I've done a couple of these, so I figured I'd do a write up on it. This is for the miter cut, or, "Chino" style exhaust stack. It's similar to a bull horn or Aussie, but it's cut and joined, instead of bent.
1:1 version:
Things you'll need:
- Miter box
- Saw (shorter teeth are best, as they won't try to roll the tubing)
- Thin wall brass tubing of your desired size for the exhaust (mine is 2.5mm)
- The next step down in size of brass tubing that with firmly slide into your exhaust tubing. Most metric tubes can do this: i.e.: 1.5mm fits into 2mm, 2mm into 2.5mm, etc. (here I have 2mm).
- Exacto or scalpel blade
- Flat file with finer ridges
- Round file
- 400 grit paper or equivalent sanding stick.
- Super glue
Measure out the lenth of stack you need. For example, mine starts all the way at the base of the model and goes through the hood, so I need to include that in my total measurement.
Mark it, and lay it in the miter box. Most miter boxes have multiple angle slots, choose the 30 degree slot.
Hold the tube firmly and make your cut. Don't press the saw down too hard or you may risk deforming the tube.
Set your measured, cut piece off to the side. Now roll the bulk tube 180 degree in the miter box so that you can create the final piece. You may as use the 45 degree angle cut for this if you wish to.
End result should look like this: (Note, my open-side angle is 45 degree.)
Clean out the 3 cut ends. use the tip of the exacto blade to remove any flash that may have curled inwards from the cut, and use the round file to clean it up. Use the flat file and sand paper to gently trim back any flash on the outside of the tube.
Next slide the smaller tube into the stack until just a little bit sticks out the top, but not past the highest part of the angle. Test fit the 2nd part of the stack and make sure the two 30 degree seams fit nicely.
Note, if you plan to solder this joint, push the inner tube out juuuust a tad more so you have a hair sized gap to allow flux and solder into. This inner tube has 2 purposes: added rigidity for the entire stack, and a seat for the 2nd piece.
Mark where the inner tube meets the base of your stack and cut it. If your tubing is too small, use a score and snap technique. To do this, simply lay the tube on the mat, and roll it back and forth under a blade, creating a score line/cut around the circumference of the tube, then put pressure on the cut and snap it like a pencil. If the part your cutting is too short to grab hold of, simple keep rolling under pressure, and you'll soon cut through it.
Slide the cut inner tube in 90% of the way, place a small dot on superglue at the tail end, and quickly slide the rest in. If you goof up and don't get it all in, in time, simply cut the remainder off, and glue it in the other end. Unless it's too short, then you may have to start over.
Now attach your end piece with super glue and clean up the seam! For soldering you can try to use a tiny bit of glue to hold the end piece in place for solder, but the heat may break the bond.
