Stretching the yoke a bit too far

(This post is from my older, pre-2009 unfinished sim project. For an article about the yoke build for my new project, which supercedes this one in all respects, go here.)

Depending on exactly what kind of sim you’re going for, you’re going to need one or another sort of main control stick or yoke. If you’re doing a fighter aircraft or a dedicated airbus sim, you’ll be using a centre- or side-stick. The latter of these can be replicated easily enough with any number of after-market joysticks designed for sim nuts, and depending on how far you’re willing to go it’s not that hard to convert one of these to look like the real thing. If you’re going for a light aircraft or non-Airbus airliners, you’ll be using a control yoke. Again, depending on exactly your requirements, these can be easier or harder to do – replicating a bolted-to-the-floor Boeing-style yoke system is a large ask compared to the simpler systems you’ll find on light aircraft.

One of the yokes most frequently used by sim buffs is from CH Products. The classic version gives you a yoke with a nice feel, good motion in two axes, and three levers on the top to use for throttle / prop / feather operations. The yoke is designed to clip to a desktop firmly and is used by many sim fans who will never go to the lengths of building a cockpit environment, but who nonetheless want a bit more realism than a keyboard-and-joystick combo will supply.

I bought one of these a while ago in my pre-cockpit phase, and since it’s a great product I decided to incorporate it into my sim rather than fabricating one from scratch or buying one of the more expensive versions out there. Some simmers use the yoke as-is, perhaps mounting it on a stand, but to my eyes that looks unrealistic. My design calls for the yoke to emerge from the MIP, as on most light aircraft and jets, and using the yoke as-is would mean either the handles being absurdly close to the MIP (<1 inch) or else somehow merging the yoke body into the front of the MIP, which with my planned use of screens would simply not work.

So, I resolved early on to extend the yoke by adding length to the rod on which the yoke handle is mounted, to provide enough length for me to mount the main part inside the console but still have the yoke project far enough out from the MIP to be useful. I calculated I’d need to add about 120mm.

The mounting rod is a thermoplastic pipe, 23mm in diameter. At first I had intended to replace the whole thing with plastic piping of the same diameter and a longer length, but such pipe proved impossible to source (20 and 25mm being standard sizes but 23mm apparently not). Once I got into the interior of the yoke and took it fully apart, I noticed that the part of the pipe inside the case had specific grooves and mouldings critical to the operation of the yoke, and a straight replacement would entail replacing these mouldings too.

That option being out, I decided to extend the existing pipe. Since I couldn’t find a piece of plastic (or metal) piping that matched, I looked around the house for anything I could find of a similar diameter. In the end I found a wooden broom handle, which is 21.5mm in diameter. Since the interior of the existing rod was 20.5mm this meant I could make a push-tight extension that would mate up with the interior of both ends of the rod when I had cut it, and be not much thinner than the existing rod once in place (this being necessary both from an aesthetic and mechanical point of view).

I cut a piece of the broom handle 140mm in length. This would give me a 10mm flange on either end to use in the joining.

On the CH yoke a set of wires runs down the center of the mounting rod, connecting the various buttons on the yoke with the controller board inside the casing. I needed to make a similar hole through the broom handle. I used a 10mm wood bit on my drill press and pushed a hole through from both ends, meeting up almost perfectly in the middle (you can see that the hole is off-center a little and indeed goes through the wood at a slight angle, but this is compensated for on the other end too).

I then used a rotary sanding bit on my Dremel multi-tool (an indispensable aid for a project such as this one) to take 1mm or so off the diameter of the ends of the handle back to a depth of 10mm, to act as the flanges. With a hand-tool this is always going to be a little hit and miss, and here I must admit that my first attempt was a bit crap and ended up taking too much off, so I had to start again and cut a new piece of broom handle. This worked a little better.

I then found the right place to cut the existing yoke rod – such that the new extension rod would not end up going inside the casing at full depression, causing it to stick in place potentially – and severed this with my reciprocating saw. The cut wood was then fit-checked and when I was happy and had done a little more Dremel buffing, I used grab adhesive to join the severed plastic pieces with the wood.

This needed to be left to dry for a 24 hours to ensure a firm grip. Then, to ensure added rotational grip against the stress of turning the yoke, I put a 4mm drill bit into the Dremel and drilled a hole through the plastic-and-wood of the flanged area on each end of the join, and then drove a 4mm machine screw through the full diameter of the shaft. This together with the adhesive should keep things firmly in place even against pretty hard twisting and pulling. 

Finally a coat of paint or two was required. I had a can of gloss black spray paint which was ideal for the job and sprayed the whole exterior part of the rod – the part that will be visible outside of the console. After the first coat I applied some wood filler into the cracks between the wood and plastic and used it to create a ramp effect at the point of each join where the wood is of a smaller diameter than the plastic. A second coat of paint was left to dry for a further 24 hours.

Finally, I re-attached the rear part of the yoke handle assembly to the rod. This involved removing the machine screw since the rod needed to clear the hole in the yoke handle designed for it and the screw was not flush at this end, so I wanted to do it once and then glue everything into place.

This is the extent of the physical alteration I intend to make to the yoke. Next step is to re-attach the electronics, notably the switches and buttons within the yoke handle. This requires that I extend the existing cabling to make up for the new length of the yoke rod. As there are 11 cables to be extended it’ll be a big soldering job. I will also remove the board carrying the potentiometers and levers that normally poke out of the top of the yoke assembly. These are not needed as it’ll be enclosed within the console, and the controller axes can be re-used for trim controls or other rotary controls. I will use 3.5mm mono jack plug-and-socket combinations to bring the wiring for those axes to the top of the yoke casing, and then mount the re-purposed potentiometers elsewhere in the sim. I then have to work out exactly how to mount the resulting modified yoke into the console, which also looks like it will involve moving the mounting for the left and right PDF/MFD monitors up a few centimeters to clear the yoke rod.

Lots of fun for later in the week.