G29 Self Leveling Reuslt value meaning

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G29 Self Leveling Reuslt value meaning

Postby MileHigh3DII » 2017-Aug-Mon-00-Aug

I run the G29 code and for the three Z values I get

0.54 (Rear left)
0.70 (front Left)
2.21 (Front right)

I really don't make many things bigger than 100x100mm, but I was running a bunch of small repeat parts and the rear in the middle parts first layer are really thin and got knocked ( I think by me 2nd (right) extruder nozzle.

The leveling program makes a plane, right? So three points are really it?

What does a positive value and the more positive value actually mean? I'm thinking of manually getting the bed more level. Can I get it to take more readings to help guide me? At least the four corners?
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G29 Self Leveling Reuslt value meaning

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Re: G29 Self Leveling Reuslt value meaning

Postby Mooselake » 2017-Aug-Mon-14-Aug

You can use a feeler gauge, or just a piece of copy paper, to adjust the head to bed distance at as many points as you want to test - zero it once (preferably near the highest point) and repeat the distance check as often as necessary. It's iterative, fixing one corner may affect the others, but you'll get it. It's how we non-alien probers adjust our beds. I think there's a way to probe a single point of your choosing but being of the non-alien persuasion...

You can recompile the firmware to use more points to level. Some of us consider it great stuff, some of it consider it a waste of time due to the 3 point thing (multiple points just average rather than actually making the leveling multiple point). Get your bed close manually and you'll be better off.
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Re: G29 Self Leveling Reuslt value meaning

Postby cbxbiker61 » 2017-Aug-Mon-20-Aug

If it reads high, it means you have to lower that position (raise the opposite positions). There's a set of color coded plastic shim stock on Amazon that can be useful for this purpose. Just cut the correct size and fit it between the blocks and the bed. Experimentation will likely be required.
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Re: G29 Self Leveling Reuslt value meaning

Postby MileHigh3DII » 2017-Aug-Tue-08-Aug

So that 2.21 needs to be lowered?

I have an old plus and I've leveled that bed manually. I almost like that better. Takes longer, but much more direct.
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Re: G29 Self Leveling Reuslt value meaning

Postby RetireeJay » 2017-Aug-Tue-11-Aug

MileHigh3DII wrote:I have an old plus and I've leveled that bed manually. I almost like that better. Takes longer, but much more direct.

That's what I have too, an old Plus with a manually leveled bed. There's no "almost" about it for me; you couldn't get me to use a probe if you tried. And how does it take longer? You spend maybe 10 or 15 minutes once, and it's good for months and months. How does that compare to spending a minute or so every single time you start a print? Those minutes add up!
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Re: G29 Self Leveling Reuslt value meaning

Postby MileHigh3DII » 2017-Aug-Wed-11-Aug

All while the nozzle drools...

ETA: On my human leveling Plus, the best add I did was a knob to adjust the Z stop. Put a line on it to make it visible if it gets knocked. Worked great.
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Re: G29 Self Leveling Reuslt value meaning

Postby MileHigh3DII » 2017-Aug-Wed-11-Aug

cbxbiker61 wrote:If it reads high, it means you have to lower that position (raise the opposite positions). There's a set of color coded plastic shim stock on Amazon that can be useful for this purpose. Just cut the correct size and fit it between the blocks and the bed. Experimentation will likely be required.



I think it will be easier to raise the low parts. If I do, I won't need to change the M212 value, right? The G29 should take care of it?

ETA: considering the trail it just left gouging my Buildtak, I'd say that the M212 value has to be tweaked. That doesn't seem right to me.
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Re: G29 Self Leveling Reuslt value meaning

Postby ktfergus » 2017-Aug-Thu-15-Aug

I mentioned this in a similar thread: Once I had my bed shimmed & level, I found that the auto-leveling feature actually made the first layer worse. I removed the G29 command from my start code ages ago & I get perfect first layers on a 150mm x 300mm bed. I simply home the hotend when I start up my printer to establish the z axis zero height, then I hit print. The x & y axes home, the hotend heats up, & the prints starts without testing each corner.

-Kelly
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