Achieving a good first layer A350

[Dojima]

In general, I’ve found calibration of the SM2 to be an incredibly frustrating experience. I wasn’t blessed with a great first layer out of the box like some.

TL; DR - The Solution

Like many others, I also reached a point of putting away my A350 as I had enough trying to print anything beyond a 2cm calibration cube. Hopefully, my experience may help others.

I’ll also mention that under extrusion seems to be a pretty common out of the box issue as well. I was about 10% under extruding.
See this guide to fix: https://all3dp.com/2/extruder-calibration-6-easy-steps-2/

Starting again
I recently went back to the start, my theory was to print out the 1st layer of increasingly larger calibration cubes using the default 3x3 matrix and adjust points to compensate.

This is using latest firmware 1.7.1.1
I also assume that the 3x3 matrix maps from the bottom left of the bed.
All calibration is manually at 60C with a good 10-15m pre-heat.

I’ve tried auto-calibration many times, with no improvement.
I’ve checked my sensor alignment.
I’ve tried manual calibration with the card.

I don’t have print settings to hand as on another machine. However, I think my first layer settings were 125% first layer height and 40% speed. No change to first layer width. I changed the first layer height to 150% at some point. I’ll add my Simplify 3D profile later.

I also tried manual calibration using a dial indicator on its own and had each point within ~0.01mm, I thought I would just need to adjust the Z and this would be the perfect layer. Not quite. However, it was a good starting point.
See: On achieving a perfect level - #93 by jeroent

First Print
I started with an 8 x 8 cube, printed okay. However, you can see it’s too close, so I adjusted the Z layer on the go and you can see the dramatic difference between the lower right which is too close and adjusting Z level up 0.05mm. For a moment that 1st layer looks good.

However, then you can see the frustration that the upper centre is too high and the upper left also looks a little high.

So I manually adjusted the points on the matrix, I only ever adjust by 0.05mm at a time.

M421 I1 J1 Q+0.05 // adjust the centre point
M421 I1 J2 Q-0.05 // adjust the upper centre point
M421 I0 J2 Q-0.05 // adjust the upper left point
G28 // home

OK this print looks a bit better, although Z appears too close now on the lower half. I’ll increase the Z on the lower left part of the matrix,

M421 I0 J0 Q+0.05 // adjust the lower left
G28 // home

OK, so for the most it’s better. Now, compared to what I was getting out the box when I first tried the SM2 this is like night and day. My first SM2 print was spaghetti.

12 x 12
Next, I stepped up the cube size to 12cm.

Really disappointing, I’ve been eyeballing each print while the skirt is printed and I could visibly see the print head was clearly much higher when printing along the upper part of the bed. So I the upper centre down by 0.05mm. Try again…

Urgh, adjustments the adjustments to make at a glance:

• the upper left-ish is too high
• the lower left is too low
• the lower right is too low
• the centre-right is too low probably

Then there is that annoying isolated patch that’s too high near the centre.

Made the tweaks and printed again:

Not bad, it’s certainly no Reddit - Dive into anything
However, you reach a point and say it’s good enough for the SM2 (not that you should have to feel this way!)

16 x 16
Next, increasing cube to 16x16

Really!!! Come on…

OK, lower the left centre, right centre and raise the lower centre.

Better, not great. Still room for improvement. However, getting quite tired of this…

Decided to try out something different, an articulated face hugger from the movie Aliens.

At this point, I felt like giving up, same old basic problems.

Increasing the matrix

SM2 Bed Leveling 101

I’ve been working on the problems with SM2’s bed leveling issues for a while now. I’ve created some Google Sheets that can help with the process. The “Introduction” page will give some background. If you have any problems at all, please ask. I’m open to any feedback or suggestions. With the link below you can copy the Sheets to your own Google sheet or do a “File:Download” menu selection to save it to your local machine. Maybe this will only be useful for a short while because Snapmaker will fi…

Great forum post here about how to calibrate using larger matrix sizes. I didn’t want to change too much so went with the 5x5 matrix. Also, the tip that once you feel the calibration card is folding when you push back on the final Z level adjustment to add +0.1mm before finishing was a good one.

So first results, pretty good. However, I could see a few areas on the face-hugger skirt that were not sticking like they should (sorry didn’t take a picture). I made a couple of manual adjustments and the increased matrix size made it easier to target the specific area.

Was really happy with this print.

EDIT: Attached A350 Medium Quality Profile - Simplify3D A350 M.fff (11.9 KB)

[Dojima]

So in retrospect, I was really just optimising towards a single model use case.
I tried another design and again just run into more issues, for me the bed just simply isn’t flat.

Going to look at the posts around using glass.

[monkeygerbil222]

Hey, I feel your pain, and a good write up on your journey. I too have been struggling to get my A350 bed leveled, and have undergone almost the same process as you have here, and I know its alot more work but I believe a 7 X 7 grid and perhaps a 9 X 9 are better suited to the large bed size of the A350. That being said, I am still tweaking my 7 X 7 and finding first layer adhesion is not perfect every where. I think we can get there, only a matter of time. Looks like @xchrisd managed to get his A250 dialed in for an acceptable initial layer On achieving a perfect level.

[xchrisd]

I am with you, 7x7 is the minimum at A350.
I am now thinking about a bigger matrix doing autocalibration on my A350, maybe 11x11 works?

