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New Yoke Overlays

PostPosted: Sat May 14, 2022 10:25 pm
by brian.olson
BACKGROUND:

Two months ago, I created a post in which I detailed the process that I used to create a new decorative instrument panel overlay from flame-retardant ABS plastic. You may recall that my wife had a coworker who had access to a thermal vacuform machine that was just barely able to accommodate the size of form that I needed. The post went into detail around the creation of a MDF blank used in the forming process, and then the finishing process that I used to paint the overlay and attach Nulite instrument lights to the back. You can find the post here: viewtopic.php?f=24&t=16040

I've flown several times since that time, both during the day and at night, and absolutely love the finished product. My wife and I took a weekend trip to Panama City Beach, FL in 62C a few weeks ago and on the way back home, cruising above the clouds at 9,000', she mentioned that perhaps we should take a run at replacing the two yoke overlays as well.

Life at 9k.jpg


Over the years - at least as far as my forensics into 62Cs logs have told the story - many different comm and nav radio systems have been installed, moved, and then replaced. The original glovebox was removed and a radio stack was apparently installed on the right side of the instrument panel. At some point - in the mid-1980s - a KX125 nav/comm was installed (btw, this was the radio that I used for my IFR training three years ago). The previous owner moved the radio to the left side of the instrument panel and had a glovebox rebuilt on the right side, though it did not use original materials. After I earned my IFR ticket, we installed a Garmin GTN650 on the left in the place of the KX125, which went just over the top of the Stratus ADS-B we had installed when we bought the aircraft a little over five years ago.

And in the process of all of these changes, the aluminum overlays surrounding the yokes were progressively chipped back, to the point that they are today. And it is at this point that we found ourselves at 9,000' somewhere over Georgia with my wife commenting that I should probably man-up and get to work replacing them.

Old Yoke Overlays.JPG


Unfortunately the vacuform machine that we used two months ago had been shipped off to another location and was no longer available to us.

So, I decided to make one.

This post will focus more on the process of making a small vacuform machine and producing two yoke overlays, but will stop short of duplicating the finishing process (painting, etc.) that I used for the instrument panel overlay. I will, however, share photos of the finished product once they are complete and installed in the aircraft.

(to be continued ...)

Re: New Yoke Overlays

PostPosted: Sat May 14, 2022 10:37 pm
by brian.olson
STEP ONE - THE PREP:

I used much the same prep process that I used to design out the decorative instrument panel overlay. I fired up a design program on my computer and quickly drafted out both a left and a right design in a few short minutes. I had spent a little time earlier that day at the hangar getting some rough measurements on the overall size and placement of the holes. I decided upfront that I wasn't' going to duplicate the original yoke overlays that extended out over the instruments on the right and left; rather, I would sharpen a vertical edge to keep it nice and clean.

Design.jpg


Once I had the design roughed out I cut templates out of card stock on our laser cutter/engraver (which, as you have heard me say before, is one of the coolest tools every developed). I took it to the hangar and made notations of any fine-tuning that needed to take place.

Paper Template.JPG


Once the placement of the overlays, the holes, and everything looked good I cut out final copies of the templates out of 1/8" MDF, again with the laser cutter.

Templates.jpg


In the same manner I used for the other overlay, I attached the 1/8" templates to 3/4" MDF blanks that I had cut out using a jigsaw. I then used a router to give the sides a 3-degree bevel, followed by a second pass with the router to round over the edges. The only holes that I would form into the plastic will be the holes for the yoke shafts; the remaining holes will be cut during the finishing process.

Blanks.JPG


Now to tackle the vacuform problem.

(to be continued ...)

Re: New Yoke Overlays

PostPosted: Sun May 15, 2022 12:38 am
by brian.olson
PART TWO - THE MACHINE

I was scratching my head on this one. Yes, you can purchase commercial vacuform machines but for the average person not only is this typically a one-use machine but they are prohibitively expensive. The good news, however, is that there are a lot of resources on the Internet for those inclining to build their own.

Let me first share that I found a wonderful individual who produced an amazingly-complete set of plans to build your own (you can find the plans here: https://www.build-stuff.com/plans/hobby ... ild-plans/). I did purchase the plans for a nominal fee, and in addition I purchased the heating element that he has created. The plans - well, these plans - are for a 12" x 18" max size machine. So ... it is still too small for someone who wants to make an instrument panel overlay, but certainly big enough for the yoke overlays. The more I thought about this, though - plans and heating element in-hand - the more I realized I likely would not use this machine again, once I had completed the two yoke overlays. It almost seemed a bit of overkill. So, it was time to pivot.

A few of the Internet sites I had previously visited talked about various - different - methods to use to heat the plastic sheet. One of which was the home stove. I quickly dismissed that idea as it would be an invitation by my wife to find a different stove in a different home to call home.

A second method that sounded intriguing was to use a toaster oven as a heating source. The more I thought about this the more I realized the size would be perfect, and I could design the vacuum portion of the machine around the size of the oven itself. A quick trip to Target and I had a reasonably-priced toaster oven in the back of the car (I told my wife I bought it so that we could "enjoy fresh cinnamon rolls in the morning when we are camping in our camper". She saw through my ruse.)

Toaster 1.jpg


I measured the interior of the toaster oven and that determined everything else.

First, I needed a rack system in which I could clamp the ABS plastic sheet. I purchased some aluminum bar stock from my local hardware store and - utilizing a right-angle jig that I fashioned using 1/8" MDF, cut on the laser cutter - created two racks between which the sheet would be clamped.

