PLA not sticking to glass

[jclega 0]

Hello folks, I have just received my UM² and printed successfully the included little robot. Actually better than expected. I am now trying to print more included files like the tetra wire and cube but the PLA is not sticking. it easily moved around with the print head. I am using the included Ultimaker brand silver PLA.

I have had some success with heading bed to 70C-80C and increasing the nozzle to 220C but kicked it down to 215C due to discoloration ( I assume too hot), I am now seeing it stick a little better but not much better. As I understood PLA shouldn't be so picky. Here is a list of my trials:

I have cleaned glass carefully with glass cleaner

I have cleaned glass carefully with acetone

Tried included glue stick (terrible)

Aligned bed 4 times with thin sheet of paper each time

Performed atomic pull but 1st time came out clean

Any ideas? I hate to heat up so much that PLA discolors and pieces are warping. Once bed cools parts just come off so easily they feel like someone just placed them there. I do have Yellow PLA and 2 spools of U-PET I can try.

 

[gr5 2,237]

The gray PLA is fine. Print it at 220C with bed at 50C. Hotter won't make it stick any more. 30C or colder and it won't stick very well. At 70C (and 60C) the bottom few layers don't come out as well.

You're problem is most likely (85%) the leveling. I know you leveled 4 times. So stop leveling with the procedure. Now do it by turning the screws. Start your print and look at the brim or skirt as it is laid down. If it's so thin it's almost invisible your nozzle is too close (not likely). If it's roundish the nozzle is too far from the glass (this is most likely in your case). You want it squished somewhat flat like a pancake as the skirt is being laid down (or brim). For brim you want the lines touching - no gaps between. If there is a gap you need to move nozzle closer to glass. If there it's so thin it's almost transparent - too close. If the feeder is skipping backwards because it can't get any filament out you are probably also too close. Push down on the bed for a sec to increase the gap and see if the PLA spurts out.

If you are still having trouble please post a video of the first layer skirt being laid down. between 5 seconds and 30 seconds is all we need to see - more than 30 seconds is a waste of your time and our time.

 

[gr5 2,237]

You don't need to clean your glass. The glue stick helps a lot with sticking. You need very little - if you want to improve the glue stick you can add some water and spread it around with a wet tissue such that there is almost no glue left - it should dry completely transparent but you can tell it's there if you scratch it with a finger nail.

Also Brim is very helpful in holding down large objects that are curling at the corners.

 

[illuminarti 18]

If you're not comfortable adjusting bed height on the fly, try using the wizard but don't use a piece of paper - just do it by eye:

The first thing to do is to make sure that all of your springs are reasonably tight. If they aren't, it's impossible to find the right height with a single sheet of paper, because the tension on the springs is minimal until they're compressed a bit. So, look through the bed from front to back, and adjust the back thumbscrew until the terminal block in the back left corner is about 1mm from touching the lower plate. Tighten the front screws about the same amount, to keep the bed roughly level as a starting point.

Then heat the nozzle and make sure it is clean at the tip.

Now run the leveling wizard again. When adjusting the rear height, just use the dial on the front of the printer. When adjusting the front corners, use the thumbscrews. I recommend not using the 1mm-then-a-paper-thickness approach. Instead, on both passes level the bed to the point where the nozzle just touches the glass. This is easy to see if you look along the surface of the glass; you can see the nozzle touch its own reflection.

When setting each point, move the bed up until it just touches the nozzle tip, then back it off and allow it to settle untouched, and then gently close the gap again.

If you find that you cannot compress the front springs enough to get the bed down to where it needs to be, then simply raise the back of the bed a few turns of the thumbscrew, and restart the leveling wizard. You want to end up with all the springs in a middle position, with a gap of about 10-13mm between the two plates of the bed assembly. The springs should be neither totally compressed, nor so loose that they aren't applying any meaningful upward force on the bed.

By doing two passes at the same height you should get fewer surprises; the second pass around should only require very minor adjustments. And aiming for the point where the nozzle touches the glass is a much easier target than trying to interpret the feel of nozzle on paper tension.

 

[jclega 0]

Many thanks to both of you! That's great info and very concise. I will attempt the adjustments as soon as the 13 hour print is complete, 6 hours left.

When I hear up the nozzle before using the wizard, so you recommend a temperature? Do I set to just under PLA melting point to avoid deposition? Or do I retract filament?

Thanks again,you guys are awesome!

[jclega 0]

 

illuminarti / gr5

I have done as asked to the best of my abilities. Tweaked the screws as best I can (I think) things are better but not there yet. I have tried to print an IronMan mask with a good sized brimm and it stuck the brimm very well to the mask base but about 2 hours into the print I noticed the nozzle was hitting the mask and this beating of process loosened the print to the point it began to pop off the bed. Is this again needing to align the bed or could I have another issue with file? My next attempt to print didn't stick again after 3 or 4 layers so I will try and align again and video the print to upload. Any place here on forum to upload video file?

 

[jclega 0]

Okay folks. As it turned out I had a bad nozzle. It was defective at the tip. Carefully with Adidas diamond file I ground it flush a bit too test and now working much better.

[gr5 2,237]

Bed leveling affects only the bottom layer. Not the rest of the print. But it also affects how well the bottom layer sticks to the glass.

However your issue with nozzle hitting print is common where there are overhangs. The best fix is more fan. Or occasonal supports to keep the mask from getting knocked over. YOu should be able to wrap tht mask with a small stick quite hard and it should not come off - say a toothbrush maximum velocity held medium loosely. It's hard to explain exact forces. Pick up a 2 pound weight (or a 16 ounce can of vegetables). That much force - 2 pounds worth at the top edge or your part SHOULD NOT knock it over. If it does you need more support so that when that nozzle wacks the raised edge over overhang - the part hangs in there.

 

[jclega 0]

Okay, so it seems like a had another problem as well. As I attempted to level the bed and follow the 'springs half compressed' method I tightened the middle adjustment screw under the bed in the rear of the unit and it inadvertently separated the aluminum heating bed plate away from the glass. This caused the front of the build area to stick but not the back half so this was causing the parts to become dislodged so many times.

On the upside, I have mastered the art of leveling! After about 30 attempts in a few days I think I got it!

 

[ProtoSound 0]

I am having the same issue with PLA sticking properly to glass, but I think I need to start by getting my bed correctly leveled. I upgraded my Creator Pro to a borosilicate glass plate with new springs and corners. I have to compress the springs almost all the way down to get the plate to level. Is there a way to permanent adjust the printbed lower, so as to allow these springs to be at or near the middle of their compression range?

Edited January 23, 2018 by ProtoSound
Align content better with thread subject.