DIY Composite Oven

So, every good shed needs an oven. Oh, and a work-bench. Bearing this in mind, it make sense to combine the two, and put it on castors so I can move it about.

I have made the bench deep and that’s for two reasons. Firstly, one needs a lot of room to lay up parts. Secondly that was the quickest way to make it using roofing boards and pressed boards. They’re already pre-cut to a certain size so there was less jig-saw action.

IMG_3669Here it is laid out and on castors. What I didn’t realise is that the roofing boards aren’t remotely stiff on their own so there’s some reinforcing under the floor to hold it all together. Once the sizes are on and the top is on, it will get more rigid.





Sides are on. Top is on. It’s now stiffer, but not fully priapic.






Here’s a perspective of the bench – big innit?






In the true spirit of being an oven, I dismantled an oven I got from ebay for £10. All the wiring and controls get gutted, and it’s a simple wiring job after that. Fans and lights are always on (rather than under control of the controls) and the element itself is under control of the PID controller.



IMG_3697Here is the PID arrangement. Again, £30 from ebay gets you a PID and a very heavy duty solid state relay. The case and assorted bits and pieces came from maplin. You can see two bolts on the front there, where the solid state relay is bolted to the case to act as a bit of a heat-sink if needed. The 3-pin plug on the front is the output power supply for the heating element. I deliberately did it this way in case I then wanted to power something like a convection-air heater or summit else. Up the back of it is a kettle-lead which powers the PID. The kettle-lead is hard-wired into the main power of the oven. If the oven is plugged in, the fans are always on and the PID is powered. You can’t have heat without fans.

The oven now needs king-span to insulate it (sat in the garage gathering dust) and a thorough soak-testing with a fire-extinguisher near by to be sure it works. I don’t think I’ll be leaving it unattended but at least it’s in a shed if there is a fire.


compound curves

Here is the join between the two bits of the tank – it’s taken quite a bit of time and bog to get this right, as well as using a flap disk on a drill to get the radius right. lots of polishing and filling as well. I managed to get some of the profiles right by taking a plastic bog-spreader and cutting a radiuses edge into it. I also found that a wooden tongue depressor also had a very useful profile for putting curves into things.


Fuel tank – ready for high-build

So, we’re moving further along with the fuel tank. The last post I did on this was more or less finished, but then I’ve done a little more.

Firstly I decided that the recess for the fuel-senser was a little tight (potentially tight) so i modified it, thus:

IMG_0062 It’s a nice shaped curve, feels organic and now there’s loads, loads of room (I tells ya) to get the sensor in there.

The black disk is cut from a piece of carbon sheet I had made and then changed direction. It was lying around.


If the bits of bog on there leave me with a surface that’s not flat enough to work with a rubber gasket (which I doubt) then I can also cut another disk and bond it on – the epoxy glue can go on as thick as I need and it’ll leave me with a good sealing surface. Similarly if the angle on the black disk isn’t quite right and the sensor doesn’t go where I need it I can adjust it a little with adhesive. I’ve spent a lot of time trying to get that disk in the right place, so here’s hoping.

IMG_0061Here’s the final tank.




So, the last things that have been done have been to paint a little resin over the wood to lift the grain. This is necessary so I don’t end up with the grain lifting when I spray it. Once the resin has set, the grain is lifted and a quick once-over with 120 paper on a sanding block did it.

Lessons Learned

  • Paint the resin on carefully with an artists brush. I used a small paint-brush (it was late and I wanted the job done). I ended up with the odd run. I’ve sanded back what I can, but if I’d used an artists brush and taken my time, I’d have had less runs.
  • When you’re mixing resin, get the quantities right. The last time I was mixing this stuff, I was mixing it one to two litres at a time. I had a little measuring jug from lakeland for cooking. This time I mixed 100g of resin, and added 20g of catalyst. It should have been 2g. It bubbles and boils and then weirdly doesn’t go off for ages. It ends up looking like cinder toffee. Of course, it also has zero structural integrity.
  • Forming compound curves is difficult.