Calibration questions

Snapmaker Original
1

Sorry if these are repeats, but I don’t think I’ve seen these questions posed quite this way.

I’ve done a little 3D printing before on a Printrbot Jr, and I recall having bed adhesion issues there, where I was manually leveling it with screws. When I first got the Snapmaker, I was amazed that all my (fairly small) initial prints were perfect - the PLA was sticking excellently to the bed. I printed four or five pieces that way.

Then I tried printing something larger, and the first layer failed. Since then, I’ve gone through calibration a bunch of times, and have also tried loosening and/or tightening the bed screws. I haven’t been able to get anything to stick at all, not even the skirt. It’s like night and day.

I’ll try some of the suggestions I’ve seen on the forums (glue stick, etc.), but I have some questions about calibration:

  • How much resistance on the paper during calibration should I be aiming for? I’ve tried everything from feather-light to fairly resistant, and nothing seems to work.

  • One thing I’ve noticed is that if I set the initial corner (1) so there’s a slight resistance on the paper, the calibration routine sets the nozzle to dig in pretty hard to the other three corners - I have to move it upwards a lot in order to unstick the paper. Does this mean I need to change the bed leveling? The screw underneath corner 1 is already somewhat looser than the other screws, so it should actually be closer to the nozzle, not farther. I originally tried tightening the screws pretty hard (thinking that the problem was that the bed was too loose) but then it occurred to me that that might be warping the bed, so I backed off from that.

  • Also, if the nozzle pushes that hard on the paper, does it invalidate the calibration? (I’m thinking that if it is actually contacting the bed, it might be throwing something off.)

  • I sometimes get into a situation during calibration where at one setting the paper has no resistance, but if I drop the nozzle down by 0.05mm, it seems to have too much. Should my response there be to tighten the bed screw at that corner?

  • In general, should I be aiming to make the bed level enough so that the calibration on each corner is about the same - i.e., there should be minimal adjustments on corners 2/3/4 after setting corner 1? I’ve been trying to do that and it doesn’t seem to help - I end up in a game of constantly loosening and tightening different screws, and it doesn’t seem to converge.

  • Does the calibration actually make it so that the Z axis adjusts itself continuously across the width of the bed so as to take the different corner heights into account? If so, how much “play” can that reasonably account for?

2

Hey!

I actually only calibrate with the program on the printer itself and I do not use the screws. I keep those fastened in order to assure that it does not wobble.

From there, I just go through each corner 1-4 and ensure that there is a moderate resistance.

I also make sure that the nozzle is clean, as any residual plastic can make it seem like it is tighter than it is, and cause the calibration to be too far away from the bed.

So yeah, moral of the story, tighten the screws (but not super duper tight, as you may want to take the bed off in the future), and then use the calibration program on the printer to calibrate it in each corner. The Snapmaker seems to adjust for each corner independently meaning the bed itself doesn’t have to be 100% flat! (I believe).

Also, try cleaning the print bed at least once a week or so. It can get some oil from your hands and other particles on it that could prevent the prints from sticking too well.

Hope that helps :smiley:

-Greg

3

This is perhaps a bit extreme but I built a bracket to hold a dial indicator and dialed in my bed that way. You don’t want the bed screws too tight as it may distort the flatness. The calibration card is close to .09mm thick so you get a little resistance and then perhaps one more .05 tick should get you pretty close to where you should be. I’ve also found that it helps to turn the “width” up to 110% for the first layer. That has the effect of maximizing the contact area of the plastic on the base. I use a print speed of 25mm/s on the first layer. Clean the bed surface with isopropyl fairly often.

4

Thanks for the feedback. I figured out my problem relatively soon after posting this, but it was held up in moderation for awhile :slight_smile: The problem was simply that I was being much too conservative with the calibration - I needed to have the nozzle much closer to the bed. I was worried about the nozzle digging into the bed, and I was assuming I should only feel very light resistance on the paper during calibration, but that seems to have been totally wrong :slight_smile:

I bought a set of feeler gauges after seeing some notes about that elsewhere in the forum, and started by using the 0.09mm feeler gauge. I found that even with that thinness, I had to bring the nozzle down fairly hard into the gauge - to the point where it actually popped off the gauge when I pulled it out - in order for it to be close enough. I’m going to try thinner gauges later to see what the sweet spot is, but for now, as long as I can feel reasonably strong resistance on the 0.09mm gauge, it seems to work pretty well.

5

I would think the .05mm gauge would be ideal, it should only have very slight resistance. If you have slight resistance it could mean you are sitting at .04mm high and one more .05 increment would put you into the bed. It doesn’t hurt to be .05mm higher than actual. My dial indicator showed a variation over the whole bed of about .012mm in spots so you really want to be high.