now assuming the 4 2x6's that make the exterior frame are all sitting on the ground assembled the next steps are easy...
you want to put the 2 2x4 center braces inside the bedframe sitting on the floor on edge...
screw those to the exterior frame
the cross supports (4) are also 2x4's
their length is irrelevant, its just to brace the corners...
they can be any length of 2x4 with a 45 degree cut on both ends
they have a maximum length limit as you need to fit 4, one for each corner
the legs are also simple 2x6's
you can make the legs any length you desire
and they can be parallel to perpindicular to the long sections of the exterior frame, basically you can put them however you see fit, as long as there is one in each corner...
the longer you make the legs the more stuff you can store, but the longer they are the more wobbly then can be without diagnol supports on the legs themselves
my bed was about 3 feet off the ground when i first built it so i could fit a large bin under my bed, but i have since cut them down so the bed is at a comfortable sitting height...
i highly recommned this height
enough room to store stuff, but not too akward or high
and the legs need no extra supports at this height
the legs should be attached to both of the 2 exterior boards making up the exterior frame via screws...
this will strengthen the corner
the legs should be mounted in the frame so they extend no further up than the 2x4 braces already in the frame...
now you just need to put a piece of plywood inside the frame, over the braces, then insert the mattress
a few things to note....
MEASURE your mattress before making any cuts...
the INSIDE measurments need to be wide/long enough to fit your mattress down inside the frame...
i used 3/8 inch plywood and screwed it to all 6 braces, as well as screwing it to the tops of the legs...
using 2x4's, actual height of 3.5 inches on edge, inside a 2x6 frame with an actual height of 5.5 inches leaves you with approx 2 inches for your plywood, using 3/8 plywood leaves you with a small indentation which should snuggly hold your mattress...
if you want to have a small place for your remote, etc you can simply make the frame 3-4 inches wider than your bed to give you a small shelf, or if you want extra room length wise, also just extend your numbers...
if you feel 3/8 plywood is not thick enough for you (it should be fine for just about everyone)
then you can use 1/2 or larger etc...
if you choose to use a larger plywood, or you would like a larger indentation to hold your mattress securely in place, you may want to use 2x8's to make your exterior frame...
if you go to homedepot, don't hesitate to PICK through the pile of lumber to find nice pieces...
you don't want pieces with excessive splinters, you don't want warped pieces, and you want to avoid pieces with the dark markings lumber companies use...
the nicer the wood, the nicer the final bed will look...
the final step would be to sand the wood/remove any rough edges, then stain the wood to your color prefrence...
the corners can be rough on the knees during the night, like any wooden furniture...
so you can use a router to lessen the severity of the corner, you can add padding, or you can just rough it like it do
i have not stained or finished my bed in any way, shape or form...
one of the legs is about half the size it originally was as my cats like to use it as a scratching post...
pine tends to take well to stain and usually has a pretty nice finish from the store, but i just went with regular old wooden 2x6's and 2x4's
see, i was thinking about using planks across.... not triangle frame-like design...
a couple things with this...
boards have more strength standing on edge than they do laying down...
so if you went with a stylish 1x4 style plank you would want to space them close together
more boards = more money, and more weight...
a 60 inch length of 2x4 laying down will bend with 200 lbs of weight
4 or 5 2x4 laying down should support quite a bit of weight, but you want to make sure your bed doesn;t sag in the middle
did you want the boards to be on TOP of the frame? or still inside the frame?
i wanted my mattress to sit in a recess so this way suited my needs
you never see the boards underneath as its covered with plywood anyway, so this is up to you completely...
i doubt the corner braces are necessary, but i used them since i was using such a thin plywood and i also did not want the bed to rack...
i had no drawings or anything, i had some 2x6's and 2x4's, some screws and a sawzall
i just started cutting and this is what i ended up with...