Okrasa Special

[911hillclimber]

Practice makes perfect, so the new wing will happen much faster and much closer!

Great stuff and always worth waiting for.

[Barry]

Just lost a huge reply I'd posted (with pics etc) upon hitting the submit button . A good 1/2hr of work wasted again (second time tonight). I might post later, or leave it for now. Oh well, time for some dinner I think ...

[Barry]

Lets try again ....

Anyway .... there is rather more of a tale behind Steve's picture than his very abridged version, so pull up a chair: I'm going to tell you a story about a front wing.

As we left it, the front wing was developing nicely, although I had a niggle that the reverses (going into the scuttle and the bonnet) might bite me as the panel developed. Sure enough, on the next session, the panel started to get angry. Then I did something I really hate doing: I started another one without understanding why the first had started to go wrong. That's not quite true actually: I thought I knew.

As it happens, and luckily as it turned out, the nice people at Eckold had a last minute place on an aluminium gas welding course, to be held at the well-known (and repected) RS Panels, to be followed with a workshop tour and discussion. The gas welding element was very good: although I've done a little, this had a lots tips that were new to me. The real value though was the tour.

The upshot was that upon describing the panel, even they said they would break it into smaller parts, ideally four (front / rear inside and front / rear outside: so a hot-crossed bun essentially). That came as something of a relief, and I was keen to get back to try it.

As I'd started the second wing anyway, I cut it down a little to avoid the two return areas. After that the wheeling went very well, and at one point the fit and finish were coming togther nicely.

With this extra part coming on, a rather greater issue was rearing it's head. In my wisdom I'd made the front wing bulge out slightly when looking down the car (as well as the curve over the wing when looking from the side). Can't remember quite why I did: I must have thought it looked good. And it did, from the front and side. From the rear 3/4 though it looked as though the wing was a wart on the side of the car.

I thought I might be able to space the doorskin out from the wirefom a little, and re-wheel the wing to remove some of the direction change between the two. It became clear after rather too long, that this wasn't going to work: there was just too much metal to shift.

Here's the wireform at this point:




So what to do?

Well, Steve said he was happy with it as was, especially when I said that I thought the best thing to do would be to bin all of the panels to date, except the rear wing. Also to bin the whole centre of the wireform as well, plus rework the rear portion of the nearside MDF eggcrate jig to match the 'new' side. So what did I do ....




That's what I did . My thought is that I'm on a fixed price, so there's no financial implications to Steve for this, and I really don't want to go through this thinking we could have done something better, especially if it's something that's down to me. O.K. so the timescale get's stretched, but not by much. The re-working below was done in one day, and it's probably another four or five days to redo the panels back to the same point. In short, had I not done this, it would have niggled at us all of the way through.

The wirefom has been re-worked to make the side of the car one curve from wheelarch to wheelarch, the rear vent has been tweaked to flow better, and yet the (successful) side view of both the panels and the vent has stayed the same.






Everything now looks much more mature, and the lines certainly look miles better. TBH, had I followed the orginal rendering a bit closer, I'd have been O.K., but at the time things were different. Live and learn and all that.

Oh well, onwards and upwards. In the meantime, spare a thought for me next time you crack open a can of something. You may well be drinking from a little bit of Okrasa Special. Cheers!

[Gary71]

A brave move Barry, but I'd say the correct one looking at the images.

I tried aluminium gas welding once, but all I seemed to create was massive holes, one second I was making a nice butt weld, the next it had all gone!

[911hillclimber]

You and Steve will only be happy if you feel this is all made to your very best ability, so you are right to re-cyle if that was your instinct.

I'm sure you will form this car by the heart and touch as much as following the wires religiously.
Alloy bodies i've seen at various show over the years have a surprising number of welds, but all i think would be painted.
I saw a Lotus XI in alloy, an original body with an accident prone nose, full of patina but all the welds were polished away, a fab piece of work. Goodness knows how the panel man did that.

The front wing into 4 pieces seems a lot of long welds. Can you wheel over a panel after welding? Seems hard to think you can as there is bound to be a lump/bump somewhere inside or out let alone metal section thinning.
Does the sheet show much work hardening at all by this stage, a growing resistance to yield to the wheel?

Facinating to me and many others I'm sure.
Look forward to the next steps, dead envious really!

Graham.

PS
Post loss via the 'submit' button has happened to me too this week on DDK

[Barry]

Thanks for the reply Graham.

TBH, even with the deep shapes, it's not noticeable that the ally is work-hardening, although it must be of course. Certainly it's no problem, and will work in our favour once the car is on the road, as extra stiffness for no extra weight here is no bad thing.

As you say, it seems a lot of welds, and that was what suprised me at RS: they would much, much rather make up several pieces that make the wheeling easier, and weld them up, rather than put all of the time into the wheeling.

I re-watched a few of my John Glover DVD's to remind myself of his thoughts on this. Although his examples are a little different, on 'Aluminium Shapes' his makes the comment that if you have a large panel with lots of different shapes in it (like the front wing), if you need to correct just one area, it's very difficult not to send another area out as you do this.

I guess much comes down to welding confidence: once you know that you can weld in pieces without a thought, then it makes sense to make the shaping element as straightforward as possible. In this case of course I'm trying to balance the number of welds against the inevitable time it will take to tap them up, let alone to a quality that can remain bare metal.

