Prusa mk1 - heatbed mounting

Hi,

I have just ordered a Mk2B heated bed for my Prusa Mendel v1.

There appear to be a variety of ways you can mount these. My plan is to mount the heatbed above the 18mm MDF bottom plate with screws and springs, and then clip the glass on top.

Is this the "right" way? Will the flex of the PCB be an issue? Should I put the heatbed on another thin MDF sheet and then mount that onto the bottom plate? (extra weight?)

Cheers

Edited 1 time(s). Last edit at 02/04/2015 07:01AM by TBJ.

This is one of the questions I've asked myself too.
I started with four corner springs, using a 6mm acrylic Y carriage, and had 5mm depron under the hot plate ( I fitted a sheet of 5mm depron under the heat bed to decrease heat loss and isolate the Y carriage from the heat above it, depron can take 125C).
The bed would sag as the bed heated up and I concluded that the acrylic Y carriage was warping from radiant heat (after observing the arcylic seeming to be warping down at the corners). So levelling HAD to be done with the bed hot. Not very nice to do...

I then tried a 3mm aluminium Y carriage, and that has had it's own issues. I have tried four post with springs, and three posts (two sprung and one not), and now have five posts (four sprung and one not).
I'm still not entirely happy, adjustments on one corner seem to effect the others a lot. There is no heat related sagging now, but adjusting is still tedious...

If anyones rejected these ideas and found a better way (baring auto-levelling)...


Edited 2 time(s). Last edit at 02/05/2015 04:19AM by mr.sneezy.