The strange is, my last run was tweaking 0.02mm or 0.01mm, this could not be repeatable positioned I think.

Ender 3Pro users, use 9x9 auto calibration, I will have a go for it.

[Dojima]

I’ve tried the 9x9 matrix, although it takes a while so by the time you get halfway through the bed will have dropped back to room temperature.

Here is a print after performing a 9x9 auto-calibration.

Have ordered some glass, although imagine it’s going to take 4+ weeks for delivery. Will report back once I get that.

[JKC20]

I wish I had a way to highlight this post. Thank you for sharing

[monkeygerbil222]

So in a fit of apparent madness I gave up on my 7x7 auto level that I had been meticulously tweaking, and ran an 11×11 auto calibration. I did this after moving the print bed to the center of the Y axis and preheating the bed for 2+ hours to 70C. Results have been pretty OK, I’ve had 4 largish successful prints. But I’m probably only printing on the middle 200mm of my bed and I’m preheating the bed to initial layer temps for hours before kicking off a print. I am now printing catan tiles again although in groupings of 6 vs the 9 I have had fail so many times.

[DroneOn]

I was going cross-eyed running so many of my 7x7 mesh prints and adjustments that I was starting to input offset errors so I made this to help my tired brain.

[monkeygerbil222]

That’s a great idea! Exactly the issue I was running into, making a mistake and hurting the mesh even further. Would you care to share the .STL? Or at least I think thats being printed on the glass and not a sheet underneath?

Cheers!

[xchrisd]

Stl please! Good work

[DroneOn]

Yes that was printed on glass bed. STL coming shortly.

[DroneOn]

Here you go. Created a 5x5 in honor of the newly released firmware. Results shortly.A350 5x5 Mesh Check.stl (2.8 MB)

And the 7x7 is too big to upload here.

A350 7x7 Mesh Check.stl

[DroneOn]

FW updated to latest, rebooted after upgrade, 5x5 autonlevel enabled, printer returned to original state with flex plate, ran 5x5 mash check at 0.2mm layer and the result was about what I expected on my way bed.

[Isaac11]

Impossible for me to have a good layer with this last firmware
I’m going back to use my Glasbed.
Is there a possibility to expand the area on the manual calibration ?

[coppertop_01]

Even with a glass bed and my modified Y-axis to add another set of carriages (custom 6mm alum bed, 4 sliding carriages) my A350 has some issues with bed level, not as bad as yours but I would like to see more than the 3x3 levelling (unfortunately my auto level was damaged due to a mishap with the X axis failing and doesn’t work, so manual calibration for me). With that said I really wanna see 7x7 grid leveling, cause I think it would vastly improve level issues. When I get some time I’m going to grab my dial indicator, map out the low spots and maybe try some ghetto leveling under the heatbed with masking tape or maybe some longer screws and springs to space the bed up and give some ability to tweak at least where the screws go…

This is one thing I’m not sure if anyone has checked, the low spots in the bed, do they coincide with the screws fastening the heatbed to the rail mounting? Think about it, if you tighten the screws and the heated bed expands/contracts it could be curving between screws. If the bed is floating on springs like other units could this allow the plate to expand easier.

Just some food for thought

[xchrisd]

Hey, there is already 5x5 calibration with firmware 1.8!

Good point about the floating bed🤔

[coppertop_01]

didn’t know there was a 1.8, Edwin told me a week or two back when I got some replacement parts that I should upgrade to 1.7

I’ll look at updating it tonight and giving it a shot.

I haven’t tried the whole bed yet, but I do know that just 40mm behind center I have a low spot, center is a dead perfect print, as I go back on the bed it gets lower, fortunately recent prints haven’t required full bed printing.

[Dojima]

I tried 5x5 auto-calibration, the results were as expected. A mixed bag, some areas okay others poor adhesion. I tweaked a bit, but it’s all that I ever do with this 3D Printer is tweak it and work on test prints…

If you take the magnetic bed off and put back on, that will change the outcome of the next print. I can’t help but feel a touch sensor would have made more sense!

It’s really frustrating, there are so many people all experiencing different results. Why is there so much variance?

First attempt after auto calibration (terrible)

Second attempt after I manually adjusted
e.g. M421 I0 J1 Q-0.05 (I did this for I0 to I4) also tweaked I0 J3 (I think)

ok better, so adjusting gets us that 1st layer, great. However, that infill is pretty bad, you can see it’s too close. Also can see the small circle didn’t stick.

So more tweaks, notice in the spiral pattern there are parts of it that are too low, where it’s faded and you can see the bed

Not sure what to do anymore, it’s certainly not been a premium experience. Happily have given up the SnapMaker animation on the LCD for a little more time put into 1st layer results.

[Isaac11]

@Dojima

Not sure what to do anymore, it’s certainly not been a premium experience. Happily have given up the SnapMaker animation on the LCD for a little more time put into 1st layer results.

Maybe it’s because the layer of the metal sheet on the bed sheet is not centered ? Don’t know if it’s make sense what I’m saying ?
I imagine the bed sheet like a sandwich and maybe the layer of metal is uneven inside of the bedsheet

[Dojima]

Yeah that makes sense, I didn’t know it worked like that, I presumed it checked for the metal mounting plate underneath. If you flip the sheet over you will end up with problems in different areas.

So my question would be. How is SnapMaker addressing this manufacturing issue?