Even at RS (surely one of the very top companies in Europe, and possibily world-wide), the point at which they signed off the final finish for cars heading for the paintshop were miles, and miles and miles (or hours and hours and hours) from where you'd need to be for bare metal. Nevertheless, they were easily as perfect as they needed to be for a painted application, and any filler would be truly minimal: spray poly would probably be enough.

Even my minimal experience is enough to show that the time difference between prepping a body to paint standards, and one to bare standards are completely differnent. I wouldn't be surprised if the prep time on a welded seam was double or triple.

As for wheeling welds: yes, it's a well known technique, and can work very well indeed. You have to linish anyway any blobs (perhaps from using a dob of filler rod here and there), and make sure all flux is well rinsed away (as you'd need to do anyway), and use an extremely light pressure. Mostly it just depends on what will fit in the wheel: as the welds are so very soft, I can imagine that it would be easy to buckle a large panel if you weren't very careful.

Ultimately, you're generally not adding any extra metal to the weld, so in theory if you merely straighten up what's there, the panel should still meet the jig O.K.

[911hillclimber]

V interesting!
One other question which I forgot to ask is if you will wire the edges or flange them (as in a production car steel panel wing 'lip')? I'm sure I've seen steel wire used in alloy (galvanic corrosion...) but how will you get stiffness to such lips and return edges?
Must admit there are several questions that spring to mind especially on the panel/chassis mounting, but don't want to bore the breath out of the audience. (or you!)

I'll sit down and be quiet.

[Barry]

No, don't do that: make as much noise as you like .

Funnily enough, Steve and I were talking about exactly this last week. I said that I would be happy to do either, and much will depend on whether we have some sort of inner outer wing (i.e. some sort of liner, or a more 'proper' inner wing that is welded directly to the outer).

At CLM 10 I saw various solutions, but overall I think we'll end up with something fairly simple, so just a flange or wired edge. We'll see, it may well be that once we get that far (and is will be very far in, as both the inner and outer structures will be in final stages), that the most sensible solution becomes obvious.

I'm rather hoping to do two days back to back this week, assuming I hit my target on the current 911, so that should get things moving forward again.

[roy mawbey]

Brave decision to re-do, but the correct one. That is one really difficult job but it looks great.

Roy

[Barry]

Thank you Roy .

TBH, the decision to undo the work isn't that hard: what's really tricky is pinpointing why it needs undoing. The times I've looked at an area and thought there's something wrong, but I'll be jiggered if I can put my finger on it. This time, with plenty of thought, and a bit of discussion, I think I've found a way forward that we're pleased with.

The rear vent area was a good case in point: it took quite a while to figure out that the angle at the base was wrong: I'd angled it in from the wing line, and then couldn't resolve how the panel would be able to follow the edge of the vent without distorting the 3/4 views. Once we realised that actually, just as long as the base of the vent is in line with the main panel, the rest of it can go wherever it likes (I'll take some pics to illustrate at the next session). So, a few minutes work with the wire has (hopefully) resolved it.

It's a funny thing, but I have zero attachment to a panel that I've made, and don't particularly feel anything when I squash it up and bin it. I think this is because I'm looking forward to getting the next one better, and as I've hinted, the primary objective for me on this project is experience. Although there is obviously money involved, that is far, far from my thoughts. I'm much more interested in coming up with something where a) the quality is good enough, and b) does justice to David's orginal build and Macaulay's body design.

Oh yes, and I'd better keep the client happy as well .

[steve wright]

all good stuff. my preference as I described to Barry is for a single skin with no liners (too much weight) and wire-rolled lips for the wings. The latter because I don't think we'll have the luxury for a lip because I've just bought a set of exotic, period rims for the Special which are slightly wider than the 356 rims and I hope will suit it to a tee when it comes to developnig the car as it might have been through the Sixties....

[steve wright]

So no update but a technical question I need help on please regarding tyres. We've go to the stage of being close to fitting a front and rear wing. The clearance between tyre and wing is going to be pretty slim and I also found a set of genuine BRM rims for the car which I plan to fit later on as part of the development that the car could've gone through had it been finished in the early Sixties. The BRM is a 5 inch wide rim (so 7mm wider than the Porsche rim) and the offset is slighter shallower (i.e. it sits out from the drum by an additional 5mm). My question is: what's the best road tyre that I can use for occasional hillclimbs and circuit races, but which is a period tyre for the early/mid sixties? Counsel and opinions welcome.

[PhilipB]

Steve, I have Avon CR6ZZ 175/70 HR 15s on my 4.5" steelies. They are road legal, used by plenty of historic racers (usually in preference to Dunlops), and have a period looking tread pattern. See www.longstonetyres.co.uk for details.

Best,

Philip

[Nige]

Come on guys you've got to up the game now on the big build updates, you're being over taken with Andy's 904, though Mikes RSR seems to have stalled for the moment.

[Barry]

Come on guys you've got to up the game now on the big build updates, you're being over taken with Andy's 904, though Mikes RSR seems to have stalled for the moment.

Don't we know it . We did actually get to a point where we did have nearly one whole side roughed out, but that's when I made that call to re-model it all.

There is another update nearly ready, but now of course we've got the issue of these wheels: hopefully they'll fit as they make for great period parts (as Steve says, they are very much the sort of thing that would have been an upgrade at the time), and neither of us want to be re-modelling for a third time.

I'm keen to get the whole side in place before doing an update, as I don't want to jinx things!

We've decided to hang fire until Steve gets a couple of tyres on, and then we can see what we're dealing with.