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 Living on the Road :: Wothahellizat Mk2: Construction Diary : #10

Sat 8 Sep 2007

I'm building shutters at present and as I've discussed them before I haven't got much to say for the moment.

At least that is the case until I've nearly finished the large shutter that covers what I call the "utilities area".

I've known for some time that the Luton peak (the bedroom) has got a droop, but with the body high in the air on its legs I was too difficult to look into so I decided to leave the problem until the body is back on the ground.

While building the utilities shutter I lower the body (those legs have been great, I can raise or lower the body to whatever height is comfortable for working) to make it easier to access the hinge area at the top of the body, I've already done the basic frame for the shutter with a 3mm (1/8th") clearance to the body, but when I lower body the clearance all but disappears on the left hand side and the shutter is nearly touching the body.

Reasoning that this is caused by the weight of the Luton peak I jack the peak up until it's taking the weight of the body. Sure enough the frame surrounding the shutter squares up and I have my 3mm clearance back.

Time to look into the drooping Luton peak.


The weight of the peak (a) is born by the W-braced beam and transmitted to the rest of the body at about point b. With no real strength at this point the force causes the vertical members in this area to deform, manifesting itself as a 2mm bend in the member at the side of the shutter (c).

By measuring from a straight edge I find that the droop at the front of the peak is about 10mm, way too much for my liking, but it's too late to do anything about it today.

Sun 9 Sep

After entertaining some friends I return to the drooping peak problem.

I cut the frame at four locations.


The four cuts.

Then I jack up the front of the peak again. The four cuts either get wider or narrower according to their locations.

I measure cut 'a' with calipers and find that it changes from 3.46mm with the peak unsupported to 2.53mm with the jack and 2.04mm with my weight added to the frame.


Cut 'a' varies by 1.42mm as the peak is loaded and unloaded.

That doesn't sound like much but it's quite a lot at a point so close to the location at which the peak is rotating, ie the body's top beam.

Now I have identified the problem I need a solution.

I really need to beef up the frame at the point that is bearing the force, but that area is almost entirely void space as we have two large shutters there that provide access to a storage bin and the utilities (plumbing, gas etc) area.


Void areas (blue) and a potential strength area (red).

There's nowhere to brace the frame to handle the force at 'b', the nearest place that could provide strength is the area near the door (red in the above drawing). So I add bracing there and make a horizontal beam from RHS to transmit the force to that area.


Location of the added beam and bracing.

Now the force at 'c' doesn't bend the frame, it is transmitted to the new braced area near the door.


The force is distributed to an area of strength.

While not a huge job this has taken all day, firstly because it took a while to measure and analyse things, but also because of the placement of the horizontal beam.

As always appears to be the case when building a motorhome, everything affects everything else. The beam goes right across the utilities area, and while it's position isn't particularly important for the purposes of fixing this problem, it's critical for the utilities area as many items have to be placed there and most have to be accessible, some even have to be removable, like gas bottles and filters.

Therefore, to fix a problem with the frame bending in the bedroom we have to decide, for example, where the spare toilet cassette is to be stored.

Mon 10 Sep

Yesterday I fixed the droop on the left side of the frame but this left the body a little lopsided, so today I repeat the process for the right side.

The right side is a bit easier though because it doesn't have the large void areas so it's mostly just a matter of cutting the peak, jacking it up, and strengthening the frame.

While doing this I notice that part of the frame has bowed in slightly, so I fix that as well.

All in all I've had a fair bit of trouble with warping frame members, much more than I did with Wothahellizat 1 and I can only assume that it's because I'm using much lighter steel that is more prone to being distorted by the heat of welding.

Tue 11 Sep

While working on the front bedroom shutters I realise that I haven't done the drain. This drain is supposed to take the water from the shutter's internal gutter and runs it away under the truck somewhere.

The gutter is a 16x16mm (5/8th) aluminium channel and the drain is a 12.5mm (1/2") tube, I'll use a length of...well that's the problem.

I have three options to hand in the workshop, some steel brake line, some copper pipe, or some CVT (Clear Vinyl Tube). I'm not keen on the tube although I will use it to run the water from the end of this drain.

