it’s been quiet, but

The day job has been a little overwhelming, but I’m now feeling like there’s time for the car. This is a bit of a pity-me post, because there’s been a cavalcade of stuff go wrong on the car jobs. It’s been a cascade of things interrupting other things and generally getting in the way.

Problem 1 – a mild amount of meh

 

Do you feel intimidated?

I have got myself a new sander to make the access hatches the right height as well as a host of other straight edge sanding jobs. It’s a great bit of gear, and the photo shows the gist of it. I have replaced my bench-grinder for it. First job is to secure it to the bench – best way for my bench is self tapping screws into the wood. Off I go, and find my screw-driver is running low. The power-tool superhero in my head says “No Problem! – we have AIR POWER”, so I put the screwdriver down and get my air-screwdriver. This leads me to problem #2:

Problem 2 – My compressor carked it

I asked the nice people on locost builders who think it’s probably a starter-cap. This is a £10 part, rather than the other issue, which is that I may have seized my all-in-one pump/compressor unit, which is a £150 part. Either way, until I find the time to get it out from its boxed-in sound reducing cabinet I built, I can’t attach the grinder (minor woe) but I also can’t spray the clear gel-coat on my transmission tunnel top, which is a larger pain in the arse. I’m 50/50 about spraying the gel-coat. It gives me two advantages: Firstly, I have some UV protection (minor) and secondly, I introduced some minor scratches in the mould, and having a gel-coat to polish reduces the risk of going through to the carbon if I want a super-excellent finish on the car. I can work around this a bit by making a the tunnel top a little resin rich. I’m only infusing the facing layer to start with.

Problem 3 – my oven is too small

I always knew this day would arrive. I knew my oven wasn’t big enough for the transmission tunnel, so I thought: “let’s make something of the day work out, and I’ll extend the oven”. It was at this point that I realised I miscalculated how much kingspan I had and couldn’t finish the oven.

So, I have a broken compressor, an oven that needs work, and a part that I can’t spray.

Solution: whiskey, and tomorrow I’ll lay the part without gel-coat and make it a little resin rich. I’m not looking forward to getting the compressor out and diagnosing it’s ills though.

forcasted 25 degrees. not great for wet-lay

I am pushing to finish the fuel tank moulds today. It’s all wet-lay all the way, and at 25 Centigrade is going to mean a couple of things:

  • hot and sweaty work – I wonder if I can do it outside
  • You can’t mix more than 500ml of resin before it starts to gel off

So, lots of mixing and swearing and sweating. At least cure times will be quick.

Footwell Fettling for Friend’s feet, Part 3 – Finished

footwell part 11

Right, so, you’ve seen the video about laying up, and here is the final layup ready for the vacuum bagging stack. It also shows extra corner bracing and there are similar reinforced corners underneath in aramid.

 

 

The stack I have gone for is as follows:

  • 6 layers of mould release wax to ensure a good barrier and a shiny finish
  • one layer of GC50 clear gel-coat to give it a good shiny finish and UV protection (which it won’t need under the bonnet)
  • three layers of chemical release agent
  • 2x 350gsm CF, for the initial outer facing layers
  • 1x 250gsm Aramid for intrusion protection
  • 1x 200gsm e-glass for a little bit of flexibility in the part
  • 1x 3mm soric for the core
  • 400g of infusion epoxy mixed with 120g of catalyst (slow)

footwell part 12Rather than go for a standard side-to-side infusion I went for a circular infusion down to the centre. This stuck me as better because going edge to edge would require the resin to also climb back up the vertical slope and could spend time infusing into the corners. The vacuum will drag it up eventually, but it could be a pain. Furthermore, if there is a long wait as it gets into the final corner, you end up with the situation where resin is going into the catch-pot and the part isn’t yet fully infused (which is money down the drain). At least this way the infusion is relatively uniform, and gravity is acting on my side.

