First Layer Adhesion / Warping Help with Specific Print

[dwpearl03 0]

I would consider myself to have a decent amount of 3D printing experience at this point, but I am struggling with this print. I am having issues with my first layer not adhering very well to my raft and then with the print warping later. I've probably tried to print this part at least 8 times with different settings and different results. I have also tried the usual fixes for these problems.

I am printing PLA on a Monoprice Maker Select 3D Printer and using Cura 2.3.1 for my settings. (I can't get version 3 to work on my computer for some reason) Here are a few of the things I have tried for the first layer problem. I have the raft air gap currently set a 0.25. I have found I get very poor adhesion with 0.3 and at 0.2 I can't separate the raft. I have tried the first layer print at different speeds. I have tried different fan settings. I felt that the fan was blowing the bead off but that was not the case. I tried unplugging the fan at the beginning of the print just to be sure.

As for the warping, I have tried different temps of both the bed and print temp. I use blue painting tape with a glue stick. When it warps, it usually pulls the raft with it. I have tried different variables of the cooling fan. Should I enable print cooling? I feel like this is only for objects that are printed vertically very fast. I was concerned that a draft in the room may be causing it be cause it is always the side closest to the wall that warps. I haven't been able to confirm this though and I am trying to block any draft on that side of the print at this point. I have enlarged the raft and tried adding mouse ears but without success.

Thanks for any ideas.

[Bossler 8]

I do not know whether this stuff is available where you live but I did recently discover "3DLac" to be really extraordinary stuff to stick things to the buildplate.

In fact I did already have several occasions where the major challenge was to get the prints off the build plate!

 

And when things stick that well to the build plate, there's no chance for warping at all.

 

I am printing without raft, even no brim, on glass plate with a very thin (one layer of 3DLac-spray) -
and that works for PLA as well as for ABS and even Nylon (other issues with nylon like humidity, but that's a different story).

 

In general about prints coming of the build plate -

a basic thing is bed leveling & the z-gap!

 

Really make sure you did a decent job at manual leveling of you print bed!

0,1mm "off" makes a huge difference...

 

Btw.: from your pictures it looks like your print temp. is too high or/and your filament has drawn humidity.

 

Edited January 29, 2018 by Bossler

[dwpearl03 0]

Bossler, thanks for the input. I'll have to look into that stuff. I think that I'm going to try printing this without the tape this time. I've had such good prints with the tape I didn't want to get away from it, but this is a larger print.

 

When you refer to Z Gap, is that the same thing as the Raft Air Gap? From a brief search, it looks like it's hard to adjust the Z Gap in Cura.

 

I have also been pretty strict with the build plate leveling when I get started.  I shouldn't be having a humidity problem since I've started several of these prints with a fresh roll. I'll try lowering the temp as well.

 

The advice is appreciated.

[yellowshark 153]

Hi I have never printed a raft before so I am limited in what I can say. I assume the light blue area is the raft, which seems to have stuck to the bed well, in which case I would not worry about the z-gap as that affects the adhesion of the first printed layer. @Bossler is correct it is one of the keys to getting good adhesion. No it is not the same as Raft air gap, although I am not sure what that is!, it is the distance between the bed and the nozzle at rest and modifying that can fine tune your first layer to get it sticking like a limpet. It is actually very easy to tune in cura by using a z-offset command. It is also pretty easy to tune manually although personally I always use the z-offset.

 

I am not sure why one would want to use this Raft air gap thing. That infers to me that you leave a small gap between the raft and the first model layer? That can only screw up your adhesion I would have thought. The first thing I would do is set that to ZERO and see what happens; BUT to reiterate I know nothing about rafts, just trying to use some common sense and leaving a gap between two layes of plastic is not going to enhance adhesion.

[Bossler 8]

On 29.1.2018 at 11:36 PM, dwpearl03 said:

When you refer to Z Gap, is that the same thing as the Raft Air Gap? From a brief search, it looks like it's hard to adjust the Z Gap in Cura.

 

Z-Gap is the distance between the nozzle tip and the build plate.

You set that during manual bed leveling, not within Cura.

