I am curious as to which methods the pros use to mock up manifolds and exhaust. How do you determine angles, and when cutting how do you determine that the cut is 90* to the pipe when cutting a bend. These are the two areas of mockup that irk me. Any insight would be helpful; links would be great too. I did a search under “fabrication tools” and came up empty. I apologize if this has been covered in the past. I am merely looking to expand my fabrication knowledge .

 

measure twice cut once, right? if you want to build, you have to know how to use lots of different measuring tools. And if you build from scratch, with no blueprints or drawings, then its all trial and error.

 

Well, you need to think things through before cutting anything. For example, if you want to cut U-bends at exactly 90deg, think through how you could do that. Since the radius is constant, you can make a very simple fixture consisting of a plate and two rods spaced some distance apart. Then you measure the outside diameter of the U-bends you have, divide by two, and that's the radius. Find the common point from the dowels, and that's the centerpoint. Now draw a line through that point and a point half way between the rods. That's the path the bandsaw blade must follow to be exactly 90deg.

And if you place the rods just right, you can rotate the U-bend about that centerpoint and no matter where you put it, it'll always cut right. Sorry for not supplying a picture...