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/
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 126.96.36.199
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
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 https://www.reddit.com/r/FirstLayerPorn/
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
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)