Control Sticks (Part 3)

Continued from Control Sticks (Part 2)
I finished cutting the steel for the main body of the assembly today.  I saved the diagonals for last, since they're the only set whose length is critical. I found a great site that allows you to input tubing diameter and thickness, angle, offset, and generates a template you can print out and transfer to your tubes. Check it out here.

I set up my shop for woodworking, so I had to get creative to cut and grind some of these pieces. I do have an angle grinder, so that got clamped to my workbench, and I cut the curved portions (where the round tube nested inside another round) with that. It was a lot easier than I envisioned it.

I used the RAS to cut my 45* to the rectangular tubing, then used my bench sander/grinder to make the fit really precise. Finally, I attached them to the jig, which will be welded after I cut and fit all my aluminum (in case there are any surprises).

I measured and cut the pushrod/shuttle that will connect the two control sticks, and drilled the ends to accept a 10-32 tap. Unfortunately, I cannot find my 10-32 tap, so this is where I quit for the day.
Continued in Control Sticks (Part 4)

Control Sticks (Part 2)

Continued from Control Sticks (Part 1)
I've decided to go ahead and post something just about every time I make progress, rather than waiting for an area to be entirely finished, and then consolidate once something is completed. I think that'll help me remember more of each step, so I'm not trying to remember what I did a month ago.

I drilled, cut, and placed my rectangular tubing today. First I marked the hole location on both sides of the tubing, then drilled pilot holes individually for each side.  (My drill press vise doesn't seem to hold material very square.) These only need to be 3/16" holes, so I jumped up to 11/64 and again drilled each side separately. Finally, I chucked up a reamer that's .0015" smaller than I need, and reamed through the entire tube. This made the holes in each wall line up very well.

After my holes were drilled, I cut the tubing to length on the RAS. I spent another hour or so making sure the blade was square and straight, and it still wasn't perfect, so I cut the pieces a hair too long and used my bench grinder to get them perfect.

I then used the drilled tubing as a guide to drill two straight holes through my jig board, and used two bolts to hold the tubing in place. This works better than building a clamp like I am for the round tubing, since the hole placement is what's really important.

Next I'll be cutting the diagonal tubing, which needs to be really perfect. I have enough material for at least one mess-up, though, so maybe I'll be able to finish this without ordering more.
Continued in Control Sticks (Part 3)

Control Sticks (Part 1)

In my research, I've come across a lot of great ideas and problem fixes other folks have designed.  While there are a few things I'm doing differently than anything I've found, for the most part my intent is to fly this thing ASAP. As a result, I'm borrowing heavily from a few sources. The main source is Mark Langford, partly because his ideas make a lot of sense to me, and partly because he detailed the problem, his solution, and his reasoning so well. In some cases, he designed his own parts and uploaded the design. The control sticks are one of those cases.(See them here, about halfway down the page.) My fuselage is not widened, as his is, so I adjusted the plans slightly to keep the sticks centered for pilot and pax. I also won't have flaps, so the brackets will be a little different. I've decided the best way to make everything line up is to build a complete jig, and then weld everything in place. I started with a piece of MDF that I squared up, then used a square and ruler to draw the design to scale.

After everything was drawn up, I routed a ⅝" channel ⅛" deep for the larger 1 ¼" tube to sit in, putting it at the right spot in relation to the 1" tubes. I made a few wooden "brackets" to screw down over the tubes to hold them in place. All of my tools are made for cutting wood, so I had to swap the blade on my radial arm saw. As if it wasn't a scary enough tool already! It took me about two hours to get it all squared up so I could start making cuts. I managed to get the main shaft cut and deburred, and it's in place with the washers ready to be welded on.

That's as far as I got yesterday. The two 45* tubes will be a lot more work, since the main shaft has to nest perfectly into them. As I was researching tig welding 4130, I came across a page that talks about a group that welds race cars. The author had asked one of the head welders what kind of tolerances they used when cutting pieces, and the welder responded that their tolerances ranged "from perfect to almost-not-perfect." Not a lot of room for error.
Continued in Control Sticks (Part 2)