What is a good strategy for removing 3d prints from an UNheated Glass bed?

Question

I have a LARGE piece of glass (36"x26") that I will soon be printing on using my newly build MPCNC machine. It is capable of printing about 34"x34"x10".

Anyway, I have had GREAT success printing on heated glass that is sprayed lightly with hairspray using PLA and being able to EASILY remove my prints after the glass has cooled. I attribute this to the slight expansion and contraction that occurs when glass is heated and cooled. This would weaken the cohesion of the PLA print to the glass.

I have another posting where I asked how to heat this LARGE glass bed. However, there weren't any feasable (inexpensive and easy) solutions to heat the glass. So, now with cold glass, what are some good strategies for removing large 3d printed objects without breaking them or the glass?

Answer 1

Because you will be printing on unheated glass, you will be using some form of adhesive material. If you use an off-the-shelf glue stick, you will likely find it is water soluble. If the bed is removable, immersing it in warm water for a relaxing soak will provide easier model removal.

I don't have experience with various tapes, so will avoid recommendations regarding masking tapes or similar material.

Thermal cycling will also provide release. Not a heat gun, as that will break the glass, but a hair dryer applied to the underside near the model, then cooling. Repeat until it releases.

I have used the Fleks3D print plate on my Flux Delta printer in the past, and it releases "like magic" but I don't think they make monster sheets of your printer size. I had also purchased a pair of 20" square Fleks3D plates for a similarly sized printer that never materialized. I'd be happy to sell you the pair, but I think they are too small for your full plate.

It has been said that one can use sand-blasted acrylic, which I believe is the construction of the aforementioned Fleks3D plates. If you have access to 1/8" or 3mm acrylic and can apply a uniform blast of abrasive, you may be able to construct your own easy-release build plate.

It is practical to consider to use a raft for your large builds. Rafts are useful for small items, to provide a greater bonding surface and avoid release, but it also provides a "wedging" location for your release tool. You can more easily slice away the middle of the raft and deal with a thinner layer after the model is completely freed.

EDIT ADD: If the bed is not removable, one can build a dam around the model with clay to hold the water for dissolving the glue.

Answer 2

It is quite common to print PLA on blue painters tape (such as this). This makes print removal very easy, since you can remove the tape entirely for those parts that don't pop off by themselves.

On the downside, you might experience issues with the tape itself lifting from the bed when printing parts that wrap a lot. A wide tape that adheres well to the glass can alleviate this issue. Also, make sure to thoroughly clean the bed before applying the tape.

That being said, if you print large parts that warp a lot, most blue painters tape that I have tried will eventually release from the glass to some degree. If you manage to strike a balance between stickiness and removability when using a glue stick/hair spray/PVA-mix etc., such solutions might be favourable.

Answer 3

3M Blue decorators tape works well for me. You can get it in different widths. I find giving it a little sand paper rub before each print helps corners to stay down and improves first layer print. I replace about every 10 prints depending on the importance of the print.