Z Axis under the table?

@Marcus you can load gcode into any text editor.

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@neil I apologize for my ignorance but i’m not sure what that means. I assume its coordinates but im not sure how i would check that if so.

I kinda guessed that. You’re using G28 retracts (usually a checkbox option when you post process) which adds this line to your gcode:
G28 G91 Z0

There’s a decent chance that your g28 location is the issue. I’d recommend unchecking that box.

G28 G91 Z0 Moves the Z axis only to your G28 location. If you have never explicitly set a G28 position (using G28.1), then that position, by default is at Machine 0 (your homing switches). I’ve seen this many times with cnc users. The Z crashes on that move and Z-zero is lost.

What post processor are you using?
Do you have homing switches?

notepad on your computer will allow you to see/read the code

@gwilki Thanks for getting me back on!

@760woodworking Thanks I see it now!

@NeilFerreri Thanks! I dont have homing switches but I did find a drop down menu in the post processing that is labeled “safe reacts and home positioning.” It was in fact set to G28 and I changed it to Clearance height and it started working! So I was not only able to get that one perimeter done but several other operations to run. Albiet not perfectly though. So inside of the perimeter there is a secondary one that is really only shallow visual reference and it was supposed to be .5" wide and it cut it out about .545." Also i have some holes that are used to place dowels in. Two large that should be .375" and 4 that should be .25" and both came out roughly .03" to small according to my calipers.

It looks like you have made some progress since I last checked. That’s good news.

I’m wondering if the holes being to small is a bit deflection and or inaccurate bit diameter. You should use your calipers to check the bits diameter and change it in F360 if it’s different than advertised. If the bit is actually smaller than what F360 ‘thinks’ it is the holes will be too small.

The other thing is that the cutting forces on the bit can cause it to deflect in a little and that adds to the hole being too small.

One final thing is that it’s hard to fit a 0.25" dowel in a 0.25" hole. I see this on my CNC and also on my 3D printer. I almost always need to allow a ‘fit tolerance’. I use 0.1mm a lot for this which is about 0.004".

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You’re welcome! Glad you’re making stuff.

Ok, just for completion on this and for reference sake. Because you most likely never set a G28 position, that position defaults to machine zero. Because you have no homing switches, machine zero is established by the location of the axes when you power on. That’ll be different every time, so all bets are off when you send the machine to G28.

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@Marcus @_Michael @NeilFerreri @Shipwreck I’m moving this topic to the Fusion360 category. There is a lot of very good information here and I believe it will be easier for others to find it in Fusion 360.

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Not sure if you guys can also help me with a similar problem: i am a relative newbie and confession - I bought a competitor machine, Sainsmart 3030, but am loving gSender. I also use Carver Maker.

My problem is a malign Z axis, it works fine on a program where i am cutting a number of the same pieces, then it suddenly decides to start a new piece by diving full force into the workpiece. So a sudden and rapid dive.

I’ve ensured the start zero is right, at the top of the workpiece, I’ve successfully cut other pieces with the same program and when i try it after the dive, its OK. So my assumption is that something is corrupting the signal from my laptop to the machine. Its happened twice (other time a different program). Hoping someone has some suggestions and thanks in advance.

@Stuartabm Did you resolve this issue?

Hi, thanks for asking. I did sort of resolve it, I resolved to stick with Sainsmart’s Z only version.

@Stuartabm Tks, Stuart. I’m marked this resolved and closed the topic
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