Does anyone have the specs of the printers max temperature?
I want to heat up the printbed, is it possible to let it reach to 90 degrees celcius without any problems/dangers?
I’ve read about heated printbeds with a external power supply, is it possible to get it even hotter with a external power supply?
Is there a given MAX temperature recommended by velleman? I assume its impossible just to set it at 150 degrees and let it reach that without problems, i havent tried anything higher then 57 degrees…
Can i just turn it up to 90?? Thats all i need to know
In the moment i had no problems with 90°C but higher i had not tested
but i had an mirror on top an the 4 screws i build off
it is fixed with metal clips.
ABS is ordered so i can make print tests in the next time.
I think it is min. an FR4 PCB, up to 115°C is possible
but this is not with out any dangers, if you touch the heatbed its very hot
and it is out of the spec. from Velleman, so it is your own risk
For sure, you will probably need this to reach 90°. But my intention for the addition power was a) faster heat up and b) to hold the temperature at least at 50° while full cooling.
You place the relais in between the controller and the heat bed. The power that normally drives the heatbed you use now to activate the relais. The relais than switches the external power of 24V.
Your heat bed heats up much quicker and I used it already at a temp of 100° (CAREFULL really hot surface!!)
I think that a diode in parallel to the relay coil (in reverse) would help to protect your board output against the peak current when relay is released.
Hi, I’m planning on doing this, would you have any advice on diodes? If I understand correctly, this article explains the type of protection you talk of: en.wikipedia.org/wiki/Flyback_diode
I have a couple of questions:
some people talk to also putting a forward-biased diode in series with the switching circuit (in this case the 12v from the PCB) to really be sure of stopping any back-emf getting to the board. Would you think this is a good idea in this circumstance?
some circuit diagrams show a very low ohm resistor in series with the flyback/claming/suppressing diode, do you think this would be needed, or would this lessen it’s effect too much and possibly risk the board getting spiked still?
Apologies for my lack of understanding - too many decades have passed since I was at school!
As the relay switches a lot of the time, this relay thing is not very good idea. You can do it better with a fet, see this topic (and others too): http://forum.velleman.be/viewtopic.php?f=53&t=9598&sid=c9aa996aa83599d4d956761821f6e55e&start=30
If you want to stick with your relay: you can use a very low ohm resistor or put the diode directly over the relay. A 1N4007 is a general choice and is known to work good. If you want to do it close to perfection, you can also use a much faster diode like the BYW96E, then your circuit will survive a nuclear war …
Hi,
I tried a 24V power supply for approximately half an hour. The PCB went to ~100°C (maybe more if I waited longer), but I see additional warping of the PCB with tightened screws. With the fan directed to the NTC it went down to ~60°C.
So far I did not dare to place glass on top and I haven’t tried to print ASB. And yes, you have to be carefully!
There’s something I don’t understand : the NTC should cut the power when the asked temperature is reached. Yet it seems it doesn’t happen with yours. How did you wire your power supply?
Hi raby,
for testing I just connected the power supply to the heatbed, no feedback, no power switching. I just wanted to see how far I can get. Next thing will be to make a small circuit for switching the current.
But maybe your question is a different one. Sorry if I explain, what you already know: The NTC is not directly controlling the heatbed temperature. The NTC is just measuring the temperature, which is then compared to the desired value by the µ-processor, which in turn controlls the heatbed current. (there are 4 wires going from the electronics to the bed) Since I connected the bed’s heater directly to the power supply, I can measure the temperature, but the board has no chance to cut the bed current. Therefore it is important not to leave the experiment alone !