Angle Brackets.JPG


Plastic in Tray.jpg


Now that I had that in place, I cut out a box using my laser cutter. On one of the sides I cut a 2-1/4" hole into which the hose from the shop vac in our hangar snugly fit. You can see that I used the laser cutter to actually cut the holes that would allow the air to pass, as well as scoring an outline of the two yoke overlay blanks (the 3/4" MDF) so that I knew exactly where to place them.

Vac Box 2.jpg


I wasn't intending to create anything that could survive a storm, just something that would hold together just long enough to create the yoke overlays that I needed.

Once everything was assembled it was time to put it to work.

(to be continued ....)

Re: New Yoke Overlays

PostPosted: Sun May 15, 2022 12:48 am
by brian.olson
PART THREE - LET'S MAKE STUFF

Earlier today, I drove out to the hangar to put the machine to use. I still had leftover flame-resistant ABS plastic sheet and was able to cut out five (5) total pieces to fit my newly created machine. In addition, I had ordered a supply of standard ABS plastic sheet from Amazon that I would use to practice. To me, the whole process is a big experiment, and I intended to waste as much plastic as needed to work out the right combination of process, temperature, and time. I wasn't disappointed in this regard, either: I effectively "destroyed" seven copies as I slowly dialed in the winning process.

In the end, I found that setting the toaster oven to "toast" setting with a temperature of 375-degrees (F) worked best. I let the oven preheat for 15 minutes while I assembled the final (real) piece of ABS.

Plastic Heating.JPG


Once the plastic achieved optimal temp (a curious process in which it first sags, then tightens, and then turns into a cat-and-mouse game where you need to pull it out just before it gets too hot) I pulled it out of the oven (using oven mitts) and quickly placed it over the vacuum box (with the shop vac running). Within seconds the plastic is sucked around the MDF plug, and within a few moments cools down.

The final product (still clamped in the aluminum rack).

New Overlay Plastic.JPG


I'll stop the tutorial at this point as I don't want to duplicate steps from the instrument panel overlay. Once I have the pieces trimmed, the remaining holes drilled, and finished - I'll post a progress photo. Since the two push-to-talk switch wires pass through the yoke overlays, I may use this as an opportunity to replace both with new - and will likely have my avionics shop take care of that detail.

(to be continued ...)

Re: New Yoke Overlays

PostPosted: Wed May 18, 2022 4:00 pm
by DaveF
This is really interesting. Nice work and keep the updates coming.

Re: New Yoke Overlays

PostPosted: Sun May 22, 2022 1:12 am
by brian.olson
After a busy travel week I had some time today to focus on the project. My wife was working on her flower gardens at the back of our yard today so I didn't feel overly guilty focusing on the plane for a few hours. I trimmed both yoke overlay panels to size using a Dremel with a cutoff wheel, in the same manner I did with the instrument panel overlay, and then cut out the holes using my table top drill press.

16 - IMG_9441.jpeg


A little sanding, a few coats of filler-primer, and they were ready for the final painting.

While I waited for the primer to finish drying I stopped by the hangar and did a little deconstruction. I removed both yokes, both push-to-talk switches, and the old yoke overlays. The cigarette lighter also had to be removed in order to get the right yoke overlay out. It sure looks barren without the yokes and yoke overlays.

15 - IMG_9455.jpeg


Once that was finished, I put a big hand-written sign on the instrument panel that said "Do Not Fly", which seems somewhat obvious since the pilot and co-pilot seats as well as the yokes were removed, but one must do things by the book. However, I am also a bit of a rebel so I put a big smiley face on the same sign, just because that's the kind of guy I am.

The primer was dry enough when I returned home that I was able to put down a couple quick coats of color (again, using the custom-matched automobile paint that I have used for the other projects). The Preval sprayer is a thing of beauty: it consists of a small bottle to hold the paint and a compressed air cartridge with a spray tip. Strain in the paint, screw on the air cartridge, and paint away. Almost. I have a personal love-hate relationship with these things ... either they work brilliantly or they splatter all over the place, and you are never 100% sure which option you will get. It certainly makes these types of small jobs easy, though.

13 - IMG_9458.jpeg


After letting the color coat dry I hit the overlays with a couple coats of 1k clear coat. And that's a wrap for the day.

14 - IMG_9459.jpeg


If I have time I may stop out to the hangar tomorrow to install them, otherwise it may be next weekend before I have enough time to finish the project.

More to come ...

Re: New Yoke Overlays

PostPosted: Sun May 22, 2022 11:58 pm
by brian.olson
Finished up the project this afternoon. Why is it (asked rhetorically) that it takes four times the amount of time you think it should take you to do something?

The painted yoke overlays were cured enough that I was able to move them out to the hangar this morning. It was good call to spend yesterday prepping everything, so today was all about installation. I was able to re-use the two right-angle brackets that were already on the plane and previously used to secure the old yoke overlays. I needed to create a new right-angle bracket for the left yoke overlay, which I did with some leftover 3032 aluminum sheet from the hangar and a #4 Tinnerman. I secured it to the panel using an aircraft pull-rivet.

17 - IMG_9466.jpeg


The right yoke overlay did not require an additional bracket since the cigarette lighter also served to anchor the overlay in place.

In the end, I decided against installing new push-to-talk switches and instead re-used the existing ones. One less variable to deal with, in my opinion. After a quick push-to-talk test for each, with the radio powered up, I re-installed both yokes.

18 - IMG_9470.jpeg


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We have storms coming through the Atlanta area this evening, bringing gusty winds and the threat of nasty weather, so unfortunately I will not be able to take 62C up for a post-maintenance test flight tonight. I'll sign off this one with the following: I'm super pleased with the end result and look forward to many years of use ahead.

And please don't quote me on this: I think this is the end of the projects for 62C. She's just perfectly right where she wants me. Time to fly some more ...