Plexiglass Panel Overlay - 170A

[brian.olson]

Back in October, as I was trying to determine the best way to repaint the yokes in 62C, I pontificated that perhaps I ought to make a new plexiglass overlay for the panel. Seventy years of use had marred the beautiful finish and - over time - the markings on the plexi no longer correctly corresponded to the function of each switch. See: viewtopic.php?f=24&t=15342&start=15.

Well, for better or worse, FedEx dropped off a Glowforge laser cutter/engraver at our house two weeks ago. So down another deep, dark hole my wife and I go once again.

My daughter was in town over the past week (she is a graphic designer living in the DC area) and with her help I was able to locate a typeface that is a nearly-exact replica of the typeface used on the plexi panel when it came out of the factory. For those interested, it's called Bernhard Gothic.

Just for hoots and hollers we decided to run a test print of it on a piece of acrylic this evening, reverse-engraved. It's quite impressive what the Glowforge can do.

Question for the group: Does anyone have a DXF or SVG file that they have created of the plexi panel for an "A" version? I think Ryan Smith had been working on one a while back.

I'll start running some official tests on the acrylic to narrow down the font size and weight, the depth of engraving I need to adequately fill with yellow paint, etc. I may spend a little time in the hangar tomorrow measuring out the dimensions of the existing plexi panel and create a cut file, if nobody else has a file that I can start with.

This will be another fun project methinks.

[Bruce Fenstermacher]

What a FUN project. I've spent hours looking for the font Cessna used for placards. I know Ryan has as well. What I found is that it seemed Cessna used different fonts depending on when the placard was created. Probably as they came from different vendors perhaps. I never found the perfect font but found combinations of several I'd use together depending on the character. Yes, I'd change fonts mid word to a more suitable font for a character and change back. I also played with type width and kerning sometimes different for each word. Most folks have no idea how challenging just this part of the project is to the graphic artist and printer who has a critical eye towards matching the type perfectly.

For example and not being critical of your effort at all and allowing that I haven't looked at panel type faces in a long time, the W in your sample does not strike me as one I remember. It could very well be a perfect match.

Another thing you might already know. The same panel overlay was used from 1948 to 1952 even though by 52 some of the wording on the panel was incorrect for what it was labeling. For example I recall there is a landing light extend position. But that was only applicable to '48.

I look forward to seeing more of your project as you go.

[brian.olson]

Bruce - I suspect you and my daughter would have a wild and enjoyable conversation regarding your typeface-expeditions. She really geeks out about that. Last night she was spouting off kerning and widths and spacing and a myriad of other technical terms that she proclaimed have absolutely no interest to anyone else unless you were deep into the mystery of typography. At the end of our discussion we pretty much agreed that I would be relegated to the task of positioning the "lines" and she would handle anything font-related; however it is now my personal mission to try to impress her with my hacks. As you know well, that's why these projects are so much fun.

I'll look forward to your critical eye and observations as this moves forward -

[barrymaas]

Here's the svg I created for my laser engraver. Also attached is the non-reverse version, which has the holes marked. Between the two of them you should have enough to cobble together yours

https://www.dropbox.com/s/fh12fm4cx6vjl ... 2.svg?dl=0

https://www.dropbox.com/s/ewd4zxys8vj6b ... l.svg?dl=0

For the sloped top edge, I used router bit 8614 from here

[brian.olson]

Here's the svg I created for my laser engraver. Also attached is the non-reverse version, which has the holes marked. Between the two of them you should have enough to cobble together yours

This is immensely helpful - thank you very much for sharing! I just ordered the router bit you suggested as well.

[Ryan Smith]

Original font is Century Gothic Bold. Modern font is an exact copy of the original font from the Monotype Foundry.

Looks great!

[barrymaas]

This is immensely helpful - thank you very much for sharing! I just ordered the router bit you suggested as well.

No problem. It took me a bit to figure out how to make all the colors work out. What I did was to paint the acrylic the base color (maroon, in my case), and then laser etch the paint (my laser etcher is a blue laser, and won't etch clear material). Then I could paint the etch lines and words, followed by very carefully drilling the control holes. It worked well. With the glowforge, you could knock out a dozen of these by lunch!

