Why heat the bed after first few layers?
If heating the bed is necessary for ensuring the first layer sticks, then why heat the bed after the first layer?
I see from the default profiles that the second fan turns on after the first layer. So it's trying to cool the print quickly. Why would the bed heating and that fan be on at the same time?
Also, after the first few layers, the bed heating won't be heating the print, right? So again, might as well turn it off, yes?
Will we risk the print curling up if turned off too soon? Ok, but then what about after say layer 30?
Perhaps another way of asking these questions is how are all the heaters/fans intended to interact?
Re: Why heat the bed after first few layers?
Best is to heat the entire chamber. No one can afford that but the bold few or fabrication lab/studios. What can be done is to heat the lowest layers mitigating chance of shrinkage detachment. Now, what do you get when you turn off that bed while printing? A massive heat sink right where you need the adhesion and have the most contact area (usually). It doesn't matter how many layers you have above, i3 is a moving platform style printer and curl will happen somewhere causing soft crashes that are usually fine but if your contact patch is compromised by localized contraction detachment, you're hosed sooner or later. Roll the dice if you shut it off, even for PLA. Or better your chances, in the least heat above ambient to avoid a COLD PLATE. I hope that helps make clear the seemingly contradictory cooling fan + heat-bed scenario.
MK2S kit owner since 8/15/2017
Re: Why heat the bed after first few layers?
How do you turn off the fan? Settings? Tune? I was printing with nylon carbon fiber getting GREAT prints and then the bed heater connection to the RAMPS board fried. I repaired it and now cannot get ANY successful print in nylon carbon fiber or ABS. Poor bed and layer adhesion issues. Spent the weekend testing evey live z setting and bed/nozzle temp setting imaginable. Moved printer to different locations (boiler room, laundry room, garage). Now focusing on fan settings. How do you do that?
Re: Why heat the bed after first few layers?
Prusa Research's Mini-Rambo has an integrated board so I assume you mean the RAMPS portion? Are you getting same heating performance from bed as before? Could whatever have caused connector failure caused issues with power max delivery? Is your printer reading out the right thermals as set in your slicer? Sorry, covering bases. You don't know how many times the answer was "not plugged in".
On fans. MK series doesn't thermally throttle the heatsink fan as I understand. Part fan is via G-code generated by your slicer. Part fan should not come on if you've not requested it in you slicer material settings. Some slicers will AUTO blow during bridges, whether you override that is up to you.
MK2S kit owner since 8/15/2017
Re: Why heat the bed after first few layers?
Best is to heat the entire chamber. No one can afford that but the bold few or fabrication lab/studios.
The reason no one can afford a fully heated print chamber is that having a temperature-controlled build chamber for 3D printing is patented. Until the patent expires (in a few years IIRC), any commercial vendor selling a printer with a temperature-controlled chamber is liable to get hit by a lawsuit.
Re: Why heat the bed after first few layers?
Yup, US patent system is in need of updating. Any sane clerk wouldn't have approved "*thing*...but in a box!" I don't care how careful your analytics of benefits are, that is just...uhg. Thanks for reminding me. Anyway, no, I meant owner operator making their own. It isn't hard, just a matter of worth to you. Not enough for me though I do have a thermally and acoustically insulated chamber. More like a Mylar tent with towels over it, works with my mad scientist / hermit nerd chic decor. Oh, sorry...off topic.
MK2S kit owner since 8/15/2017