That leaves steel or copper and there are advantages either way. The copper won't corrode as much as steel with the water passing through it, but I can weld the steel. Also, with both of them I run the risk of galvanic corrosion (often erroneously called osmosis) between the drain and the aluminium gutter.

I decide to use a length of steel brake line, partly because as I said I can weld it, and partly because it's closer to aluminium on the galvanic table than copper is, and therefore less inclined to cause corrosion between it and the aluminium.


Any water that manages to get inside the shutter hinge area will be caught by the gutter (red), run down the drain (blue) inside a frame member, and be spirited away somewhere under the truck by some tubing (yellow).


Two shots of the frame member before welding onto the frame, the drain can be seen protruding from both ends.

Wed 12 Sep

Chris planned to go into town today by herself to do some shopping. While there she was going to pick up some bolts and such for me. But the time I totted up what I needed, and realised that some things require me to make a decision at the counter, I go as well.

Bang goes another day, and after all that most things I need have to be ordered in, so I'll have to go back again.

We get back late in the afternoon and I only have time to finish off the steel in the bedroom floor. I actually thought it was finished a few weeks ago, but we've decided to try another method of constructing the floor by sandwiching ply and insulation. This should keep us nice and warm in the bedroom, but is not as strong as the thick sheet of ply I planned to use, hence the extra steel to provide better support.

Thu 13 Sep

It's a well documented fact that the entire western world is getting bigger, modern humans are taller and fatter than their predecessors. So what's that got to do with building a a motorhome?

Well this bit us in the bum with Wothahellizat 1 and it's done so again this time. When I designed the last motorhome I allowed for beds with single mattresses of the "standard" 2'6" width, only to be told that the standard had become 3 feet wide and would soon be 3'6".

This time we're using simple self-inflating foam camping mattresses, we've had two in the cruiser for a couple of years and find them very comfortable. They're also extremely light which is a good thing as I'm trying to keep the bedroom as light as possible because it's over the front axle.

As we haven't had these mattresses that long I designed the space for their size, even though we plan to buy new ones. With this in mind Chris does some web searching for them and finds that almost all brands are 195cm long these days, that's 5cm longer than our current mattresses and the space I have allowed.

We do eventually find mattresses the right length, however in an attempt to "future proof" the bedroom I decide to cut some of the frame to allow larger mattresses if we have to buy again in a few years.

Fri 14 Sep

It's the bedroom floor that gets our attention today. The floor will eventually be a ply-insulation-ply laminate but today just want to cut the bottom ply layer.

TIP: When cutting across the grain, especially with ply and with a jigsaw, splinters can ruin the look of the cut. An old chippy's trick to get a clean cut is to score the cut line first with a blade. If you want to keep the off cut free of splinters as well, score a second line a cut-width from the first.


A cut across the grain, the upper side of the cut has been scored with a blade and is nice and clean. The lower side has not been scored and is badly splintered.

The floor requires two sheets of ply, they meet on top of a 20mm (3/4") steel bar but if I just butt them together I will only have 10mm on each sheet for screws. Not enough I think, so I dovetail the two sheets.


The two floor sheets dovetailed together

Now each has plenty of timber for screws.

Sat 15 Sep

Having got the bedroom floor sheets cut I put them aside for a while so I can work on the pop top.

When using the pop top we plan to use two gas struts to take the load and raise/lower it by hand. The position of least stress for these struts is at the opposite end of the pop top roof from the hinge, however that requires a strut with a 750mm (29.5") stroke, much longer than we have.


The best (that is lowest stress) location for a strut is as far away from the hinge as possible.

We do however have some very strong but short struts from the deck roof on the old body. These can be used at a point closer to the hinge where the stroke requirements are reduced.


An alternative and fairly standard location for a gas strut. This however places a lot of stress on the three pivot points.

Not wanting to buy any more components than absolutely necessary I retrieve two 150kg (330lb) struts from the pile of Wothahellizat 1 bits, weld up some temporary pivots for them from a couple of bolts, clamp everything to a likely spot on the pop top and give it a try.

The clamps cannot hold the struts with the force, so I have to apply small welds to the temporary pivot points.

This works but the pop top is too easily pulled down, as it's not yet at it's final weight this would mean that, in their current location, the struts would be too weak.

I cut the pivot points off and re weld them in a different place.

This time I cannot lower the pop top even with my entire weight hanging from it.

