cut-off wheel in a grinder?

Seriously. Its my go-to for shit that is odd shaped and can't easily be clamped.

 

You know; i know it sounds stupid, but what do high end performance shops do? I just can't imagine those guys using a plasma cutter or angle grinder and getting good fit up.
I see a lot of fabricators out there getting damn perfect results all the time. Do they really use angle grinders to cut parts and get perfect results or do they have a huge scrap bin of mistakes that most of the pieces go in?
I need to spend a day at a fab shop; that would be great. Too bad most people i know that work for fab shops don't tell you anything.

Recently completed an entire exhaust for an old race Lotus. Used horizontal band saw, probably 1/2 the cuts, vertical band saw, plasma cutter, cut off wheel on grinder, cut off wheel on air tool. Would much prefer the band saws, but as you have found out, that is not possible on all pieces. I have got pretty good at jigging up the tube in the horizontal band saw to get the cuts I need, even way off angle. Sometimes think laterally, like spot welding other tube to what will be your waste piece. Flap discs are your friend for clean up.

Also going to need an easy way to sand the inside and outside of the tube. The Harbor Freight sanding roll kits are cheapest, and will work for a few jobs. I also have a pipe sander for doing jobs where the welds are sanded back to flat tube, but that is $$$.

I have that little drum sander that goes in the drill. It sucks, the belt keeps sliding around but I get it to work for small things. I'm going to pick up their spindle sander soon.
how do you know what angles to cut at? I guess the other issue and I had to say that this happens more often than not is I'll take that U bend the customer dropped off eyeball and cut and then the cut piece ends up being larger than the 3" od because of the angle. How do you avoid stupid mistakes like this?

On a recent custom 67 Camaro, I worked off site, and about half the cuts I used a chop saw. Admittedly on fairly big 3" tube, with no fancy small precise cuts. I hate my chop saw so try to limit the times I use it, but it does have its place. Some guys will use a chop saw for 90% or more of their cuts, and still have 10 fingers too.

Exactly, I'm trying to keep all my fingers and keep things not from flying around

 

Recently completed an entire exhaust for an old race Lotus. Used horizontal band saw, probably 1/2 the cuts, vertical band saw, plasma cutter, cut off wheel on grinder, cut off wheel on air tool. Would much prefer the band saws, but as you have found out, that is not possible on all pieces. I have got pretty good at jigging up the tube in the horizontal band saw to get the cuts I need, even way off angle. Sometimes think laterally, like spot welding other tube to what will be your waste piece. Flap discs are your friend for clean up.

Also going to need an easy way to sand the inside and outside of the tube. The Harbor Freight sanding roll kits are cheapest, and will work for a few jobs. I also have a pipe sander for doing jobs where the welds are sanded back to flat tube, but that is $$$.

 

On a recent custom 67 Camaro, I worked off site, and about half the cuts I used a chop saw. Admittedly on fairly big 3" tube, with no fancy small precise cuts. I hate my chop saw so try to limit the times I use it, but it does have its place. Some guys will use a chop saw for 90% or more of their cuts, and still have 10 fingers too.

 

I like using these donuts from Pro-Werks, more than the U-bends:

They tend to have a tighter bend radius...

Best thing I've found so far is a Portaband to cut them. You'll almost always be able to clamp it in a vise and get to the outer radius easily.

You can make a circle guide on a piece of paper easily enough to lay the donut on, and mark angles. I do that more just to get a true line across it; the actual fit-up and measuring I mostly just do as I go along, visually.

A vertical disc sander or a belt sander with a wide enough belt works well for squaring up cuts afterwards.

 

Donuts look nice but again i have no way to hold them lol. and the customer provided U bends since the last company that made them for him used U bends.
I'm still a little salty he didn't like the pie cut. It was 1 section, so that will set me back a lot of time.
I've only got the HF porta band and it's LOUD. Ear piercing loud. Going to keep looking for a better one.
Is there a reason some places use 1 saw for SS only and another for Aluminum only?

never thought about it before, but I can weld pretty well when I'm comfortable, but doing this exhaust stuff is a whole different story. When you need to find a way to hold it down to the table, and support it some other way and have a pipe hitting your helmet and have to have your head at a messed up angle it makes things not so easy

 

I've only got the HF porta band and it's LOUD. Ear piercing loud. Going to keep looking for a better one.
Is there a reason some places use 1 saw for SS only and another for Aluminum only?

Get a good portaband and/or metal cutting bandsaw good square cuts will make fit up so much easier.

Separate tools (grinding wheels, wirebrushes etc) for stainless and aluminum to prevent weld contamination.


Some posterboard rolled around the tube can help you eyeball/ cut the correct angle. Hose clamps work good for marking a square line if you need to make a freehand cut.

 

I cut with either my chop saw or an angle grinder. Eyeball the fitment and trim the angle slightly long. Then butt up the next piece and observe/mark where the gap is and grind to fit.

I also use a hose clamp to get a straight line on the pipe before cutting. You can also use them to clamp a small tab of metal to rest the next pipe on, even clamping two pipes to the same tab to add stability when visualizing it. Odd to put in words, I can take a picture if it's not clear.

As far as welding, do it by sections instead of starting at one end and going to the next. It cuts down the number of awkward welds and can help manipulate shrinkage.

Edit: just remembered, they're pricey but a pipe vise can help stabilize when you're cutting and welding. I used to do tons of steamfitting off of one.

 

Edit: just remembered, they're pricey but a pipe vise can help stabilize when you're cutting and welding. I used to do tons of steamfitting off of one.

