So I came to realize today that I’m actually working on the living area interior right now, even if it’s currently outside the bus. This marks a significant shift in work on “the bus” because up until recently it’s just been either reassembly (since the roof raise) or a lot of ground work that will get covered up (insulation).

Having a fresh perspective on this has made it easier to slog through all the tiny details to make transforming bunk interiors with desks and other neat latching, pivoting, rotating gizmos possible.

Anyway, on to some stuff I did recently.

I got all the pivot pins installed. Interestingly enough, if the bunk units are clamped to each other back to back, you can fully extend the frames on one side and it won’t tip over, which makes it really easy to work on.

Next, You can see some detail of the pivot pins. They’re pretty stout. I don’t know if I said this yet or not, but if that setup is good enough for Kubota, it’s good enough for me.

Next, a latching system made out of various flat bar components. It’s dead simple, and should last a while before it needs rebuilding or work. All the pieces of tape on the parts are reminders for me if I run out of materials, since I have to build 8 of these latches.

Here’s a shot of the “prototype” latch tacked into place. Obviously the return spring will get attached a little more firmly.

And finally, a shot of the latch tongue in the “unlatched” position. As you can see, it’s a fairly significant piece of metal. I do NOT want these bunks to release unless it’s intentional. On top of that, they will carry loads in the closed position, in the form of a fold out desk. So I’m expecting these parts to carry the full weight of a work desk on the bottom bunk, and a full set of work chairs on the top bunk.

Add the weight of kids and beds, plus desks, chairs, other bits, and in scientific parlance “dynamic” loads, uh, kids rough housing as well as simply remembering it’s a vehicle that drives down the road, and suddenly there’s a reason for building the parts like a backhoe attachment.

I’m looking forward to constructing the remaining seven hinges and getting the spring system working. I think a centralized lever with some cable actuators will work really slick – twist to retract, and it should click into closed position.

The open position is easier to maintain – the center of gravity is far to the wall, and simply needs a single sided spring detent to keep from closing unintentionally.

Bunk bed idea

I think at the beginning of this project I had envisioned bunks that were fixed, like little kennels or cubbies that the kids can hide in. Recently though, I’ve come to terms with the limited space inside the bus, and I think that foldable “murphy” beds are the best option.

This setup with a tall ceiling height allows a pretty comfortable arrangement I think. In the photos below, the bed is a full size twin frame, that allows a mattress up to about 12 inches thick without any spring support, or about a 7 to 8 inch mattress with a wood rib support.

Not shown on the dimensional drawing of the bunks is a cross support that the cantilever bunks rest on when open. That is a full 1×3 square tube (one for each bed) that both ties the ends together, and acts as a stop to keep the bunk from pivoting too far.

The hinge pins are simple weld-on pins. I am mulling over the idea of how to cause the top bunk to intentionally over-extend to facilitate making it up (like stretching the fitted sheet over the mattress. Not entirely sure yet.

It’s pretty clear there’s some significant space savings with folding bunks. I’ll use sliding pocket doors to access the bath and shower on the opposing side, so that should afford a little walk way in the night time.

I’m pretty excited about the design, I’ll be out to buy the metal tomorrow – hopefully I can start assembling this in the next few days.

Foam cake recipe.

The foam insulation is a couple layers. There are two foam layers, with the foil backing facing both the outside and the inside. I’ll describe it here:

1. Exterior Sheet metal
2. Small air gap where possible (approximately 1-2 mm)
3. 2″ polystyrene foam
a. foil backing
b. 2″polystyrene
c. poly plastic substrate
4. Mylar hvac tape on foam block seams
a. There are 1×3 furring strips at 24″ intervals the length of the bus to hold the foam in place and provide a solid backing for attaching the final interior wall and other items (lights, walls, cabinets etc). A single self tap screw holds the wood to each metal rib. The screw is the cold bridge between the steel exterior and interior.
b. 0.125″ thick acrylic foam tape placed over each screw head to mitigate thermal conduction.
5. 0.75″ polystyrene foam
a. poly plastic substrate
b. 0.75″ polystyrene foam
c. foil backing
6. Mylar hvac tape on foam block seams
7. ABS sheet panels (this is the final interior permanently affixed)
8. Wallpaper, fabric, or other decorative coverings.

