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need help making a hotbed controller work

Posted by thequestor 
need help making a hotbed controller work
July 30, 2018 02:57PM
I currently have one of these


100W 30A MOSFET Hot Bed High Power Expansion Module DIY and I am trying to get it to work with a Zonestar Prusa i3 and am having 0 luck.

From what I can see it is not a hardware relay but uses what I am guessing a pid controller to turn on and off. But I know very little when it comes to "this" stuff. I also bought one of these


3D Printer Part Motherboard Hot Bed Expansion Interface Adapter Module+Cables

which appears to be the pid control board as it plugs into the "control" portion of the expansion module and is where I plug in the thermistor and then to the motherboard.

What I am curious most about is on the actual mosfet part the 2 wires coming in and plugging into the pid controller are they a simple on/off thing? Can I power the board, [it does power] and just cross the wires to test if it does send the 12v out to the hotbed? I can't see any "logic" chips on the board itself which leads me to believe it's just an on/off thing but as normal I could [and probably am] wrong here.

any help/insight/oversight would be greatly appreciated here as right now I am not able to get my hotbed to go much higher than 60C and it takes forever just to heat up that much and I want to pull the volt/amp draw off of my motherboard completely so all it has to worry about is printing smiling smiley

Thanks.
Re: need help making a hotbed controller work
July 31, 2018 12:23AM
so nobody has one of these sad smiley sigh.
Re: need help making a hotbed controller work
July 31, 2018 12:43AM
Without knowing the polarity of the 'control'-input terminal, it is hard to give advice.
I think, you can use it without the second PCB by figuring out, how to wire it directly to your controller. Thermistor may need a different connector, but TBH I don't know what controller Zonestar uses...
Re: need help making a hotbed controller work
July 31, 2018 12:46AM
Here's something for you to meditate on: If the lights in your room are too dim, will changing the switch make them brighter?


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: need help making a hotbed controller work
July 31, 2018 01:06AM


It plugs into your current bed output (ie 12v)
Re: need help making a hotbed controller work
July 31, 2018 03:26AM
Quote
Dust

It plugs into your current bed output (ie 12v)

so I would still be using the thermistor from my motherboard aye and just run my external PSU to the controller and the 12v from where I "used to" run to the hotbed. I guess I can live with that. I'll try tomorrow and report back. Too tired tonight,

Thanks for replying and clearing a little up. I was trying to figure out how to send the PWM signal using the adapter so if this works I don't even need to worry about it smiling smiley
Re: need help making a hotbed controller work
July 31, 2018 03:36AM
Quote
the_digital_dentist
Here's something for you to meditate on: If the lights in your room are too dim, will changing the switch make them brighter?
No I would re-wire which is what I am doing as your analogy doesn't quite match up to my issue.

I have had issues with the zonestar board as it has a weak point.



These get hot [the arrow points to the weak point] and the leads kind of burn where they screw into the motherboard.
This is my 2nd board as the rev 2 board had an even smaller fuse there and they knew it so they added a sligjhtly larger one on the v2.1 and up and it looks like the v3 is different again as well but I don't want to spend out the 40+ bucks after shipping for a new board when this one works great EXCEPT when I print ABS or similar.

I'm just taking the hotbed out of the loop completely by giving it its own PSU and taking the load off of the zonestar motherboard.

I originally was going to use 1 of my PID controllers but they use a hardware relay and after reading a few other posts saw that it is hard on the relay and would allow the temps to fluctuate too much so I wanted to try this way smiling smiley

Edited 1 time(s). Last edit at 07/31/2018 03:39AM by thequestor.
Re: need help making a hotbed controller work
July 31, 2018 05:31AM
How did you determine it is a PID controller, that the bed heating is using it and PWM ?
Oh and DD analogy is valid.


"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
Re: need help making a hotbed controller work
July 31, 2018 06:19AM
I did not determine it WAS a pid controller. Not sure where you got that. I said I had a couple of pid controllers I thought about using and should have said in place of this unit. They are self contained controllers so they would not be attached in any way to my printers motherboard. just the PSU to the pid controller to the hotbed.

with the solid state relay.But I am using this on my filament extruder and didn't really want to use it for this. So that is why I bought this current setup.


