So, I’m replacing my mild steel access hatch with a carbon fibre hatch, and here are some pictures. I’ve also done a detailed cost analysis, and included 20% for wastage/accuracy as well.

It’s a 5 layer part and the cost for materials (on the open market) is £27.89 inc vat, and it doesn’t include my time.

Total weight saved – 500g.

Layer	Specification	Cost
1 – Carbon Fibre	2/2 Twill 200g	£3.20
2 – eGlass	2/2 Twill 200g	£0.54
3 – closed-cell foam ribs	3mm	£0.10
4 – Carbon Reinforcement	2/2 Twill 12k 450g	£2.98
5 – Soric Hard Point	3mm	£1.33
6 – eGlass	2/2 Twill 200g	£0.54
7 – Carbon Fibre	2/2 Twill 200g	£3.20
8 – Peel Ply	–	£1.26
9 – Infusion Spiral	–	£0.25
10 – Infusion Mesh	–	£0.72
11 – resin Tube	–	£1.19
12 – Gum Tape	–	£1.32
13 – Resin and Hardner	300g	£6.63
14 – Labour	6 hours	–
		£27.89

Here are the inevitable pictures:

This is the part laid up before infusion

 

 

 

Vacuum bagged ready for infusion – not quite full vac yet.

 

 

 

full vac, ready to go

 

 

 

300g of resin with a 50/50 mix of fast and slow hardener.

 

 

 

This is the part out of the mound (well, a piece of double glazing window – gives a nice smooth finish).

 

 

 

clamped to the original footwell access hatch for drilling. Note the bolts to keep it all in place when I moved the wood around. You need to drill through into another medium else you may chip it as the drill goes through.

 

 

wrapped in gaffer tape and being drilled. It was necessary to be sure the wood or the clamps or the metal face didn’t scratch the part. Carbon fibre manufacturing does seem to involve a lot of disposable materials, and gaffer tape is just one thing of many.

 

finished part, with ribs for extra pleasure or stiffness. This is the side you’re looking at here is the peel-ply side, so it’s rough in finish.

 

 

Finished cosmetic side. Pity this side is the one that goes down into the foot-well.

 

 

Lessons Learned

1. I should have used washers when bolting the metal side to the part for cross-drilling. The nuts dug into the carbon a little, leaving some slight indentations which you can see in the picture above. No big deal though because the areas that have been damaged will be covered over by a gasket when the part goes in the car.
2. I would have been better off making the ribs by cutting a cross shape out of closed-cell foam rather than 4 individual ribs. It would have been much easier to align it all and I could have made a larger center point which may reduce stress.
3. It took me 6 hours to make this part – I could have saved an hour with getting the bagging right (I have a better technique now) and I didn’t make it from templates because I don’t see how I need to repeat it. If I need to remake it for any reason, I could get it down to 3 hours I reckon.