I’ve had BLTouch working on my Ender 3 Max for some months.
Recently, I had to change the heater block and nozzle, and took the opportunity to install a new mount for the BLTouch.
I’ve set it up again, everything from manually re-levelling the bed, entering new X, Y, and Z offsets.
However, since this, I’ve been unable to get a first layer. The front left side won’t stick at all, while the other parts do at least stick.
I do an ABL each print in my start gcode - the printer does the ABL routine, but then ignores it?
BL are a ‘finishing method’ The bed needs to be good before it will work, you also need to accurately set the z height as well. I have this kind of issue and after multiple times with BL they determined in my case the bed was warped beyond the BL ability to correct it. They said 2x the nozzle diameter was a lot and beyond that was unreliable.
0.8 mm is not very much, it needs to be accurate first.
Connect to the printer via pronterface, Within pronterface run the G29 command and post up the output when it’s complete. Will show you if you need to adjust the bed before printing.
Not sure what firmware your running but it sounds like the Z-offset is off. I do baby stepping or live z adjustment at the beginning of every print just to make sure things are dialed in on the skirt.
I know my bed is not flat;
here is the ABL grid. Looks like I have some work to do…
Bilinear Leveling Grid:
Recv: 0 1 2 3 4
Recv: 0 +0.105 +0.065 +0.010 -0.065 -0.105
Recv: 1 +0.227 +0.125 +0.013 -0.100 -0.218
Recv: 2 +0.287 +0.130 +0.000 -0.098 -0.243
Recv: 3 +0.178 +0.082 -0.003 -0.065 -0.143
Recv: 4 +0.145 +0.075 +0.037 +0.015 -0.005
Now, if I were to to want to get this closer, I could lower the left side?
you could lower the left but honestly, you are within .5 of a mm across the bed I would call that more than acceptable.
As long as I can get it below 2 I will give it a go.
This actually looks good to the point where I would look to something mechanical causing the issue with the BLtouch. Just as a question, try in your start Gcode the following commands.
G28 ; Home all axis
G29 S1 ; Enable ABL, do not probe, Load saved mesh from Slot 1
Try a print that has a lot of surface area, Keep a finger on the Z-axis leadscrew as it moves over the bed, See if you can feel the micro-movements in the Z-axis leadscrew up and down as it moves over the bed.
If you are feeling the movements (or put a piece of masking tape on the top of the leadscrew and look for movement.) then the ABL is working.
Check for a loose wheel on the Bed, I grab the bed on both sides and give it a little shake up and down to see if there is any excessive play in the bed. On the same note how much give is in your bed springs? I try to keep them wound pretty tight to increase the preload on them so the weight of the printed part does not start to compress them additionally.
An update.
I definitely hear / feel the ABL working. It seems it has a lot to do…
I’ve tried a lot of things here - almost a complete overhaul… Some things were a little loose, but not much.
I’ve done:
-Removed, cleaned, adjusted the Y axis traveller (is that what they call the thing that holds the bed?
-Replaced the bed springs, and tightened them almost to the bottom.
Take apart and re-adjust the X gantry.
Naturally, re-level the bed many times.
Everything appears perfect…
Regardless of what I do, I get the same symptoms.
The left side of the bed, both front and back, has a poor first layer - I can see individual lines in the print, and no connection between them. The right side, however, appears to be almost mashing the nozzle into the printhead.
It acts as if the bed were tilted down toward the left.
I’m going to replace the BLTouch next, for lack of a better idea.
I’ll persevere on this one - it’s turning into quite a challenge.
Kitedemon, I think that I’m coming to agree with you, that this bed may be too warped to redeem.
I’m looking at a print that I had just started in the centre of the bed. On one side of centre, I have a nicely laid down first layer. 25mm away from it, I have a layer that’s about as ugly as it can get, with gaps between the lines, and portions of it torn up as the head passes by.
I really haven’t been looking forward to that.
only to a point. The BL people suggest it is best if the bed is not out by twice the nozzle diameter. For most the is 0.8 mm it isn’t exactly a lot. You might be able to find a median between the lowest and highest spots but it is just a poor solution. The best is a bed less than 0.4 out anyway. Then the ABL is just a confirmation and slight adjustments here and there not for gross errors.
Is it the same bed you had when you installed the BL Touch.
Did the BL Touch work OK at first after you installed it.
Did the printer print OK after the BL Touch was installed.
Did the printer fail after it was printing OK with the BL Touch.
If the answer to all of these is yes then it is doubtful that it is the bed unless something drastic has happened to it. Something else has happened after the Touch was installed that is affecting the ways it works.
The printer wasn’t working well prior to the BLTouch installation. I couldn’t level the bed by hand well enough to get a reliable first layer.
I was hoping that the BLTouch would resolve that. And it did, to a point.
At that point, I was so happy to be able to print ANYTHING, I didn’t do much further testing, but was able to do a fair bit of printing, as long as I was careful where to put the print on the bed.
The BLTouch’s mounting plate was cracked during the initial installation, it got crazy-glued back together. But seemed to work.
I have noted that the ABL matrix isn’t very stable, there is a variation of maybe .005 between consecutive levelling sessions. This may be normal, and I didn’t think that it was enough to cause problems.
I now have a new BLTouch sensor, and will install it as my next step.
The new Creality glass plate that I got was also warped, that’ll have to wait until I can get another.
I just replaced the BLTouch, and manually re-leveled the bed (not, perhaps, very well)
But I ran the bed levelling multiple times in a row, and each time the numbers that came back were different…
It looks like something is shifting every time.
Here are the levelling grids, as reported by the machine, and my comments as to what I did.
Is this normal?
Thanks
July 23 bed levelling after new BLTouch
Bed manually levelled, bed at 60C, nozzle at 215C
Do it 3 times… No home in between
Try 1
Recv: 0 1 2 3 4
Recv: 0 +0.080 +0.080 +0.035 -0.040 -0.125
Recv: 1 +0.115 +0.062 +0.020 -0.053 -0.163
Recv: 2 +0.097 +0.065 +0.012 -0.055 -0.153
Recv: 3 +0.060 +0.010 -0.013 -0.068 -0.178
Recv: 4 +0.050 +0.027 -0.005 -0.050 -0.135
There is always a difference between the various levelling’s and that is normal as long as it isn’t to far out then your OK. There are factors that are constantly changing on the printer, springs flexing is a big one, that can affect the printers performance but those numbers don’t look that bad. As Jason pointed out you are within an acceptable amount.
Glass bed are always out a little bit and depending on how much it may not be a problem, heating up the bed will usually warp it a little bit in the centre. Put a straight edge across the bed corner to corner and measure the gap in the middle or on the outside if it bows upwards and see how much it is actually warped.
P.S. the underling aluminum plates on these printers is frequently warped too, mounting a glass surface on it frequently makes it better. It is just a piece of plate sheared into sections and is not milled or otherwise made flat. That is pretty much the norm.
Thanks for the interest.
I’m finally back to the point where I can lay down a first layer that sticks…
I turned the glass bed around 180 degrees.
Now, instead of the front left with adhesion problems (too far from the bed), it is the rear left…
Right front now almost grinds into the bed. So close that it pops.
I’m working through the calibration process now. Go back to square one.
Did you manually adjust the bed level by the springs before using the ABL? That sounds like a levelling problem that can be adjust back to normal by adjusting the springs. An ABL will not correct a badly levelled bed.