I forgot to add that a number of areas where I was lazy or didn’t get the foam cut quite right, I filled cracks with the red can “great stuff” spray foam. I probably burned through about 10-15 cans of the stuff. It was on sale for like 2 bucks a can when I got it so it’s not like I put a lot of money into dow’s bank.

Heating ideas

The space heater is enough to keep the vehicle at about 66-68 degrees F during the nights when it has been about 28-30 degrees outside. When the temperature is in the 40’s (F) I have to turn the heater down a bit or I get too warm working.

I hope that in the summer, the reverse is somewhat true, that I can maintain workable temperatures without too much effort.

I have a number of ideas/plans for heat. Since I will be involving a propane tank mounted on the road side of the vehicle, behind the front wheel (a large empty space between the skirt and the frame) I would like to leverage that fuel.

1) (propane) Forced air propane furnace
2) (diesel) Hydronic diesel heater with a re-purposed under seat heater core (this can keep the engine and /or the bus warm with valving)
3) (diesel, prime mover waste heat) Engine heat (while driving)
4) (propane) instant on hot water heater (not really a “heater” but a source of heat)
5) (diesel, apu power and/or waste heat) air conditioning – see below

#5 is a little out there and I’m not sure if I can get it done or not:

Basically, I would like to get a 1.6 litre VW diesel engine, and adapt it as an APU. It would have a very large alternator and an air conditioning compressor attached to the flywheel output. With some relatively simple valving, it is possible to combine it’s cooling system into the existing heater core. From the APU I can get heating, cooling, and electricity.

I have concerns about it’s size and weight with the additional accessories, as well as it’s overall fuel consumption. It might be ok, might not. They are relatively cheap and easy to work on, and certain models have hydraulic lifters so maintenance is not as much of an issue. Since the engine would be driving a DC system, (rectified ac alternator) RPM dependency isn’t really an issue.

The split AC system I’m looking at is a DC only split system reversible (can be used as a heat pump)

Between all of that laundry list, cooling and heating should not be terribly difficult. Budget will though!

Bunk bed fabrication started

I have spent all of my spare time on a parts drafting project so there hasn’t been any progress on the bunks for the last, oh, week. Sigh.

I at least managed to weld together the support frames. They’re constructed in such a way to allow them to be transported through the front door.

Next steps are to locate the appropriate hinge pins, and build the brackets to fasten the support frames to both the bus chair rail and wall ribs.

Below are some photos illustrating the size. Its basically 12 linear feet of bedding. When closed, this “wall” will intrude about 12 inches into the cabin. It will end up a little deeper than that, since I plan on building stowable flat chairs and desks that mount on the underside of the bunk frames. (there’s a reason they’re built as if you could park a car on them)

I’m pretty excited about this arrangement because it gives all of us a workspace we can use, which I feel is important.

This is just one unit.

This is both units next to each other, as they will be in the bus.

I’m pretty happy at how all the framing is coming together – I’m trying hard to keep things measurably accurate. I clamped the two frames together and they seem to be the same, within probably 1/32″

Snow and insulation performance

We had some snow for the first time this season. I am pretty pleased with the results on the roof. As you can see the garage which is unheated, has most of the snow melted off it, probably due to the dark roof.

The bus next to it still has snow on it, and the interior is kept at about 68 Fahrenheit with an electric space heater. I’m happy to see that my effort is not in vain.

Taking an insulation break

Amazingly I can see the light at the end of the insulation tunnel. A couple more finish panels in the cockpit, the rear, and floor is all that is left.

I decided to take a little break from the polystyrene and fix the remote start in the engine bay. I was pretty sure the bus wasn’t going to start in the cold weather but at least it will be ready later. New starter switch and engine bay lamp switch. I cleaned the gauge up a bit too. Now I can fire it remotely which is cool.

Still needs the key switch in the on position though.

Oh OK, here are a few insulated bus shots too. I should draw future window frames on the walls.