I also have this I was going to play with


and this


The little board




says PWM on the back where the arrow'd lines go to the circled so I figured I needed to make a pwm controller and was thinking of making one out of my million or so arduino nanos I have in the drawer but since I don't know what signals it expected to get THAT was more then I was really wanted to do.

anyway it seems like I was given the solution that is easiest to implement and should get the job done and still be compatible/attached enough to allow me to just use repetier server/host to control it so all is good if it works smiling smiley


Thanks for replying
Re: need help making a hotbed controller work
July 31, 2018 07:48AM
Controllers and outboard switches are nice, but they don't make the bed get any hotter (just like changing the switches won't make that dimly lit room any brighter).

If the bed won't heat up to the desired temperature or it takes too long to do so, the heater is under powered, which is typical in kit printers. So are most of the aftermarket "upgrade" heaters specifically targeting 3D printer hobbyists. PCB type heaters are junk. Don't waste your money on them.

If you really want to make an improvement, get a higher powered heater. About 0.4-0.5W / cm^2 should get you up to temperature quickly. If the bed is large (>500 cm^2) consider using a line powered heater, which eliminates potential power supply and controller board interface problems, and can use lighter gauge wiring to deliver the power. You will need an SSR. You won't need a bigger power supply. This is the sort of thing that will solve the problem.. Use an electrical fuse (about $0.1) and a TCO (about $1) for protection.

The controller board firmware has PID temperature control built in. All you have to do is turn it on.

Edited 1 time(s). Last edit at 07/31/2018 07:52AM by the_digital_dentist.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: need help making a hotbed controller work
July 31, 2018 11:03AM
Quote
Dust


It plugs into your current bed output (ie 12v)

I'll be dipped in cheese. Works like a charm. Thank you very much!!!
Re: need help making a hotbed controller work
July 31, 2018 11:06AM
Quote
the_digital_dentist
Controllers and outboard switches are nice, but they don't make the bed get any hotter (just like changing the switches won't make that dimly lit room any brighter).
.

That looks awesome. BUT way more than I want/can spend on a 200x200 hotbed smiling smiley Still now it's on my "maybe list" smiling smiley

Thanks for the info.

And just for the record it still takes a while but it does heat up WAY faster and now I can take it to 100c no probs where as the best I could do directly off the motherboard was 75c. Odd but true so I'm good to go for now.

ok seems I lied. this pos hotplate will not go above 75 no matter what sad smiley it's the PCB red plate and now I wonder if I have it upside down..

Also I am asking it to do a lot lol. The Zonestar has a steel plate on top of the heater and on top of that I have Tempered Borosilicate Glass so it's having to heat a lot of layers.

I'm thinking of removing the metal plate as it's really only there for the auto leveler sensor that came with the kit and it never worked right anyway nor was it ever really needed so I took the sensor off a long time ago.

This plate has been is use for 2 years now and I am glad it still works at all to be honest lol. Wow I just checked and it is 2 years and 1 day old lol. And it has printed so many things and run for so many hours I am amazed that it still works.

Edited 2 time(s). Last edit at 07/31/2018 12:39PM by thequestor.
Re: need help making a hotbed controller work
July 31, 2018 11:12PM
The other common issue with these beds people don't insulate under them..

The underside needs to be insulated or you just heating up the air.

Cork or wool felt is good. Corrugated cardboard is better than nothing. Lots of options. Not polystyrene, that will melt.


Also if your using a separate power supply, and it has a variable output, crank the voltage up.
Most cheap power supplies have a little variable resistor near the screw terminals. I tend to set these to 13.5v It makes a huge difference
Re: need help making a hotbed controller work
August 01, 2018 03:51AM
Quote
Dust
Also if your using a separate power supply, and it has a variable output, crank the voltage up.
Most cheap power supplies have a little variable resistor near the screw terminals. I tend to set these to 13.5v It makes a huge difference

+1. I do this on mine as well, it makes quite a difference.
Re: need help making a hotbed controller work
August 01, 2018 06:44AM
I'm just using an old PC power supply I had laying around so no variable, just on and off smiling smiley
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