I see many improvements after switching the heated bed off after the first layer
So i've been doing this since June or so last year, i've been switching my heated bed off after the first layer when printing with PLA or PETG.
First layer for PLA is usually 65 degrees, second layer is 0 degrees (off)
But! This can only be done when printing with a Brim.
This has the following upsides:
- energy saved; the heated bed consumes an average of 50 - 60 watts after the high powerup phase. This usually saves you a couple of dollars of energy cost per week.
- no print lifting or warping; since there is no hot zone below the print, and the cool air from the fan blowing on the base of the print, the prints will never popp off the bed. The bed naturally cools down over 10 - 20 Minutes, which will slowly cool down the layers directly on top of it, too.
- cleaner prints; since the filament blower will not suck in warm air anymore from the heated bed and blow it towards the print, you can print a lot of things cleaner now and a lot steeper overhangs go without a hitch now.
- no hot ambient temps in a case; since you remove 60 watts of heat from the system, leaving only the 30watt filament heater element. Can print without a enclosure fan with PLA.
The downside is that when printing without a Brim, the cold air will still dig itself below the first layers of the print and the bed for bigger objects, removing them from the heatbed. The Brim will act as a 'wave breaker' for the air, not letting it below the print.
Also doesn't work with ABS, but who still prints that today...
I print just about everything with a 6 - 8mm Brim now, except objects which i can't remove the Brim cleanly and need to set the Elephant Foor compensation to 0.2mm.
I never had a failed print with this method before.
Anyone else tried this before?
Re: I see many improvements after switching the heated bed off after the first layer
Can you post some before & after pics to show the difference? I'm curious...
And for what it's worth, ABS does have its uses and I frequently print with it. There's no one material that does it all.
Re: I see many improvements after switching the heated bed off after the first layer
Can you post some before & after pics to show the difference? I'm curious...
And for what it's worth, ABS does have its uses and I frequently print with it. There's no one material that does it all.
Examples laying around, hmm, i should have a few old Benchies where the front of the hull was always dented in with the heatbed on, and not dented in with the heatbed off. Have to look for them, but they were the same gcode.
The filament fan was blowing hot air onto the layers for cooling, didn't work so well.
Note this was in a enclosure, so a bit restricted airflow, but there were 2 fans in the case for pumping the hot air out.
Works better if the printer is out in the open, since there's much more colder air in the entire room than the case. Still, the principle works also for printers in the open.
Re: I see many improvements after switching the heated bed off after the first layer
I've just recently had the use of a robo C2 without heated bed and I am astonished at how good the bed adhesion is. I believe the bed is PEI.
Do you print models that have to be dimensionally accurate. Would like to here your experience with regards to this.
Re: I see many improvements after switching the heated bed off after the first layer
Can't you just print PLA without any heated bed at all?
Re: I see many improvements after switching the heated bed off after the first layer
I'm using this trick to print with FLEX. It sticks pretty well to the bed, so no heating is required after couple first layer.
In case of PLA and PEI sheet I wouldn't do that. The risk to loose adhesion is too high. It might work if you slow down and everything else is going perfectly well. But from my experience so far, it's a rare case. Usually there is always a friction between the model and the nozzle. And sometimes something is curling up. In this case I prefer reliability and keep it at 55C.
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Re: I see many improvements after switching the heated bed off after the first layer
I'm using this trick to print with FLEX. It sticks pretty well to the bed, so no heating is required after couple first layer.
In case of PLA and PEI sheet I wouldn't do that. The risk to loose adhesion is too high. It might work if you slow down and everything else is going perfectly well. But from my experience so far, it's a rare case. Usually there is always a friction between the model and the nozzle. And sometimes something is curling up. In this case I prefer reliability and keep it at 55C.
For small and tall objects like a tube this could be true, since there is leverage.
Normalish objects (with PLA) usually stick so good that i have much trouble removing them from the bed. I made a bent spatula that is almost as sharp as a razor at the tip and have been using this to get the objects off since November last year. Before that much Banging on the print or prying it off with flat pliers was done. PEI sticks amazing when 100% clean. Acetone wipes also helps a lot for adhesion.
Re: I see many improvements after switching the heated bed off after the first layer
Do you print models that have to be dimensionally accurate. Would like to here your experience with regards to this.
Now where did that come from?
Sure, we have 3x MK2s in my care at my company, and we mostly print production helping tools and various forms for testing the electronics with it.
The big prints are often very accurate, with +-0.05 tolerances on XY, and +-0.1 on Z
Holes never work though, its just the way the plastic flows. Have to be drilled up.
Small parts may or may not work, usually the CAD designers give these to the CNC guy.
Re: I see many improvements after switching the heated bed off after the first layer
Considering the thermal shock from nozzle heat to ambient cooling, heated bed is contributing little to the overall thermal transition of a part being printed save for keeping the contact surface just that little bit more pliable improving adhesion. But that for some is everything.
All material have differing characteristics, be it cooling-vs-shrinkage, molten thermal conduction vs cold thermal conduction, deformation over load vs. temperature range, so many factors rarely provided by filament producers it is criminal in my opinion. In more simple terms, durable materials such as PC, Nylon and PETG tend to be "softer" where the elasticity is what provides impact resistance. These materials suffer more from a cool bed than brittle materials such as PLA because they allow the accumulation of shrink strain ultimately creating delamination or full bed detachment without even considering curl crash forces. As these materials are just that little bit more pliable when heat is applied over a large contact area, shrink stress accumulation is reduced (not eliminated) allowing a higher chance of success.
If you can manage the thermal mass layer per layer to reduce curling crash chances, you've designed the object with print stress compensation devices (infill as an example), then heated bed could be an unnecessary expense. If not, a couple kilowatts is a small price to pay to lower risk of detachment due to curl crashing or complete bed delamination due to accumulated shrinkage strain for most home printing.
MK2S kit owner since 8/15/2017