I measured and modeled all the instruments in 2D - including the holes and the case cross-sections. I managed to arrange them such that they form a near-solid block (many of them touch cases to add stability). I also measured the backside of the panel because there is some curvature and wall thickness to account for, so I created a standoff buffer/border around the edge.

I taught myself to use AutoCAD as part of this exercise, so I did some simple checks to ensure that there was clearance along the length of each instrument. With some additional effort you can create a 3D model of the instrument panel and cavity as well as each instrument. I didn't find this necessary for the -27. A friend who did a panel for his Ventus used SolidWorks to make a full 3D model (Fusion 360 will allow you to do this without spending $4000 on software). It may help for specific situations though generally there isn't a significant constraint unless your instruments are super-deep.

Here's a link to the panel layout I did. You can see each instrument case is modeled in addition to the cutouts - as well as the panel backside offset. I used very tight tolerances for the instrument holes - so much so that I had to do a little bit of sanding on some holes to fit the the instrument. Makes for a very clean installation - much better than you get using a standard hole cutter and suits my perfectionist streak.

https://drive.google.com/open?id=1YH...VONRIDR67sUJlY

Andy

Sweet! I expected no less from you.

Sorta like I did 27 years ago. In my workshop, I occasionally find one of the cardboard circle templates I used to draw around before I used my saber saw (rough work; e.g., ASI) or coping saw (fine work; e.g., the adjustment tab on my altimeter) to make the cutouts. Like you, I had to do a little sanding, too.

Of course, the next level of sophistication is "future proofing" your panel by building in the ability to accommodate a range of possible/likely instrument changes/upgrades. When I added the proprietary CAI sleeve/RAM mount for the Compaq 1550 handheld 20+ years ago, I'd cleverly left room for another 57mm instrument. So I plopped the CAI mount on the existing hole and moved the clock to the new hole I cut.

Technology marches on.

Chip Bearden