What's An Aluminum Falcon

Work on the Falcon's suspension system continues. I usually try to maximize my time when I'm in the shop. While the Tormach mass produces the more complex parts, I work on the parts that can't be made that way. This time I tackled the custom hangers.

The suspension system is basically a seesaw. The hangers hold one end of the seesaw at the correct position and provide the tension needed to hold everything together. They are made up of two bearing tubes and two spacer bars.

I first tackled the eight bearing tubes. I cut steel tubing roughly to length on the bandsaw and turned the ends down to size–pretty easy to do on the lathe. I also widened the inside of the tubes slightly so the bearings would fit.

The spacer bars were harder. The distance between the bearing tubes had to be the same for all the hangers. I needed to make these on the Tormach, but there was one problem with that. The finished part was shorter than the vice holding it, so I couldn't mill both sides in a single setup without cutting into the vice. I'd have to do it in two setups.

In the first setup, I milled the desired profile into the free end of the bar and then milled a small hole on the other side. Why a small hole? Since I had to take the part out of the vice and turn it around to finish it, I needed a way to reorient the bar and set an origin for the second setup. The hole provided this function.

To set up the other side, I mounted a gauge pin on the Tormach like a drill bit. Then I slid the bar over the pin, auto-aligning it with the machine. I locked the bar into the vice and set the machine's X and Y axes to zero. Then the Tormach cut the second profile while also removing the registration hole and finishing the part. I repeated those steps seven more times.

Once I had all the pieces, I was ready to weld them into the final parts. I machined a gauge block to ensure the correct spacing between the bars, then clamped up each assembly and tack-welded all the hangers together.

I'm getting a little better at welding with all the practice. The thing I'm learning most is patience. Instead of trying to weld everything everywhere all at once, I welded a quarter of the way around on each bar. Then I let each hanger cool off before welding it again.

I still seemed to overheat the metal periodically, causing porosity when the molten metal hit dirty air. I had thought it was because of the air inside the tube, but I later discovered that the torch had sprung a leak. Not enough gas was flowing out of the torch to create the curtain of inert gas necessary to form strong welds, causing all the pock marks (porosity).

I eventually switched to the MIG welder to finish welding the parts, but that added the extra step of cleaning up the welds with a grinder.

The last step was to clean up the inside profiles of the bearing tubes. I had smoothed them out on the lathe when I made the bearing tubes, but welding always deforms the metal a little bit. I used the ever-versatile Tormach to re-contour the tubes.

With these four parts, the suspension system build is 61% complete!

Rudy June 30, 2025

Fabrication of the new suspension continues. I made the last of the hanger brackets, so we can now officially attach the new suspension to the Falcon!

I also made the next four parts in the build: the alignment bracket that keep the hangers and the suspension arms in the same position, relative to each other.

These were deceptively difficult to make. First, because of their size, I had to hold them in the machine differently than usual. That wasn't too bad. I just moved the jaw bolted to the front of the movable block on the vice, onto the rear position.

Carving out the first side of the part went well. I like to call this the "Han in carbonite" phase.

I was able to remove all of the interior material without cutting through the bottom of the stock plate. The stock I used is 3/4 inches thick and the bracket is .7 inches thick. That 0.050 difference made sure I didn't accidentally cut into the vice. Because the vice jaws were in the way, I couldn't cut along the outside of the part. That left the bottom .25 inch thickness of material to avoid that.

I usually just flip the part over and remove the "carbonite" layer to finish the part, but since I need to maintain bracket thickness I also had to precisely trace the outline of the part from the other side. That's why there was one hole cut all the way through the first side. That hole became the origin for all the flip side operations.

I began finishing the second side by manually cutting away most of the extra material using a bandsaw. It didn't take very long and helped reduce CNC machining time.

Because the part is triangular, I had originally planned to hold it along the hypotenuse but that wasn't possible. In that orientation, the part is not wide enough for the vice to hold it. And, yes, it was also too wide to move the vice jaws back. smh

I was stuck. To finish the part, I needed to make a custom jig–a part to finish the parts. If I could clamp the jig in the vice I could then secure the triangular brackets to the jig. I began with a 6 inch by 6 inch stock plate and designed the jig to use the central trapezoidal shape of the part to keep each bracket from shifting or rotating. I added 1/2" threads so I could lock each part down onto the jig with bolts.

Using bolts on the inside of the part meant that I couldn't use the Tormach to finish the back face of the bracket, so I did it manually. I had to keep the face mill moving to avoid tool marks. It reminded me a bit of playing the drums.