Sheet metal shaping

[Daniel BrannanParticipant @danielbrannan48897]

Hi

I appreciate model engineer might not be quite the correct place for this post because this is nothing to do with model engineering, it’s a motorcycle tank but here goes.

Does anyone have any experience with sheet metal shaping/panel beating? I am attempting to make a fuel tank using 1.5mm 1050 aluminium hammered around an old tank filled with concrete. This approach was suggested to me by a respected local fabricator. Basically I heat with a blow torch and hammer with dead drop hammers or a planishing hammer for more intricate areas.

It started off ok however I’ve reached the point where I have large folds of metal I don’t know what to do with. I’ve read I should ‘tuck’ them but if I’m honest I don’t really know what this is. I have another sheet of aluminium I could use if I need to start again but the problem I now have is my hammering has actually dented the underlying tank. Anyway here’s where I’ve got:

The black areas are just rubber off the hammed. Any advice or comments welcome

 

regards

 

Dan

[BazyleParticipant @bazyle]

First you don’t want to use the original as a former – you need to make a solid wood mould to hammer on or, more skilfully roll and hammer off the mould until nearly there. Some shapes are better hammered from the inside.
The starting sheet needs to be only just larger than the final item, perhaps needing to be an odd shape. It will stretch anyway. The ‘extra’ you have is a problem to fold out of the way.
Gradually as you form it before the excess gets out of control, you can either use a ‘shrinking tool’ in a press or very skilled workers can do it with a special hammer with a rough surface.
If the extra gets significant it can be cut out and welded shut.

My late neighbour was a coach bodywork repairer and he could make a complex shape in minutes for the private jobs he did at weekends. Was a bit noisy living next to him though.

[Daniel BrannanParticipant @danielbrannan48897]

Thanks for your reply. It did occur to me that I should trim the sheet but I had no idea how to calculate what the 2d shape should be on the flat sheet. Also how would a rough faced hammer work 🤔

I think this is what they call a steep learning curve 😂

[noel shelleyParticipant @noelshelley55608]

Hi Daniel, As above, a REAL panel beater would use special tools but for us meer mortals cutting out a section and then welding the 2 edges together is easier IF you can aluminium weld. Regular annealing may help ? For getting a development of the shape first start with a large sheet of paper or light card and fold it over the pattern tank cutting as needed. Good luck. Noel.

[John HinkleyParticipant @johnhinkley26699]

Dominic Chinea (of Repair Shop fame) made a video of the construction of a replacement tank for a Triumph motorcycle he rebuilt.  The tank was formed in several separate sections and welded together.  Search YouTube for “Making my new aluminium tank”.  The constructors are a commercial firm but the video shows the whole process.

John

 

[Dave HalfordParticipant @davehalford22513]

A shrinking hammer has a cross hatch pattern on the face. When the metal is struck some goes into the hatch.

You use you wrist to work the hammer not the whole arm

Have you got the right grade of Ally plate?

[cedric 1Participant @cedric]

There are a lot of excellent well illustrated books on doing sheet metal work for automotive hotrod building and classic car restoration. Mostly American.  They have all the tricks of the trade you need. Search Amazon for sheet metal work/fabrication, bodywork, etc.

There is a LOT more to it than beating a flat sheet around a former. Some of those folds you have will need more than shrinking. Probably cutting and welding. You might get away with a tucking tool, maybe.

A domed wooden or plastic mallet and a leather sand bag is pretty much essential for petrol tank work too.

And an English wheel is right handy for smoothing out the hammer bumps.

Rather than an original tank, many pros make a wooden buck then use mallet and sandbag, mallet and formers etc etc to shape the metal to fit the buck.

Read a few books on the subject before you invest too much time in tin tapping without a clear plan.

[Daniel BrannanParticipant @danielbrannan48897]

Via the blessing of Amazon prime, a sheet metal working for beginners book is on it way to me 😀

[roy entwistleParticipant @royentwistle24699]

Daniel    Sheet  metal working was/is a trade which had a 6 or 7 year apprenticeship. Your  not going to learn by reading a couple of books

Roy

[Daniel BrannanParticipant @danielbrannan48897]

Where’s your faith Roy. He who dares wins (after he fcks it up a dozen times) 😂

[roy entwistle]

On roy entwistle Said:

Daniel    Sheet  metal working was/is a trade which had a 6 or 7 year apprenticeship. Your  not going to learn by reading a couple of books

Roy

But it’s a good starting point.

[old martParticipant @oldmart]

Aluminium motorcycle tanks are more likely to be made of three parts, left, right and underside. Someone who knows how to use an English wheel could make the parts. Unfortunately learning how to use one could take years of practise. There are tank makers who would make one for you. As for your piece of aluminium, it looks like a sculpture by one of the modern artists who charge millions.

[Author]

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