Auto_Bed_Leveling: Enhanced G29 command

[Astek777]

Thanks for reply.

So is the routine not able to cope with such large offsets? I only ask as I saw some videos of people printing on really slanty beds (1cm+) just to prove it worked.

As I said in my previous post, it was nearly level originally but I was still getting the same results in the same places as I am now. I was actually getting better results at the time if I just did a G28 and printed without doing a G29 at all, so seems a little odd.
Thanks!

[Roxy]

Well... There may be more going on than you realize. It depends on your printer, but a lot of times when people are having trouble they can make the problem go away by specifying more points. Usually a 3 x 3 grid is sufficient. But sometimes, it is necessary to go up to a 4 x 4 or even a 5 x 5 grid.

Also... It would be helpful for you to do an M48 command at a few places on the bed and see how repeatable your probe is. If the number is too big, that directly factors into how well the Auto Bed Leveling can compensate. Can you post a few M48 commands for us?

[Astek777]

Originally I was using 2x2, but generally I've been using 3x3. For the examples above in my original post and further testing I've been doing over the last couple of days I've been using 5 x 5. They all seem to give the same results in the same places.

Here are the results of the M48. I did the 4 corners of my probing square, plus the centre:

M48 x32 y23
RECEIVED: Mean: 2.164063
RECEIVED: Standard Deviation: 0.002223
RECEIVED:
RECEIVED: ok
SENT: M105
SENT: M105
RECEIVED: echo:endstops hit: Z:2.16
endstops hit: Z:2.16

M48 x262 y23
RECEIVED: Mean: 3.819562
RECEIVED: Standard Deviation: 0.001582
RECEIVED:
RECEIVED: ok
SENT: M105
SENT: M105
RECEIVED: echo:endstops hit: Z:3.82
endstops hit: Z:3.82

M48 x262 y253
RECEIVED: Mean: 3.848125
RECEIVED: Standard Deviation: 0.001452
RECEIVED:
RECEIVED: ok
SENT: M105
SENT: M105
SENT: M105
RECEIVED: echo:endstops hit: Z:3.85
endstops hit: Z:3.85

M48 x32 y253
RECEIVED: Mean: 1.183125
RECEIVED: Standard Deviation: 0.001768
RECEIVED:
RECEIVED: ok
SENT: M105
SENT: M105
RECEIVED: echo:endstops hit: Z:1.18
endstops hit: Z:1.18


M48 x149 y172 (X/Y Safe Home Position - Centre of Bed)
RECEIVED: Mean: 2.000750
RECEIVED: Standard Deviation: 0.002634
RECEIVED:
RECEIVED: ok
SENT: M105
RECEIVED: echo:endstops hit: Z:2.00
endstops hit: Z:2.00

Thanks again for your time looking at this.

[Roxy]

OK... The repeat-ability seems fine. It is plenty good. I think you should try to level the bed as perfectly as you can and try printing again with a 4 x 4 grid. It that still has issues, please post another G29 T V4 n5 so we can see how the bed looks once it is better leveled.

[Astek777]

Hi Roxy

OK, I've levelled the bed back out so it's now within about 0.3mm across the bed.

I've done two test prints, one using G28 followed by G29 T n5, and one just G28. The print with just G28 seem to print better, although far from perfect. The one with bed levelling was far too close on the front-left (nearest X0,Y0) to the point where it was just blobbing.

PRINT WITH BED LEVELLING

IMG_0612.jpg


PRINT WITHOUT BED LEVELLING

IMG_0615.jpg

Here's the 'G29 V4 T n5' response you wanted to see:

