I am using acrylic sheets as my 3D print surface. I have tried many other types: glass, ABS slurry on Kapton, blue painter’s tape, and Kapton on aluminum (described at the end of this previous post). This surface works the best BY FAR. I use a thin sheet of acrylic on top of an eighth inch precision aluminum plate over the heated bed. The RepRap bed is not very rigid, and the acrylic is even more flexible. The aluminum sheet passes the heat from the bed to the acrylic and also provides complete rigidity. When the print is done, the acrylic can be flexed to pop off the model.
If you are prying your 3D prints off of a bed using a chisel, STOP. You will usually wreck your model and might hurt yourself. This is super easy to use, and very satisfying when you see your new, perfect model just pop off of the base. This works every time, even if the model has a large, flat base adhered to the sheet. You don’t need a raft.
The sheets are reusable several times and then become disposable. I typically print 2-3 times on a side and then flip the sheet. Once it warps from heating or once any ABS sticks to it, I throw it away (recycle it actually) and use a new one. I buy 0.093 inch acrylic sheets from Home Depot. The model number I use is MC-09, Store SKU #241903. The cost for a 36 x 48 x .093 inch sheet is $34.98 plus tax. I cut 20 sheets from this piece, so my cost per sheet is $1.84.
I started by sawing the sheets using my bandsaw, but it is pretty easy to press down a heavy duty ruler, score the sheet with a linoleum knife or similar cutting tool, lay a piece of 2×4 lumber on the seam and flex the sheet to crack it right along the line. Make sure to flip the sheet so that the scored line faces downwards, away from the flex direction. Put both knees on the 2×4 to apply your full body weight to the sheet about 1 inch or less from the score line and then pull up pretty hard on the free end of the sheet. Do this operation on clean carpet so that you don’t scratch the acrylic sheet. There are no debris or dust involved in the process, unlike the bandsaw, which makes an unholy mess of things! Make sure that the score line reaches both edges of the sheet, or the corners will crack in undesirable directions. I only need to saw the corners to fit on my RepRap heated bed. The bed is 21.5 cm (8.465 inches) square.
As you can see in the pictures, I use a heated build chamber. I built this entire 3D printer from scratch (not a kit). I operate at 70 C in the chamber, heated by the extra build platform mounted to the side wall, and of course heat is also added by the extruder and heated bed. I also run 200 W of halogen lamp since this provides both light and heat. I use a PID controller to turn the sidewall heater on and off to maintain 70 C. The bed is also heated to 70 C, same as the chamber temperature. This minimizes any temperature gradients anywhere in the build area. This has ELIMINATED delamination in even my largest prints.
I use 13 binder clips to hold down the acrylic sheet. I found that this helps to keep it very flat. That is super important for 3D printing if you want high quality and if you never want to deal with extruder jams.
I can not recommend this method highly enough. There is a reason why commercial printers use disposable base sheets. Well, honestly, a few reasons. The important one is that it works well. The second of course is that they can sell you extra beds at a high cost. The DIY path costs you less than two bucks! Not bad.
Here is a video demonstrating how well this works.