Impossible First Layers

[bobh]

Team, I recently finished my V 2.4 with Stealthburner and immediately began printing getting pretty good results. As I was going through the process of tuning (Voron/Ellis), the first layers went to crap bad enough that I can no longer print. I have taken the toolhead completely apart twice and found no obvious issues. It still looks new.

Following extensive inspection and testing I have concluded that there is a problem with the nozzle. As it begins to extrude, the PLA curls back on the nozzle eventually creating a ball of plastic. It looks like that ball of plastic contacts and rips up the first layer (see second photo). You can also see on the second red patch that it appears that the flow of plastic is insufficient in that it is necking down?

I know very little about printing plastic and would appreciate some help. 

As part of the tuning process I have played with the Z offset. It hardly makes a difference as I adjust the value.

The extruded plastic should exit straight down? Is the nozzle partially clogged causing the curling?  If yes, how do you suggest I clear it? 0.4 mm drill?

Thanks all for your input. In the meantime I am going back to square one and repeating the initial startup procedures.

Edit:

Bob

 

Edited January 29 by bobh

[claudermilk]

It may be a partial clog. It may also be that the plate needs cleaning. I'd address both and try again. The partial clog should be as simple as retracting the filament and jamming a cleaning needle in the nozzle, or doing a cold pull (more of a PITA IMHO). For the plate, if I'm having issues with the first layer pulling up I just go to the dish soap scrub; take the plate to the sink & wet down with warm water, drop a bit of dish soap on it, and scrub around with a brillo pad. Then rinse and dry. If that doesn't work, for a couple of new plates I've had to lightly sand with 600 grit sandpaper to give the PEI some tooth.

[Dirk]

Hey Bob,

I wouldn't use a drill. Use more metal surface friendly methods, like @claudermilk mentions: a cleaning needle and cold pull (google how to).

Your black square I can't really 'see', but the red one is missing A LOT of filament.

What is your printing speed and what temperatures do you use for the plate and hotend? 

Are these in line with recommendations from the pla producer?

 

[Penatr8tor]

I'll chime in here with a couple of tips... But a few questions first.

What slicer are you using?

What material are you printing?

What is the bed temp?

What is the nozzle temp?

What is your 1st layer speed?

Now some tips...

Enable "skirt" in your slicer. Make the skirt 8-10mm away from the part and set the loops to 6. Some will ask why and some will comment that 6 loops is way too much but, here's why we're doing this. You want to have a record of your 1st layer height to measure and then compare to your slicer settings. If you have your 1st layer set to 0.2mm then the skirt thickness should be 0.2mm if it is not... that's what you set your Z offset to compensate. If it measures 0.25mm then set the Z Offset to -0.05 then click save (you machine will reset). Keep playing around until you get close. Once you have the height set... you can then reduce the loops to 2-3.

Once you have the 1st layer height dialed in... the rest is all about flow. Too much flow and you'll see the plastic bulge up from the surface too little flow and you'll get gaps. I suggest always printing a skirt and always checking the thickness with calipers. One word of caution... you want to apply light pressure on your calipers when measuring... it's 100% possible to squish a 0.3mm thick skirt down to 0.2mm with enough thumb pressure.

Once you get both the 1st layer height and flow adjusted, you'll be printing 1st layers like this...

 

Edited January 29 by Penatr8tor
Spelling, of course

[bobh]

3 hours ago, claudermilk said:

It may be a partial clog. It may also be that the plate needs cleaning. I'd address both and try again. The partial clog should be as simple as retracting the filament and jamming a cleaning needle in the nozzle, or doing a cold pull (more of a PITA IMHO). For the plate, if I'm having issues with the first layer pulling up I just go to the dish soap scrub; take the plate to the sink & wet down with warm water, drop a bit of dish soap on it, and scrub around with a brillo pad. Then rinse and dry. If that doesn't work, for a couple of new plates I've had to lightly sand with 600 grit sandpaper to give the PEI some tooth.

Since my original post I have cleaned as suggested and used a needle. The cold pull worked perfectly but did not reveal any undesirables under magnification. Will try the sandpaper but at this time I am not convinced this is an adhesion problem. Even the bad first layers are well stuck needing a lifter to get off.