After routing the top of the panel, you can buff it back to a clear state with Novus acrylic polish.

[brian.olson]

Barry - thanks for the advice on the order in which you produced the part. I ran a few tests this weekend to determine a few things like engraving depth, speed, quality, etc., and then did a few tests with a variety of different paint types and painting order. To your comment, the best way seems to be to paint the back color on first, reverse engrave through it, and then paint the lettering (and lines, when I get out of the test phase). The back paint serves as a nice mask for the paint that goes into the engraving.

The background paint color is pretty close to what is in the panel (I grabbed a bunch of paint sample chips from Home Depot and held them up to the panel, then went back and bought a sample jar of the paint). It's not a perfect match yet so I'll keep looking (I'll hit up Sherwin Williams next and see if I can find something even closer), but things are definitely coming together. At least the process seems solid.

I used the Preval paint sprayer system for my yokes and it worked very well for that purpose. However, it seems really finicky with the latex paint I'm using for the plexi. I found an online site that will let you choose a custom color and then they will create a spray can from it (https://www.myperfectcolor.com/) for not much more than a twenty-dollar bill. I'll probably go that route and be assured that I'm getting the highest quality application.

Next step will be to fine tune the file that you so graciously shared with me with the labels needed for my panel, and then give it a test print.

I'll likely wait until 62C goes into annual this coming fall before I ask the A&P to swap the plexi panels out, so I am not feeling the need to rush the project.

[dstates]

Great Project! I think a gray background color would look nice on your panel with all of the black…

[GAHorn]

….

Another thing you might already know. The same panel overlay was used from 1948 to 1952 even though by 52 some of the wording on the panel was incorrect for what it was labeling. For example I recall there is a landing light extend position. But that was only applicable to '48.
….

As we all know….Just because we witness an airplane in the field which appears to have original parts…. ain’t necessarily-so.
As the years have gone-by, undocumented changes have occurred to these airframes and many times parts are observed which are presumed to be original….but in-fact are not…having been changed or substituted by owners without fanfare or note. A plexiglass plate from an earlier airplane may have been sourced as a replacement for a later aircraft.

Just looking at the IPCs for the various models it appears that the : “PLate, Instrument panel decorative plexiglass” changed each major model:
170 utilised: PN:0413316
170A utilised: PN:0413316-4. (SNs 18729-19365) (Fig 34, Item 56) (SNs 19365 and On)(Fig 35, Item 42) ( I.E., all 170A used same PN)
170B utilised: PN: 0413316-4 (SNs 20267-25372) (Fig 37, Item 17)
……………….…. PN:0513032 (SNs 25373-26038) (Fig 42, Item 33)
………………….. PN:0513043 (SNs 26039-26995) (Fig 42A, Item 32)
………………….. PN: unknown (SNs 26996-On). (stopped use of plexiglass plate?, same as early 172s, SNs 28000-36965)

Also, as for painting the back-sides of them… I believe Cessna painted the stationary panel beneath the plate…the clear, plexiglass plate was etched/placarded….and the stationary panels’ color simply shone-through the plexiglass.

[Ryan Smith]

….

Another thing you might already know. The same panel overlay was used from 1948 to 1952 even though by 52 some of the wording on the panel was incorrect for what it was labeling. For example I recall there is a landing light extend position. But that was only applicable to '48.
….

As we all know….Just because we witness an airplane in the field which appears to have original parts…. ain’t necessarily-so.
As the years have gone-by, undocumented changes have occurred to these airframes and many times parts are observed which are presumed to be original….but in-fact are not…having been changed or substituted by owners without fanfare or note. A plexiglass plate from an earlier airplane may have been sourced as a replacement for a later aircraft.

