After watching a review of the GMax 1.5 from The 3D printing Nerd, the heated bed got me thinking. Do you all think that we will ever have heated beds that only heat in sections. For example a 20cm bed that has a grid of 16 sections and only heats the ones that have parts on them? I’m not an electrical engineer but I was just curious.
Yupp, I’ve heard of that being done before. Also if you go ask around how to heat a bed on a large format I guarantee one of the options presented to you will be to create a grid of normal sized heaters. The issue is that if you don’t heat glass uniformly you can crack it.
I am sure you will have to have something else than glass as the bed surface. I do not know if you can print directly on a pcb which is what some heatedbeds are. Uniformity of heating is also important for the printed part, I believe, but I am not sure.
Aluminum with glue, maybe blue tape on top of it.
I had used two Prusa PCB heaters for a long while and had an individual control loop for each - so once configured correctly, using one or both wasn’t anything more complex than picking the right slicer profile. I had plain 4mm float glass on there and never had an issue with cracking. It reduced my print area to 150x200 or 120x200 when only one side was heated, as a large strip of the heated side was significantly below the nominal temperature. Using an aluminum surface would further increase this issue.
However, it was a pain to set up, as (afaik) no standard firmware supports dual independent bed heaters yet, let alone 16, so i ended up using one of the hotend slots in Marlin for the second bed, which had its own set of issues. If you can live without individual control loops, you could simply write a slicer profile with a custom start.gcode, turning certain section on or off as needed (using M42 etc) - and that would work with almost any firmware and hardware, given an appropriate extension board.
I saw the new bed from e3d. I think it has this selective zone heating but I cannot find the product on their web
Here it is http://e3d-online.com/BigBox-Heated-Bed
@Ariel_Yahni_UniKpty it outputs more power towards the edges to compensate for losses, but it’s still only one heating zone.
@Thomas_Sanladerer yes but how this is done could be the way to get selective zone heating?
I imagine that two bigbox heated beds side by side may have an excessively hot zone in the middle if you use both regions.
It’s just more complication than it’s worth. Why would you want to deal with all the wiring and control challenges when you can just heat the whole bed? Electricity isn’t all that expensive.
I wonder if using less insulation on the bottom near the middle would even out the bed temperature.
Just build a separate controller for the heated bed array. For now, use the printer firmware to set temp, manually control which pcbs heat
The loss of reliability due to the extra complexity is probably not worth the effort.
The mass of bed wiring alone would be so complex it would be very prone to all sorts of failures, ruining any theoretical advantage.
If there was a simpler way to get multiple heat zones, other than directly wiring each heat zone, then the concept could be really good.
One theoretical advantage of separate heat zones would be to print PLA on one portion of bed and ABS on another portion of bed at he same time. I think I saw a post about being to print PLA on ABS layers before though and if so, maybe you could print a layer of ABS and then print PLA on that right next to an ABS print.
I do not know if you can print flexible filament on top of another type of filament or if the bed temperature requirements are different, but flexible filament printing next to ABS or such might be another advantage of multiple heat zones.
One thing that I have to wonder is if the heated bed temperature rarely changes during a print, why is it even controlled by the main board instead of its own separate circuit? You should just need it to adjust its pwm based on the temperature relative to the target temperature.