After several attempts at different locations Chris notices that the hinge has bent. This is a hazard when using a powerful strut close to a hinge. I haven't used a particularly strong hinge as I did intend to either buy longer struts and use them as mentioned above, or even to get a linear actuator, but these cost money, add more complexity, and are just another thing to break down.

This is turning into a pain in the you-know-what and we have a good think about what we're doing and why we're doing it.

Chris is wondering exactly what we get from this pop top, so when I say "Do we even need a pop top?" she instantly replies "No".

In the old truck the pop top gave the bedroom a full-height ceiling, and it was great, but we didn't raise it that often. It was common for us to leave the roof down for six months or longer. So we can live without a pop top

We do need a hatch however.

We always planned to have a hatch in the pop top, this would have been used for ventilation and also access to the roof.

After bandying around a few options Chris comes up with the idea of having a huge hatch. I'm quickly convinced so we get to work.

The first thing to do is remove the hinge and weld the pop top in place. Then I cut the central roof beams from what was the pop top and also a couple of feet into the main roof.

I box in the area and before long we have a 2-metre (79") by 800mm (31") hole in the roof. I'll have to design the actual hatch, but a big hole is a good start.

We're really rapt in our change, it gives a huge opening in the roof which will allow us to look at the stars while in bed, use the bedroom as a viewing/camera platform, and increase the truck's ventilation enormously.

This change solves a few other problems as well, like how to deal with solar panels on a tilting roof. It removes a lot of complexity, and saves both weight and time.

You gotta love that.

Mon 15 Sep

I'm spending all my time trying to get the 11 shutters finished at the moment so there's not much to report.

Meanwhile here's a photo of the new roof arrangement over the bedroom.


The blue area is the old pop top, mouse over the photo to see the new hatch in red.

Note that the hatch has been cut into the roof to the rear of the pop top, this brings it over the kitchen and will greatly increase the ventilation in this area. The old body had a dead area around here and it sometimes got quite warm when cooking.

Wed 19 Sep

As the shower floor is also the entrance floor we need to make it from some material that lets water through and is comfortable to stand on, and the other day I spotted a piece of punch plate at the engineering workshop while buying some steel.

After thinking about it I decide that the punch plate will make a good shower floor, the only problem is that it's mild steel and it will rust. I'll use it but will probably get it hot-dip galvanised.

The plate is quite rusty already, so I spend some time with a wire brush on the grinder.


The punch plate shower floor looks good after a wire brushing.

Thu 20 Sep

After spending the morning in town we return to the workshop with a view to raising the body and putting it back on the truck. I want to do this for a couple of reasons, firstly I need to see exactly where I can put the steps, and secondly, after all the straightening of the frame we've done, I'm worried that the mounting bolts may no longer line up with their corresponding captive nuts.

After about 20 minutes jacking the body up I decide to put the truck in line so we can just back it under when the body gets to the right height.

The truck however will not start, the motor turns over well enough but it won't fire.

It's been difficult to start for a while now, ever since I plumbed in the fuel lines, filters, changeover valves etc. I wonder if there's a connection.

After much ado I find a connection that appears to be sucking air, that would explain why I've been seeing bubbles in the fuel lines. But we have another problem.

The fuel pump I use to pressurise the lines to make bleeding easier doesn't appear to be working. Chris reads the instructions printed on the side of the pump. "Not to be mounted more that 12" above the fuel pickup point" it says.

I did relocate it recently and now realise that the new location is actually a couple of inches higher than before and about 12" from the bottom of the fuel tanks. By adding a longer length of fuel line I can lower the pump and it starts pumping fuel.

With this going it doesn't take long to get the fuel system primed and running.

I line the truck up with the body and we resume jacking. Before long it's at the correct height and I reverse into position, or at least as close as I can in the now dark shed.

We'll have to leave it there until tomorrow.

Fri 21 Sep

First job today is to bolt the body onto the chassis. It takes about half an hour and I'm pleased to report that the bolts line up perfectly.

It will have to come off again for painting, but while it's on I'll add some bracing to strengthen the body.

I start by adding some to the lounge room wall, to do this I need to know exactly where the water tanks will be located so I get three of them from our pile of parts and put them in position.

Having decided where the tanks go I can add the braces between them.


