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SandervG

Tips for bed adhesion

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Good bed adhesion is one of the most important facets of 3D printing. When your print properly adhered to your bed you can sit back and relax while your print finishes. At the same time, when it does not adhere properly you are guaranteed of a fail. So, how can you ensure good bed adhesion?

A few ingredients are important. 

 

1) Bed leveling. 

Make sure your bed is level, and the space between your nozzle is not too much and not too tight. 

An Ultimaker 3 has active leveling which can help you achieve proper leveling. It is advised to manually level your bed before active leveling, so a potential offset is reduced to a minimum already. The less it has to compensate for, the better. For an Ultimaker 2, 2+ and Ultimaker Original you can use a calibration card supplied with the Ultimaker. The calibration card has a thickness of 0.15mm, which is exactly how much space you want between your nozzle and bed. 

 

2) The first layer

Ultimaker Cura has default settings for the first layer. In Cura, they're called 'initial layer' if you want to find them. This concerns among others the speed and thickness. We recommend printing your first layer at 20mm/s. A slower first layer gives the filament time to be squeezed onto the bed through the pressure it receives from the nozzle. Even when printing a high detailed 3D print, we recommend to print a thicker first layer, for the same reason as mentioned above. You want the first layer to squeezed on the glass plate. 

 

If the distance between your nozzle and build plate are correct and your first layer is printed at the right speed and thickness; your first print should look like #1. The layers are spread out and squeezed on the build plate evenly. 

5a8c0aaf40a24_goodfirstlayerUltimaker.thumb.jpg.ddd0463665608dab99cb99018922146b.jpg

In example #2 you can see some transparency in the first layer, this is usually an indication that the build plate was too tight to the nozzle. You can see near the edges how the excessive material is being pushed to the outside.

In #3 there was too much space in between the nozzle and build plate because of the roundish layers you see at the top. They are not squeezed on your build plate. 

 

3) Heat.

Heat can be a great source of adhesion. Different materials require different temperatures to ensure good adhesion. What temperature exactly may differ between filament manufacturers. For Ultimaker filament we recommend using the values proposed to you in Cura. 

As a rule of thumb, you could use these values as a starting point:

PLA: 60ºC - ABS: 80ºC - CPE: 70ºC - CPE+: 107ºC - Nylon: 60ºC - PC: 107ºC - PP: 85ºC - PVA: 60ºC - TPU:60ºC. 

 

4) Adhesives

Some materials are more prone to warping than others. Warping is when a material shrinks when it cools down. This shrinking can apply forces on the base of your 3D printed model which can result in the corners pulling up. To prevent this, you want to prevent a material from cooling down too fast (like by adding a door) and you can apply an additional adhesive. This can be a thin layer of glue applied with a glue stick, an adhesion sheet or other appliances like spray or partially dissolved material substances like ABS-slurry. 

Make sure you inform yourself if your material requires an additional adhesive. Your supplier should know. 

 

These tips should help you nail that first layer. Do you have any other tips or questions about your bed adhesion? Post them below! :)

 

 

 

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Parts coming loose can be a disaster worse than just having a failed print so I tend to squish more than sander indicates.  All the above steps are important but squishing like photo #2 above results in parts sticking even more. So for large prints or if you are still new at this then aim for #2 until you are more experienced.

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In the beginning, 2 years ago, I did several tests on the effect of bed temp on bonding of PLA.

 

At 60°C bonding was optimal for me.

 

At lower temps, for average objects usually it still worked well until 50°C. However, at 40°C models were likely to pop-off suddenly, with a loud snap, in mid-print. Below 30°C there was no bonding at all, for my models.

 

At higher temps at 70°C the PLA became too soft. And then corners would lift and be peeled off the bed, due to the shrinking forces from the layers above, and the whole model would warp and come off.

 

Thus a balance has to be found between hot enough for a good bonding, and not too hot so it does not stay too soft. The default value of 60°C for PLA seems to work best on both of my UM2. These tests were done on light blue Ultimaker PLA, and on colorFabb white and orange PLA/PHA, but they seem to be valid for other Ultimaker and colorFabb PLA too.

 

As bonding agent for PLA I only used my "salt method", because this worked better than the glue stick at that time. But back then I didn't know yet how thick the glue layer had to be (probably I made it too thick?), and I did not wipe the glue with a wet tissue afterwards, which seems to equalise the glue into a very thin layer and improves bonding.

 

For PET (or is it PETG) from ICE, a bed temp of 90°C seems to work best for me.

