Prusa Mendel Print Surface
From HacDC Wiki
Glass is an ideal print surface material. It binds strongly to the plastic while warm, and releases the part once cool. Additionally, glass is somewhat rigid, flattening out the print surface.
Obviously, is all good for first layer alignment, warp prevention, and easy part removal at the end of a job.
Ideal Glass Surface
Pyroceramic Glass, 9" * 9", Four Mounting Holes. Recommend against the similar bed design here. The wiring cutout and larger 9.5" * 9.5" size may contribute unnecessarily to thermal stress.
Can be ordered from One Day Glass.
Ordinary glass can be purchased from a variety of stores, cut to size, the drilled with a dremel and the cylindrical diamond abrasion tool. After a little practice, new glass beds can be manufactured with just a few dollars and 20 minutes.
Tenleytown Ace Hardware is especially helpful, offering cutting service with the glass.
Unfortunately, ordinary glass does tolerate thermal stress well. Although we are in theory using a PCB heater to evenly warm the bed, in practice the thermal gradient from center to outside edge can be high as 30C. Catastrophic failure becomes likely given mechanical stress, spot heatingcooling from some 3D printed parts, or microfractures on a poorly cut edge. Further, ordinary glass may be less rigid, prone to representing complex warped shapes underneath it.
Plastics tend to offer extremely tough adhesion, without the quick release behavior offered by glass. While this may be helpful at times, care is needed to prevent parts from permanently binding to the print surface, even if paper or kapton tape layers are used.
When printing on these surfaces, please set the bed temperature as low as possible. Recommend no more than 45C for PLA.
Additionally, plastic surfaces are inherently less rigid than glass, particularly if thinner than ~5mm.
An 8.25mm acrylic sheet has been salvaged from a disassembled LCD monitor, and laser cut to fit. At this thickness, rigidity seems to be exceptional. Probably the best choice for laying down a paper tape or kapton printing surface.
A 5.75mm polycarbonate sheet has been cut and drilled to fit our printer.