 

On 29.1.2018 at 11:36 PM, dwpearl03 said:

I have also been pretty strict with the build plate leveling when I get started.  I shouldn't be having a humidity problem since I've started several of these prints with a fresh roll. I'll try lowering the temp as well.

 

The advice is appreciated.

 

I recently did a 1,5hrs print with Nylon. The roll of Nylon was inside a closed box, humidity inside the box 20%.

And after just 1,5hrs the Nylon started to make sounds of humidity ("brizzle") while extruding already...

But PLA should not be that sensible as Nylon so I guess humidity might not be the problem here..

 

Normally, using the fan at 100% is a good idea with PLA.

What you could try:

- if available, apply a very thin layer of 3DLac (w. the build plate outside of the printer, please;-)
  (PLA really sticks as Hell on that stuff, just one layer of it is enough!)

- manually level the bed precisely again (after 3DLac has dried)

- print at the lowest temp. +5°C as stated by the PLA-manufacturer (e.g. if it says 185-225°C, try 190°C)

- use no raft, just brim or even just skirt

  (you'd be surprised how shiny the underside of your print can be)

- may lower the print bed temp.; try 45°C for instance (I even print PLA on 3DLac with the bed temp set to 0°C...)

 

1 hour ago, yellowshark said:

I am not sure why one would want to use this Raft air gap thing. That infers to me that you leave a small gap between the raft and the first model layer? That can only screw up your adhesion I would have thought. The first thing I would do is set that to ZERO and see what happens; BUT to reiterate I know nothing about rafts, just trying to use some common sense and leaving a gap between two layes of plastic is not going to enhance adhesion.

 

If you use raft with the Z-Gap set to 0, you'll be having a hard time (at least) to get the raft off your print.

But you are right, the higher the gap the less adhesion there is.

 

[yellowshark 153]

Hi @Bossler, OK I get your point about setting the raft air gap to 0. I still do not see the point about printing PLA on a raft rather than on the bed; unless of course you need to do that because the bed is in such a poor state that one needs to put plastic down to create a “smooth” base for the model to print on?; if it were that bad I would buy a new bed, in reality a new plate.

The important point to make is that it is not accurate to say that the z-gap is not set in Cura; sure it does not have to be set in Cura but it can be, I do and IMHO it is a better method. One can be more accurate; even a difference of 20 microns but certainly 40 microns will move you from optimum distance to sub optimum distance, try getting that accuracy with your finger and thumb. It does not affect your bed level; one is not turning 3 knobs imprecisely the same distance; if they are not the same, one spoils the bed level.

Of course all this is after setting the bed level manually which sets the distance hopefully reasonably close to the optimum - except one can see it does not do that consistently when one sees pictures posted on the forum by people with adhesion problems.

The alternative method to tuning with z-offset is to tune the distance on the fly, which a lot of people like and I have used. I.E. start a print, preferably with a skirt and adjust the distance with the screws so you can see visually the exact pressure you are inducing. With some practice it is pretty easy to get it done accurately and I am sure quickly for those who are good at it. As an ex IT guy I guess I just lean towards using code rather than manual process for rigour and repeatability .

[dwpearl03 0]

Thanks, for the input guys. When I first started printing, I struggled with adhesion to the bed issues. After checking in several forums, I tried the blue tape. Honestly, I have had great results printing on the tape and with a raft in regards to adhering issues. I guess in a way, those may be a crutch that is hindering me now from getting great results. I probably need to break down, buy some glass and give the 3Dlac a try. I've never been happy with the surface on the bottom of my prints.

 

I understand what you mean by z-offset now. The air raft gap would be comparable to the z-offset but instead of measuring between build plate and nozzle for first layer, it is between the raft and the first layer. If the air raft gap is too large, the first layer won't adhere to the raft and if its too small, the raft won't separate nicely. It essentially becomes part of the model.

I kept I higher bed temp in hopes of preventing the model from cooling too fast and therefore shrinking.

 

I did make some changes and had better results with the warping. I blocked some of the airflow and also added some right angles that were about 10mm tall around the corners but separate from the corners that were warping. I also lowered the temp a few degrees. I had much better results from that. I also lowered the raft air gap back to 0.2 and luckily I did not have any problems removing the raft. Maybe I could go lower.

