Tips/tricks/hints for doing fab work
Thread Starter
Joined: Apr 2007
Posts: 9,711
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From: Evansville,IN
Tips/tricks/hints for doing fab work I was going to post this in the fab/tool section but I am wanting input from exhaust and F/I guys. Mods if you think it should be moved please do.
I haven't done much fab work in my life, not successfully anyway.
With the new job I am finding myself doing more and more. I have mad respect for guys that do turbo builds, build their own headers, etc.
I know some of it has to do with natural talent and some has to do with practice.
I know this is really basic but bear with me.
Lets say you want to cut some 1 1/4 boxed tubing 4 1/2 inches long.
-where do you make your at? Right on the 4.5 mark or to one side or the other, in the middle?
-then where to you cut it?
-you have to consider how wide your mark is
-how wide your hacksaw/cutoff wheel blade is
The reason I ask is depending on how you mark it and how you cut it, on the line, next to it, will decide what the length REALLY is. It can be anywhere from 1/16 to 1/8 off from what you want it to be. I guess it comes down to consistency but what's the best way you guys have found?
My other question is how to cut exhaust pipe for a turbo build or header build. With all the curves how do you cut the pipe so it will be straight and line up with each other.
I'm sorry if this seems really basic or stupid to ask. I've been working on cars for almost twenty years and learn something everyday.
The skills of some of the people/sponsors on this board are amazing.
I wish I would have taken a machine shop class in high school and paid more attention in math class.
Don't flame me too bad and thanks for any help.
J
I haven't done much fab work in my life, not successfully anyway.
With the new job I am finding myself doing more and more. I have mad respect for guys that do turbo builds, build their own headers, etc.
I know some of it has to do with natural talent and some has to do with practice.
I know this is really basic but bear with me.
Lets say you want to cut some 1 1/4 boxed tubing 4 1/2 inches long.
-where do you make your at? Right on the 4.5 mark or to one side or the other, in the middle?
-then where to you cut it?
-you have to consider how wide your mark is
-how wide your hacksaw/cutoff wheel blade is
The reason I ask is depending on how you mark it and how you cut it, on the line, next to it, will decide what the length REALLY is. It can be anywhere from 1/16 to 1/8 off from what you want it to be. I guess it comes down to consistency but what's the best way you guys have found?
My other question is how to cut exhaust pipe for a turbo build or header build. With all the curves how do you cut the pipe so it will be straight and line up with each other.
I'm sorry if this seems really basic or stupid to ask. I've been working on cars for almost twenty years and learn something everyday.
The skills of some of the people/sponsors on this board are amazing.
I wish I would have taken a machine shop class in high school and paid more attention in math class.
Don't flame me too bad and thanks for any help.
J
You always measure to the side of your blade (curf, the offset tooth pattern on a saw blade). It's not too critical because you will be massaging quite a bit of stuff with cut off wheels, sanding disc and what not to get things to line up. It takes practice just like anything. One thing I've read that help some people is to buy those foam noddles people use in pools. Insert that inside your pipe and it will help hold it in place.
what ever you use to make your marks with, make sure its thin tipped (NO fat tipped Sharpies!). That way, it will be easier to make your cuts true...that and learning your equipment, there are two different band saws at my job and each one is has a mind of its own, so keep that in mind when using your own tools.
And remember the old saying: "Measure twice, cut once."
And remember the old saying: "Measure twice, cut once."
do be afraid. after about an hour of cutting and welding that initial anxiety will dissolve and you can really get to business. when cutting radiussed material cut it perpindicular to the center line so when you look at a profile of it it's still a circle and not an oval(or whatever it's origional shape is). chop saw would be a great investment but if you have access to a bandsaw that would be even better. what ever it takes to get your final dimension and with even the best intentions you will have some waste or botched pieces, it's just part of the game, and you just want to minimize it. having the proper tooling is paramount but i have seen some pretty macgyver **** work well so there is also something to be said for creativity. you'll be shocked at how much more art than science is involved. and yes measure twice--cut yourself errrr cut once. 
good luck.
good luck. Regarding how to cut angled exhaust pipe to maintain the "perfect circle" - I take a piece of thread and wrap it around the pipe where I want to make the cut, then use a sharpie to make dots along the thread, remove the thread, then connect the dots to form a solid line all the way around the pipe. Then I simply make the cut on the line, and it comes out perfect every time!
Made this kit using the "thread" method. Also, as mentioned in the truck manifold sticky, cutting up some of the pool "noodle" floaties and using them to hold the un-tacked pipe together while you get your angles figured out works great too.
Made this kit using the "thread" method. Also, as mentioned in the truck manifold sticky, cutting up some of the pool "noodle" floaties and using them to hold the un-tacked pipe together while you get your angles figured out works great too.
Last edited by evo462; Jun 5, 2011 at 01:53 PM.
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Go to your local muffler shop and get some scrap to practice on. That's assuming you live some where that exh tubing lasts more than a few years.
They make abrasive cutting blades for the 4.5 grinders. Well worth getting some.
They make abrasive cutting blades for the 4.5 grinders. Well worth getting some.
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A milwaukee portable band saw and table was the best fab tool Ive bought. Cuts exhaust pipe like butter without sparks and debris flying everywhere. Mig welding a mild steel kit is way more forgiving that a stainless steel TIG welded kit. TIG, the gaps need to be very tight. Like said above, pick up some scrap and practice.
Tools: You can get by with a sawzall, an angle grinder, and a mig welder. I use a chopsaw style bandsaw, a 90 degree air grinder, a couple files, and a TIG now.
Tools: You can get by with a sawzall, an angle grinder, and a mig welder. I use a chopsaw style bandsaw, a 90 degree air grinder, a couple files, and a TIG now.
TECH Enthusiast
Joined: Jan 2004
Posts: 608
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From: New Zealand
I use a zip tie around tubing and a marker pen, works great for marging cuts, even on angles. I thread the zip up opposite so it doesn't lock and is easily released when your done marking out.
Also I see a lot of people fully tack it together and then weld it all at once. Piping/tubing will shrink when you weld it. So doing it all at once you could have a lot of warpage/shrinkage.
I peice it together and then fully weld everything in sub assemblys and then final fit it and then the last joint or piece that ties it together can be put in and welded - IN PLACE.
I peice it together and then fully weld everything in sub assemblys and then final fit it and then the last joint or piece that ties it together can be put in and welded - IN PLACE.
Joined: Nov 2001
Posts: 8,484
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From: Cecil County Raceway!!!
when doing pipe joints... tape the joint together with a wrap of blue painters tape to hold everything in place where you want it. Cut a small section of the tape away with a razor blade to reveal the joint and tack there. do this at least on the other side of the joint (I usually like 3 tacks) then remove the tape to weld the rest of the joint.
I also got some good tips here. I have a place literally around the corner from me that will do the tig welding for my aluminum charge pipes, and never thought about using the pool noodles to hold them together.
Now the trick is to use them without the kids seeing me cut them up.... they'd have a heart attatck over that, even if I bought them a dozen, if I cut one up they'd freak lol.
Now the trick is to use them without the kids seeing me cut them up.... they'd have a heart attatck over that, even if I bought them a dozen, if I cut one up they'd freak lol.