Heated Bed QUBD Silicone vs MK2 vs ? for Prusa i3

So I was planning to use the reprap.me MK2 heated bed, as it is only $14 and I was getting my MK8 drive gear from there anyway.

I read somewhere that the QUBD silicone heaters heat up much quicker though and they are only $19.

Has anyone used either one with a Prusa i3 or Mendel?

How long will an E3D hotend take to get to temperature? Is it a big deal if the heated bed takes 3-5 minutes or longer to get to temp, if the hotend takes the same amount of time? No idea how long it takes for the MK2, I just assume it takes longer.

Qubd claims 'Heats To 120 Degrees C in About ONE Minute (assuming adequate power supply)'

This is physics. You have a maximum amount of power the Ramps (or what ever) can handle The standard heater board just about maxes out the Ramps 1.4. The silicone gizmo probably maxes it as well. Heat rise is related power you put in and the heat capacity of the material. That silicone is a very flimsy material. It doesn't hold much heat. Less heat capacity / same power gives faster rise. If you attach it to something to stiffen it, you will soak up heat It will heat up slower. Silicone plus stiffener probably equals pc board based heater speed.

If you do indeed come up with a very fast heating bed, remember to modify the PID (heat control) settings in your setup. Otherwise you probably will get unstable bed temperatures.

That all of course assumes that the "alternate source" is selling you a 1 ohm pc board based heater. There are people out there selling 1.8 and 2.2 ohm boards. Those will not heat up as fast as they should. There are also 12 V / 24V versions that won't heat up very fast if you put 12V on the 24 V connector.

QUBD tells you NOT to use RAMPS to drive the silicone heater. One would just put a relay off the heated bed output and then have the relay trigger the heated bed.

I guess my question then is:

How long does an MK1 or MK2 PCB bed take to get to printing temperatures (~100C)?

How long does a cartridge based hotend take to get to printing temperatures?

Has anyone used the QUBD and is it better, the same or worse and why?

thanks.

Well they (on their web site) say:

"... We have tested these with a Azteeg X1 and X3 from [www.panucatt.com] as well as the RAMPS 1.4 directly with no problems (YMMV)....."

RAMPS 1.4 directly sure sounds like a no relay situation.

Considering that silicone heater draws 15A, I wouldn't recommend using it directly with RAMPS even if it does "work".

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I got on the IRC chat, and QUBD is not recommended at all. Not necessarily the silicon heater, just in general; failing to produce what they claim/poor quality control, I guess. Think I will go with the MK2 or MK2B.

With a 12.0 volt supply, an 8" x 8" one ohm heated bed gets to 110C in under 10 minutes. A Magma hot end with 40W heater gets to 220C a couple minutes faster than the hot bed. SInce power goes up by the square of voltage in this case, bumping the supply to 16 volts would cut those times about in half. You would need to do some hacking to get everything to be happy at the higher voltage.