Three of our six tanks in location under what will be the lounge room floor. On the left can be seen the the location of the other three tanks and the bracing I've just added.

Sat 22 Sep

We'll be doing the roofing soon but before that can happen I must add a lot of diagonal bracing to the roof frame.

This will strengthen the frame and also provide more support to the thin roof sheets.


The diagonal bracing in the bedroom roof area.

Mon 24 Sep

Mark and Gail (motorhoming friends) are arriving for a short stay today, but before they arrive we work on the roofing steel.

Because the roof is slightly gabled the sheets must have small folds applied at two locations and I originally thought I would have to have this done by someone with a pan brake. However we find that the old trick of clamping a sheet between two lengths of RHS and bashing it with a mallet works a treat.

Tue 25 Sep

With Mark and Gail visiting and able to lend a hand it seems like an opportune moment to glue the sheets on the roof.

We'll be using Sikaflex with no mechanical fasteners and in the past I would just have bought some tubes from the nearest hardware store, cleaned the areas to be glued with a cleaner like PrepSol, and stuck the sheets on.

This time however we decide to get some advice on the correct method. I ask several people which Sikaflex to use for truck bodies, and they all say 227. But why not go to the source, sika.com? On the manufacturer's web site we find that 227 is called an adhesive/sealant and the recommended product for adhering panels to truck bodies is in fact 252.

So far so good, we'll use 252, but how to we prepare the areas to be glued? Unable to find any info I phone for technical advice. Here are some tips from Sika.

DON'T clean with PrepSol, it leaves an oily residue.

DON'T undercoat the welds with Red Oxide primer, Cold Gal, or any other zinc-based primer. The Sikaflex will not bind to these paints.

With galvanised steel and aluminium DO abrade the metal with sandpaper or other abrasive.

DO use Sika 205 cleaner.

DO use Sika 210 primer, it's resin-based and designed for the job.


The Sika 205 cleaner (right) and 210 primer.


It takes all day, but we get five sheets on the roof, that's the majority of the body covered.


Five sheets of roofing are fixed to the frame.

Wed 26 Sep

In terms of square metres the roof is seven sheets in area and yesterday we did five of those sheets so we should finish in no time today.

However the remaining area is more complicated and we spend all day folding and cutting sheets.

By the end of the day there is only a small area to be done, this area though is recessed to house the TV and other aerials, it still requires some thought so for the moment we're done with the roof.

Thu 27 Sep

Some time ago I was working on the shutters but the job ground to a halt because we were sent the wrong hinges.

After weeks of telephone calls that cost us more than the actual hinges we finally take delivery of them and can return to some shutter building.

As you may remember from the description of the shutter hinge design the hinges are not straight forward.

Both the shutter and the fly screen have to be openable either independently or in unison, this means they both have to have hinges that pivot at the same point. I could use two hinges but have decided to use a single piece of continuous hinge and cut one of the flaps, this effectively gives me two aligned hinges that only need one fastener to hold them to the body.

I cut some continuous hinge into 11-knuckle lengths, then cut one of the flaps at a point four knuckles in to create two flaps, one for the shutter and one for the fly screen. The smaller of the two (for the fly screen) is then cut again to create a shorter flap. This will place the fly screen at just the right spot within the window frame.


The cuts (red lines) create two independent flaps.

Now I weld a 30x24mm piece of angle (cut from a length of 35x35 RHS) to the short flap and a length of 15mm flat bar to that.


The short flap is modified to go around the gutter and connect to the fly screen inside the window frame.

The angle takes the hinge around the gutter, and the flat bar attaches to the fly screen frame, this will allow more fasteners to be used which will spread the load out over a wider area of the relatively flimsy screen frame.

With me cutting and welding and Mark cutting and grinding it takes most of the day to make the 26 hinges required. We finish undercoating them just in time for beer o'clock.


Thirteen left-hand and thirteen right-hand shutter hinges.

Fri 28 Sep

With my bevy of newly-made hinges I set to hanging the shutters. This takes a lot longer than I anticipated and I only get the four bedroom shutters hung after working all day.

Below can be seen a photo of a hinge in place.


Mouse over the text to see the various components of the shutter and hinge assembly. (photos may take a few moments to load the first time).

 

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