Building the murphy bed.

Over the period from July 2021 to July 2022, I have constructed and refined a murphy fold up bed. Here, I discuss the phases of the build and problems encountered.

My functional requirements for a bed are:

Comfortable to sleep full length.
Take a standard mattress.
Easy to make up with sheets etc.
Not intrude on living area when not in use.
Good clearance away from the ceiling ie sit up room.

July 2021

A medium-hard foam king single mattress was chosen as this will provide plenty of room for me and on the rare occasion a second person. It is probably on the heavy side, I could get away with a thinner one, to save the weight, but choices were limited in these times of pandemic lock-downs. A murphy style ie fold up bed allows plenty of daytime living area.

I did not wish to go for the popular setting where the bed is at the rear with a storage area below as I felt that the sit-up room was insufficient and the storage for all my gear would be limited.

The mattress was used as a full scale model in the van to determine its best location.

I created a series of mud sketches to work out how I want the frame and tilt mechanism.

When the bed folds down there is very little space to work with. Consider the kitchen counter and walls, then the fact that when you rotate the bed from horizontal to vertical that the diagonal is wider than the bed. I had to also come up with a way to pin the bed against the van wall at all times to stop it moving away. Not only did it have to be pinned that pinned hinge needed to move up and down on a slide .

A gate riser slide provided the vertical motion constraint, and a standard butt hinge provided the support for rotational movement. This solution was not the easiest to come by !

I thought that the best thing to do for the frame construction was to purchase a second hand bed base and attach a box frame around it to contain the mattress. The box frame was a composite panel of foam insulating board, 3mm plywood and 25mm Qubelok tube.

In practice the assembly is too flexible. At some stage I will need to fabricate one out of welded aluminium box section with a proper truss structure, using thicker walled tube than the 25mm Qubelok tube. Also use a lighter, thinner mattress.

August 2021

There were numerous iterations of the frame, it had to be stepped on the side to allow for the wall curvature. Here again, the use of Qubelok hampered the design. I don't like the sharp edges either.

For the time being I am sticking with what I made (hours of work expended already) and have elected to take care when I use the bed. I can phaff around forever and need to get on with the build. Things can change later.

The frame constructed, it fits well in the space constraints of kitchen bench, shower and cupboards both at the end and on the ceiling to wall corner.

It was hard to locate a position for the gate risers as there are many hollows in the wall. As tempting as it was to plate out the wall cavity, I worked to avoid that in order to keep the weight down. The other thing I could have done was to add furring strips all around (which are basically wooden slats). I chose not to use furring strips at all, it would have made life a lot easier for fixing, but the added thickness meant that I could not get the bed in the remaining space and precious standing height would be lost if used on the floors and ceiling (1.8m is not a lot of height).

A locker box will be used to support the bed at its working height and serve as a seat when it's in its vertical position.

A check with the locker box and slide mechanism proves that there is adequate space to clear the kitchen cabinet (which is 500 wide). I also have a Vitrifrigo C130L fridge that is 525 wide x 565 deep sitting in front of the bench.

November 2021

The next issue I had was to work out how to deal with the lower corner of the bed when the bed is operated. The corner is sharp. I had all these ideas:

A plain slide surface
It was hard to get decent materials. Pandemic constraints abound. Some sort of radius relief was needed for the corner. Rejected.
A castor wheel on a ramp.
I tried these complex curve calculations to minimise the rise and fall and load variations. It wasn't an elliptical path either, with the wheel being offset to the bed frame.

Ultimately I went with the castor wheel and a simple ramp on the side of the locker. The inclination of the ramp and depth was such that the bed rises immediately upon lowering it and on the full horizontal, the wheel is clear of it, ie the dead weight of the bed is on the locker.

January 2022

After a few trials on the road, I found that with the bed so close to the front seats that there was very little in the way of access, should I wish to change or get out of the bed. I could get to the shower, but it was all too awkward. Those hard corners of the bed too somehow always managed to taunt me whenever I made any moves.

I looked long and hard. Do I really need a fixed shower inside ? For that five minutes of pleasure, I felt it really was a luxury I cannot afford. By eliminating it from the interior I save 900mm of space. That is a lot of real estate.

So, I took the shower out, removed the slide assembly and locker, took out the rear bulkhead wall, laid some more flooring and relocated the bed back 900mm. It only took 1/2 an hour (I wish).

The improvement was dramatic. I had enough space to set up a picnic table between the seats and bed, change and even set up a portable shower inside should I wish. (I bought an Evershower for that purpose.)

Why didn't I think of this before ? I could have saved a thousand dollars and hours of work. This is what happens when you get carried away with Youtube videos and your imagination.

Moving the bed such that it was close to the rear bulkhead wall exposed a new issue. With the previous arrangement I could raise and lower the bed by standing alongside the long edge. Now I have to stand and lift on the end. This new position causes me to apply a lot of torsion on the frame, the lower corner was lifting and the frame was scraping the bulkhead.

I put a 200kN gas strut on the pivoting edge to prevent the lifting at that corner. There is still a bit of torsion in the frame so I put a plastic sheet on the other end to act as a sliding surface. There is also enough roof between the bed and the fridge to place my hands and reduce the leverage.

As I said at the beginning, the frame will ultimately need to be a fabricated truss structure, and a lighter mattress purchased.

The next issue I had was securing the bed whilst I am traveling - ie when it is vertical. I cannot use cinching straps forever, especially when the upper cupboards are installed. I came up with a toggle latch on one end .

July 2022

Having only the front end secured vertically was inadequate in my opinion. What happens if I didn't put the latch on ? To ease my mind, I added a spring loaded gate bolt to the other end.

One final bit of detail is how the bed is supported on its top end when it is laying flat. I created a step that runs along the combined length of the fridge and kitchen cabinet. This works well and negates the need to have some sort of drop down leg. The image below is just the frame below, but now it is covered with 12mm plywood.

Long Term

After a couple of years of use I am liking the comfort of the bed. It is a little heavy for my daughters to use, though they can manage.

I am thinking of using a 75 or 100mm mattress .

If the comfort isn't adequate I will look at special modular bed springs either external or internal to the mattress. See https://www.abetterwaytogo.com.au/froli-travel or Flexima Nautic, foam/plastic spring boat mattress. These I will investigate when time permits.

Having a lighter mattress will also reduce the torsion that causes the end to at times catch on the bulkhead as I lift it.