After setting up the correct angles on the head tubes and clamping them into place I started on the steering boom tubes. My first attempt following the instructions was a total failure (you can see how far off it was in the bottom picture). Guess-timation never works for me, so while looking for a better way to do this step, I realized that there was a big difference between the first boom cut in the PDF and the second. The first boom looked more like it was guess work and the second boom was precise and clean, so my goal was to make my 2nd boom 1st, so I figured out how to take the measurements I needed and cut a template out of the scrap from the first failed attempt.
I already cut the fish mouth cut in the failed steering boom, so I cut it off and used a tube clamp to hold the piece so I could get the alignment right. I needed a way to point it to directly to the spot on the frame where it will be welded to, which there was a measurement in the book, so i marked the frame with a sharpie and that was my alingment or reference point. (FYI, this step took a lot of clamps)
While I was checking out at Menards they had yard sticks in the impulse buy second. I grabbed one and it happened to be almost 1.5 in wide, which made it perfect to use as a support base. I clamped the yard stick under the fishmouth cut square tube clamped to the head tube (the pic above) and lined it up to the reference point line on the frame and clamped it to the frame. I was then able to set the scrap steel on the yard stick and make sure it lined up with the head tube (hence the stir stick to get the angle)
In the pic above, there is a white line about the middle of the boom. That was my starting point for all four measurements. You don't need to measure the whole length from the frame to the head tube, multiple times to get the correct cuts, you just need to measure from the same spot every time and connect the dots. On a normal cut, you measure, for instance 2.5", make a dot and cut. If you want to make an odd angle, you could make two dots, one at 2.5", then another 2.25", draw your line, connecting the dots and cut. That is how he made the second boom so clean, he used the first, marked where each cut ended, connected the dots and cut.
That's what I did here as well. Since this is just scrap it doesn't matter the length of the boom, fishmouth cut, etc. just the dots in references to each other is all that's important. I measured from the white line on each corner of the tube, down to the frame this gave me a number, we'll say the first was 4.5" and the second was 4.25". I picked a number and subtracted it from all four measurements I took, we'll use 2" for this example. I measured down from the white line 2.5" made a dot and 2.25", made a dot and connected them with a line, that's the black sharpie line on the tube. Do the same thing two more times for the corners on the bottom of the steering boom and you will have enough dots to connect and cut all four edges of the tube.
Once cut, slide it against the frame and make sure it lines up to the head tube piece still clamped and if so you're all set, if not you can tweak it as needed. Then the repeat for the other side, if the scrap template lines up correctly, then it's just replicating like in the PDF.
Use lots and lots of clamps, the more locked into position everything is as you're making it the easier it is to keep everything consistent and tack it into place. It sucks to measure, cut then find out something moved or you can't line it back up to work with that measurement again.