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Getting good first layer bed adhesion

Nov 26 2015
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One of the challenges makers face is how to make the first layer stick to the print bed. In this article I talk about my experiences with different types of adhesives, filaments and surfaces.

When I started out with 3D printing I did some research on forums what people used to make their prints stick. There's a wide variety of things people have tried and stick with (no pun intended).

The more common types of bed are aluminium and glass plates. It seems that no filament sticks directly to aluminium while glass is a hit and miss affair, it sometimes sticks, sometimes it doesn't. Borosilicate seems to be more consistent. Chemicals like alcohol and acetone are used to clean the plates for better adhesion.

Less common are acrylic and PEI sheets. PEI seems to be a good bed to print on, you don't need any adhesives and prints come loose after printing very easily. It's a bit expensive though and if the nozzle hits the surface, the surface gets dented. There are commercially available beds, sheets and adhesives that give good results, though I haven't tested them myself. I like to use cheap and readily available materials to use in my printing.

Common types of adhesives are: hair spray (extra strong hold), PVA / regular water based school glue, ABS slurry, mixture of sugar, water and lemon, blue painters tape sometimes combined with wiping it with alcohol or acetone.

Less common are vinyl table cloth, acrylic varnish and nylon sheet.

I've experimented with painters tape with PLA and it sticks well enough but often leaves some tape residue on the print. The print surface that makes contact with the tape is rough. I didn't like the rough finish and tried hairspray. It doesn't stick well enough with the one I got, and it can be pulled from the glass plate easily. I've tried a number of types of glue, terpentine based, water based. The best results comes from PVA glue in combination with glass and nylon. PLA and ABS don't stick that well it it while nylon is difficult to remove. I've found that diluting it with water makes it easier to remove.

I then tried vinyl table cloth, the clear variety. It worked very well with ABS. PLA doesn't stick as well as ABS but it's certainly usable. Nylon doesn't stick so well so I have another glass plate with PVA glue for those cases.

The advantage of vinyl is that it's cheap and easily available, can be easily removed from the glass plate and lasts 10-50 prints. I sand the print side of the vinyl to make ABS stick better. In fact the first layer sticks so well I can tear the vinyl if I'm not careful. After the first print it becomes easier to remove prints. The vinyl sticks to glass very well and can be applied bubble free when heated to 60 degrees on the print bed. When printing I use 110 for ABS and 40-60 for PLA.

Vinyl also works well with HIPS. The adhesion is between ABS and PLA.

Recently I've been experimenting with acrylic varnish. ABS sticks well to it, and is also easy to remove. The finish is a bit smoother compared to vinyl.

 Pla shrinks upon cooling, like most filaments do. There are a few factors that has influence on layer adhesion and delamination.

- the ratio of extrusion width and layer height should be about 1.2 as a minimum. So it should be wider than heigh. The wider it is, the more pressure is excerted, pressing the layers together.
- wall thickness, if you have thin walls like 0.5 to 2mm, the chances of delamination are higher.
- object design. If your object has large wall areas and 90 degree sharp corners there are stresses in the material due to shrinking unevenly. You can design your parts with holes to relieve the stresses, and use chamfered or rounded corners.
- If the corners don't lift during printing or after cooling, it means it's sticking very well to the bed. The consequence is that the stresses needs to go somewhere and often result in delamination. Printing in an enclosure to keep the temperature more constant may help. With pla one often uses a part cooling fan. If the ambient temperature is too low the part cools too quickly and too much.
- using a heated bed helps. For pla 40-60 degrees is usually working well.
- As said above print temperature has an effect on adhesion. Normally the higher it is the better it is. At some point it gets too high and causes stringing, blobs during retractions and expands/shrinks more.
- often when the print is just finished, it's not yet delaminated, but during cooling, too rapidly, it cracks. Let it cool slowly in an enclosure, or put a few sheets of paper kitchen towels over it to insulate it. It's also possible to use some end gcode to lower the bed temperature in steps of 10 degrees until 30 degrees is reached, waiting between each step a couple of minutes.
- if the extruder isn't extruding evenly the chance you get weak parts increases. If one layer prints thinner than the next you need to find out why the extruder isn't running consistently. Check motor current, the filament path isn't blocked or binding, the hobbed bolt should be propetly aligned and the idler should apply the proper pressure, not to much, not yoo little.
- a very level bed helps with first layer adhesion and also the next layers as they may be squeezed or too far apart.

Last changed: May 16 2017 at 9:27 AM

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