PLA not sticking to glas

Hi,

my printer is a RepRapPro Mendel and I think I got it basically working ok now. And I had no problems with the PLA that came with the assembly kit. But the first PLA I purchased (from [fabber-parts.de] ) seems to dislike the glas bed.

My experiments so far show this:
I can extrude it a temperature of 176° (didn't try lower) and I already got it stick to the bed (heated at 85°) with a small part that had little contact to the bed. But I had to slow down the feed rate to 4mm/s for that. It seems to be very crucial that the glas is absolutely clean (the PLA leaves traces of some sort that don't go away with acetone, so I have to dismount the glas and clean it in the kitchen with hot water and rinsing agent).

So far so good, but now with a bigger part I tried all day to get it to stick to the glas and while I succeeded at last, I wonder if I am missing something here. I had to dial up the temperature of the hot end to 225° and heated the glas up to 102° (feed rate still at 4mm/s). After the first layer I dialed back the temperatures to 185° and 85° rsp. The part finnished quite ok; it was still sort of sticking to the bed at the end, but barely. About a fith of its base warped up and lost contact to the bed during printing (4 hours).

Is this normal or am I missing something important here? Any comment or help is highly appreciated!

tl;dr: PLA does not stick to glas until heated to insane temperature. Why?

Thanks and best wishes,
Holger.

Hi Holgero,

When I first got my printer a little over a year ago, I spent maybe 100 hours to get everything dialed in (calibration, suitable profiles for my slicing programs and getting PLA to stick to my heated glass print bed).

This is what I have learned :

NOT all PLA Filaments are created equal (so keep a log and you might have to create variations in your slicing profiles; Filament Diameter, Temperature, Flow Rate, Filament Density Ratio etc.).

To get any type of filament to stick to your print bed, the bed has to level within about 1/4 of your Layer Height (Layer Height say is .2mm, your bed should be level within say .05mm).

Z Home height of course is critical.

Forget Rafts (you don't need them), but you do need a good First Layer (slow down the Feed Rate and adjust the Flow Rates and use a Skirt/Brim Feature (Slicer has this feature and so does Skeinforge v50 with Brim Plugin; adjust setting so that Skirt/Brim is part of/touches the outside Perimeter of your First Layer), this feature will prevent your print from curling the edges or worse separating when your print has progressed and almost finished.

Bed Temp is critical, for PLA set to 55c-60c. Under 55c your PLA will not stick, and over 60c the first layer may actual blister which makes for a very ugly First Layer and increases your risk of the print lifting later during printing.

I experimented with Acetone, Isopropyl Rubbing Alcohol etc. I found that my prints stick and adhere perfectly every time by using this method.
Use Rubbing Alcohol moistening a clean paper towel, wipe bed, and then immediately gently blow it dry (if you do not blow it dry, it seems to leave a slight residue that prevent the PLA from sticking to the bed). This method WORKS 100% of the time !

The temperature of your extruded filament to the print bed in my finding has no real effect in adhering to the print bed.

Hope this helps !

Shawn

Edited 2 time(s). Last edit at 01/05/2013 12:44PM by ShawnT98027.

I'll bet you'll get as many different solution as people who post in reply. I no longer have peeling problems. I extrude my first layer of PLA 10 degrees hotter than subsequent layers. I use a solution of 50 percent PVA glue on a bed heated to 45 degrees. When the print finishes, let the bed cool to ambient and your printed item will come off easily. Don't have the bed too hot or you'll never get your thing off it without breaking the glass.

I paint the solution on with a paint Bruce and let it dry. One treatment does several print runs.

---

Using ABSPrusa Mendel Zaphod with Pronterface and slic3r 1.3.0. Printing well with 3mm PLA and ABS through 2 x J Head Mk IV b and Wade Geared Exruders. Controlled using RAMPS1.4 board running Marlin_v1.1.9

Hi Shawn,

Thanks a lot for your tips! Iwill try Isopropyl Rubbing Alcohol for cleaning the bed next. I think the bed is quite level, but I am not sure if I can measure that with 1/100 mm accuracy. But I was always watching the extrusion and didn't notice anything (like changing thickness of the filament while the perimeter was printed or so).
But further slowing down the printing speed might help, perhaps I will reduce the speed settings for the first layer further and give that brim plugin a try.

Thanks very much and best wishes,
Holger.

Hi MotoBarsteward,

that's ok, I can try them out and perhaps one works for me (or better put: works for this kind of PLA), too. So thank you for your tip with the glue. What exactly do you use as solvent for the PVA glue? I googled PVA glue and found in the german wikipedia that a common glue here (UHU (TM)) is made of a 40% solution of PVA in Acetone/Methyl acetate, would that come close to your solution? Or is it a solution in water, like in "white glue" or "carpenter's glue"? And will I be able to get the glass clean of the glue again? (E.g. when I want to switch the plastic.)

