Help: LM8uu bed talk

I'm currently building a prusa mendel using the metric-prusa-lm8uu parts found [github.com]

I have the entire thing built except for the bed which i plan to cut from 1/4inch MDF (so ~6.35mm)

The problem I'm having is everywhere i look for info about the mendel with lm8uu's talks about it being an iteration 2 and only needing the single thick sheet for the bed (which i guess your bearing mounts and belt clips attach to)

But comparing that idea to the previous prusa mendels where they had a smaller thick sheet under the bed (which has the bearings and belt attached), wouldn't just having the big sheet reduce the Y travel?

I plan to use a MK2 heated bed that measures 215x215mm, but it isn't nearly flat so ill need support to push it flat. and I'm going to try printing on a sheet of glass that is slightly smaller than the heated bed.

Any advice toward getting this whole thing to work? (sorry if the idea is scattered)

The Y smooth rods are mounted on top of the frame threaded rods in iteration 2 so the single large thick sheet won't have any clearance problem. You can see it in this video.

In my opinion, it's better to use a bigger glass plate over the Mk1 or Mk2 PCB heated bed. Don't push it flat against the thick sheet or you'll end up heating your thick sheet also. Put some space between them. I used a couple of M3 nuts for clearance. You can clamp the glass plate on top of the Mk1 or Mk2, mounted with the heating circuit traces down so that it bows upwards towards the glass plate when heated.

well at the moment my heated bed bows in the direction of the traces.

so just mount the bed on the big thick sheet above the bolts that hold the belt clamps and bearing holders, but possibly a little higher so i can use clamps to hold the glass in?

That's odd. I was sure that mine bows out towards the opposide side of the traces. I'll have to check it again tonight. Some people use cardboard sheets between the thick sheet and the Mk1/Mk2 for insulation and to keep the PCB flat.

I use a couple of nuts and 1 or 2 washers between the Mk1 and the thick sheet so it just clears the printed nut holders for the belt clamps and bearing holders and it also has enough room for bulldog clamps.