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.

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.



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

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

galvanic corrosion = mullered alternator

alternatorSo, I am going to try and sell my old pinto outfit again, so I started going through all the things I had carefully boxed up, including the alternator. I had placed the alternator in a plastic storage box (with a clickable sealable lid) with some other bits. One of the bits was a steel door hinge.

Needless to say, the hinge and alternator have been cosying up and touching each other in inappropriate ways. The end result is galvanic corrosion. What a mess. The alternator is so buggered the pulley won’t even turn. However, it did get me thinking that I could make carbon fibre door hinges in the future … go to be lighter.


Getting ready for this summers work

Today, campers, I’m off to the garage to tidy up the winter detritus. This will involve:

  1. making good coffee
  2. appropriate selection of music for the day
  3. convincing my 14 year old teenage son that this has to be done before we start on the new engine build
  4. trying to sell my old pinto race engine as an outfit again, rather than in pieces
  5. moving things that were wall mounted onto other walls
  6. a trip to the DIY store when I realise I don’t have wall plugs
  7. serious scratching of head when I have more ambition than wall space tidyness
  8. manliness when I GO TO THE TIP
  9. booze
  10. powerwashing everything down
  11. cleanliness

angled sump design – needs new flap gates

So, following is the photo-record so far for the 10 degree angled duratec sump I’m making for someone out of stainless.

What you can see is the longer side (40mm longer) which has been tacked every inch at 70A. Deep penetration isn’t actually needed here (and you tried you would run the risk of of blowing through the thinner wall or warping the base plate). Stainless is really tricky for warping. I guess there’s no such thing as a free lunch.

Here is the front, and again, one inch tacks. It also shows the internal sorted flap gates. These aren’t fully tacked in place yet, just in for positioning.



Here you can see the problem that comes out when adapting the design and not redesigning the flap-slats. Bear in mind this sump is upside down and the flange is sat on the welding plate on the side that goes on to the block. The central flap-slat matrix is designed to mate with the flange and sit snug against the sump bottom (or lid in this orientation).

I don’t think this is going to work because there is a lot of room for oil to flow under the flap gates, and if I cut angled plates to make up the gap then the flap gates will be too high, restricting oil flow and defeating the design of the sump.

Here it is the right way up, and the orange hammer handle shows the gap between the flap-slat plates and what would be the bottom of the sump.



So, next steps are:

  1. remove the flap-slats, which are tacked in, so a little time consuming to get out
  2. get the cad out and recalculate the profile of the gates
  3. whilst 2 is being cut, I can still complete the seam welds and test it for oil-tightness.

This is a little frustrating because it’s the neatest sump i’ve made yet.

Fuel Tank Design Completed

Here is the new 3d design for the fuel tank. If you click the image you can download the 3d pdf of the tank that will allow you to rotate it.

What’s missing in the image is the internal flap gates between the bottom fuel pump holder and the tunnel riser, as well as the tunnel riser and the top part of the tank. I haven’t decided if i’m going to internally baffle the top of the tank left to right, of just add the hollow golf balls or foam. I have options.

I’ve designed it in 1.5mm stainless which means the total weight is 10kg. It’s not the lightest but it does weigh the same as an elise aftermarket tank. I’ve built in as many folds as possible to cut down on the welding.

I might make the tank and then use it as a mold for a carbon tank instead.