only using the basics, learn how to fit exhaust tube the right way! mainly focusing on stainless
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Step 1: The Tools!
I like to use high quality tools when I work! as working with tube is a big part of my job i like something that is nice to use and will last me a long time. I try not to fall into the trap of buying useless "infomercial" tools that rarely get used because quite often it just takes longer.
It is soooo important to have a nice file, something that is nice to hold and half round. I like 3rd cut files over anything and the brand Bahco have never let me down.
good cutting disks for a 5" or 4.5" grinder is important! super thin INOX cutting disks makes like so much easier, I find that, PFERD and FLEXOVIT are good but there are others that also work well such as 3M.
a tig welder, with Ramp up and slope down makes life a lot easier! but they arent cheap so live with what youve got along with a purge set up. Mig can be used if you want to spend a lot of money on a nice mig welder.
a nice clean welding helmet, either flick up, or 3M speedglass is all i use but its ups to you! i just dont trust anything else.
A good square is so important for fitting!
nice pair of welding gloves with no holes and heaps of movement.
tacking clamp makes life easier again,
a pipe wrap is helpful! flange wizard is a good brand!
and safety gear, eye protection and ear protection!
watch this video for full show!
Step 2: Cutting and Squaring and Fitting Tube!
I normally cut any tube under 3 inch is a cut off saw GF cutter or band saw! and anything above with a grinder! if done right a grinder can get the perfect cut!
I then use the flat part of a cutting disk and press up against the butt of the tube untill it has all been evened out to the same level. I then use a file to clean it up and check the square. If it isnt square i grind off how ever much i think is right off the high side of the tube, face it and clean it up again and keep checking till it is right.
cutting pie slices is something else that is unique to exhausts, marking 2 lines opposite of eachother on the tube running long ways makes it easier to cut the tube into slices to then piece together making a bend, this is something i think you need to learn for yourself and you should try it before using this method.
Step 3: Welding, Walking the Cup.
Walking the cup is a method of tig welding using the gas lense to wobble along the materiel moving the torch forward without changing the distance of the tungsten from the metal and being steady. this is the method most people use to weld pipe and tube in the water industry, and is the strongest way of welding along with the best finish.
think about how you would walk a 44 gallon drum across the floor and its sort of like that, you really have to feel it for yourself a few times before it really makes sense, it can be used for fillets, it can be used for butts, it can be used for laps! so really its something worth learning!
most the time I just hold my filler wire in the puddle and let the back and forth motion of the torch disburse the extra materiel into the weld. this looks a lot neater.
with stainless it is important to have a purge inside the tube, by taping up each ends and putting a hose in one end running about 8lpm, and a hole in the other taped up end to let the air out this will make sure that your weld looks just as pretty on the inside as it does on the outside.
the last photo is of someones repair on the pin hole leak! dont be this person do it properly!!!
i show how to do this method in this video as well