Just read all of the comments on RocketSurgeon’s post but I think I’m having the exact same problem. The reason I think it is the Z limit switch is that, when I initialize and the router is supposed to be recognized by the Z switch, it just bangs into it and sits their without being recognized. If I leave it that way, I will get a message that the limiter doesn’t recognize it (or something like that.) By accident I discovered that, as soon as it starts trying to get to the Z limit, if I reach out and jiggle the hardwired cable at the top of the switch, it finishes its cycle and all is well until the next time I initialize. I am contacting support of course since that feels and looks like a faulty switch.
Yeah very similar to what is going on with mine. Its very odd honestly because I’ve seen the light triggered and the Z still crashes. I’ve been playing phone tag with support I guess waiting on at least getting a replacement sensor and cable.
Check your gcode has z1.00 at the start (and throughout just search for “z” to see if you’re going to some weird z coordinates, zero out your cnc work and set a start point…
I always check my gcodes, I use meshcam it sometimes throws random gcodes like start at z7900, my machines will try do the gcodes regardless of if they physically can or not
Go into your settings and set the right shapeoko pro machine. You might have sent the wrong setting to the machine, I had a weird z moving with mine at the start and if I hit stop it would have a mind of its own. Mine had the wrong machine sent to it.
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I had definitely been down all those roads. This isn’t my first shapeoko, so when a new one is behaving different than the old one you start scratching your head looking at new stuff. I think its been narrowed down to a bad homing sensor.
Hi, I am a new to this machine (Pro XXL) and the Z axis seems to be an interesting thing for me. I see a couple of people with issue here so just sharing incase it helps. I am happy and it is all part of the learning curve for me 
I have had G-Code go bad where it plunged into the work. I just exported the design again, sent the G-Code to the machine again and it worked perfect. IDK For now, I will also use a simulator before running code. but it seem to be a bad code. Not sure.
I have had it when I turned on the machine from a soft off state (front switch ) then pressed Connect >> Initialize, and the Z went right pass the Z home sensor with the light coming on. It over traveled. Short version; I unplugged the machine, tried again, same thing, Unplugged again AND rebooted the CM, worked fine. Again IDK :). I sent a message to support (good response ) and found out the soft limits are disabled by design ( this I believe is a change from older firmware or …, guessing a bit here). So basically if it is told to go somewhere via code, it going to try. CM Jogging does not seem to over travel. I have had on several occasion over travels while bit setting, “User Error” most likely, However this does tell you there is no soft limits, if you make a mistake …
Also found out while custom writing G-code that the CM converts the Z axis. ( In my findings) normally Z0 is fully retracted, and this is true if you bypass the CM and send direct or passthrough code. If I send Z0 through the CM it goes down to the deck. So just be aware CM seems to translate the Z axis or does something different. Still figuring that one out so if anyone know why … Thanks
Just thought some of my findings might help others
Disclaimer: I said I am new to this machine.
I am having fun learning:)
Please send the .c2d file, and the two different G-Code files from it and we’ll do our best to look into this.
My issues were related to a bad batch of inductive homing sensors and bad cable. I managed to win the lottery and both the original and replacement homing sensor were bad. Third sensor did the trick and I haven’t had a z crash since.
Thanks Will
However I was sharing on what I have learned about the Z axis and over travels.
I will assume User and Learning Errors
More the point was, yes the machine will let you over travel if you tell it to.
I had one glitch which was resolved by turning everything off and back on
and the translation of the Z axis that I dont really understand yet, Again Learning curve.
So I had some time today. And decided to look at this Z axis thing that I don’t seem to understand. It is not a problem, it is just a learning thing:) I am one of those guys that just needs to know.
So we have a Machine Home and we have a Workplace Home.
The Shapeoko / CM seems to create a Pseudo Machine Home. ???.
When the machine is turned on, you Connect and then you Initialize. it comes to the front and ask for a tool and then it runs to the bit setter. I just thought the machine was overly Bit Setter happy. It appears to set this Pseudo Machine Home from this. This pseudo home is near the deck not at the top of the Z axis
With the Work Place home not set yet, G0 or G1 to Z0 goes to this Pseudo Machine Home position. If you clear the Work Place Home it sets it back to this Pseudo Machine Home, If you use passthrough GRBL with the “/” , /G0 or /G1 to Z0 it goes to the top. Like I am use to.
If you use G53 G0 Z0 it goes to the top. So the CM seems to translate the the Z axis on some G codes ??? IDK
Is that right ? What do I need to learn here ?
It like the Controller has a Machine Home and the CM has a Pseudo Machine home for only some G-Codes
Jobs run off the Workplace Home and run great.
Can someone help me understand why this Pseudo Machine Home is set.?
It seems confusing to me.
I did get my Macros done, I just had to use passthrough codes.
Thanks
This is all because of how CM manages the BitSetter Z zero adjustments (if you disable bitsetter and power cycle/re-zero, you should get the Z behavior you expect).
CM has a number of ways it manages internal variables to support the recommended user workflow, and it’s a fact that this do not play well with also manipulating native G-code commands yourself, as you found out. CM is designed for users who do not really care about what is going on under the hood, so if you are going to manipulate a lot of custom G-code, you may want to consider one of the other Gcode senders that do not enforce any workflow and pass the G-code commands through unmodified. Both approaches have their merits. I like to use CNCjs for those cases where I need to tweak the G-code / machine behavior. Other folks here have been trying gSender too.
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Awesome Thanks
Yep, starting to make sense now
I keep finding good reading material on the site too
And Yes I did plan on installing CNCjs in time and as you say flip back and forth
Hey Sean, funny. Same thing here. They replaced all of it, but the X/Y carriage they sent was for the wrong machine. To give everybody there credit, the correct carriage was sent within 24 hours of me notifying them.
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