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RMU's and Display Units by Project45

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Quick update.  I got the knobs finished for seven sets of Display Units.  Keep in mind that there are four DUs in each set!  As I am moving forward with almost everything that I am doing, I am trying to make a few extra set of things to eventually get to the point where if someone wants something, we will be able to supply it in a timely manor. So in other words, two of these knob sets are not spoken for yet.

Display Unit knobs

Unlike previous knob sets from past suppliers, these knobs will come with the set screws already in place.  One less thing the end user has to worry about.


More updates soon!

Hey guys,

I apologize for not updating this thread sooner.  I got side tracked with higher priority sim issues, mostly to do with the TQ modules, the FGC and redrawing every panel in the Lear45 sim!  I felt before we could move forward, we all needed a solid foundation to stand on and we are almost there.  Eight sets of the Display Units will be completed no later than Christmas AND, all the DXF drawing for anything you can imagine to do with the Lear45 sim build will be available in the Builder Resources page on JAN 1st 2020!  So keep an eye out for that.

Now that I have my plate cleaned a little, I can focus more on the Display Units.  I have actually been working on them for at least the past four weeks and have been privately updating those of you who are on the build list.  If you are one of those guys that like what you see, you can either get on the build list for the second batch or, if you have a CNC, you will be able to make your own with the drawings and G code that will be available soon.

I will say this, if you are new to CNC work, the Display Units are not a good place to start because of the complexity of multiple cuts on several pieces front and back.  However, with a little CNC skills, every panel and part in the Lear45 can be made to a high degree of satisfaction!

So let me get you caught up with where we are at this moment.  Initially I started making five sets of Display Units and I got to a point that I was about 70% complete with them.  But now I have added three more sets and have got them caught up to the first five sets.  Keep in mind that there are four Display Units in each set so I am working on no less than thirty two individual Display Units  which every piece has to be cut front and back!  So you can quickly see how fast making just a couple sets can slow things down.  Long story short, after four weeks I am still just 70% complete!

Along the way I have discovered several places where I could improve on the design of the DUs.  The first being what I call the backlight pocket.  There are several hash lines on DU's 2 and 3 that need as much help as possible to get them to illuminate.  So extending the backlight pocket up a little higher will help with that.  Additionally, in order to keep the DU backers uniform and interchangeable with each other, I went ahead and made the changes on both types of DUs.  In other words, all the DUs are still going to be interchangeable.

In this photo below, the DU backer on top has been properly cut with the additional backlight chamber.  The one on the bottom still needs to be updated:

(As always, right click on photo to maximize using Firefox)

This photo shows the template jigs to properly mark the earlier DU backers with the update:

Last but not least, the DU part is secured in a placement jig and the cuts are controlled manually:

I think it is important to share some of the "behind the since" details with everyone, especially those who want to try to make some panels on their own.  Sometimes we have to make some manual cuts if they are easy enough to maneuver.  If the cuts were anymore complicated, I would have to scrap the part and let the G code make a whole new piece.  In this case, I had around 25 pieces to save!  They all turned out perfect by the way.

Another area that I wanted to revisit before I got too much further down the road was the knobs.  The real Display Knobs look so simple and you would think that they are all over the internet and available.  Well, after looking at thousands of knobs and using multiple search terms, I was unable to come up with an easy and cheap solution.  There were a few that were close, for $2 a piece, but still not close enough.

So I went to the Learjet Super Store (Home Depot) and found these:

They are .5" Birch wooden furniture dowels.  They are the right diameter and can be cut down to the correct height which I believe is .75".  They have the splines or if you prefer to call them grooves or channels which is the look and feel I was looking for.  If you do want to try to work with these on your own, two things to keep in mind.  First, wrap them in blue painter's tape.  This will keep them from splintering up when cutting.  The second thing is be SUPER careful when cutting!

So after wrapping with tape, cutting the first ends off and then the second ends leaving exactly .75", I made the holes for the set screws.  Then I made a quick G code file that created a six piece jig that I could press the "would be knobs" into and let the CNC make the final inside cut for the encoder shaft.  This method insures that the hole is perfectly centered.  AND, it was important to have the set screw holes done before the final encoder hole because most of them required running a 22 gauge wire through that hole in order to pull the knobs out of their jig holes!

This is what I have so far:

At this point I have not yet sanded them or put the small 45 degree beveled edge on the top and bottom of the knobs.  I think these are going to be a nice solution to the real Honeywell Display knobs that we can not yet find.  If nothing else, these knobs will make an excellent temporary knob while we continue to wait for a better option to show itself!

The last BIG update that I wanted to catch you up on is that Jason Hite is working on a new and improved way to interface all of the Jet45 modules with the sim using Arduino cards.  So far he has successfully interfaced the RMUs, CDU/FMS and the FGC using Arduino interface cards.  Every avionics module including the Display Units and EFIS panels will be interfaced using Ardunio cards.

To date, I have created several Arduino Interface boards to help with wire management so that we have a nice clean looking sim.  In the next few days I will be creating a couple prototype Ardunio interface boards for the Display Units and the EFIS panels.  We will have more on this as it all develops so keep an eye out!

Progress on the Display Units is heading in the right direction and there are so many areas to get you caught up on!  First, the wooden knobs turned out really well, although time consuming.  I am going to continue to keep my eyes open for those elusive Honeywell knobs!  In the meantime, we have a coupe replica options, see photo:

display unit knobs


I made up a complete set of Display Unit Sub  Modules and a couple RMU Sub Modules for Jason to do some testing.  What we are trying to achieve here is a true "plug and play" solution using Ardunio Nanos and Mega interface cards.  Here are a couple photos:

I have since sent these onto Jason and we discovered that I needed to make a few changes and the second set is in the mail!  Nothing is ever easy with this project and as I said to Jason, I had it in my time budget to make them at least twice!