 

Before printing real objects, I recommend you design an inverted prism, with a very small ground base, and wide top. This excerts huge warping forces on a very small base, due to the overhangs. And the edges curl up, causing the nozzle to bang into them. So it is a very hard bonding test. Print this model with various bonding methods, and bed temps, stay with the printer (!!!!), and carefully watch what happens, and try which bonding method works best for you. If you can print such extremes well, it should work for average models too. I could not print this test with the glue stick, nor on a bare glass plate: the models came off and produced spaghetti. But it worked with the salt method, although edges did lift, so it was on the edge.

 

inverted_pyramid.thumb.jpg.c3c49b00905b923abd3f6e8f02b77847.jpg

Picture of a sort of inverted prism being printed. If I remember well, the base was only 2mm wide, but the top was going to be 10mm wide, and somewhere around 5 or 6mm high. And as you can see, at that time I also didn't know about atomic pulls and about worn-out white teflon couplers, so there is a little bit of underextrusion.

 

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On 20/02/2018 at 1:06 PM, SandervG said:

The calibration card has a thickness of 0.15mm, which is exactly how much space you want between your nozzle and bed. 

 

Question: is this also true for the UM3/E?

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yes.  Well here is what I think is a more precise explanation for leveling on both UM2 and UM3.

 

The calibration card has a thickness.  Say it's 0.15mm (not 100% sure).  when you level with this the firmware is assuming the nozzle is this distance from the glass (0.15mm or whatever the thickness is).  At this point the printer realizes that the nozzle and the glass are 0.15mm apart so it stores this calibration information such that forever in the future if you tell the printer to go to Z=0.15mm it will go to this location.  If you tell the printer to go to Z=0 it should hopefully touch the glass.

 

Typically the bottom layer thickness is 0.27mm meaning the printer sets Z=0.27mm while printing the bottom layer and it also extrudes just the right amount of material to fit that gap.

 

I prefer to level the printer without the calibration card (although then I tweak the 3 screws again when it starts printing) such that when you tell the printer to go to z=0.27mm it actually prints about 0.12mm between glass and nozzle.  This squishes the bottom layer extra hard.

 

Alternatively changing bottom layer height in cura to 0.1mm seems to work very well also.

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glass preperation

 

After "squish" the next most important thing is glass preparation.  Keeping it super clean is important.  Wash in soap and water and then dry AND THEN also wash with glass plus or similar window cleaner.  This will remove the last bit of soap and oil.

 

That's good enough for most prints but if you want it to stick even better I recommend a very thin layer of PVA.  The most common ways are:

1) 3DLAC - you spray this on the glass.  Easy.  But expensive compared to:

2) Hairspray.  I like aquanet unscented (blue can).  Make sure to remove the glass from the printer so you don't get PVA all over your printer and on the z screw

3) glue stick - for CPE you want a very thick layer so you can get the parts off but for PLA, ABS, Nylon and most other materials use a wet tissue to remove most of the glue and spread it very thin.

4) Wood glue.  I use Elmer's wood glue.  Mix it 10 to 20X parts water to 1 part wood glue.  I like to use a glass jar with wide lid.  Shake it up well.  Then open and use a small paintbrush to spread the milky liquid on the glass.  Heat to 60C and usually right about when glass reaches 60C it dries.  it should be thin enough that it's hard to see once dry.  Rinse the paintbrush afterward to keep it clean. 

 

The strangest thing about PVA is the thinner you make it the better parts seem to stick.  But obviously, at some point, you have no glue left.

#4 is my favorite method but I've tried 2 through 4.  They all work quite well.

 

5) Instead of PVA You can try salt water.  google it.

6) For ABS you can try ABS juice.  Google it.  Make it yourself.

 

I don't use any PVA glue for CPE as it can chip the glass (remove chunks of the glass) because it sticks too well.  I just clean the bed extra well.  Or I'm very careful not to squish the bottom layer much.  Or some people put extra thick glue stick down for CPE to keep the part from bonding to the glass too much.

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Side note on this, about the window cleaners: having made some test, most standard window cleaners you find in shops or malls are not to be used because, beyond cleaning, they deposit a thin layer of some anti-adhesive. Which is nice on your windows, and very bad for your printer. In my experience, avoid the cleaners that are blue, and most of the transparent ones as well. So far, the only one I've found that works well is the yellow one from Karcher: https://www.leroymerlin.fr/v3/p/produits/nettoyant-karcher-e1400355260

 

 

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I swear by Dimafix four our PLA prints to date. Works great and self releases once the bed cools down. Requires nothing more than a quick rinse under the tap to remove all traces of the adhesive.

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