What surface to use for 3D printer?

Question

I'm mechanical engineering student who want to construct 3D printer. I have a problem choosing right and cheap material for bed. Bed will be big for a 3D printer, around 700mm x 500mm. I want to print PLA, PETG, ABS, PC. Bed MUST be heated, and i sensor for height is also necessary.

I googled it a lot, I have been checking out forums (even here), but I still don't know what to choose. I just know i don't want to have borosilicate glass, because it is too heavy and bed will be moving up and down along Z.

This is my list of material for bed:

PEI great surface, even here i think this is what everybody is suggesting. These are sheets, so I will need a base to put it on. What should be a base? Alu is great for machining but it has really big temperature coefficient. Do you think zerodur is OK? Does anybody has any experience with it? Can I buy it in EU? Zerodur

Phenolic laminated G10-FR4 this is composite that MarkForged uses it on their printers. I had an opportunity to work with Mark 2 and i like it a lot, but glue is really necessary for good adhesion. Is it because Mark2 does not have heated bed? I saw it has a lot of different variations of material and not everything is good for bed surface.

Coropad - Tom's 3D really praised it. It is magnetic, so you can peal it of base. But what can i use for base? Regular S235 steel or C45? Can i use anything lighter and still magnetic? Does anybody uses it here?

This is my list, I'm choosing between one of them. Do you have any other materials that you recommend? What would you choose. IMO this is is critical component of 3D printer, while we know that most of mistakes on print is because of first layer adhesion. Hopefully you'll help me choose right surface :)

Answer 1

I have used both window glass and aluminum on mine with hairspray for adhesion and have had good luck with both; so you don't need to go overkill on high cost materials. Most of the print failures I have seen (on mine and other printers) are usually print head plugging/feed issues.

ABS has shrink problems that can't really be addressed with just adhesion; you need to print in a heated environment to reduce the layer by layer shrink effect. You are certainly better researched on these new materials than I, but know that it is likely that some will work better in some conditions and some will work better in others. Plan on it requiring some amount of experimentation and adaptation.

Adhesion is just one aspect to consider:

• The surface also needs to be very flat throughout a range of temperatures. Consider your mounting options.
• I don't know your printer design, but typically the z axis is gear reduced and experiences very little acceleration so mass is not a big issue. Mass can be an issue for high speed y (and possibly x) movements.
• Larger thermal mass does take longer to heat, but also provides a more stable temperature since most heat sources are controlled by an on/off relay.
• Higher thermal conductivity and larger thermal mass both produce a more evenly heated surface. The circuit board heating pads are not perfect especially with very thin materials.
• Some of the plastic bed materials have good adhesion, but only last 20 prints before needing to be replaced. Balance per-print prep time with repair time.