RECEIVED: Roxy's Enhanced G29 Auto_Bed_Leveling Code V1.81:
RECEIVED: Full support at http://3dprintboard.com
RECEIVED: Bed x: 32.00 y: 23.00 z: 0.83
RECEIVED: Bed x: 89.00 y: 23.00 z: 0.96
RECEIVED: Bed x: 146.00 y: 23.00 z: 0.99
RECEIVED: Bed x: 203.00 y: 23.00 z: 0.95
RECEIVED: Bed x: 260.00 y: 23.00 z: 0.82
RECEIVED: Bed x: 32.00 y: 80.00 z: 0.82
RECEIVED: Bed x: 89.00 y: 80.00 z: 0.82
RECEIVED: Bed x: 146.00 y: 80.00 z: 0.94
RECEIVED: Bed x: 203.00 y: 80.00 z: 0.89
RECEIVED: Bed x: 260.00 y: 80.00 z: 0.82
RECEIVED: Bed x: 32.00 y: 137.00 z: 0.70
RECEIVED: Bed x: 89.00 y: 137.00 z: 0.70
RECEIVED: Bed x: 146.00 y: 137.00 z: 0.89
RECEIVED: Bed x: 203.00 y: 137.00 z: 0.77
RECEIVED: Bed x: 260.00 y: 137.00 z: 0.80
RECEIVED: Bed x: 32.00 y: 194.00 z: 0.61
RECEIVED: Bed x: 89.00 y: 194.00 z: 0.70
RECEIVED: Bed x: 146.00 y: 194.00 z: 0.80
RECEIVED: Bed x: 203.00 y: 194.00 z: 0.80
RECEIVED: Bed x: 260.00 y: 194.00 z: 0.80
RECEIVED: Bed x: 32.00 y: 251.00 z: 0.38
RECEIVED: Bed x: 89.00 y: 251.00 z: 0.61
RECEIVED: Bed x: 146.00 y: 251.00 z: 0.74
RECEIVED: Bed x: 203.00 y: 251.00 z: 0.80
RECEIVED: Bed x: 260.00 y: 251.00 z: 0.74
RECEIVED: Eqn coefficients: a: 0.00 b: -0.00 d: 0.85
RECEIVED: Mean of sampled points: 0.787550
RECEIVED:
RECEIVED: Bed Height Topography:
RECEIVED: --0.40880 --0.17317 --0.04692 +0.01433 --0.05067
RECEIVED: --0.17755 --0.08380 +0.01370 +0.01120 +0.00870
RECEIVED: --0.08567 --0.08567 +0.10308 --0.01880 +0.01683
RECEIVED: +0.03620 +0.02808 +0.15558 +0.10245 +0.03308
RECEIVED: +0.04745 +0.16870 +0.19933 +0.16245 +0.02995
RECEIVED:
RECEIVED: planeNormal x: -0.00 y: 0.00 z: 1.00
RECEIVED:
RECEIVED:
RECEIVED: Bed Level Correction Matrix:
RECEIVED: 1.000000 0.000000 0.000586
RECEIVED: 0.000001 0.999999 -0.001098
RECEIVED: -0.000586 0.001098 0.999999
RECEIVED: ok

Again, any help or suggestions greatly received!

Thanks

Sean.

[Bob]

Thanks Roxie for your help. I have the code the same now. I will try to load it up later today and see what it does.
Thanks again. I REALLY do appreciate it. Other forums just don't seem to want to respond.

Bob Keyes

[Roxy]

Your bed is almost flat. It is much better than mine. I have a high spot in one place and a low spot in another place. The only issue I see with your bed is your right hand side looks a little bit low. Can you level that back left corner a little bit more? It should be OK where it is at, but everything else looks pretty good. It seems you should be able to raise the back left just .2 or .3 mm and have everything really good.

I don't know what is causing your bed leveling problems. It might be time to make a short video of it doing that same print you have up above so we can see how the z axis is compensating and what the plastic looks like as it comes out of the nozzle.

[Astek777]

Hi Roxy

Unfortunately the back left corner is pretty warped, and there isn't anymore adjustment available...I'm already using longer M3 screws.

I've uploaded a video as recommended. It does a 'G28', followed by 'G29 V4 T n5'.

https://youtu.be/WzPmOrYJEh8

Thanks again.

[Roxy]

Wow! Everything looks good but that one corner. It almost looks like you are too close to the glass for the first 3 legs of the print, but on the 4th leg it is too far away. I don't know what is going to fix it. But I would suggest slowing the Z axis down for the probing. Your M48 numbers seemed good, but that is faster than I would dare take measurements. It may be with more accurate measurements things get better.

The other thing I would try is another piece of glass. It maybe that piece is warped too much. Do you have a glass cutter? At the Dollar store you can usually get a cheesy picture frame with some thin glass for $1.00. It probably is worth a try just to see what happens. Also, what happens if you rotate the piece of glass, or maybe even flip it? Does the problem area move?

PS. That looks like a really nice printer!!!

[Astek777]

Hi Roxy

Thanks. I think the printer will be great if I can just get some reliability.

It does seem strange. When I made the bed really wonky it printed exactly the same as it is now, so it seems like it's always out by the same amount in the same places. I had tried printing on top of a 300mm square sheet of aluminium just resting on top of the glass (not clamped down). It's thick enough not to bow by itself, but this didn't seem to make any difference either. Exact same issues in the same places.

I'm in the UK, so not so easy to get cheap glass, but I'll have a hunt around and see what I can find.

There's nothing configuration wise that could be causing the issue. I don't have any X-offset, but do have 32mm of Y-offset. Everything's printing in the correct place though, and the probe points, as you can see from the video, are perfectly set around a 250mm square in the centre of my print bed.

Just to confirm how the topographic map works, what point does it use as it's base point to decide what is plus and what is minus? It can't be the default Z-home position or the centre probe point would always be zero. Is it just a mean value? Also, are the plus points the higher positions on the Z-Axis OR the points further away from the probe?

Whereabouts in the firmware is the Z-Axis speed set, or would that be in the print software (for me Simplify3D)?