 

The first layer was still not great. I think I need to find a way to ditch the raft and get some good plate adhesion from the start. Maybe I can fine tune it while it's getting started. Does that 3Dlac seem to about $40? The only place I can find it is Ebay.

[Bossler 8]

Wow, 40$? Here in Europe it starts around 10,-€ plus shipping...

 

I have been told there are ordinary hairsprays that work well too.

But after trying at least 5 different hairsprays without too well results,
I tried this stuff and as said I am more concerned about prints sticking too well than anything else.

 

But - for PLA you should really not need this stuff.

 

If you did really do a good manual leveling and the print does not stick to the really clean glass plate,

you may try a smooth layer of Elmers as well. You may want to lookup how to apply that smoothly.

In a nutshell you smear one layer of it onto the glass plate, then a second one perpendicular to the first.

Thin - it's not always more equals better;-)

Then using a wet piece of cloth/a wet soft sponge, distribute the glue evenly so a very thin layer is left.

 

Let it dry and print...

 

This is cheaper than 3DLac (@40$...) but more work, I'd say.

 

[Bossler 8]

18 hours ago, yellowshark said:

The important point to make is that it is not accurate to say that the z-gap is not set in Cura; sure it does not have to be set in Cura but it can be, I do and IMHO it is a better method. One can be more accurate; even a difference of 20 microns but certainly 40 microns will move you from optimum distance to sub optimum distance, try getting that accuracy with your finger and thumb. It does not affect your bed level; one is not turning 3 knobs imprecisely the same distance; if they are not the same, one spoils the bed level.

 

These two way of influencing the z-gap are to address two different issues.

Setting the z-gap during manual bed leveling should make the print bed as parallel to the gantry as possible while defining the default z-gap.

 

Changing the z-gap from within cura is a way to finetune this setting.

 

If the first one is not done precisely enough, the later will be of little value...

[yellowshark 153]

Oh for sure, if the print bed is not level then you will not get a consistent z-gap across the bed. That is one of the advantages of using the "on the fly" method because you can correct a bad level using the process.

 

BUT I clearly take a different view on life to you, which is that bed levelling is that. It does not set THE z-gap; it sets A z-gap, by the nature of the process, which is hopefully usable but not THE optimum z-gap; this is done by using the on the fly method or the Cura method.

 A lot of people will use an A4 sheet or whatever during levelling (bearing in mind that certain countries have A4 sheets of different thicknesses) and then generally lessen the gap to get the optimum setting for them.  

 

[geert_2 558]

I think, if your printer has a heated glass bed, and you print PLA, you really should consider printing directly on the glass. Heat the bed to 60°C (for a start, adjust in steps of 5°C as required), and use one of the many available bonding aids as required by your models: 10% wood glue dilluted in water (=gr5's method), hairspray (=neotko's method), 3DLac, salt method (=my prefered method), glue stick (wipe with wet cloth afterwards), etc... Give them a honest try and chose the one that works best, and/or that you like most. On the Ultimakers, I think no one prints on rafts anymore, unless for a very good reason (e.g. model has no flat bottom). I believe rafts were a good solution from the past before heated glass beds existed, when only ABS was available, and before the current good bonding methods were developed. But now they are obsolete for most printers, materials and models, apart from a few exceptions.

 

[dwpearl03 0]

Alright, you guys have sold me. I'm going to order some glass!

[gr5 2,267]

Don't order the glass if you can't heat it.  It's pretty useless below around 30 or 40C.

 

I mean you can put blue tape on glass - that works also.

 

I have been printing for about 5 years with all kinds of print surfaces and I finally created a video that explains how to get your parts to stick like hell.  So well that you will be annoyed with me because now you don't know how to get your parts off.  But I explain why you need to do these things also.  How to use blue tape correctly (you must remove the wax!!!!).  How to use glass or kapton or abs slurry.  why to do these things.  why people use warmer temperatures (2 reasons).  And so on.  It's a long video but it has a lot of info in it: