Often when you’re focusing on cars there is a should form tubes with bends, depressions or any other shapes within them. You may well be taking care of carbon steel oval tube, intercooler plumbing, a cylindrical airbox, or perhaps heater or turbo oil drain plumbing. How do you form these bent bits of tube?
Should you be making such as an exhaust or intercooler plumbing, buying pre-formed bends and then joining these is the easiest way to travel.
The bends – best are mandrel bends in which the internal diameter remains constant – can be purchased in steel, stainless or aluminium. An exhaust should take advantage of the steel or stainless bends, while intercooler plumbing can use the three types of metal.
Joining from the bends might be carried out by welding – MIG, TIG or gas welding with regards to both steels, or TIG in the matter of the aluminium bends.
When you don’t have a welder, tape the bends together after placing ‘witness marks’ (the place you used a marker to perform a line along the pipe and all over the join, showing exactly how the bits align) then go ahead and take assembly to your welder.
Mandrel bends are available in a range of angles (eg 15, 45, 90 180 degrees) and diameters from about 1.5 inch to 4 inches.
When you make plumbing using these bends, make sure that you:
Work with a friction saw using a large diameter blade to cut the bends to length. Don’t try using a hacksaw – it is actually nearly impossible to generate a cut that is certainly sufficiently straight it may be easily matched to a different one bend.
Do not cut the bends anywhere except where they are straight – cutting around the bend itself will disclose a wall thickness thinner in comparison to the unbent tube (as the wall has become stretched) so the weld is more likely to intrude and also the join will likely be weaker than whether it were made where tube is straight.
If you use mild steel bends to create intercooler plumbing, the last result could be blasted, undercoated then powder-coated to get a durable and professional outcome. Stainless steel or aluminium may be polished.
The benefit here is that you can make the bend the actual required angle, instead of being limited to the angles where preformed bends are offered. The down-side is that if you do not happen to have an extremely expensive mandrel bender sitting at your residence workshop, the bends could have a degree of crush and you can get some wastage just before getting a bend you’re completely satisfied with.
Generally speaking it’s not truly worth trying to make your own bends in large diameter tube. A elliptical tube which utilizes a hydraulic jack and curved tooling is designed for heavy-wall pipe and may give poor bends in thin-wall tube. (However, in desperate situations you could possibly get away with sand-filling the thin-wall tube – see later.)
However, small diameter tube can be successfully bent by using a hand bender like this one. It comes with dies to fit 3/8 inch, ½ inch, 9/16 inch, 5/8 inch, ¾ inch and 7/8 inch (most tube sizes are imperial).
This is a piece of 5/8 inch diameter steel tube bent with a hand bender like this shown above. It is really an oil drain pipe for a turbo.
If you want to gain some clearance, it is easy to ‘ovalise’ round tube – even whenever using a preformed bend.
The secret to success is to fill the tube with a coarse sand before beginning to reshape it. The coarse sand has lots of voids involving the grains that will progressively close-as the tube is squashed. The presence of the sand resists the modification in good shape, giving the tube more support and so preventing deformation within the wrong directions.
This 2.5-inch mandrel bend was utilized as being a turbo dump pipe – it’s shown here after being ovalised. It had been ovalised for 2 reasons – firstly, the oval shape matched the exhaust dexopky14 in the turbo, and secondly, the oval shape necessary to continue over the tube to offer clearance to the alternator and steering tie rod (shown in its worse position of maximum suspension droop and full right-hand lock).
The bend was loaded with coarse river sand. Keep in mind that if you plan heating the tube (eg with an oxy) the sand needs to be absolutely dry. Here the sand is shown in the cast iron baking tray drying out spanning a wood stove.
After being loaded with sand, the ends of the tube were capped with aluminium foil and tape. In contrast to first thoughts, the end caps aren’t under a lot of pressure – the sand doesn’t flow down the pipe that easily.
The sand-filled pipe was then put into a hydraulic press. Two hefty components of flat timber were placed above and underneath the pipe, by using a steel plate placed beneath the press’s ram. A clamp was adopted to stop the arms of the bend spreading since the ovalisation occurred. In this instance the task was done without having the tube being heated.
The pipe will try to make a figure-8 cross-sectional shape as it is being compressed; the outer edges might be pressed separately (as is also occurring here) to lessen their height as required. Note using the timber block – this deforms a little and spreads the stress. Utilization of a metal plate straight on the tube will often dent the tube.
Ensure that you look at the sand level through the pressing process – because the grains are crushed together, the amount can drop.
When you have a need for clearance at only one spot, you can put a depression from the wall from the tube. As was described above, ideal results occur in case the tube is first filled up with sand.
This stainless steel gas pipe needed a dent put into its wall to offer adequate clearance to a starter motor solenoid. The dent was put into the tube (ex truck exhaust tube) as step one once the tube was cut to length.
Be aware that this strategy gave a far neater result than utilizing a ball-pein hammer and forming the depression by traditional panel beating techniques.