Rob Gray :: ontheroad :: wothahellizat :: wot2 :: diaries :: issue-011


Tue 2 Oct 2007

I'm taking a break from shutters and working on the front door today.

I'm hanging the door from gate hinges but as I don't want any fittings to be visible from the outside I've mounted the hinges inside the body and extended them with a semi-circular arm that allows the door to swing out.

Animation showing the door opening.

The gate hinge and semi-circular extension, all just tacked together before proper welding.

Having got that working I look into using the lock from the door on Wothahallizat 1.

The door lock is installed.

There, now we're at lockup stage.

Thu 4 Oct

The other day, while Mark and Gail where here, we put the roof sheets on but left them overhanging the body. The most obvious overhang is at the front where we had a lot of extra material and today I've fold it over the front of the roof.

The front overhang after folding, it will be trimmed when I decide exactly where to trim it.

But the rest of the roof overhangs by about an inch and I originally planned to fold the excess down over the aluminium cladding to provide a waterproof seam, however I also want a gutter as we plan to collect rain water with this truck.

Also, the old idea would have allowed the aluminium cladding to touch the steel in several places, most especially where the rivet pierces the material. This may lead to galvanic corrosion.

The terms galvanic corrosion and electrolysis are often intermixed. In galvanic corrosion there is a flow of current generated between dissimilar metals when they are touching while in the presence of an electrolyte.

Electrolysis is a similar process, but in this case the electrical current is from an external source.

There are other issues at play that affect the amount of galvanic corrosion, for example the distance between the touching metals on the galvanic table and the relative sizes of the objects, but I've seen the results of steel touching aluminium and it's not pretty, so in general I'm trying to nip these problems in the bud.

So I decide to fold the excess up instead of down and add a 50mm steel bar all along the edge of the roof to both act as a gutter and a fixing point for the solar panel mounts.

The original idea (left), and as it will be done (right). In the new version the materials that touch are steel, whereas with the old version steel and aluminium touched.

Note that although the roof is steel it is galvanized so I guess the steel gutter is actually touching zinc. In fact all three metals are quite close on the galvanic table so I may be being a bit paranoid, but I've never seen problems between steel and zinc and have between steel and aluminium so better safe than sorry I guess.

Having done the roof folding it's time to lift the body from the chassis again so we can paint underneath and do a few other small jobs.

The body is getting heavier and the legs are straining, they also sway alarmingly with the slightest lateral movement. As I plan to be working underneath for the next few days we decide to X-brace the legs by welding some RHS between them.

The X-bracing temporarily welded to the legs.

My cheap 60kg-rated wheels are starting to feel the pressure.

We ease the truck from under the body.

As an added safety measure we also sling the body to the overhead crane beam using our plasma rope we recently bought for the winch. This stuff is amazing, 50m (162 feet) of the 11mm (<1/2") rope weighs just a few kilos, is rated at 12.7 tonnes (28,000lbs) and even though it is all coiled up it hardly tangles at all.

50 metres of 11mm plasma winch rope.

The old steel cable was much larger at 16mm (5/8th"), was too heavy to lift without mechanical help, and was all but impossible to handle.

With the body safely secured about 1400mm (55") off the floor I can work on the underneath for the next few days.

This is the last time the body will be off the truck, until I build version 3 that is :-)

Sat 6 Oct

With the body off is seems like an opportune moment to weigh the chassis again. I weighed it a couple of months ago of course but that was before I added all the tanks, body mounts etc.

Last time it was 6 tonnes, what will it be now?

This time it's 6.5, not bad considering the amount of stuff now hanging off the chassis.

Now I know that I will be able to weigh it again when the body goes back on to find out exactly how heavy that is.

I spend the rest of the day spray painting the underneath of the body.

Sun 7 Oct

More painting, this time it's the chassis. It's amazing the difference a coat of paint makes, it's like having a new truck and $50,000 cheaper.

Mon 8 Oct

Another job that needs doing while the body is off the chassis is to drill some holes for the plumbing, specifically the hoses running from the utilities area to the two tanks (actually there's six tanks but they are plumbed as two banks, so I guess we have two banks of tanks, or two tank banks).

I could of course just run the hoses under the body but running them through the body should look neater and provide more protection.

I have two designs for this part of the plumbing, one that fills and drains to and from each bank with separate hoses, and the other that fills and drains with via a single hose per bank.

I can't really decide if there's any benefits either way from a plumbing point of view, but the decider is the number of holes I have to drill. With a choice between 10 and 20 holes (really 20 or 40 because each RHS beam requires two holes) the single-hose option gets the nod.

Four of the holes, in the spot where the hoses hang a left into the utilities area.

The same holes after insertion of some short lengths of steel pipe. These pipes will be welded and caulked to seal the interior of the beams.

Thu 11 Oct

In between painting various items I've been working on the step runners.

I plan to have the steps slide out from under the body and so I have to make some runners. I'm doing this by having some 40x40x4 RHS slide out from inside some 50x50x4 RHS and if you do the maths you'll realise that this gives a 1mm clearance so these two sizes are a pretty good match.

More about these runners later when I build them but for the moment I have to make the outside parts as these bolt onto the body and it's much easier to make all the brackets without the chassis in the way.

Three of the four outside RHS lengths have to have a long slot cut in them to accommodate brackets for the steps, a simple enough process involving scoring a couple of lines and cutting with a thin cutoff wheel.

There is one thing to realise about RHS though, RHS stands for Rolled Hollow Section (although I've also heard Rectangular Hollow Section) and as the name implies it is made by rolling steel into shape and welding it. This leaves the section under some tension so when you make a long cut along its length it will tend to splay apart.

The slot has been cut in a length of 50x50x4 RHS.

Looking from the end you can see that the side that has been cut has splayed by 1mm.

This is probably not a problem for this application, just making my 6mm slot vary from 6mm where it starts to 7mm at the open end. However it's something to keep in mind if you do need the section to remain truly square.

I may still press the sides back together later, I'll see how things work out.

Fri 12 Oct

For the time being I'm finished with the step runners so I unbolt them and put them aside for later. I then spray all the new mounting tabs under the body.

Initially I planned to just spray the roof and back wall of the cab as the rest can be done with the body on, however we've decided to re spray the entire cab now and get it over with.

The rest of the day is spent with me pulling parts off the truck, Chris cleaning them, and me spraying them.

By day's end we have quite a collection of nicely painted truck parts. I've also removed the doors, bonnet, windscreens etc. from the cab.

Sat 13 Oct

First priority today is to get the winch sheave block finished. It doesn't need much as most of it was bolted together weeks ago, but while I'm in a painting frenzy I've decided to pull it apart and paint all the parts and they are now ready for reassembly.

Yes I know, painting pulleys is a bit anal, but they look so good, and anyway with any luck we'll never use the winch. Even if we do, maybe the plasma rope won't scratch the paint.

The sheave block with its top plate removed. The winch cable comes from the centrally-mounted winch (yellow) through the rear body mount to the sheave block, then either around two of the sheaves, back through the mount and along the chassis to pull forwards (blue) or straight out to pull backwards (red).

Once that's done I concentrate on the cab, removing the seats, engine cover, internal panels, bumper bar and just about everything else.