As I explained in the last post, my heated bed failed on me and the relay board had to be replaced.
One good thing about having a dead bed heater is that it forced me to experiment with printing PLA on a non-heated bed. Plenty of printers don't have heated beds after all so it should work for me too.
First I tried printing on the hairspray I have been using with the heated bed. I didn't have much success with that. the first layer of PLA just didn't stick and I ended up with scrap.
Moving on, I tried using washable glue sticks and painters tape. Both gave pretty good results in some situations, once I got the setup right.
Washable glue sticks worked fine for me as a bed material if I was printing small parts. I had trouble with warping when I got over about 20 mm. The longer parts wanted to pull up at the corners. That might be because I don't have just the right glue thickness or some other variable figured out yet. I am trying variations.
You can see the warping at the wing and horizontal stabilizer tips in this picture of a jet I was printing.
Small parts come out great. They stick down during printing yet come off the plate with only a little effort when they are done.
This lion is well attached to the bed.
Glue is my choice for small parts and I hope I can master using it with larger ones too. It is easy to use, lasts quit a while and is easy to remove.
Blue painter's tape is another very popular bed material so I tried that too. You can also use Kapton tape but that is better suited to a heated bed. The rougher surface, or "tooth" of painter's tape should hold better on an non-heated bed.
My first attempt with it was a total failure. This is with PLA at 190 degrees C. It just didn't stick down at all.
Attempt number 2 went better. I upped the temperature to 200 and that stuck a little better. The first layer wasn't great but it stayed down enough to get some of the upper layers on top of it. The good news is no warping at the wing tips on this jet.
I should be able to make the tape work if I can get the first layer right.
I was also disappointed on how short a time a layer of tape lasts. Any little rip from removing prints or whatever and that section has to be replaced.
I haven''t given up on tape. I will play around with it a little more but, so far, I prefer glue for a cold bed and hairspray when using the heated bed.
I also tried using rafts and brims to get better adhesion of the print to the bed. These tools made a big difference in stopping the warping.
Rafts are a few bottom extra layers that extend out from the part to make a larger surface area. They worked very well for sticking the part to the bed but, it is hard to get them free from the printed part and still leave a clean bottom. Anyone know a good way to do that?
Using a brim seems like a better way. They are additional loops of materiel that extends out from the part in a single layer. Since the brim does not add anything to the bottom, it is easier to clean off and almost as effective in holding the part down as a raft.
To make a brim in MatterControl, use the skirt settings. I set the number of loops to 8 and the spacing from the part to 0 so the brim touches the printed object.
I want to pick up a couple more 10" X 10: pieces of glass so I can have them set up with different bed materials. That way I can just swap the glass and not have to clean off one coating to use another.
To really make it easier, I should be able set up Z Offsets to match the thickness of each material. That should be a lot easier than moving the end stop and re-leveling the bed every time I change material.
So what do you prefer for your bed material? To you always use a heated bed or run it cold when you can? Your input is welcome. Please leave comments and question below.
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