Step 4: Loft Bed: cross members and rail

by now your frame and legs are attached - you can turn it upright and start cross member placement.

cut four 41 inch boards and notch them as done previously for the frame. (there is some overlap in this instructable - hopefully you'll read the whole thing through and realize you can compress some steps). these will hold the legs together and the notches are for the long cross members.

cut two 74 inch boards and notch them as well. these long cross members will be attached using bolts.

cross member placement:
using a jig is important in this step. grab some scrap lumber and cut it to about 18 to 20 inches or so. mine ended up being 19 inches, and upon reflection i would have been happier if i had put more thought into the spacing, but at least with a jig it is consistent. 

start with the 41 inch cross members that are notched. hold the jig in place along the inside of one of the head legs pressed upwards against the bottom of the frame and press the cross member against the other end of the jig and clamp the cross member in place. do this for the other end and repeat your measurements with the jig to be sure it is precise. with the 41inch cross member clamped in place, screw it to the legs - see pic - i used 4 screws as shown. remember to use a pilot hole - it reduces splitting. repeat on the two foot legs. now use the jig to repeat for the lower cross members - pressing the jig against the bottom edge of the mid-cross members. make sure the cross members are all the same orientation - that is, the notches should all be facing the same way. i choose "notch down".

a note on jigs: a jig is just a measuring device, and in the case above, it's simply a stick cut to the exact length i want to measure. jigs are useful because they produce consistent results, and your work won't look crooked and rickety.

now that the 41 inch cross members are in place, get out the long 74 inch cross members, turn these over so the notches fit (in my case, the long cross members need to be "notch up") and wedge them into the notches on the small cross members and clamp them. use a wood chisel to shape the notches if they don't fit. after they're clamped in place, then drill 1/4 inch holes for the bolts. i put 2 bolts on each end of the long board - for a total of 8 bolts. why bolts? because they're removable and i can't shove a completely put together loft bed through the doorway, so i need it to be modular.

why are the long ones "notch up"? my logic is this: due to leverage it would take less force to crack a long board than a short one, so i wanted to put the notches on the long boards "inside" the force - this is the same concept used when they make old fashioned long bows (you know: bow & arrow) - they shave & work the wood on the inside of the bow, leaving the wood uncut along the outside - it keeps the bow from splitting.

i could have put a ladder at both ends to make the bed more symmetrical and reversible but i was running out of wood and, frankly, feeling kinda lazy... cut 2 rungs to a length of 41 inches - no notches needed. and measure the gap to put the rungs in the middle of the space. i made a jig for this too. screw them on - bolts not needed, since the ladder is permanent.

i chose a 4 foot length for the rail - it's a round number and during mock up, it seemed to be the right size. i wanted the rail to be removable so the bed can be made easily and etc. so here is how i did it:
the width of the cross board of the rail is 5.5 inches (a 2x6) and based on the height of the mattress i needed it 6.75 inches above the frame, so i cut two 2x6's to a length of 6.75 inches and set them aside. i cut 4 2x6's to a length of 16 inches and sanded them and beveled them. i laid the 4ft cross rail sitting upright along one edge and clamped it to the table and made a 3-board sandwich as noted in the pic and screwed everything together - leaving a gap where the rail will be wedged onto the frame.

there you have it!
please leave a comment, and be sure to rate this instructable (on the right side of the screen) so i can improve it if necessary.

is this a full size? & if not would you know the measurements?
no, this is a twin sized loft bed. full size mattresses are usually about 48 inches wide (approximately). you can get precise measurements by taking a tape measure to a mattress store or perhaps this info is on the net somewhere.
It's been 6 weeks and i can say that this loft bed design is extremely sturdy. after constant climbing up and down on it by my football player sized teenager son, it does not creak or shift. i expected a few creaky sounds when climbing on it, but this thing does not utter a peep. my son loves it!
Well written intructable. Thanks for the ideas!
Back in my college days a lot of beer and pizza money was generated from scavenging and assembling similar furniture, from a set of 'master plans' we produced matching style chairs, sofas and various sized tables. <br><br>Excellent plan, thanks for sharing !
thanks for the praise!
A design flaw thats more a safety issue is with the bolts sticking out. For around $10 you can buy a recess bit package and make recess holes in the wood so that the bolts can be shorter to keep people from catching themselves on them. Use carriage bolts that have smooth domed heads on a non recessed side and place the retaining nut into the recess being sure that you made a large enough hole to get a socket into to tighten the nut on the bolt.
hi! thanks for your comment! i wouldn't consider that a design flaw - just a cost saving measure. i thought of using recessed holes, but i was reluctant to thin out the wood at a focal point where all the forces are acting on the structure - since yellow pine is a soft wood, i was afraid it would weaken the joint too much. about the only solution i came up with was buying some cap nuts to cover the exposed thread, but since i don't have young children running around in my house, i considered that to be a safety measure i could do without.
You can use a washer behind the the retaining nut to increase the strength and you don't have to go deeper then the height of the nut itself. Take a look around at the two top builders of wood loft beds and they use recessed holes for the nuts on the adult sized beds as well and use hard wood as well as plywood. Send me a private message and I'll send you the url for one of them to look over.
oh, thanks, but i like my design. i think it gives the bed an &quot;industrial aesthetic&quot;. besides, what would be the fun in doing things the same way everybody else does them? much appreciated though! :-)
Good job well done.<br>I love to see people using reclaimed &amp; salvaged timber.<br>I am with you on the sources many companies are glad to see the back of what they see as waste material; I used to run an air conditioning company &amp; we built all our outside storage area from crates the kit was delivered in &amp; timber salvaged from sites we worked on.<br>It's amazing how much gets thrown away in our society even now.<br>I must say however that pallets are very useful for certain applications, I have used many of them for garden projects the trick is to keep the deconstruction to a minimum we have a huge decked area that is entirely made from pallets &amp; looks great , back in the 80's I built a 20&quot; x 15&quot; workshop with my brother in law from 3&quot;x3&quot; &amp; 6&quot;x3&quot; pallets; all we had to buy were nails, coach bolts &amp; hinges, it' is still there now &amp; is used daily.<br>I look forward to seeing other projects from you.
thanks for the praise!

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Bio: Just another Rogue High School Math Teacher!
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