12V bed heating 'too fast'?

Hi, so, this is kind of a weird question.. I have been building a Kossel at home for some time now and finally got around to activating the heated bed for the first time yesterday and today. It has a 220mm heated aluminium bed.

The strange thing is, compared to my other heated beds, that this bed hits 60ºC within a minute. As compared to the other printers I've built, that all take around 4-5 minutes to hit a stable 60ºC (for PLA printing).

Can it be that a heated bed heats too fast? Will it damage anything? Should I slow it down so that the SKR 1.3 that controls it all doesn't have to deal with such high current?

I'm going to do a PID on the bed now, in order to check what values come back. Right now it's on the standard PID settings.

Second to that, I currently do not have a relay on my bed, do we really need it? I have been 3D printing since 2012 and I've never used a relay and none of my boards has ever died on me. I do have a spare SSD relay meant for a heated bed. It simply doesn't fit in the small box of electronics that is in the Kossel base, but if it is really advised/stressed to use a relay, I might consider rebuilding part of the electronics organization to allow for an extra relay.

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http://www.marinusdebeer.nl/

... the heating time depends on the "thermal mass" of the bed, eventual insulation or "heat leckage" to attached thermal conductive parts (like extruded aluminium frames or metal sheets) ... and the generated energy in the wires/tracks.

If any (or more) of the parts change, the resulting heating time will change too ...

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Viktor
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Yes, exactly, that's why I made printed brackets and created a cork base for the plate to sit on. Free from any other metals and shielding the heat from the electronics underneath. So I take it that superfast heating is no issue? The cables do not seem to get very hot (I used very flexible silicone-covered thick wire from an old vacuum cleaner).

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http://www.marinusdebeer.nl/

Fast heating indicates that you have a lot of power available, and that's good in terms of temperature regulation. The only downside to it is that if the device switching power to the bed fails, it may get so hot that it can damage the printer or even start a fire. It's always a good idea to add a thermal cutoff to the heater (not the bed plate) to kill power to it if it gets too hot. I would not use a self-resetting type- a one shot device is what you want for safety. TCOs made by reputable manufacturers with full specs and safety certifications cost about $1. Don't cheap out and buy 10 of the no spec/no cert parts for $1 from China.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Quote
the_digital_dentist
Fast heating indicates that you have a lot of power available, and that's good in terms of temperature regulation. The only downside to it is that if the device switching power to the bed fails, it may get so hot that it can damage the printer or even start a fire. It's always a good idea to add a thermal cutoff to the heater (not the bed plate) to kill power to it if it gets too hot. I would not use a self-resetting type- a one shot device is what you want for safety. TCOs made by reputable manufacturers with full specs and safety certifications cost about $1. Don't cheap out and buy 10 of the no spec/no cert parts for $1 from China.

Ah, I'm using an SKR 1.3 and kind of assumed the replaceable fuses on it were redundant. I'll try and see if I can salvage such parts in my local area. Probably cost a fortune though, I live in the Netherlands and somehow everybody thinks they can make quick money selling small parts for triple the usual price unless you buy 100 haha.

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http://www.marinusdebeer.nl/

Okay, so I went ahead and got a solid state relay board to split up the power going to the SKR 1.3 and the heated bed. Also built a special box that can hold the PSU and relay in a different space than where the other electronics are to keep the heat down. This will also keep the strain off of the power cables since then I can put the heated bed on a separate terminal on the PSU (it has three Vout's).

I'm still waiting for the proper cooling fans to arrive as I notice an axial fan has much less air displacement in a small space compared to a radial fan that simply pushes the air through in a brute-force style.

It seems like the fast-heating bed isn't causing any issues otherwise but I like to keep it cool.

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http://www.marinusdebeer.nl/