Just looking at the IPCs for the various models it appears that the : “PLate, Instrument panel decorative plexiglass” changed each major model:
170 utilised: PN:0413316
170A utilised: PN:0413316-4. (SNs 18729-19365) (Fig 34, Item 56) (SNs 19365 and On)(Fig 35, Item 42) ( I.E., all 170A used same PN)
170B utilised: PN: 0413316-4 (SNs 20267-25372) (Fig 37, Item 17)
……………….…. PN:0513032 (SNs 25373-26038) (Fig 42, Item 33)
………………….. PN:0513043 (SNs 26039-26995) (Fig 42A, Item 32)
………………….. PN: unknown (SNs 26996-On). (stopped use of plexiglass plate?, same as early 172s, SNs 28000-36965)

Also, as for painting the back-sides of them… I believe Cessna painted the stationary panel beneath the plate…the clear, plexiglass plate was etched/placarded….and the stationary panels’ color simply shone-through the plexiglass.

I have handled three original plexi panels for 52 models. One from my airplane, one from Gary Friesen, and another from John McGuire.

All three have the panel color painted on the back of the panel. There are two bolts holding the piano keys in place that are behind the plexi panels that aren’t visible because of the paint.

[IA DPE]

If/when someone gets set up to create one for a ‘55, I’d be interested.

I don’t want to buy the machine as I’d never use it again. Plus, it’d show me (again) how ignorant I am of CAD/ CAM operations.

[GAHorn]

The last N.O.S. / OEM plate/panel from Cessna was auctioned-off at the Bardstown convention and it was clear…not painted. This is the sort of puzzles/assumptions that can exist over this type discussion… just because three panels have been observed which were painted doesn’t mean Cessna did that…they may have…or they may have been painted subsequently. But it doesn’t make much sense for Cessna to carry parts in-stock that cannot be applied to existing stationary panels which are already painted…. nor make much sense that panels offered in the IPC wouldn’t specify which color paint the customer might desire in accordance with the interior-code on the door-placard of the airframe….if the panels were supposed to be painted on their backs.
My predecessor Tom Hall and our gone-West historian Cleo Bickford both told me they were all clear and gained their background color from the stationary panel…. so that’s basis of my belief…. but if that’s not correct it wouldn’t be the first time we were surprised by some detail like this.

[n3833v]

Dave Stokes has some from the 170 table at Oshkosh. Not sure what application. We had some questions about them.

John

[Ryan Smith]

The last N.O.S. / OEM plate/panel from Cessna was auctioned-off at the Bardstown convention and it was clear…not painted. This is the sort of puzzles/assumptions that can exist over this type discussion… just because three panels have been observed which were painted doesn’t mean Cessna did that…they may have…or they may have been painted subsequently. But it doesn’t make much sense for Cessna to carry parts in-stock that cannot be applied to existing stationary panels which are already painted…. nor make much sense that panels offered in the IPC wouldn’t specify which color paint the customer might desire in accordance with the interior-code on the door-placard of the airframe….if the panels were supposed to be painted on their backs.
My predecessor Tom Hall and our gone-West historian Cleo Bickford both told me they were all clear and gained their background color from the stationary panel…. so that’s basis of my belief…. but if that’s not correct it wouldn’t be the first time we were surprised by some detail like this.

It was likely clear because they were all screened the same and the didn’t want to paint it blue if they needed a red one or vice-versa. The later model plexiglass overlays had their trim colors matched specifically, the older panels had the white grids and Ostwald 2GA lettering. The paint backing is the same as what was applied to the panel, near as best as I can tell. I have only removed one panel and held the other two that have been removed with my hands. I can give you at least five other references that prove my point, if you care to see them.

I mean zero disrespect to Cleo, but he was a human and could have been mistaken or simply not known. AFAIK, Cleo had a 1955 or 1956 year model 170, not an older one. How many airplanes did he put his hands on that were known originals and flying or disassembled to that extent to know beyond a shadow of a doubt that’s how they were? I’ve been around these airplanes LITERALLY my entire life, and I have learned quite a bit about them, too. If you can find me a picture of a known original 1948-1952 where the two screw heads attaching the piano keys are visible behind the plastic overlay, I’ll make a $1000 donation to the association in memory of me not knowing what I’m talking about.

I’ve been around these airplanes for 35 years. I may not be Cleo, but I’m not a neophyte either.