Thank you for your suggestions.

Bob

[Dirk]

42 minutes ago, Penatr8tor said:

I'll chime in here with a couple of tips... But a few questions first.

What slicer are you using?

What material are you printing?

What is the bed temp?

What is the nozzle temp?

What is your 1st layer speed?

Now some tips...

Enable "skirt" in your slicer. Make the skirt 8-10mm away from the part and set the loops to 6. Some will ask why and some will comment that 6 loops is way too much but, here's why we're doing this. You want to have a record of your 1st layer height to measure and then compare to your slicer settings. If you have your 1st layer set to 0.2mm then the skirt thickness should be 0.2mm if it is not... that's what you set your Z offset to compensate. If it measures 0.25mm then set the Z Offset to -0.05 then click save (you machine will reset). Keep playing around until you get close. Once you have the height set... you can then reduce the loops to 2-3.

Once you have the 1st layer height dialed in... the rest is all about flow. Too much flow and you'll see the plastic bulge up from the surface too little flow and you'll get gaps. I suggest always printing a skirt and always checking the thickness with calipers. One word of caution... you want to apply light pressure on your calipers when measuring... it's 100% possible to squish a 0.3mm thick skirt down to 0.2mm with enough thumb pressure.

Once you get both the 1st layer height and flow adjusted, you'll be printing 1st layers like this...

Wow... This is such a great explanation, that it should be under the 'tutorials' section! 

I wish I had had such explanation when I started out printing

[bobh]

3 hours ago, Dirk said:

Hey Bob,

I wouldn't use a drill. Use more metal surface friendly methods, like @claudermilk mentions: a cleaning needle and cold pull (google how to).

Your black square I can't really 'see', but the red one is missing A LOT of filament.

What is your printing speed and what temperatures do you use for the plate and hotend? 

Are these in line with recommendations from the pla producer?

Yes, the red is a serious problem compared to the black (both PLA). Have set the red aside for the moment and calibrating with just the black.

I realized that I should have offered up the software and settings. In order to keep it all in one place I will outline settings in responding to Penatr8tor who also asked for additional settings.

Thank you Dirk, I very much appreciate the help.

 

[bobh]

3 hours ago, Penatr8tor said:

I'll chime in here with a couple of tips... But a few questions first.

What slicer are you using?

What material are you printing?

What is the bed temp?

What is the nozzle temp?

What is your 1st layer speed?

Now some tips...

Enable "skirt" in your slicer. Make the skirt 8-10mm away from the part and set the loops to 6. Some will ask why and some will comment that 6 loops is way too much but, here's why we're doing this. You want to have a record of your 1st layer height to measure and then compare to your slicer settings. If you have your 1st layer set to 0.2mm then the skirt thickness should be 0.2mm if it is not... that's what you set your Z offset to compensate. If it measures 0.25mm then set the Z Offset to -0.05 then click save (you machine will reset). Keep playing around until you get close. Once you have the height set... you can then reduce the loops to 2-3.

Once you have the 1st layer height dialed in... the rest is all about flow. Too much flow and you'll see the plastic bulge up from the surface too little flow and you'll get gaps. I suggest always printing a skirt and always checking the thickness with calipers. One word of caution... you want to apply light pressure on your calipers when measuring... it's 100% possible to squish a 0.3mm thick skirt down to 0.2mm with enough thumb pressure.

Once you get both the 1st layer height and flow adjusted, you'll be printing 1st layers like this...

First, my apologies for the delay in responding. Your post compelled me to check a few things and do some tests so that I could respond appropriately.

Answering your questions:

Orca, PLA, Bed Temp=65C, Nozzle Temp=205C first layer, 200C subsequent layers, first layer speed = 100 mm/s.

I have been calibrating per the Orca calibration section and adjusted the print temps and flow (flow adjusted to 0.9212).

Checked a two loop skirt from my earlier work and found it to be 0.337 mm thick, 0.137 mm too high. Adjusted Z offset by 0.137 mm. Thanks for the note about measuring with calipers. I measured thickness with a Mitutoyo micrometer accurate to 0.0025 mm. By using the ratcheting thimble one avoids the heavy thumb problem and assures consistent readings.

