Hello all,
I have had an unopened Kuman kit(UNO R3) in my closet for I don't know how long. In starting the design of my next 3d printer, it looks like I may need to jump into the Arduino scene more than just editing the Marlin code on my Mega 2560.
Anyway, I am designing a multi-use 3d printer. It will have a 600x600mm print bed, but my plan is to make it useable as a small printer(300x300) and only activate the rest of the bed as needed. This way I don't have to have such a large bed heat up for smaller projects.
The bed will be made of (4) 300x300 silicon heating elements(300 watts each), each with its own thermistor. I will use the 2560 & ramps to control all of the usual printer functions and temperature control of one 300x300 area of the bed. The other three quadrants I want to be externally controlled by an Arduino(no idea which will be best suited for this). I want to have an three switches to activate them individually, an lcd(displaying set point, current temp, and current state for each element), and a potentiometer for setting temp.
The elements are 110v so I will be using a SSR for each. I would also like to have some sort of thermal runaway protection to kill all if something fails.
I have searched google a bit and I've found projects for single element beds and some other somewhat similar projects, but not quite like what I'm looking for.
Any suggestions on the above and where to get started on learning to accomplish what I'm looking for?
Thanks in advance!
I have configured marlin on my 2560 and that’s it as far as arduino is concerned. So basically nothing. I have wired cars, soldering experience and some light raspberry pi work. Very little coding work.
From my limited knowledge of 3D printing you will never want different parts of the bed to operate at different temperatures so why not power the whole lot through a single Mosfet (or mutliple mosfets controlled by a single Arduino pin) and just implement some simple switches to disconnect the power from the parts you don't want in use?
Other than sections that are powered and those that are not, they will be all at the same temperature when turned on. I just don’t think I can get a set temp out from the 2560 running marlin and into the second arduino. The reason I don’t want to run them all together and just break power is the temperatures won’t be the same.
I could take all four thermistors and average the reading, but I don’t know how much the temperature variation will be across the elements. I’m thinking that the idea I have will do a better job of making all four elements be the same temperature.
So basically if I’m printing with a filament that requires heated bed, I’ll have my slicer set at say 100C and then I’ll set the second arduino to the same 100 and flip on which parts of the bed I will be using. With the first quadrant be unstitched and completely controlled through marlin.
To combat warping across the non-heated and the heated sections I will be using a heavier duty base platform and a thick aluminum plate. Since this will be a corexy type printer, the bed will only move in the Z axis and the extra mass will not be an issue.
I must say I would be tempted to try sending the same signal to each bed with a thermistor on one of them and see if the temperatures of the other beds are satisfactory. As they are all heating the same piece of aluminium there will be a lot of heat transfer between them. Which also makes me wonder if you could actually save much energy by only heating a part of the bed. Aluminium is a very good heat conductor.
Separately, and just thinking out loud ... I wonder if you were to wire the 4 beds in series would they all reach the same temperature as the same current would be passing through all of them.
ideally, you need feedback from the heated plate, via the thermistor, for each quadrant. You also need individual PID loops analyzing the feedback against the set points for each quad.
That would indicate the need for four PID's running at the same time (lot of memory, I think).
Also, the adjacent quads, on or off, will have an effect upon the single one running (through heat transfer from one zone of the plate to the adjacent zone (unless the 'zones', quads, whatever are thermally isolated ( which will cause big problems when you are trying to use the full 600x600, or more than one quad of the, heat bead)).
123Splat:
ideally, you need feedback from the heated plate, via the thermistor, for each quadrant.
Have you experience of that sort of arrangement?
I certainly don't, and in the absence of someone with experience saying it is essential I remain sufficiently doubtful that I would try it with just one thermistor before making the system more complex. The best can be the enemy of the good.
I am in the same position with a large 3 plate system. I have been looking for an arduino thermostat project that controls the two beds that marlin does not. Each bed has its own power supply for now and i have the 3 beds turning on with mosfets when marlin send signal. I unplug 2 power supplies when not using 2 unused beds. I want to use the thermistors on those beds to get accurate temperature control. If i find anything i will let you know.
I have a Geeetech A20M and i am using an Arduino Mega and a RAMPS 1.6. I'm also trying to add a second bed in order to do some test without undangering the one from the printer. In order to do so i've tried to modify the Marlin but it does not compile and i'm stuck. Didi you find anything during your research ?