Ex-Racer Spitfire Mk1 Rebuild

[Escadrille Ecosse]

4 minutes ago, Nick Jones said:

Good luck with the weather! 

Quite!

[Escadrille Ecosse]

Thursday's weather actually turned out better than the forecast, dry, light winds and even some occasional sunshine.

Having been bitten the previous attempt I decided to put the gazebo up anyway but wasn't needed.

Used up the last 1/2 litre of primer but at least I had enough to get a decent coat on, especially on the areas where I rubbed through the first coat and the sidelight. And realised that I had forgotten to form the dummy seam lines between the top panel and quarter panels.

Got it rubbed down again today.

Pretty pleased with it. The area round the sidelights was within the thickness of the paint and most of the other areas flatted out nicely. Couple of areas on the wings both sides and on the top of the bonnet and a (hopefully) small amount of filler needed along the reconstructed 'crease' at on the passenger side.

With any luck one more coat of filler primer will do the trick. I've ordered more and hopefully we'll get another break in the weather. Mostly dry and sunny in Weegie today, and weirdly warm too but pretty strong winds from storm Kathleen.

[Nick Jones]

Well done. 

Warm and (very) windy down here too.

[BiTurbo228]

Seconded on both fronts! Excellent work, and the wind gave my 1yr old a perm while we she was helping me outside 

[Escadrille Ecosse]

Well I managed to do a 'Nick Jones' and put my back out on Monday. Been lots of medication, stretching and walks round the park trying to get it mobilised again.

Today it was actually possible to move about a bit and as long as I avoided bending seemed manageable. So as left it the bonnet was ready for another (last?) coat of the primer I had ordered at the weekend and arrived yesterday.

Paint time then... after I put in fake seam lines in the top panel.

Lot of thinking about how to do this as it's a 3D surface with variable hardness due to some being filler and some GRP and with the radius to the headlight. And the lines need to be 'straight' and of a uniform width and depth. And the two sides need to be visually similar.

In the end I decided to make up a double template from thin aluminium to form an inner and outer edge for the 'seam'

These could then be stuck to the bonnet with double sided tape to to act as a guide for a needle file.

Do one side, remove the guides, flip over and stick to the other side in mirror image.

Slightly scary but seemed to work. Difficult to be abslutely sure with the different shades and textures but once the paint is on it should be clearer.

Now time for paint. Tomorrow is forecast dry but windy and anyway I think the back needs a bit more time before I'm humfing heavy stuff about.

Frustrating.

Edited April 10, 2024 by Escadrille Ecosse

[Nick Jones]

33 minutes ago, Escadrille Ecosse said:

Frustrating.

Very. Trust you recover quicker than I am…. I’m not completely broken all the time but it’s not reliable.

Seam lines look good 

 

[Escadrille Ecosse]

48 minutes ago, Nick Jones said:

I’m not completely broken all the time but it’s not reliable.

You have my sympathies Nick.

[Nick Jones]

Thanks.

Can’t help thinking a bit of warm dry weather might help. May have to go abroad for it…..?

[Escadrille Ecosse]

1 hour ago, Nick Jones said:

Thanks.

Can’t help thinking a bit of warm dry weather might help. May have to go abroad for it…..?

Good excuse at least 

[Escadrille Ecosse]

Got the next coat of filler primer on and rubbed down and then needed a fourth (and final) coat.

And the final rubbing down.

Light all all over with the dry 320 grit on the long board to make sure it was all basically level. Then wet sanding with 400, 600, 800 and 1200 grit. A few very small areas where I've gone through the primer but we can cope with that.

Now I'm half way through finishing off with the DA polisher. It's primer so I'll never get a perfect finish but good enough to take the mould (and hopefully release properly afterwards) and I can get the final polish to full shine in that.

Then I can start on applying the would release and wax.

Materials for making the mould all got delivered the other day. In those boxes by the bike. At last getting somewhere.

[Mark]

Wow, great work, as usual.

[Nick Jones]

Exemplary patience in the pursuit of perfection 

[andymcp]

I must say that after all the time, effort and expense (no doubt?) you have expended, I would be most reticent about taking it out of the garage to expose it to the ravages of the general 'motoring' public! 

[PeteStupps]

This really is an inspirationally detailed and laborious job.

The effort going into this buck (or mould, or whatever it is) suggests some bitter memories of imperfections in previous work, perhaps? Or just a serious case of perfectionism 

[Escadrille Ecosse]

6 hours ago, PeteStupps said:

This really is an inspirationally detailed and laborious job.

The effort going into this buck (or mould, or whatever it is) suggests some bitter memories of imperfections in previous work, perhaps? Or just a serious case of perfectionism 

Thanks Pete. There probably is an element of perfectionism there but the cost in time/money isn't that much greater to get a part at least as good as the factory than one that looks like a 'cheap glassfibre' copy.

Although time consuming it's much easier to get a decent finished article on the car starting from a good mould and it's much easier to get a good mould off a good buck.

Basic shape aside, getting things smooth and shiny also makes separation of the buck to mould and then mould to part considerably easier and less stressfull as well.

And unlike steel panels which can be finessed a bit afterwards to match sill lines, etc. GRP and to an even greater degree carbon fibre pretty much stay the shape you made them.