Per your instructions I set skirt to 8 loops 8 mm away. Initiated a calibration print again that failed miserably (see photo). The intact skirt thickness now measures 0.2032 mm. (close enough or should I go another round adjusting z offset?)

Now that Z offset is close I am thinking I should go back and repeat flow calibration?

I completely agree with the comment about this becoming a tutorial. I had blindly played with Z offset for hours while the micrometer was next to me (duh).

Can't thank you enough for the thoroughness of your response and willingness to help people like me that are new to printing.

Bob

PS - cant stop drooling over the photos of your first layers... lol

 

 

 

[Dirk]

28 minutes ago, bobh said:

first layer speed = 100 mm/s.

I think this explains a large part of why you have so many troubles the first layer. Try more like euh.... 5mm/s... then later 10mm/s and maybe when you think all is right, go to 30mm/s. 

Even the Ellis profile first layer (for super slicer, so not for orca) does 60mm/s at the fastest profile... so.... Start there...  

[bobh]

2 minutes ago, Dirk said:

I think this explains a large part of why you have so many troubles the first layer. Try more like euh.... 5mm/s... then later 10mm/s and maybe when you think all is right, go to 30mm/s. 

Even the Ellis profile first layer (for super slicer, so not for orca) does 60mm/s at the fastest profile... so.... Start there...  

Yes, it seems obvious now, particularly given that I was a technical guy. I will slow the first layer right down and give that a try.

Thank you for the helpful suggestion.

Bob

[Penatr8tor]

@bobh Lol, Thanks, Yours will be just as nice in no time.

I agree with @Dirk Definitely slow down the 1st layer speed, 30mm/s is plenty slow. Also, I would go 210c on the 1st and subsequent layers in the beginning.  You can reduce temps once you get decent adhesion. In addition, pull off the build plate and give it a really good scrub, wash and rinse with dish soap (Dawn works well) and water. I've had build plates that needed some breaking in, they'd really suck on the 1st few prints but as time went by, number heat cycles and alcohol wipes and rarely do I have adhesion issues.

So, to recap... Wash the build plate. Print a bit hotter (210c). Slow down the 1st layer speed (30mm/s)... And if you're over extruding on the 1st layer... Change the "Bottom Surface Flow Ratio" (like below) to adjust flow.

In the end... it all comes down to flow. Flow is going to determine not just how good of a surface finish you have on the top and bottom but also on overhangs, which is a whole 'nother rabbit hole LOL.

 

 

[bobh]

9 hours ago, Penatr8tor said:

@bobh Lol, Thanks, Yours will be just as nice in no time.

I agree with @Dirk Definitely slow down the 1st layer speed, 30mm/s is plenty slow. Also, I would go 210c on the 1st and subsequent layers in the beginning.  You can reduce temps once you get decent adhesion. In addition, pull off the build plate and give it a really good scrub, wash and rinse with dish soap (Dawn works well) and water. I've had build plates that needed some breaking in, they'd really suck on the 1st few prints but as time went by, number heat cycles and alcohol wipes and rarely do I have adhesion issues.

So, to recap... Wash the build plate. Print a bit hotter (210c). Slow down the 1st layer speed (30mm/s)... And if you're over extruding on the 1st layer... Change the "Bottom Surface Flow Ratio" (like below) to adjust flow.

In the end... it all comes down to flow. Flow is going to determine not just how good of a surface finish you have on the top and bottom but also on overhangs, which is a whole 'nother rabbit hole LOL.

This makes perfect sense. I tried 5 and 10 mm/s and am now back up to 15 mm/s. Will keep increasing until 30 as results allow.

The skirt is now very close to .2 mm (0.2032 +/- with some variability around the skirt).

When you have the first layer fixed at 0.2 mm and then flow too much does the excess plastic drag around a little bit? Makes a rough surface? Or does the profile of the line have a flat spot and bulges at the edges outside the width of the nozzle?

What should the first layer line width be? Currently at 0.4 mm to match the nozzle.

