From what I understand, it takes a really long time for the heated bed to heat up using an MK2a heated bed. I've heard some people suggest that using Polyisocyanurate (PIR) foam (insulation that takes quite a bit of heat to catch on fire) can be used under the headed bed to make it heat up faster.
Now of course there are other methods for doing this too, for instance using a larger power supply, but at this point I'd rather just use the parts that I have without re-soldering many of the components on the RAMPS board.
I was wondering what a proper way to attach this to the bed would be for instance, should the springs go on the bottom or on the top of the bed? Do I need some extra parts? Are there any other considerations for doing this?
If you use a seperate powersupply for your bed (or if your controller has a built in voltage regulator so it doesn't damage at higher voltages) you can sometimes find an small potentiometer near the connection terminals of your powersupply, turning this potentiometer up can raise the outputvoltage of your powersupply by a few volts max. In my case the potentiometer was orange and allowed me to turn up the voltage by almost 2Volts!
If your printcontroller is running from the same powersupply and is critical about input DON'T do this since it will damage the electronics. Better option then is to find a higher voltage powersupply and power the bed Seperately.
A buddy of mine runs his MARK2a bed on 19V and it heats up very fast. (he uses an obscure 15V powersupply that was able to be cranked up to 19V). And he doesn't use insulation at all!