Thanks and best wishes,
Holger.

Goo, old fashioned, tap water.

holgero Wrote:
-------------------------------------------------------
> Hi MotoBarsteward,
>
> that's ok, I can try them out and perhaps one
> works for me (or better put: works for this kind
> of PLA), too. So thank you for your tip with the
> glue. What exactly do you use as solvent for the
> PVA glue? I googled PVA glue and found in the
> german wikipedia that a common glue here (UHU
> (TM)) is made of a 40% solution of PVA in
> Acetone/Methyl acetate, would that come close to
> your solution? Or is it a solution in water, like
> in "white glue" or "carpenter's glue"? And will I
> be able to get the glass clean of the glue again?
> (E.g. when I want to switch the plastic.)
>
> Thanks and best wishes,
> Holger.

---

Using ABSPrusa Mendel Zaphod with Pronterface and slic3r 1.3.0. Printing well with 3mm PLA and ABS through 2 x J Head Mk IV b and Wade Geared Exruders. Controlled using RAMPS1.4 board running Marlin_v1.1.9

I've just started getting problems with prints not sticking to the glass for more than about 10mm high prints...

To begin with every print stuck so well I would have to wait for a bed temp of 30degC before I could get the print off. It was often hard to get the print off the bed.

Then suddenly prints started coming unstuck after 10mm height.

I tried turning the glass over and using the other side but that made no difference.
I've always been cleaning the glass with basic nail polish remover or a lens cleaner.
I did change the PLA spool but the first prints from the new spool were fine (however none of them were very high prints).

Could the moisture content of the PLA have an effect??? If there was moisture in the PLA then it might sweat as it sits on the bed and then become unstuck.

Cleaning the bed more and using higher and higher temps might just be compensating for moisture in the PLA.

Do printers in humid enviroments suffer more than printers in dry environments?

Higher Temperatures do not help, they create the opposite: Warping which leads to detachment from the printing surface.

Try 55 Degrees for the Glass. Remove any fingertips with acetone. Silicone from the mirror production can lead to bad adhesion as well.

Now try printing at 185 for example. Slow speed on first layer and maybe brim/skirt with 0mm distance to your object. Lets say 6 rounds or about 3-5mm wide in total.

When you printer finishes the first layer please tell your slicing software to turn on the fan. Without any cooling the core of the plastic heads up with every layer will the outside perimeters as well as the part attached to the headbed cools down to the environment temperature. When printing flat things this does the curling edges.

If it works this way you can go from there and try to remove the part directly after printing. If you are unable to remove it everything is fine. Maybe you can print without brim. Test it on another part.

If not you should adjust you Z-Distance and you could turn up the first layer which would create even more stickness.

Another hint: Recheck your Extruder, maybe everything settled down a bit and now the pressure applied to the transport mechanism has changed and therefore changed to amount of filament transported?

Thanks for your tip! I will try to explore the real low temperature range, too.

Keep an Document of your changes. So you can always go back to a working profile. Many times I messed up with to many profiles and minor changes making big differences.

Its good to have some states documented by printed things you keep. So if things go wrong you can always recheck the exact setting on the same .stl

Hi Holgero,

DerKulturfolger has it right also...
"Higher Temperatures do not help, they create the opposite: Warping which leads to detachment from the printing surface."
100% Correct !

The higher extrude temperature on the first layer, is in fact wrong as stated by a previous poster . The more heat, the more cooling occurs in regards to heated bed temp and ambient room temperature, hence MORE warping and curling of your print.

I generally print my first layer at normal extruder temperature to 3c-lower than my general extruder temperature.

If you think in mechanical terms and physical properties (in regards to your machine, your filament properties, and how heat affects materials used) you can't go wrong.

Happy Printing !!!

Best Regards,

Shawn

Edited 1 time(s). Last edit at 01/10/2013 02:13PM by ShawnT98027.

Hi,

the last days I used ABS, which didn't cause any trouble and stuck to the glas just fine. Today I switched again and tried out your hints.

First try: 55c bed temparture and 185c extrusion on plain glas. This didn't stick at all and just produced a glob of plastik.

Second try: I used a solution of 1 part PVA glue (Ponal classic (R)) in 2 parts water and painted the glas with it. (Didn't have a proper brush at hand, so I just soaked a piece of a paper towel with it and applied the solution to the glas). Let that dry again (gave a thin whitish layer on the glas). Printed with the same settings (55c/185c) and voila: it stuck just fine. It was just a small print and I had no problems to get it of the glas afterwards (let it cool just a bit).

In short: the PVA glue did it for this type of PLA! Many thanks for all your help and the many tips!

Now I am going to print some spare parts for the printer...

Best wishes,
Holger.

Tried something completely different: I removed the glas and replaced it with some plywood. Works very well, too! I still heat the bed to 55° C and the PLA sticks firmly to it.