The DU paint plugs turned out very nice and have since served their purpose well:

Simply pop them in the light pocket, paint and pop out after the paint dries!

I also got the DU screen mask back from the laser shop.  They are made of thick construction paper like 1st graders play with in art class.  The laser did a great job cutting these pieces out with crisp and clean edges!  In the photo below, the smoked lens is in place and the screen mask is held in place with Scottish tape!

Here is a group of four just waiting for the lower front plate and some bottoms.  (Aren't we all!)

I took some time to add a little "Eye Candy" for guys like myself and Shane Barnes.  I have no idea what it is for, maybe some sort of test port, DonnyRay would know.  I used a 4-40 brass inset and then painted some 4-40 hex set screws gold.  The look is authentic!

(Right click to enlarge)

Last but not least, here is a photo of a couple DUs mounted to a MIP.

Pretty sweet!  I know it is taking some time but everyone on the list to receive a set will truly appreciate all the effort and work!

Now that I have the chores of the DUs just about behind me, I am free and clear to move forward with the lower front plates and some buttons!  Keep an eye out on this thread, it's getting hot!


I have finally got to a part of the Display Units that I have to be honest with you, a little worried about, but no more!  The DU lower front panels are now well on their way to being completed.  Over the past week I have just about completed all the DU1&4 lower front panels. (Remember DU2&3 is a different design)  Because of the complexity of these pieces, they have to be milled on the front side, the top side to create the 45 degree edge and then last but not least the back side.

In this photo, the front face of the DU1&4 lower panels have already been milled.  I have a .03" relief built into the face which you can see if you look closely.  Because I do not have an expensive CNC that comes equipped with a forth rotating axis, I had to think outside of the box and designed a mounting jig to be used with a 45 degree milling bit:

Lear45 Display Units

Here the part is flipped over and the back side is being milled.  Notice I have two screws holding the part in place, however, the very first cut the screws were in the middle two screw holes.  In other words, after about eight minutes of cutting, the CNC stops and the screws have to be moved to the outer screw holes to make way for the next cuts.  A pain but very effective!

Lear45 Display Units

Here are several DU1&4 lower panels milled on all three sides:

Lear45 Display Units

And here is the DU1&4 lower panel lit up and on the DU bezel!

Lear45 Display Unit

I am not sure which DU lower panel set is going to be more challenging.  The DU2&3 panel has it's own set of issues that I will need to overcome and those issues are all but handled, I just have to make them next week!

Getting closer to having the Display Units completed and delivered!

Real quick update on the Display Units!  All the lower DU panels are cut front and back, now to sand them and cut the inside 45 degree angles in DU's 2 and 3.  I have not yet figured that out yet but I am working on it.  Hopefully I will have that resolved by next week.

Display Units

The photos above has 32 DU lower panels in it!  Additionally, I have the button bezels for DU14 cut out and the button dividers for DU23 in small bags at the top of the photo.  Lots of sanding and painting ahead of me.  Another update shortly.

At last, the final update on the Display Units is here!  The first batch is complete and in the hands of several members as of this date.  I am planing on making a second run of the DUs in April 2020 and they are now available in the HANGAR PRODUCTS page.

To get a closer look at the detail of these DU panels, right click on the photos below:

DUs lit up with 5 volt power.  Notice that there is no light bleed around the buttons:

Both types of Display Units have several 3D elements to them on the front side and on the inside:

Like all the Project45 panels and products, the Display Unit DXF drawings and files have been made available if you want to take a look behind the curtain.  If you desire making your own DU's, you will find everything you need in the BUILDER RESOURCES

If you have questions about the Display Units, please ask here in this thread!

I made the holes for the set screws.  Then I made a quick G code file that created a six piece jig that I could press the "would be knobs" into and let the CNC make the final inside cut for the encoder shaft

hi Ron

how exactly does this jig look like that you have made?

i am curious.

Hi Roel,

I did not use a jig to make the smooth version of the Display Unit knobs.  They are a two piece solution.  Booth pieces are made of .375" thick cast plastic.  When they are glued together, they are .75" tall.

The first piece has the encoder shaft hole drilled all the way through it and a shallow lip cut in the top of it (which is actually the middle of the knob) so that the second piece snaps on like a puzzle piece.

The second piece only has a shallow opposing lip with no encoder shaft hole.  A small amount of cyanoacrylate glue, otherwise known and "Crazy glue", and the two pieces are bonded together forever.  And because of the lip locks, they are perfectly aligned.  A Small amount of sanding and you have perfectly round knobs, .75" tall with an encoder shaft hole.  All you have to do is manually add the set screw holes.

In this photo it is hard to see that each of these knobs are two pieces.  And that is what we want!

I have added an updated dxf drawing to this post so that you and others can see the knob drawing and other detailed aspects of the Display Units.


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Thanks Ron

i made my fgc knobs like that 😉

but i like your idea about the wooden ones also.

but then you need a centering device to drill the hole, i was thinking you made something like that?

Yes, with the wooden dowel knobs, I created a short G-Code file of the outer diameter of the wooden knobs and the inner shaft hole.

I then cut just the outer hole into the CNC spoil board.  You might have to refine the diameter of the hole so that the knob fits snug in the hole.  Then I altered the G-Code so that the outer knob diameter cut was not included, just the shaft hole.  So when you press the knobs into the holes, only the encoder shaft hole is cut.

The key is that the CNC machine's X, Y, and Z axis are remembered from the first cuts in the spoil board to the next cuts in the wooden dowels pressed into the spoil board.  This way you get the encoder holes as centered as possible.

I hope this helps.  I do not have any photos of that process.

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