 

[Penatr8tor]

@bobh I would jump straight to 30mm/s for 1st layer. I generally print my 1st layers at 60mm/s with 80-100 for the infill but, that's something you'll tweak later.

As for your 1st later height... It will never be spot on and being within a few 10th of a thousandth is the best anyone could hope for. You are good!

OK, Let's talk about what's happening at the tip of the nozzle. The tip of the nozzle isn't just a cone shape with a hole in it, there's a flat portion that's there to act as a sort of trowel or smoothing surface so that as the nozzle travels across the surface of the build plate, or previous layers depending on how far along the print is, that flattens and smooths out the molten plastic as it flows out of the tip. See the pic below, the blue highlighted surface is the little flat donut that does the smoothing.

Below is a photo of what you're trying to achieve. You want just enough flow to let the little donut section flatten out or trowel the melt smooth. Yes, there will always be some variation but overall, there's not an excessive amount coming out of the nozzle, squeezing out from the sides, etc.

Over extrusion would be like the photo below... You can see where the tip of the nozzle has left grooves into the surface and the plastic has squished out on either side and of course the telltale blob at the ends points to too much flow.

So, what do you do? One of two things... Raise the nozzle or reduce the flow. I also want to mention that there are numerous factors like speed, etc. but the slicer does a good enough job at compensating for it not to be worth worrying about. Since you already have the nozzle set at 0.2mm there's only one thing left to adjust... flow ratio.

Hope this gives you a better mental picture of what you need to do.

...And if that wasn't enough, LOL. Check out this video.

 

[Dirk]

5 hours ago, bobh said:

What should the first layer line width be?

I think the better you get at laying down that first layer, the more questions you will have

I think also that the 'settings' for the first layer, and the whole 'how to lay the first layer' is a philosophical topic, with a huge amount of variables variances and varieties. 

It helps a lot to understand the basics. Like @Penatr8tor has laid down in the above posts. However, how you do things exactly, you will have to find / figure out for yourself. I guess if you ask the 10.000 members here on TeamFDM how to handle the first layer, you will get 10.000 different answers, which is a good thing.

I can tell you how I discovered mine, but it was with the help of a very friendly printer (artillery sidewinder x2), which does not allow a lot of variation (you can start the print or stop the print), and a slicer (cura), which comes with standard settings for 3 simple sorts of project types. All I did, was hang the plastic on the printer, find a stl, slice it and put it on a stick. The printer did all the rest.

When you start out with a voron 2.4 and orcaslicer, I guess you are jumping straight into the deep to learn to swim. These machines and the accompanying software/firmware are so powerful that you can do anything with them.  With great power... 

Anyway. I would suggest go through the steps on the Ellis' guide. Maybe consider using SuperSlicer (I'm sure it is all also possible with Orcaslicer, but it will take you longer). It will help you follow the guide. 

The guide takes you through everything: extruder tuning, cleaning your surface, first layer, squish, how to look at it, recommended line-width/height, pressure advance, extrusion multiplier, retraction, cooling, layer time, infill/perimeter overlap and even more...

I think once you are through the guide, you will have printed so much, that you will be able to dream the first layer

One other place I like to look at if I do not understand what I run into is this one. It will explain certain terms that you will run into when browsing online.

Finally, the answer to your question... Theories say for a better first layer and adhesion of the perimeters, a slightly larger size than nozzle size is chosen. Cura sets this standard at 0.44mm for a 0.4mm nozzle. But you will see that in other slicers there are other options. 

About the speed at first layer, where your post actually started with, if you have a finely tuned printer, with a very good extruder and the best hotend, and have the experience of failed hundreds of first layers (all factors true for @Penatr8tor), you will be able to print the first layer at 120mm/s. But the first layer is usually only the first of many. After the first, the rest you can usually print as fast as your hotend can handle

 

Good luck

 

 

 

[bobh]

5 hours ago, Penatr8tor said:

@bobh I would jump straight to 30mm/s for 1st layer. I generally print my 1st layers at 60mm/s with 80-100 for the infill but, that's something you'll tweak later.

As for your 1st later height... It will never be spot on and being within a few 10th of a thousandth is the best anyone could hope for. You are good!

