por cpl em 21/05/12, atualizado em 10/05/11

Fazendo linhas hidraulicas metálicas

(Hard-Line Bending Basics)

The first step with hard line is to choose the material. While some racers prefer it for its light weight, Bohlen rarely uses aluminum tubing, telling us, "It's easy to bend by hand, but you can hardly ever get it perfectly straight since it always comes in rolls. It's so soft that it flattens out if you try and unbend it, and AN flares in aluminum gall up after a few times being connected or if you overtighten them. It can be polished, but it gets dull quickly." Another option is mild-steel tubing, which has the advantage of being easy to bend. Even so, Bent Custom Shop does not use it often because it has a seam that can be problematic, and because it cannot be polished. Bohlen's material of choice is aircraft stainless tubing, despite the fact that it is the hardest material and the most difficult to bend. However, Bohlen from Bent Shop says, "Stainless is great because if you leave it unpolished it looks race, or the show guys can polish it and it stays shiny forever. Small dings can be polished out. It's hard enough that you can use single flares rather than the double flares that you have to do with soft mild-steel tubing. It might take more effort to make an actual bend in it, but it's cleaner to work with overall."Even so, Bohlen warns that some so-called aircraft-quality stainless tubing still has a seam inside it. He's found that the seam leaves a hard bump anytime a flare is added to the tubing, and that the imperfection can cause sealing problems at the junctions. Bent sells its own true seamless stainless tubing to avoid those problems. Bohlen typically uses 0.035-inch-wall tubing in sizes 11/42 inch in diameter and smaller, and 0.040-inch-wall for 51/48 inch and up. The thicker walls on the bigger tubing help prevent it from collapsing in hand benders, which do not have a mandrel inside them to support the i.d. of the tube as it is formed.





These clamps and brackets are available for most tubing sizes in both single- and double-tube designs.


Here, on a different car, is another solution to dual fuel lines: a Y-block.


Never connect hard line to flex line without a fixed attachment point. If you just leave it flopping, it's ugly and the hard line will probably work-harden and crack. This shows a bracket welded to the Bomb's frame where the fuel lines merge from hard line to Earl's AN hose through bulkhead connectors.


In all, the bending job helps the car look very orderly and purposeful, and is easier to work on than it would have been if we'd done everything in flex hose.

The F-Bomb engine, as seen on our HotRod Oct. '06 cover, has lots and lots of plumbing by Bent with the turbos, twin fuel systems, power steering, and Hydratech hydroboost. This guide will help you know what's what. A) Tandem fuel injector rails; B) twin Aeromotive fuel-pressure regulators (return lines extend from the bottom of each one); C) boost-reference line to both regulators; D) braided flex lines from the power steering pump to the Hydratech booster; E) brake proportioning valve and Line-Loc; F) oil feed to the turbos (the oil return to the pan is a flex line on the underside); G) boost-reference lines to the dual blow-off valves and wastegates. What you can't see are the oil and trans cooler lines underneath.



Here's another example of welded frame brackets, though two of these are hard line to hard line, providing both a tight, 90-degree direction change and a quick-release fitting for servicing the parts.


Never runs hard or flex lines through holes in the frame without supporting them with bulkhead connectors. This also shows how stainless tubing may be polished


Another advantage of stainless tubing is that stainless fittings may be TIG-welded to the tube (arrow) to clean up and shorten a connection that would otherwise require a series of fittings.


Bending Tips:


Here's Bohlen's 15-year collection of hand-benders in a number of tube sizes and jaw styles. The various brands clamp the tubing in individual ways, allowing different shapes to be formed without the bent tube interfering with the tool itself. Don't buy electrical conduit benders.


While the benders have clamps that hold the tube, Bohlen has found that he can often get the bend closer to the end of the tube-especially when a fitting is in the way-by holding the tube closer to the die using a pair of pliers with the teeth ground off of the jaws to prevent galling. Note that the bender is marked in degrees; this tube has been bent just past 90 degrees, though it will likely spring back to a clean right angle.


Here is an example of a tube bent using the normal method (top) versus one held with the pliers. Note how much closer the bend is to the end. This is also handy for getting lines parallel with each other, as shown.

Flaring Tips:


While some insist that you should not cut tubing with a hacksaw, Bohlen does it every day. He recommends a 32-tooth-per-inch blade and never uses a regular tubing cutter. After hacking, he squares and cleans the end of the tube with a sander, as shown, making sure not to overheat the material, which will tend to reharden the annealed stainless.


After sanding, the end of the tube is further cleaned using two deburring tools to clean the i.d. and a fine file to smooth the outside.


While Bent has a trick aircraft flaring machine, tubing can also be hand-flared. This is a Ridgid single-flaring tool available at Home Depot or other hardware stores. It can be used with stainless tubing.


If you are working with mild steel, the tube must be double-flared with a tool like this that includes dies (arrow) used to fold the tube in on itself. These tools are always pretty frustrating to use.


To double-flare the mild steel, you first flare it with the die, then remove the die and advance the tool's cone-shaped bit into the mouth of the tube (arrow) to ensure a double layer of metal that helps prevent cracking.

Remember that in the world of flares, there are two common types: 37 degrees in the AN world and 45 in the automotive and industrial hydraulic venues. Most 45-degree fittings are brass or steel, while AN is usually aluminum. It is by far best to mate 45 to 45 and 37 to 37, and stainless-to-stainless tapers need to be the most concentric because the metal is so hard. Going aluminum to stainless, you can often get away with mating 37 and 45 degrees, though the sealing surface is smaller so this is not optimal.


If you have a poor seal in a tapered fitting, these soft brass tapered washers can help by making a soft surface for the taper to seat upon. They are available through Orme Brothers.


Look closely at the arrow and you can see the hard spot that is created in the tubing when you flare a stainless tube with a seam in it. The tube to the right is Bent's seamless tubing.


TUBE SIZES TO AN SIZES

TUBE (in) AN
11/44 -4
51/416 -5
11/42 -6
31/48 -8
51/48 -10
31/44 -12


Carb Inlet How-To


Want to make your own carburetor hard inlet kit? You'll need 31/48-inch lines, two male -6 fittings that fit your float bowls (Holley and Demon are different), a -6 tee, and three sets of -6 nuts and sleeves. Start by deciding how long the front line must be to clear the carb linkage, then cut the line to length. Don't forget to install the nuts and sleeves before flaring.


Flare one end of a length of tubing and attach it to the front tube with the tee. Using a pen and a piece of hanger or welding rod, mark the center of the secondary inlet.


Next, put the tubing in the bender, lining up the mark you made with the 90-degree indicator on the tool (arrow). Shape the tube, and the center of the bend should end up right at the mark.


Finally, eyeball the location of the flare on the carb fitting to determine where to cut the tube, then slip on a nut and sleeve and flare the end.


There you have it-your first custom bending project.

source: http://www.hotrod.com/projectbuild/fbomb/113_0708_hard_line_bending_basics/index.html

keywords: HARDLINE TUBE BENDING DOBRA LINHA HIDRAULICA FREIO COMBUSTIVEL