Apart the Audio Panel I also recently received two real Davtron M877 clocks. Obviously Ebay has been my source for them. I bought earlier a first one that turned out to have a dead digit, so I decided to also get the second one from the very same seller to get replacement parts for and make at least one completely working. The price was just right (less then 70$ each) while a single replacement digit costs as much as 45$ and the second out turned out to be fully functional so I hadn’t either to mess with it.

While the Learjet45 has a Davtron M850 it seems that it is just the same as M877 but with a custom faceplate. The overall look indeed is the same, but an M850 might cost even 300$+ and it’s not worth in my opinion for a simulation purpose. The back of the clock exposes a 9 pin D-Sub connector. It wasn’t hard to find on the Davtron’s site the datasheet for the part and the wiring, so I successfully lighted it through 12V DC (though the manual says it needs something between 14-28V DC). Backlighting is 5V driven but I’ll make some mods to it to add a customized front plate similar to the needed M850. What’s nice for the project is not just having this real part but the fact that the clock can be started by closing a contact on one of the D-Sub pins. This way I’ll be able to control flight time start-stop from an FSUIPC offset and my own interfacing board.

written by l45 captain \\ tags: 850, 877, chronometer, clock, davtron, FSX, learjet, learjet 45, m850, m877, simulator

The acrylic and plastic parts we use for our projects are very weak, and I’m sure it happened to anyone to have some important pieces broken because of dropping on concrete or unintentional force applied on them and you can’t find a missing part anymore. This happened to me as well with the electrical panel. I was having it in my hands and opssss… it slipped away and I found a corner missing in it I wasn’t able to find the missing piece anymore… so now what? Make such a complex part again would have took me at least 2 days of work.

I then looked around for a good way to repair it and found out that the polyurethane resin used for casting parts in silicon molds is just perfect for the job. What to do then?

1. In the first image you can clearly see the broken corner of my elec panel. If the part has been already painted remove the paint a bit around the junction point with the specific remover and sand a bit to help the resin to attach to the acrylic piece. I had it painted only on front and I did it on that side. Clean thereafter with acetone or generic home usage alcohol.
2. You need to create a frame that will reproduce approximately the missing piece. In my own case as you can see in the image the part to restore was plain and squared, so using Lego blocks I made a wall around the corner where the resin will be casted. Be sure that the base is closed (use some adeshive attached on bottom to prevent flooding). Keep everything ready for cast the resin, because it usually dry very fast (less then 5 minutes) and you don’t want to ruin the part even more.
3. Mix the polyurethane resin. This one I have is 1:1 mix so easy to make in very small doses. I used a syringe to get 1ml of each component and mixed in a glass with a tipped stick. Cast the resin in the frame slowly until it reach the level needed to reproduce the missing part. Don’t mind if you put a bit more, you can sand it later before repaint the part.
4. Wait for it to be dry a bit (5-10 min) and remove the frame. The resin attaches perfectly to the acrylic by actually gluing to it. The specific strength is a bit less of the polycarbonate or cast acrylic but for this job is just perfect.
5. You can now remove the bulk extra with a cutter while it’s still slightly soft and then wait at least 30 minutes so that the resin will reach the final state. During this period pressing with force on it will leave your fingerprints on the part so use with care. Once rock solid sand the new reproduced part to match the old one.
6. Finally paint again following your usual way. To prevent paint signs don’t cover the remaining part of the piece by sticking adhesives on it else paint signs will be seen from different paint timings and thickness. Just put a newspaper sheet covering the part you want to care of and paint with the gun or the spray can  at a fair distance. That will spread the paint enough to give a good result.

Operation completed.

written by l45 captain \\ tags: acrylic, cast, plastic, reconstruct, repair, resin

I know I didn’t update the blog a lot during past months, but don’t think I gave up the project..! In truth I’ve worked a lot on many different parts of it but simply haven’t had the chance to make one of my usual build stories because none of the pieces were really complete. Actually I’m working at the same time on different jobs:

The avionics set is about complete. All the parts have been milled, painted and engraved. PCBs for the Display Units are ready as well and I managed to have the RMU ones (that are very complex) fabricated in a professional center. Those should arrive during this week, so I hope I can complete them very soon. Also a lot of time was needed because those sets have been made in multiples because some will be sold to finance other parts of the cockpit (this is a very very time and money consuming hobby…)

I’m also hardly working on the lower panels. The elec panel is complete so as the Gear and Lights panel that only misses the gear handle (I will receive one soon from Ron of hangar45.us). In this moment those parts are having a small makeup to allow a different backlighting way. In the early periods I chose to use wheat of bulbs to backlight the panels. Though this is the way the panels are backlit, for our purposes the power drain and hot that they produce can become an issue, so I gave a shot to both SMD and 3mm high intensity leds and both gave me the sensation that they can substitute bulbs still giving a very good overall eyecandy.

Also the small details of the cockpit are in production. Six full sets of MIP and glareshield knobs have been created and shipped oversea past Fall to take part to other fellow builders projects. Now the Lower MIP and pedestal knobs are being developed. It will still take about 3-4 months to complete them, but I can say that this other part of the building has had a start as well.

I leave you with some spare images took here and there from the various progresses:

written by l45 captain