I find, no matter how many times I calibrate the bed, one corner is always off. I start with the middle, then to the left front corner, and then the right front corner. When I adjust the right front corner, the middle is off. I fix the middle, and then the front right corner is off again. Then I just go back and forth until I get tired of adjusting it. The middle itself stays pretty level. I don't have to calibrate very often.
Ive never been able to achieve a completely level bed. It is always higher in the center then on the front left right an rear center.
I used the dial caliper but that makes the bed dip ever so slightly from the tension in the spring on the dial.
With that said, i level the bed front and rear then lower the z just a touch so the tip doesn't smash into the glass and then make fine tuned adjustments with my first print or two based on how the first layer is laying down.
I have noticed that the more i use the printer, the worse the build plate is. Ive tried to determine if the glass is warping but it seams to be holding fine. My only other thought is that perhaps the aluminum platform is warping and the magnets are pulling the glass into a slight warp. I'm not sure how i would check that though.
Its still usable on the full build platform however the first layers are less true the further from center you go.
Im just keeping an eye on it to see if i can spot a different culprit. Ive thought about making the glass attach in only 3 points or make brackets that hold the plate in place without magnets to see if it still warps the glass.
Recalibration, once every 20-30 prints and that only takes a slight adjustment of the z stop and ever so slight turn of the plate adjustments.
Is everyone using a dial indicator? That's by far the easiest method. I wouldn't use a digital indicator as trying to get the corners 'perfect' will turn your hair grey!
As some of you stated, the center is slightly higher than the sides/corners.. has this adversely effected how your printer prints? how much drag do you have on the piece of paper between the center bed and nozzle? You should be able to remove the paper, and re-insert with a little wiggling.
Also, the first layer height and extrusion width could also adversely effect the first layer quality, these can be changed in your slicer.
Along those lines, with the dial indicator, you should only be taking a measurement at the 3 mounting points. rear center & front corners. The theory is, as you lower/raise one corner, that will cause the opposite corner to raise/lower respectively. The rear center should not move, as it is mounted rigidly.
It may be possible my instructions are unclear, or not enough info was provided.. I should do a video....
Let me know your thoughts... I am only aiming to improve the CreatorBot, and your experience with it!
On my printer when the rear and front left and right are a prefect match with the dial indicator the center of the nozzle drags tightly across the plate.
Once level i adjust the z on the center of the plate to a paper thickness. At that point the rear and front right and left corners are about .4mm off. I can still print to the edges but the first few layers are more rounded than smushed to .2mm at the edge and the center is perfect.
This is why I'm thinking the magnets are pulling the edges of the glass down over the heat bed.
Interesting thoughts Adam..... It may be worth it to pull the magnets off just to see if that is the culprit!
alexthepunk - that shouldn't be happening with the heater. the heater pad is supposed to fit perfectly inside the metal tabs on the glass. You may have gotten a slightly larger than normal heater pad. If you look closely at the pad itself, the heat lines do not go all the way to the edge, you CAN carefully trim off some of the silicone from the edge for it to fit better (do this at your own risk). I had to trim one or two of the assembled units due to a larger than normal heat pad (probably normal 'acceptable' manufacturing from our supplier)
The heater pad isn't too wide. The insulator underneath isn't thick enough to hold the pad to the glass in all of the spots. If I put thinner glass mounts it may make up for that
You may have already modified them, but i did a little on the mounts for a fellow member. I already had them in tinkercad, Stock height is 11mm. I guessed that 9mm would be a good start. I attached it for you