Once infused, I baked it at 50C for 12 hours in the oven, and then pulled the infusion stack off. Following is the video of me using the air-line lazy method for getting the first part of the stack off (the vacuum bag). I also used a new kind of peel-ply (knitted rather than the standard spikey flat stuff). It’s great for this kind of infusion because it will pull under vacuum into all the difficult corners. However, it remains a little stretchy after infusion, so it requires more effort to tug/haul/swear out.

 

Once the entire infusion consumable stack is removed, the part is left in the mould and the second stack is laid upon it in reverse order (without the GC50). The mould performed well and managed to split without too much trouble and about 50-75g wasted resin. I know Warren (who manufactures parts at volume) has a much more refined process for managing resin amounts – he writes the amount a part needs on the back of the mould. My parts are one-offs, so there’s no need to stress about that.

 

footwell part 14Once I had split the mould, and got the first half off, the second gave up the ghost really easily and I had a part! This was a hell of a moment because it’s the first time I’ve gone from idea to composite part in 3 dimensions. On the part you can see the extra shiny side, which was incredibly easy to get to. I washed the chemical release agent off with warm soapy water (didn’t seem to make much of a difference, to be honest) and then I put a little Farcela 300 Polishing compound on to a cloth and gave it a bit of a rub – no real application of elbow grease required and this is the result.

footwell part 15 The part has been partially trimmed (dremmel with a steel slitting disk, P3 safety mask) and offered up and it’s a great fit. You can just see the deliberate fitting gap between part and chassis, which should be between 1 and 2mm for the adhesive to work well.

 

 

footwell part 17This time the view is slightly different in order to show the clearance a little more between the part and the chassis. I had deliberately left a min of 5mm to allow for some absorption in a side-ways impact. I could have taken the footwell deeper if I hadn’t welded in the extra strengthing bar you see there to complete the cradle around the engine.

 

footwell part 18Sorry about the crap qualitty of the photo, but this is where you shove your feet. It has been sized to take size 11 trainers so most normal feet will fit fine. For final fitting, I’ll trim that remaining lip off, and bond the part of the contacting edges only. If I decide to go belt-and-braces, I will make some 90 degree angle and bond that onto the chassis and wrap it around on to the part.

Stronger than steel, far better shape, and I’ve not yet made a weight for weight comparison with the steel I cut out. I’m proper thrilled.

How many layers of carbon fibre = 1mm?

“Hmmm” – I hear you say. “I hadn’t thought of that”, and “Why on earth do you need to know that?”, you follow up. I sense you ponder, as you pour yourself a nice New Zealand Sauvignon Blanc, what with you, dear reader, being the carbon fibre sophisticate I know you are.

Well, the reason is, I’m making some brackets to hold my new handbrake actuator in place, which weighs 2.4kg. In the world of normal steel stuff, I’d get by with 1.5mm brackets and that would hold. So, bearing in mind that cabon is stronger and lighter than steel weight for weight, I shouldn’t go much thicker.

so, what’s the answer? Well, my research (for resin infusion only) is that for every 200gsm, you get 0.2mm worth of thickness.

Also, I’m using 3mm Lantor Soric as a core for all of this, which separates the layers and adds stiffness for little extra weight, but more volume consumed. What’s more, the soric also works for compressive hard-points.

This bracket pair (post to follow) follows Warren’s Rule (every composite part must do at least two different jobs). The brackets hold the handbrake actuator, they couple the bottom of the transmission tunnel side to side, making it a box for part of it’s length (adding rigidity) and it’s a flat piece of carbon, improving underfloor aero.

The new composites shed – digging foundations reveals nasty secret

So, I’ve engaged the services of Jon-The-Builder, who is wonderfully classically, old yorkshire. He’s a 60 year old experienced builder for whom belt and braces are not enough. You accept that when you engage his services, you just have to step back and watch the force of nature in action.
In my head, I wanted a few concrete pads set at ground level, and where the ground drops off, I would box in the concrete laying to take it above ground level. Simple, or so I thought.

Then, along comes Jon. He’s wonderfully old-Yorkshire. To quote (ish):

Tha’ don’t want pads, we need do level it, dig down, 2ft square concrete pads, brick pillars. Then, young’un, tha’ll have a solid foundation. T’shed won’t blow away.

