Mystified by lack of filament adhesion

[aarong]

I'm very new to 3D printing, and have only had my M2 for a couple months. It's the pre-assembled model with the V4 hotend.

I had a lot of success out of the box printing with the original black filament - I could go print after print with no issues, only requiring that I scrape the bed clean (never had the need to clean with alcohol or acetone).

In running out of black filament I decided to purchase some bright orange Hatchbox filament. I heated up the hotend, retracted the black filament out, then extruded the new Hatchbox filament through. I gave it a few hundred mm of extrusion before trying my first print. In trying to first print the filament would keep balling/curling up behind the hotend as it moved along the bed.

With the successful prints of the original black PLA I ran with the hotend at 215 degC, and the bed at 70 degC. I had kept this settings for the first attempted print of the orange filament, but I changed them afterwards thinking that would help adhesion - it was fairly inconclusive whether it was having any real effect; whether I tried going hotter, colder, with both the extruder and the bed - attempting to print the object it would sometimes grab, and sometimes not. I then tried a layer of kapton, and that seemed to do the trick, however the print quality was very spotty, and there was evidence of very significant underextrusion. Additionally, on some layers the extruder would still pick up pieces of filament.

Unhappy with the quality of orange filament and wanting to make sure it was only the filament that changed to affect how poorly prints were turning out, I thought I'd go back to the original black filament I had left.

I changed the extruder and bed temp back to 215 degC and 70 degC respectively. Now trying to print with the black filament on bare glass seems to not work - it seems to be doing the exact same thing the orange filament did when I first tried it. I heard it could be a bad first layer height, so I used the business card trick to check my z level adjustment, and I tried leveling the bed - both seemed inconclusive.

I've attached some pictures of the extruder height at the 4 bed corners, and I recorded a video of a following attempted print with the original black PLA. I've been using Simplify3D exclusively - I've also attached a zip file of my FFF file.

Thank you in advance - I'm a bit mystified by the situation.

Photos of extruder leveling height: http://imgur.com/a/RkeK1
Video of black filament extrusion: http://sendvid.com/qt6l1jz1

[jsc]

Bare glass is always an iffy prospect. If you insist, you can try cleaning your plate with dishwashing detergent until it's squeaky clean and try again. But my suggestion is just hit the glass with some hairspray or glue stick and live an easy life.

Have you seen this: viewtopic.php?f=8&t=2778
Lots of good suggestions in there, all in one place. Covers adhesion. You will want to calibrate extrusion and bed height as well.

[aarong]

Thanks for the quick reply - I'll take a look.

I understand it's iffy to print on bare glass, however I'm concerned I've changed something, and modified some setting that has altered the way it prints permanently.

I'll give a couple different tapes a try and report back.

[MagicEngineer]

It is difficult to tell by the picture if the z stop is set right. I would look at that first if the problems are consistent. Since you have the v4 tip. just loosen the hotend set screw, carefully pull the tip out about a centimeter, set a business card on the home corner of your bed, and push the home all button. Then tighten the set screw back.

[Pekish79]

honestly Z seem a little far in the picture anyway is impossible to tell i really was never lucky to print on glass so i shouldn't talk i print on Zebra or PEI

and i dont like to heat the bed too much with Zebra 35-38 with PEI 50-55
i know with glass probably i should use 70 not my thing i just like zebra and how cool i can keep the plate

anyway best way to tell if Z is right is follow this...viewtopic.php?f=3&t=3124

obviously you need to be able to make the cube stick in first place but to see how far u are from the right distance printing the cube and measuring is cool

i am one of the crazy one that like to get 2.00 messing around with the Z screw rather then with the sofware

[sthone]

When you changed to a different roll of filament did you Calibrate Your Extrusion Width and set your Z-Offset for that particular roll of filament? This should be done for every roll.

Sometimes (but not always the case) when the filament is curling right out of the nozzle this can be an indication of a clog forming. Get some cleaning filament and run some through when changing brands/rolls.

Another thing... you might want to do is after heating up the nozzle and bed prior to printing is to take your tweezers and clean all the old filament off the nozzle before you start the print and the bed starts to rise. Then after you start the print when the nozzle moves off to the right to purge again take your tweezers and grab the filament and stretch it down just as it starts to purge. This will keep it from curling back against the nozzle and affecting the first layer.

One last thing.... like others have said use some type of bed adhesion. 3M blue painters tape works great for PLA (and it's easy/clean to use) or Glue stick or hairspray works awesome too for PLA as well as other types of filament.

-Steve

[aarong]

I apologize I haven't updated with status - thank you so much for your quick and informative replies.

I managed to fix the issue - it looks like my z-stop was a little too high.

I tried painter's tape as one of the first recommendations, and immediately noticed a slight improvement in how long the filament would stick to the bed before clogging up. Characteristic would always be that as the extruder would begin an extrusion, it would take some "distance" along the bed for it to drag the filament before the filament would actually hold to the bed. After including the painter's tape, there was still a major issue, but the filament went from hardly sticking at all, to sticking after a couple inches of lateral movement.

I figured it could be the magic of the painter's tape surface finish, but as one last ditch effort to printing on glass again I tried slicing the print -0.05mm off of the Z start (again including the painter's tape) and immediately saw more improvement. So I started inching the slicing process down on the Z axis by 0.05mm each time until the filament was adhering to the bed (painter's tape) immediately upon an extrusion (within about a mm or two of lateral translation). Then I removed the painter's tape, subtracted another 0.1mm off of the Z start height (-0.2mm at this point), tried printing, and it worked like a charm.

I know I could have adjusted the Z stop screw until the extruder nozzle would firmly hold a business card on the bed; however I tried that initially, and it may be because I happened to have only very thick business cards lying around, but the nozzle was still too high. I am also nervous about performing things consistently by hand.

So I have to give credit - I remember seeing the process for slicing the model at lower and lower Z start heights as a way of very fine tuning between filaments.

Thanks again for all of your help - it's truly remarkable how supportive this community is, and it makes me very proud to be a Makergear owner. I promise to also do my best to contribute in return.