar is activated, a relay breaks the E-Stop circuit for safety. Could this be causing a problem?

.....-

Thanks... Richard
Yes it does. It is recommended to re-home after E-Stop.

If you are concerned about safety, break only the power supply to the spindle.

Uwe
RJS100
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Re: Homing & Limit Switch UNSOLVED MYSTERY! <solved>

Post by RJS100 »

Wow... After 77 posts and three videos.... I think this problem may be solved.

I ran the routine of measuring master tools and tool offsets again. But this time I did NOT physically change the tool, hence not breaking the E-stop circuit. I repeated this three times, then rebooted everything and did it again. EVERY TIME... the machine returned the correct Z=0 homed height!!!

This was a crude test without fine jogging associated with measuring an actual tool... but all is looking good. I am very new to this and not aware that I had to re-home after E-stop.

I am going to rewire the E-stop/spindle and do an actual test but I think we found the culprit. THANKS TO ALL.

Just a few questions:

During the above test, I had Parameter 3 = 0, Uwe suggested using it set to 4. What is the difference between the two?

There was a mention in this post that when the homing sensors are wired in series and the input is set to HomeAll, the homing proximity sensors are only active during the homing sequence, but if they are wired separately to three different inputs set to HomeLimit, they are active at other times. Can someone confirm that this is accurate?

Thanks for all your help.... Richard
suntravel
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Re: Homing & Limit Switch UNSOLVED MYSTERY! <solved>

Post by suntravel »

Who had thought you consider a tool change is a emergency situation :shock:

Uwe
ShawnM
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Re: Homing & Limit Switch UNSOLVED MYSTERY! <solved>

Post by ShawnM »

Why would changing a tool trigger an estop? Something is wired incorrectly if this is happening. The estop should only be triggered as a last resort when the you know what hits the fan. :D
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