Jon is brilliant and I’ve learned not to second guess him.
image

Here he is, about to get started.

Then, more or less straight away, he let me know I had a problem. This wasn’t a normal ‘air sucked through the teeth’ kind of problem, nor was it a dead king with an identity crisis. It turns out the people (or landscapers) who landscaped the house (before we bought it) had the soil tipped in up to the damp-course level. Looking at it, one can see the moss blooming up the wall.

So, we agreed and he went digger-tastic and took 6″ off the top-soil. It meant we could level-out the soil and I now don’t have a problem emerging in 5 years time.

The shed wins again.

So, why do we make these cars?

I’ve been asked multiple times why I invest so much time and money, thought and energy into this build.

You need to listen to the “Space Tourism” episode of Infinite Monkey Cage (with Brian Blessed). There’s a bit where Martin Ince says that we need to drive around with Brian Blessed on a flat-bed truck … and then Brian comes out with

and I need to say: “You there! Get off your sofa, stop watching homes under the hammer, AND GO OUT AND MAKE SOMETHING”

Brian managed to put it very well.

Transmission Tunnel Top Panels

So, the three ally top panels that constitute the transmission tunnel are next for the carbon fibre, aramad, flat-panel treatment. One is riveted on, and two are bolted into nutserts. I need to go around the nutserts and put a tiny tack in place to remove the risk of them spinning, but that’s another job before the chassis goes off.

In order to give really good impact resistance from inside the tunnel and not risk the panel should there be a stone chip or other underneath, I’ve added two layers of aramid. If I weren’t to be manufacturing composite prop-catchers as well, I would feel secure in just using the two layers of aramid and the other parts of the composite to do the job.

Here is the layup is aramid, aramid, eglass (to add a little flexibility), carbon, carbon for stiffness and pretty facing bling. The pictures follow, before the price breakdown.

laid outHere you can see it all laid out with the aramid on top of the e-glass. I have decided to lay out an entire panel rather than three separate panels, or one panel just the right size, which would have created unnecessary offcuts. I at least have some finished offcuts of a good size that can be reused or sold on ebay.

 

baggedHere we are, fully bagged up and ready to go. The panel is more or less the size of the double-glazing unit I use so there’s no need to pleat the bag – envelope bagging will be fine and for my level of technique it’s quicker as well. The downside is you use a little more resin because the resin will run to all the corners of the bag.

 

infusedNow we’re fully infused, and you can see that the e-glass more or less vanishes. You can see the gaps around the aramid panels. If I were to go for a consistent aramid layer, then you’d get the fluffy edges when the panels were cut which would be visible in the cockpit and not meet the goal of being a cosmetic panel. As such, I’ve allowed a 15mm boundary around each panel for cutting. This is also the width of the metal that it’s mounting onto and means the aramid should fully sit in the exposed space and fill it completely.

 

disaster

And … Disaster … I didn’t spot a couple of stray threads on the panel before I laid it out and they’re now set in there for good. There’s no recovering this panel without making a new panel to bond on top. There’s nothing here that affects the strength with the stray thread, but I will make up a repair panel. Arses.

 

Layer Count Material Width Height Cost
1 2 200g Carbon 600 730 £22.60
2 1 e-Glass 600 730 £1.91
3 2 300g Aramid 130 540 £3.37
4 2 300g Aramid 130 480 £3.00
5 2 300g Aramid 130 320 £2.00
6 1 Peel Ply 650 800 £2.18
7 1 Infusion Spiral 730 £0.31
8 1 Infusion Mesh 650 800 £1.50
9 1 Feed Tube 500 £0.60
10 1 Gun Tape 3000 £1.32
11 300g Resin £6.63
12 1 Vac Bag 1500 1000 £3.72
£45.41

Ouch – I’m £45 in, and can’t use the panels from a cosmetic.sense. I’ll need to make a repair panel.

In order to cost the fina