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16. Welding

11/03/2012

On Wednesday and Friday we ventured into the depths of the countryside to see Allen Haseldine, our CAA-approved welder.

Allen lives in Craswell, a very remote village under the lee of Hay Bluff, on the border of Wales. My estate car made it, but every other vehicle within a 20 mile radius is a 4WD or tractor, I would guess. There’s no mobile signal, and the last 10 miles or so are on single track roads with only the sheep for company.

Allen himself, has been involved in metal fabrication and welding all his life, and has a very well-equipped workshop at his home set in a valley with no other houses in sight.

Allen Haseldine in action

Allen’s manner may be rough and ready, but it became immediately apparent that his welding isn’t. We quickly established a great rapport, the insults flying back and forth as we fed him the pieces for welding.

There’s an awful finality about welding. Once it’s done, it’s done – there’s no going back. If you make a mistake, it’s unlikely you’ll be able to fix it.

Although we’d brought lots of smaller brackets for Allen to be getting on with, the first priority was the rudder. It would be a big psychological boost if we could complete the rudder ready for painting.

But we couldn’t start any welding until the horn was ready to go on.

I’ve explained in part 14 how we formed these, and the first job was to weld the two dished halves together to make a single horn. It wasn’t quite as simple as that; there are reinforcements at the ends that have to be inserted, lined up, and located while you weld everything up.

And if you think the two halves come out fitting exactly together, think again – for some reason there is a gap in the middle, so as well as lining up the inserts you have to squish the two halves gently together while Allen wields his TIG torch.

That done, we than had to drill large holes in them to thread them over the relevant structure. We weren’t looking forward to this, since the horn has to sit at an angle on its tube, and it meant setting up a jig to hold it in place while we drilled it. And using a hole saw is always a bit risky, with the chance of it grabbing the workpiece out of the jig and  whirling it round and round, or going completely haywire.

In the end, the whole thing went much easier than expected and all of them were the most beautiful fit, with just the correct angle on them.

Rudder horn detail

With the rudder horn complete, we could complete the final assembly and start to weld. We carefully eyed up the set of the horn to make sure it was at exactly the right height and wasn’t crooked or twisted, and gave Allen the nod, then shut our eyes while he applied a couple of tack welds to lock it in place. You have to shut your eyes while he’s doing that, and when he’s finished you open your eyes and give it the final check. After that Allen settles down to complete the weld.

That done, the ribs had to be welded, and there was a mass of silver solder to be applied near the hinges. When that was done, I took it outside with Allen’s shotblasting machine, and cleaned off the glaze of flux that was all over everywhere. Job done!

The completed rudder, with the original drawing behind

 

The aileron horns, with the nasty little ‘ears’ at the top that took such a lot of fiddling to get set correctly. Setting them onto the square bracket at the bottom was no joke either.

We weren’t finished with horns; there are two on the elevators, four on the ailerons, and another one on the joystick mechanism. The aileron ones are particularly troublesome; in addition to the reinforcement inserts in the ends there’s a little tongue that sticks out sideways and has to be posted through a slot in all three thicknesses – the two sides as well as the insert. Getting the slots to line up was a very fiddly job; I broke two 1.5mm drills and only had one hole to show for it. Rick was more skilful and patient, and managed to do the lot, with only a small pile of broken drills…

Elevator hinge brackets before welding

The worst job, however, was the hinges for the elevators. There’s a single tube forming the back of the fixed tailplane, with two tubes forming the front of the two moving elevators. Each elevator has three hinges which have to be fitted into slots in the tubes. The slots have to be EXACTLY in line and parallel, and EXACTLY opposite each other. As you’ll have gathered, slots are horrible things to cut in metal; there isn’t a convenient hand tool that does the job reliably and accurately, and each slot needs a great deal of personal care and attention, and several hundred swear words to get right. All of the above were supplied by Rick, and once the horns were made, they could be slipped over the elevator tubes so that the hinges could be assembled and welded.

This took a great deal more swear words and when finally the whole thing was ready to go, we took them across to Allen for welding. The way these things sit makes it a very difficult welding job too, but thankfully Allen’s got a more or less inexhaustible supply of swear words too, some of which were directed at the design, and some at us for not getting the metal clean (dirt in the joint can make a real mess of the welding process).

 

But Allen did a first rate job; the welds are smooth and even with no arc strikes, undercut, cold lap or any of the other potential pitfalls in a weld.

We came away with a car boot full of bits and pieces and a plan to return in ten days’ time for the next round of bits for him to weld.

At the weekend the sun was out, so we took the opportunity to spread out all the bits we’ve got so far and crow over them.

The empennage – all the tail surfaces more or less assembled – with Donald’s son and grandson looking on.

Rick admiring our handiwork so far. The completed rudder is at the back, with all the other bits laid out in front.

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From → Building, Technical

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