OK, Let's talk about what's happening at the tip of the nozzle. The tip of the nozzle isn't just a cone shape with a hole in it, there's a flat portion that's there to act as a sort of trowel or smoothing surface so that as the nozzle travels across the surface of the build plate, or previous layers depending on how far along the print is, that flattens and smooths out the molten plastic as it flows out of the tip. See the pic below, the blue highlighted surface is the little flat donut that does the smoothing.

Below is a photo of what you're trying to achieve. You want just enough flow to let the little donut section flatten out or trowel the melt smooth. Yes, there will always be some variation but overall, there's not an excessive amount coming out of the nozzle, squeezing out from the sides, etc.

Over extrusion would be like the photo below... You can see where the tip of the nozzle has left grooves into the surface and the plastic has squished out on either side and of course the telltale blob at the ends points to too much flow.

So, what do you do? One of two things... Raise the nozzle or reduce the flow. I also want to mention that there are numerous factors like speed, etc. but the slicer does a good enough job at compensating for it not to be worth worrying about. Since you already have the nozzle set at 0.2mm there's only one thing left to adjust... flow ratio.

Hope this gives you a better mental picture of what you need to do.

...And if that wasn't enough, LOL. Check out this video.

This is very helpful indeed. And thanks for the video - I could not stop watching...

At 30 mm/s now and tuning as I go. Latest first layer .

You have been more than helpful and your teaching style is awesome - your instructions with reasons completely align with my head. Thank you again!

Off to more tuning...

[bobh]

18 minutes ago, Dirk said:

I think the better you get at laying down that first layer, the more questions you will have

I think also that the 'settings' for the first layer, and the whole 'how to lay the first layer' is a philosophical topic, with a huge amount of variables variances and varieties. 

It helps a lot to understand the basics. Like @Penatr8tor has laid down in the above posts. However, how you do things exactly, you will have to find / figure out for yourself. I guess if you ask the 10.000 members here on TeamFDM how to handle the first layer, you will get 10.000 different answers, which is a good thing.

I can tell you how I discovered mine, but it was with the help of a very friendly printer (artillery sidewinder x2), which does not allow a lot of variation (you can start the print or stop the print), and a slicer (cura), which comes with standard settings for 3 simple sorts of project types. All I did, was hang the plastic on the printer, find a stl, slice it and put it on a stick. The printer did all the rest.

When you start out with a voron 2.4 and orcaslicer, I guess you are jumping straight into the deep to learn to swim. These machines and the accompanying software/firmware are so powerful that you can do anything with them.  With great power... 

Anyway. I would suggest go through the steps on the Ellis' guide. Maybe consider using SuperSlicer (I'm sure it is all also possible with Orcaslicer, but it will take you longer). It will help you follow the guide. 

The guide takes you through everything: extruder tuning, cleaning your surface, first layer, squish, how to look at it, recommended line-width/height, pressure advance, extrusion multiplier, retraction, cooling, layer time, infill/perimeter overlap and even more...

I think once you are through the guide, you will have printed so much, that you will be able to dream the first layer

One other place I like to look at if I do not understand what I run into is this one. It will explain certain terms that you will run into when browsing online.

Finally, the answer to your question... Theories say for a better first layer and adhesion of the perimeters, a slightly larger size than nozzle size is chosen. Cura sets this standard at 0.44mm for a 0.4mm nozzle. But you will see that in other slicers there are other options. 

About the speed at first layer, where your post actually started with, if you have a finely tuned printer, with a very good extruder and the best hotend, and have the experience of failed hundreds of first layers (all factors true for @Penatr8tor), you will be able to print the first layer at 120mm/s. But the first layer is usually only the first of many. After the first, the rest you can usually print as fast as your hotend can handle

Good luck

Yes, but I have now have a basis to proceed with tuning and learning. Before all of your help it was just a frustrating experience.

When I decided to build a Voron it was out of complete ignorance. All good.

Thank you for your help and patience. It is very much appreciated.

[Penatr8tor]

@bobh You are so very welcome. It's one of my great joys to pass along some hard-earned experience. 

BTW... That's a good looking first layer ya got there!

Glad you're on the right track and again glad that I could help.

Cheers,

Pete