Z-axis offset woes

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ritmopat
Posts: 100
Joined: Wed Feb 13, 2019 9:22 am

Re: Z-axis offset woes

Post by ritmopat » Sun Feb 24, 2019 5:53 am

think this has anything to do with why one side is off? a video i made https://youtu.be/k7jnekVjxw0

Aha
Posts: 34
Joined: Sun Feb 18, 2018 8:25 am

Re: Z-axis offset woes

Post by Aha » Sun Mar 10, 2019 12:39 pm

Prenote on the youtube video, I don't think that is the reason at all. A proper bed leveling levels relative to the bed and it can be quite a bit off and still have perfect layers if it's done correctly.

Also, just email lulzbot support and ask this question - they get back fast and are helpful. They might solve this better than what I'm about to say.

I think I have a general answer for you from my problems/issues (in other threads), I'm quite annoyed by this as well. Take this with a grain of salt because I'm using a Taz 6 with a dual hotend, which is it's own nightmare. And because I prefer to use simplify3d which has an offset command easily implemented for each print to change that offset.

First thing to note is that this is supposed to be fixed by the autolevel sequence, so check what's wrong with your leveling first and see what might be misprobing (and if it works fine but doesn't offset right then it's probably hidden in arcane firmware somewhere, but I'd still try reflashing it).

If all of that is on the up and up and doesn't solve it, here's a place you can start - but be VERY careful and have your finger on the off button, I've crashed all my printers into the glass HARD at various times and this could be a way to do that. Go to your start sequence, in cura it's under printer, machine settings, then look at start gcode. I don't know what your printer has first, just the general strokes, so you'll have to experiment and figure out the start sequence gcode. Look for the G29 command, the probe sequence for autoleveling - or at least the G28 Z for leveling on the Z. You need to figure out what height your z probe goes to after leveling, then insert the command "G92 ZX.X" and put in an adjusted height for what it should be vs what it is (even better if there is another command using that but it is just off). This command alters where the printer thinks it's at. For example, my Taz probes the Z, then returns to 15.5 height. So I take the print head to the center of my printer, lower it slowly, and find that it is at 0 bed height when the printer reads 0.5. So I added in "G92 Z15.0" to make it realize right after that that it is 0.5 lower than it thought. And it's definitely better to err on the side of HIGHER and slowly get closer by printing over air than too low and smashing into the plate.

And all that's thrown off if the leveling sequence is often thrown off, so if the Taz 5 has it (as I think it does?), you should tune it and make sure all the connections and stuff works as it should before doing all this.

Hope that helps!

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