Find those on craigslist all the time for $50-$250 depending on condition, might get another just for the **** of it.

 

we do a lot of custom exhaust work, believe it or not any custom work is typically done in pieces like what your doing.
best tool for cutting u-bends into usable angles is the chop saw, followed by a 4.5'' grinder with the biggest cutoff wheel it will fit.
bandsaw is really only good for cutting long pieces as the vise usually needs the length.
we use angle finders to estimate where we're going, we have tube specific tools; but you can use 2 sticks bolted together.

cutting with the chop saw requires removing the vise, leaving the back of the vise
mark your tube squarely and hold it in the chop saw, no need to fixture or clamp the tube in an abrasive chop saw

the best chop saw fixture i've seen for cutting u-bends i found here on pirate4x4 (sorry can't give credit to the fabricator)
i have not made one yet but here's a pic of the fixture, it pretty well guarantees a straight cut



here is the angle finder i made on a cnc plasma table for finding angles
it's made for 2.5'' tubing but works well enough for 3'' tubing
bolting 2 sticks together gets you the same angle, use a plastic protractor to find the angle



as for welding exhaust tube? forget everything you learned about welding and fabrication. ok forget 95%
i was a pipe welder for years, nothing like welding pipe either
we get welders that can weld anything... anything. they usually last 1 to 4 weeks trying to production weld 2.5'' ss tube
all i can say is tack weld 4 places, go fast and keep the torch angle the same

this is a set of headers for a 69 mustang (dynacorn body) with coyote motor



turbo intake manifold for 07 ford fusion, tack welded with tape for fit up



same turbo fusion and all the intercooler piping, mig welded and ground seams
oh yeah; painted and hydro dipped too



we go thru a couple of miles of 2.5'' ss tubing and half of that in 3'' ss tube per year
mostly for production exhausts plus 30 customs per year
most of the custom work is pieced together like your doing
we have a cnc mandrel bender for 2.5'' and 3'', everything else is bought as u-bends and straight tube

 

exhaust sucks, it takes alot of trial and error to even start to see the angles and how thing fit together. I've done just a little bit and it's probably the worst thing I could think of doing. Brain just hurts thinking about it. Anyways I found these thing that exhaust shows claim to use and they would be tits but are quite a bit of an investment for just 1-2 jobs.

icengineworks

They are little lego segments that you assemble to design the pipe and determine the bends, etc. And they also have the clamps to hold 2 section together while you weld them. Portaband seems to work well for the cuts.

This is what I cobbled together on my first try, pretty crude. Welding was tough and I tried snading it smooth and it didn't really work out all that well. Anyways I ended up screwing something up on it and had to redo the whole thing, so I boxed it up and sent it to SPDX Exhaust to have them make a new one from the old one. They used very few sections as I did and the welds were all nice and neat so no need for sanding, etc.

No picture of the new one, not sure why I didn't take one.

 

ICE engineworks also makes an awesome fixture to cut U-bends. I will own one of those some day.

Icengineworks Icengineworks Cutting System, 1750 Cut 1-3/4, Turbo Manifold, Headers

 

I have never used any of the Bend Tech software and its probably a bit more than the average home fabricator would want to spend for 1 time use but they do have one to design headers and exhaust.
Bend-Tech | Perfect bending software solutions for tube, pipe bending, & sheet metal, headers, roll bending.

 

I use a 7" cutoff wheel a lot.

i'd like one of these someday

Slow n steady with the hacksaw is actually very precise.

 

that looks like it would work pretty well. Lots of cutting edges, vs the 2 on a normal cutter.

 

Has anyone ever tried a big pipe cutter for cutting staright cuts? I saw one at harbor freight and thought about it.

 

I use a big pipe cutter for 3" intercooler pipes. Works perfectly and it's guaranteed to be perpendicular to the pipe. Just gotta clean up the edge on the ID of the cut.

 

I can't tell you how many hours I've spent deburring pipes I've cut on a bandsaw. I'm going to try out a pipe cutter. This brings me back to the day when I found out deburring tools existed. :smokin:

 

A little late to the party but I made this table after seeing a friend build headers on a similar saw. It's easy to line the bend up square to the notch on the backstop, all you need is to have your tube marked where you want to cut.

Fwiw, I made the table for about $10 using a free broken saw from work and scrap metal plus a remnant from the steel yard. Works great for lots of stuff.

 

i use to work for hooker header and have done alot of custom headers, exhaust work, turbo stuff etc. i use a 14" chop saw with the vise taken off i just hold it with my hand. some times i use a vert bandsaw. i square up the cuts on a 20" disk sander. the disk sander is a must for me, you don't need one that big. i use u bends and j bends i put them on the table with a angle finder and mark them plum where it hits the table to avoid a back angle.
heres a aprilla motorcycle exhast that i build.

 

I really wanna get together a disc sander, or a ballsier belt sander. Probably eventually do the belt sander to avoid gluing discs onto the plate.

Anyways, I use an angle grinder with worn out (under 7" diameter) chopsaw discs on it. Got some 4.5" cutoff wheels but they don't have enough reach. Then use the flat of a normal grinding wheel (or the side of the bench grinder wheel) to square the end if it's off.

As an aside I actually prefer the stick to the mig, use 5/64" 6011s and about 40A. On stainless the thinnest rods the LWS carries are 3/32", so it really sucks using them with no arc force to blow the slag outta the way. Then the TIG comes out and you guys laugh at me for my pedal. :flipoff2:

 

Cold or dry cut saw, angle grinder with a flap disc and a die grinder with a carbide burr. My usual go to for exhaust work. Belt sander also come handy.