Until I discovered folding metal with the English Wheel covered with a rubber band, skinning the bonnet was taking me ages. I was getting frustrated and even questioning whether I’d even finish this project at all.
Looking back, my initial approach probably wasn’t ideal, but I did start to learn a few skills.
Unfortunately, I couldn’t just put the skin through a large sheet metal roller as the radius tapers from front to rear. The sides of the bonnet are essentially cone shaped. That’s why I took the decision to manually panel beat the bonnet into shape.
I managed to get the panel beaten version reasonably straight, but it would still need a ‘skim’ of filler.
As I hammered the steel, I left a lot of small dents and stretched the steel. I used a large rubber mallet but distortion was inevitable. Too quickly remove it, I ran the skin through my homemade English wheel. I believe I had the wheels a little too tight and yet again, stretched the metal. This left the top with a bit of ‘oil canning‘.
To cure this annoying pop, pop, firstly I clamped it on a flat bench and gave it a coat of engineers blue. I then ran over it with a long sanding board to expose the high spots. Using my acetylene torch I heated those high spots, gently tapped them and then sprayed them with cold water to cause the metal to shrink rapidly. The oil canning was gone but the metal was slightly rippled. To cured these ripples, I returned to the English wheel, but this time I used very little pressure and moved the metal rapidly back and forth. I now had one more flat and tight section, so I could move onto the next. – That’s if I didn’t mess up and have to go back ten stages.
This process was repeated dozens and dozens of times across the bonnet. I used a vintage maple bossing mallet to correct all the other little dents. The nearside of the bonnet was hit thousands of times. It was rolled, heat shrunk and even passed through my deep throat shrinker / stretcher. I even invested in a 4½” shrinking disc.
I know I’m useless at this but, I was totally convinced professionals wouldn’t do it this way, so I decided to do some research.
English Wheel with a rubber band covered top wheel
With the rubber band in place, the English Wheel only ‘folds in 2 axis’. Without the band ‘stretches in 3 axis’. The rubber band turns the english wheel into a form of sheet metal brake. Instead of a sharp crisp edge, the fold follows the curve of the lower wheel. There is far less distortion to correct, barely any stretching and the time taken is dramatically reduced by countless hours.
Lazze uses 7.00×7.50 R16 (700/750 – R15/16) truck inner tubes, but delivery on eBay was slow and my top wheel is 7.5″ not 8″. As a work around, I had some 60mm x 4mm strip of solid neoprene rubber lying around and so I super glued the ends together with Gorilla Glue Gel.
Circumference = π diameter
I have a 195mm diameter top wheel.
612.61 = π x 195
If you were to try and stretch the neoprene it would appear to be stretch free. However, under compression by an English wheel I figured it would be different. Therefore as a starter, I went for 610mm and kept tightening it, but eventually the glue couldn’t cope. I got down to around 605mm but that snapped virtually instantly.
You can buy very similar to my home-made version on eBay and to be honest I reckon the truck inner tubes are a better bet. My thick neoprene barely grips the wheel and even at 4mm thick offers no more compression than an inner tube.
As you steer your sheet, the neoprene simply slips off the side of the wheel. You can’t get enough tension on the rubber because firstly the rubber won’t stretch and secondly the glue just snaps.
I not an expert, but I definitely wasn’t impressed and I couldn’t get on with this thick neoprene at all.
English Wheel with Inner Tube vs English Wheel with Neoprene Rubber
As I couldn’t get along with the neoprene there was no choice but to wait for an inner tube to arrive. I was worried it would be baggy, but upon arrival, it turned out to be incredibly tight on the wheel. So tight in fact, I decided to use soap to get it on. I later found out this was a slight mistake as it also allowed it to slip slightly and talcum powder was better.
Cut the inner tube slightly too big so it wraps around the sides. This allows it to grip a little better and reduces the ‘slip’ from side to side as you steer.
When I mean ‘slip’, this is an exaggerated example of what I mean.
For me, there was absolutely zero contest. The inner tube won hands down. It slipped considerably less on the wheel, so you could concentrate on the work-piece, rather than the rubber. Over-tightening the neoprene version would leave a bead in the steel, whereas the inner-tube was a lot easier to control and left fewer marks. On my neoprene version, the points where I would turn and steer the sheet were clearly visible and would need panel beating. The inner tube version was much smoother to the touch with barely any noticeable folds.
I came to the conclusion, it would be no quicker to have thick rubber than a thin inner tube as each side of the bonnet took a matter of minutes.
The thick neoprene would gain an advantage if you needed an anvil with a radius < 120mm. However, with an anvil that rounded, you’ll be compressing the rubber considerably. Keeping the neoprene on the wheel as you steer and stopping it from snapping would be close to impossible. Before going this route, I’d try a double layer of inner tubes.
An inner tube(£8) is a fraction of the price of a length of neoprene (£30). Each inner tube will provide enough strips to cover my top wheel at least 20 times.
I left the neoprene out for 3 weeks and it became hard and cracked. I’ve had some inner tubes for my pre-war Austin in the same garage for over a decade and they’re fine.
English Wheel Shaping With the Rubber Band
The time saved over panel beating was absolutely amazing and the results were instantly rewarding. There was practically no stretching of the metal. You do not need to have the rollers very tight to cause bending. Compared to panel beating, I’d almost go as far as saying it was almost idiot proof. If you have a long bonnet, it helps if you have two people to hold and steer the metal. As a newbie, I found drawing guide lines on the steel invaluable.
What had taken 2 weekends and thousands of hammer blows was duplicated in less than 5 minutes using this technique. I hadn’t used a sander, no heat had been applied, no shrinking, no stretching and yet it fitted pretty closely on first fitting.
Once, I’d made the second, I soon came to the conclusion that the first side wasn’t as good. When you have countless weekend invested in something it’s hard to just chuck it away, but that’s what I did.
You’ll notice this MK2 version fits just as good, it’s not been heat treated, hammered, sanded and even has the original marking out lines. It took me as long to cut the profile with a disc cutter as it did to roll it to shape in the wheel. My first aborted attempt had over 200 hours invested in it.
What I’ve learned
My advice would be, use hardly any pressure on the wheels and take it slow.
I was working alone and due to the size, the steel was floppy. To get some rigidity and the shape started, I used a 120m radius lower anvil. With just one very light pass, the skin was curved and rigid. I then swapped to a 300mm radius for the top section and reduced the tension still further. The very light pass helps remove any ridges left by the first pass.
Remember, you are not stretching you are only gently bending, so it is much easier to re-flatten any over working of the metal.
I would cut the work-piece over size so your turning points are outside the target area. Keep your strokes nice and close together. My Strokes were tapered but even at there widest were only ½” apart. I passed my skin through the wheel five times, each time slightly offset from the last.
Top Tip – Keep your Anvils Rust Free!
My workshop is cold and damp. Some say you shouldn’t coat your wheels in oil as the pressure can force the oil into the steel and cause problems when it comes to painting. I found covering an inner tube in talcum powder made them easy to put on and off and it also absorbed any moisture. Leaving the the inner tube in place whilst the wheel was in storage kept them fresh, bright and rust free.
Rust isn’t an English Wheels only enemy. Not every garage is huge and sometime grinder sparks can hit things you don’t want them too. If they hit your wheel, that could be hundreds on pounds of damage. A 40pence piece of inner tube is good insurance.
I bought some 2.35 x 26″ mountain bike inner tubes from the pound store to cover the lower anvils.