Some bitter experience with 'cheap glassfibre' copies probably contributes to this too.

8 hours ago, andymcp said:

I must say that after all the time, effort and expense (no doubt?) you have expended, I would be most reticent about taking it out of the garage to expose it to the ravages of the general 'motoring' public! 

Yeah, always a concern but what can you do?

My first Spitfire, a 1972 Mk IV had a rather badly warped GRP bonnet. This was 40 years ago and I managed to acquire a good steel bonnet off a rear ended 1500 write-off, fitted it to the car and got the whole vehicle resprayed by my cousin's then boyfriend who ran a paint shop.

Two weeks later car was hit by a bus which took the new bonnet off the car. Fortunately everything above the front bumper was essentially untouched, so a pair of upper wishbones and a repaired radiator and the car was good to go again the next weekend once I refitted the hateful GRP bonnet.

C'est la vie

At least with this build I have the moulds to make replacements...

 

Edited May 3, 2024 by Escadrille Ecosse

[Spit131]

Endlessly impressive .

[Escadrille Ecosse]

Two coats of chemical sealer and six coats of release wax. My arms hurt, but at last it's ready to start prepping for taking the mould.

After much pondering I have come up with a plan for the mould. Essentially it will be one main section with a single split line all round the lower edges, wheel arches and grille panel. This gives maximum strength with minimum flash lines to deal with.

Slight concern that because of the returns round the front quarters it's not a straight vertical 'lift out' of the finished part but having done a reduced version of this in making the buck from the steel bonnet I'm 99% confident it will work. Removing the buck which is much more rigid than the final part will probably be the hardest but there are ways to deal with this.

First I need to turn the bonnet over to start adding the correx sheet mould flanges. Need to do this a couple of times making the mould without resting on edges or bumping the finish in any way so made up a poor man's rotisserie for the job.
 

And started on the correx. Big area at the rear edge is where the infusion vacuum will be applied and gives plenty of space for the resin brake.

Nice not to be rubbing down for a while...

[Hamish]

This really is an amazing piece of work.

and it’s to make the mould to allow for the making of the part 

my mind boggles 

very much respect Sir

[Escadrille Ecosse]

Progress has been rather slow on getting the ready to take the mould for the bonnet with too many diversions. However it is proceeding.

With the bonnet upside down i've fixed a strip of Correx all round, suitably braced, to which I will attach the main Correx flange to form one half of the split joint.

Then turned it all back over as it makes fitting the split former a lot easier

Bit of card on the floor from some CAD

The strip running all the way round provides a solid base for the actual split former and allows this to sit up past the 'roll' of the panel so the split avoids creating a return on the mould which would make removal of the part difficult/impossible.

Best illustrated at the front edge of the bonnet where there is a large radius and needs a packer.

[Escadrille Ecosse]

Too many distractions (the bags of mortar and concrete mix hint at that) making progress very slow on the bonnet. But a bit of a push these last few days and it is now ready to start laying up the mould.

Board all the way round to form the flange for the removable lower edge returns. Gaps between the board and the pattern filled with wax and alignment buttons made from wax in place.

And the first layers of glassfibre cut out ready. Surface tissue, then 100gsm bonding layer and then two 300gsm layers over the gelcoat. This time I'm using a vinylester gelcoat which is a bit tougher than the usual polyester. Also more resistant to sticking by the epoxy in the final carbon fibre layup. Helpful where there is such a large area or contact.

Need to build up the laminations in stages to avoid things getting too hot as the resins cure. Once this lot is down the next on will be the balsa cores.

This will be the biggest single GRP layup I've done since making the GRP tub for the other Spitfire. The street will be a smelly place for a few days

[Escadrille Ecosse]

Got going at last. Two coats of gel

Surface tissue

And don't normally bother but given the size of the bonnet and the complexity of the shape and the high-ish temperatures making the resin shoot fairly rapidly, I made paper patterns for the subsequent layers of mat.

First being 100g/sm for a bonding coat and a check fit for all the bits

Did the job. Built up the sharp internal angles with a paste of choppped ends in resin. Around the flanges and particularly to bridge over the wing seams as these are otherwise awkward to laminate without bubbles and structurally important for the strength of the mould. And filled in the recess for the air vent with coremat again to make things a bit easier to laminate.

A few more structural layers to go next.

[BiTurbo228]

This thing's a work of art and it's not even what's going on the car!

[Nick Jones]

11 hours ago, BiTurbo228 said:

This thing's a work of art and it's not even what's going on the car!

This!

[PeteStupps]

Brilliant stuff. I look forward to these updates like I used to look forward to Project Binky videos! 

[Escadrille Ecosse]

Two layers of 300g CSM and then 3/8" balsa core bedded into a layer of 100g CSM to stiffen the flat parts of the mould.

And another couple of layers of 300g CSM to build up to final thickness.

Then to provide some 'beam' stiffness and give something flat for the mould to sit on fitted some foam cores. These will be glassed in for strength and the wooden rubbing strips glued on top.

These strips will also provide anchors to bolt on a pair of beams lengthwise so I can turn the whole thing over safely.