January 30th, 2012

Or rather the firewall hoop. I did go and collect the steel the other Saturday. More tube, some flat strap and a 600 x 600 x 6mm plate to put on top of my work bench. The plate alone was about $100NZ. But well worth it. It’s a great, flat surface to work on and a nice, straight edge to bend metal over.

So finally, after days of not doing anything I spent this Saturday welding the flange to the front hoop. I knew it would take a long time even though it seems simple so I made sure I had a whole, uninterrupted day. First an outline of the hoop before I started as a template to be sure it didn’t move while welding it. I just traced it onto the pavement outside my house in chalk. I am sure people must wonder what the hell I am up to.

To provide a face to wrap the aluminium of the body to and a place to  bolt the firewall up against I am welding a flat flange all around the front hoop. It is much easier to work against a flat surface than a round tube! You can’t make it all in one go though so first I made the curved tops. I cut two pieces of steel strap then heated them up red hot using my oxy-acetylene gear. Then I was able to simple bend the flat using the vice. It’s as simple as putting it in the vice and bending it by hand then hammering it (on my new steel plate!) to make sure it stays flat.  I made two to fit the top curves.

IMG_1509_1 IMG_1508_1 Curved tops.

Next I made the corners. These were too tight to make curving some strap so I cut them out of 3mm plate. I made a cardboard template first.

IMG_1510_1 Template corners.

The rest was just a vertical piece so I cut some strap to the right length.

Next you weld it all together. I used a wooden board with some nails in it as a guide to hold everything against. Of course the board catches fire as soon as you start welding but that’s all part of the fun!

IMG_1512_1 Template board.

I welded all the pieces in short lengths to try to minimise the distortion the welding caused.I just MIG welded it since that was the fastest and easiest way.

It still distorted. To straighten it I used the oxy-acetylene again to heat everything up again and hammered it flat. I didn’t try to weld all the way around. Stitch welding will be fine. It welded on both side so is plenty strong. I used a sanding disc on the angle grinder to grind the welds flat. Unfortunately I caught and edge and the sanding disc backing wheel got damaged. Have to throw that one away and get another!

IMG_1519_1 Shattered backing plate.

The angle grinder is such a dangerous tool. It’s very easy to get complacent with it but if it goes wrong and that thing hits you whatever sanding or grinding disc you have on it is no match for flesh so it will go right through you. I already have a small scar on the back of my hand from angle grinding, I don’t want more!

IMG_1516_1 IMG_1517_1 Welded flange.

Once finished I tired it on the car and found it had moved slightly. Comparing against my footpath template confirmed so I used more oxy-acetylene to heat things up and bend them to the right shape. Eventually I ran out of acetylene! That’s not too bad since I got that bottle in 2007 according to the label! Will have to go swap it during the week.

IMG_1521_1 IMG_1522_1 Hoop on the car.

With the hoop on the car everything actually still lined up! Well, mostly. I still think the hoop is slightly off perpendicular to the floor. Then again the floor isn’t exactly flat! So it should be good enough.

Joss popped round to check on my lack of progress I guess and he thinks it looks good. He is keen to see the thing take shape!  So onto the next step, making the firewall from sheet steel. This takes some careful measuring and planning.

I was hoping to do that today but I got distracted on another project and my broken lathe. My mini lathe broke and by the time I fixed that it was 3:30 so no time to start on the firewall. We have another long weekend next weekend so will start on that then.


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