Front hoops. Again.

January 5th, 2012

Right, today I tackled the two front hoop tops. Only this time instead of trying to bend them in one go I made them in two halves and welded them together after cutting them to the right size.

First I used a piece of cardboard to draw up the shape I wanted. I ended up using a rear Austin hub to draw the curves since it seemed about the right size. Previously I had used a smaller radius but the hub seemed to match the radius on the radiator shell better. I used more sticks to see what the curve I had drawn would look like.

IMG_1403_1 Sticks. Again!

Once I was happy with it I used my bending unit (not this one) to bend up more tube. I just hand bent it to match the cardboard pattern. I only did one half though instead of trying to do the whole top in one go.

IMG_1406_1 IMG_1404_1 More tube bending.

Now sometimes when you read about tube bending people suggest plugging the ends of the tube and filling it with sand then heating it to get nice, even bends without the tube kinking. The block of wood with the hole in it works fine though for the small tube I am using (16mm diameter) as long as you don’t try to bend it too tightly. The inside of the tube does kink a little but it’s the outside curve that important.

IMG_1407_1 The Kinks. It’s how you build Lolas.

The kinks won’t be seen unless you look up under the body once the car is done so they don’t matter. As Joss told me a block of wood with a hole in it is all you need to bend the curves.

To check the tubes on the frame I stuck temporary wooden dowels into the tube as pins. Then I was able to just plug one end of tube into the vertical stick already on the body. I could then check the bends and tweak as needed.

IMG_1418_1 Wooden dowels to hold tubes in place.

Once I had one side done and I was happy with it I just bent the other side to match then welded the two halves together in the middle. Then I tack welded  the hoop to the uprights. The two sides fitted either way around which should mean the body is fairly symmetrical side to side.

IMG_1410_1 Hoop tacked in place.

Everything is just tacked for now since things keep being tweaked and adjusted and changed. At this stage you are trying to get everything right which is why there are so many posts lately with me just bending damn tubes! The frame needs to be right though. Once you start hanging the aluminium skin it’s too late to change!

So, with the rear hoop in place I had the problem of making the firewall hoop that goes between that and the radiator. I might have been better off making this one first then making the rear hoop to suit. To get an even curve I made a sort of jig using a plank, a pen and another cardboard template. I cut the cardboard to the approximate shape then cut a slot in the plank so I could run one end on the radiator surround and the other on the first hoop and the cardboard fitted into a gap in the plank. A pen then traced the line the plank made as I slide it over the radiator and the existing hoop.

IMG_1415_1 IMG_1416_1 Second hoop.

I am probably making things difficult for myself but it generally worked. I then bent more tubes to match the new pattern. With the hoops made to that shape and sat on the body things didn’t look right. So I threw away the pattern and just bend things till it looked right. I am not sure what right is exactly but I tweaked things until to my eye the curves looked good. Apparently God was overhead saying the same thing about Eve’s boobs. The curve of the hoop follows the curve of the radiator. I also stuck my long stick along the middle of the corners radius to make sure everything still lined up.

The problem then was with sticks laid across the where the bonnet would wrap over the firewall the curve didn’t match that of the rear hoop. Bugger.¬† So I modified that! I cut the rear hoop in half again, adjusted the curves and ended up welding in about an inch in the middle. The top is now much flatter than I originally had it. Previously the scuttle was more V shaped but with the side dropping how it does and the radius of that curve I think what I have now is what works.

The most important line is that sweeping line that goes from the top corners of the radiator right back along the car to the tail. That’s the curve from the sides to the top of the body. I want that to be one smooth curve going from the high front right back to the low tail in one nice, even swoop. You can see that with the bottom stick in the left picture below.

IMG_1423_1 IMG_1425_1 Hoops in place.

If I wanted more of a V shape I would have to drop the sides down which would make the sides be too low behind the driver at the rear of the cockpit which would look silly. You need the rear high enough so the driver doesn’t look like they are sticking out of the car like a Noddy. But the car definitely won’t look like an Ulster!

So I think the car now looks right but I’ve been working on it all bloody day so I needed to stop and take a fresh look tomorrow. The top is now much flatter but I think that’s how it needs to be for everything else to work.

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