First, Build a Shed

[Cherrybark]

High praise for Garmin's Experimental Aviation Support Group!

I decided on a Garmin G3X single screen avionics package with the usual Comm, Transponder, etc. SteinAir, a sponsor, knows these systems inside and out and they made it painless to select components to build the system I wanted. Then came wading through the online G3X Installation manual to learn how all of the boxes plugged together. This is a very thorough manual!

Printing out the sections for my components, including the pin assignments for the wiring connectors, made it easier to understand how the various boxes needed to plug together but there still were questions. Such as, why do these two boxes share both a CAN Bus and RS-232 connection? Garmin's Experimental Aviation Support Group is just an email away and answers to questions were usually returned in a day.

One of the forum regulars, who will remain nameless in his role of innocent bystander, kindly emailed me drawings of his electrical circuits which included a different collection of Garmin components. These were beautifully drawn using the free Draftsight 2D CAD program and inspired me to put aside my yellow pad, covered with wavy lines, and do a more professional job. Garmin's support group had encouraged me to send drawings for their review, so off went five pages of documentation. In a day, a return email said everything look good excepting one change requiring a swap of two RS-232 ports.

While working on the design I exchanged three or four emails with the Garmin Experimental Group. Various staff responded but they were always helpful and their answers were more friendly explainations than curt "yes or no." I was very impressed and wanted to take a minute to praise this group.

They can be reached at g3xpert@garmin.com and you might have seen them post on the Rans forum under the user name G3XPERT.

[efwd]

Great to know Carl. Thanks for the contact. It won't be long before Im head over heals trying to make sense of all that.

Eddie

[Cherrybark]

Seems like I've been planning wiring and laying out the console forever. Part of the slow down is the Fall like weather that brought out the "Honey Do" list for outside projects. One of those tasks was to finally paint the shed that was Step 1 of this project.

The console layout is based on a 10" Garmin G3X with a Comm radio and a 9.7" iPad Pro slaved to the Garmin. Decided to mount the iPad with the RAM Ball system. It will just fit as a flush mounted unit but I wanted to first try this approach. Cooling and adjusting to avoid glare were some of the considerations. The unusual unit next to the row of breakers is a CAV-13 912iS Engine Monitor. Transponder is Garmin's remote mounted unit and Auto Pilot functions will be through the G3X Display. Thought the Scotch Brite "brushed aluminum" looked nice till I took it outside and it turned into a mirror in bright sunlight. After all of the holes are drilled, it will be powdered coated flat black.

Have started string CAN Bus, power and other connections to the various components. Plan to complete wiring and install the console before covering the left wing and fuselage.

[efwd]

Nice Job Carl
Just dropped off my panel at the powder coat company today.
I can appreciate the time you spent away from doing fabric. By time I was finishing the last wing I was pretty tired of taping.
Eddie

[jrevens]

Yeah... you're doing the fun stuff now, Carl. Be careful - you won't want to go back to messing with that Oratex!

It's gonna' be nice, and I think that you and Eddie have the right idea in doing the powder coating.

[David47]

Couldn't agree more John. Happy wiring Carl and hopefully all the electrons do what they're supposed to !.

[PaulSS]

Haha, glad I'm not the only one who saw the advantages of the iS status monitor. I can't wait to eventually get mine going, although I did have a play with one in June.

I don't know how the Garmin stuff links together with the CAN bus, power, ground etc but maybe have a look at this chap's blog:

http://elder.ninja/blog/p/3521

I think he's come up with a very elegant 'daisy chain' design and it's one that I'll be using on my MGL gear.

Of course, if you've already cut the cables.......

[Cherrybark]

The guy Paul linked to had the interesting idea to build a collection of short "Y" connectors to wire his CAN Bus. A "Y" was made up of two 4-pin Molex connectors with DB9 in the middle. The longer CAN Bus wires were basically extension cords with the opposite sex 4-pin Molex plugs to string everything together. Apparently his MGL Avionics manages to communicate everything with the two Hi & Lo signals along with +12V and ground. And they have cleverly made the DB9 pin assignments identical between devices. The idea was to have the flexibility of adding additional CAN Bus devices by simply plugging in new jumpers.

A couple of the Garmin devices have identical DB9 pin assignments (the GSA 24 Roll Servo and the GMU 11 Magnetometer oddly enough) but that commonality falls apart quickly. For instance, the GSA 24 Pitch Servo adds a jumper between pins 5 & 6 to specify it as the "pitch" servo. And other units have multiple unique pins.

My plan is to neatly bundle multiple cables to each device. As example, the GEA 24 Engine interface will have three cables: shielded pair for CAN Bus, shielded 3-strand for RS232 communications, 3-strand for Power 1, Power 2 (stabilized during engine starts) and Power Ground. Bundles will be tied with the traditional wire cord rather than zip ties.

[Cherrybark]

Major holes cut and drilled in panel. Still have a the keyholes for the round switches and a couple of LEDs.

Agonized on how to cut the larger circles for the two vents and the CAV-13 engine monitor. After reading almost universally poor reviews on affordable tools, I bought this very cheap cutter from Harbor Freight. Practiced on scrap aluminum sheet using only one knife and the drill press on it's slowest speed. Carefully set the cut radius with calipers and did test cuts on scrap wood to double check setting. Used high school geometry and a compass to find the mid point of the desired circle. Clamped the panel to 2 x 4 that were clamped to the press table and, with frequent shots of WD-40 for cooling, slowly cut the circles. Despite being rated for wood and other soft material, the tool did a great job.

The 3/4" switch holes were pilot drilled then finished with a step bit, again in the press. Lots of clamping and making sure 2 x 4 pieces were providing support before drilling. Started by laying out the center points then used a socket as template to draw the circle. It wasn't too important to have the socket centered perfectly as the drawn circle was just a reference to insure I didn't take an extra step on the drill. After all of the holes were drilled, the step bit was used to deburr the reverse side.

Rectangular holes were made using Dremel knock-offs - Black & Decker ("pop" then smoke") and a $17 Wen with a collet that fits Dremel tools. Tossed the B&D in the trash and ordered two more Wens to have backups. Used a clamped strip of aluminum as guide to cut just inside the lay out lines. A hand held hacksaw blade was used near the corners. Then a couple of metal files to smooth and size for final fit.

The panel goes to the powdercoating shop tomorrow.

[efwd]

Looks really nice Carl. I looked all over my garage for that tool and could not find it. The first thing I noticed was the very uniform edges on your holes. I knew right away you must have used the drill press. I free handed mine and you can tell the difference. Luckily for me the switch bevel conceals it.
Eddie