Originally these drive shafts were made from high tensile steel and heat treated to handle the torsional (twisting) forces being fed through them. The customer was fitting a turbo diesel lump from a Golf into the back of a type 2 vw van similar to pictured below, and needed the original shafts shortening.
I was asked to manufacture a 5 gallon tank for a customer building a BMW Mini race car, after discussions about size fittings baffling etc a fag packet sketch was produced in order to make the job.
I started with 1.5mm thick NS4 Aluminium sheet, plastic coated 1 side. Once dimensions were worked out I decided to complete as 2 pressed panels. Panels were marked out using tape measure, engineers square and fine tipped marker pen.
Once marked out the sheet was cut using a hydraulic guillotine for speed and accuracy, de-burring panels before proceeding reduces chance of cutting yourself whilst working with the sheet. Fold lines were marked on the panels but, before folding the strengthening swage lines needed to be put in – this I completed using a standard manual swaging machine, after which folding the 2 panels on a Box Pan Folder was completed. Results as shown –
Main body complete and ready for assembly, however I need to add filler hole, fuel pick up, return and breather hole, this will be completed in due course with a drill, hole saw and drill bits before tacking up.
Splash pan was manufactured again using 1.5mm NS4 aluminium and again marked out from sheet cut out using a guillotine and bench knife before pressing on the trusty box pan folder to the correct degree for the corners to meet up.
Once formed up to a square splash pan with a flat base I used a hole saw of 41mm diameter to cut a hole in the centre of the base for the filler neck to welds into. The filler neck was tig welded from the back of the into the base of the splash pan during welding the pan corners up, After welding the main body a drain stub was welded to the splash pan to drain away any spillage during topping the tank up.
Before assembling the tank, I used an electric hand drill to cut all holes in the tank body as required, this then means we can ensure a totally clean tank inside as we do not want swarf or aluminium dust inside the tank once complete for obvious reasons.
Tank foam was added to fill the tank to reduce fuel slosh before the 2 halves of the tank were assembled. Some adjustment was needed using clamps and small wedges to ensure that a neat outside corner joint was tacked up all round the edges to be joined by welding. If the set up is accurate a neater stronger weld can be produced and even penetration can be achieved, thus reducing chance of leaks or fractures. A good joint set up is also critical for speed of welding and aesthetics – e.g. weld will be a more even corner fillet if joint is tacked up correctly. So its worth spending a little for time and effort to get this part of the job right.
Using a coin tor score plastic coating reduces chance of scratching panel when removing plastic around areas that have to be welded. Aim is to leave as much plastic coating on the tank during manufacture to reduce scratch marks. Once complete it can all be removed.
Safety is a must when welding, you may have noticed in some images I have a fire extinguisher to hand should anything untoward happen, I wear TIG gloves and work overalls (fire retardant are best) and a quality air fed (& filtered welding helmet).
TIG welding produces a quality weld (dependant on welder skill, set up, gas flow, torch angle, torch aim etc), I aim for a nice even regular ripple effect and whilst welding tanks with outside corners a nice small “teardrop” effect in the bottom of the root, which tells me I am achieving a nice even bead of penetration – essential to ensure you get a strong, leak free joint.
Picture of completed tank, ready for pressure testing, which I do using a battery powered pneumatic pump, connected to one of the pipe stubs whilst blanking off the rest. Once under pressure ( a couple of bar is sufficient) the welded seams are brushed with soapy water whilst I look for a steady stream of small bubbles indicating a pin prick of a hole in the weld. As with all tank caps, aluminium or stainless steel it is a good idea to put a small amount of copper grease on the threads which helps prevent thread “pick up”.
What is a “SWAGE” in sheet metal work ?
A “swage” is a recessed or raised area of material (a bump or a dip) put into sheet metal components typicaly to strengthen the panel.
The swage is made by 2 matched dies – one a “male” and one a “female” these are used on what is known a “swaging machine” where the sheet can be placed in between the dies and pressure is used to clamp the sheet and “roll” it through the “dies” producing the bump or dip. Usually other shaped dies can be swapped onto the machine to produce various shapes of form to strengthen, shrink, stretch or even add decorative patterns to sheet panel work.
See example of swage below and also a typical manual swaging machine.
SWAGING MACHINE SWAGES IN TANK PANELS TO STRENGTHEN THE SHEET