Marking ribs & spars

[zspivey]

Does anyone have a suggestion on a way to mark the spar, ribs and other parts prior to disassembly for dimpling and deburring. I am considering an engraving pencil. I have also considered filing marks on the appropriate location.

If I remember from my engineering mechanics courses of 40 years ago, the stress at the neutral axis of a beam is low. The engraving pencil mark on the neutral axis is my first choice. Any better suggestions?

[RV7ator]

Zack,

Use a marking pen on a surface that will be against, and hidden by, its assembly to another part. Or out in the open. Who cares once it's skinned? Something I do when some future process might eradicate pen marks (cleaning, priming) is to make a tiny pit with the end of a drill, and this is just instances where I really need to maintain orientation or matching. Note the drawing for reference later. One mark vs. no mark distinguishes left from right, up from down, etc., so only half the parts need be marked. Most parts are really very interchangeable in spite of clecoing and drilling, so your need is minimal.

Mechanical scribing is poor practice on aluminum.

John Siebold

[PJSeipel]

Mark the parts with a sharpie or other permanent marker while they're assembled or as you take them apart. If you're not going to prime, the sharpie should stay on just fine while you dimple and deburr. After you rivet, acetone takes it right off.

If you're going to alumiprep/alodine/prime:

Go to Home Depot and buy a sheet of thin aluminum (.025 works) and cut it into small (1/2") squares. Drill holes in the corner of the squares, mark the squares with an engraving pencil (L/R/assembly location), and then use pieces of safety wire to attach them to the part through a rivet hole.

Yeah, it's extra work, but you can be sure the part gets back in the right location and that your markings aren't coming off when you alumiprep/alodine/prime. I've re-used the little squares over and over.

PJ

[jcoloccia]

Originally Posted by zspivey

Does anyone have a suggestion on a way to mark the spar, ribs and other parts prior to disassembly for dimpling and deburring. I am considering an engraving pencil. I have also considered filing marks on the appropriate location.

If I remember from my engineering mechanics courses of 40 years ago, the stress at the neutral axis of a beam is low. The engraving pencil mark on the neutral axis is my first choice. Any better suggestions?

If you read through the manual, you'll see that Vans says it's perfectly OK to make light marks with an engraving pencil or punches. I tried the punches, but it's too easy to hit it a little too hard and make a dent in the part, so I use a pencil.

Just FYI: and engraving pencil is NOT the same as a scribe. The pencil leaves very smooth, round marks. A scribe leaves a scratch. Honestly, I'm not even sure that the pencil removes any alcad. If you look at the mark closely, you'll see it's not scratched off...it's mearly slightly dented in.

[Red Voodoo]

A trick I used to make sure I re-installed the wing ribs in the proper order (in case I got the primer a little heavy and hid my Sharpie marks) went like this: I took short lengths (2 or 3 inches) of soft aluminum wire and looped them through rivet holes to identify the rib. On the left wing, I used the upper flange and identified the inboard-most rib with a wire through the forward-most hole, loosely twisted. A loop through the next hole aft in the second rib going outboard, and so on, until the fifteenth or outboard-most rib had the wire in the fifteenth hole from the forward end. Same scheme for the right wing, but using the lower flange. I used a similar system for the leading edge ribs. Worked great, and I needed the help, since I primered a LOT of parts that session.

Ben R.
RV-9A #90217
Wings in cradle, stored in garage
Fuselage box beckons!

[zspivey]

Originally Posted by PJSeipel

If you're going to alumiprep/alodine/prime:

Go to Home Depot and buy a sheet of thin aluminum (.025 works) and cut it into small (1/2") squares. Drill holes in the corner of the squares, mark the squares with an engraving pencil (L/R/assembly location), and then use pieces of safety wire to attach them to the part through a rivet hole.

Yeah, it's extra work, but you can be sure the part gets back in the right location and that your markings aren't coming off when you alumiprep/alodine/prime. I've re-used the little squares over and over.

PJ

Thanks guys, I like this idea better than the engraving pencil

[lucdbedard]

Originally Posted by Red Voodoo

A trick I used to make sure I re-installed the wing ribs in the proper order (in case I got the primer a little heavy and hid my Sharpie marks) went like this: I took short lengths (2 or 3 inches) of soft aluminum wire and looped them through rivet holes to identify the rib.

Ben R.
RV-9A #90217
Wings in cradle, stored in garage
Fuselage box beckons!

I cant wait to build another RV and use this trick, it's so simple and it would have saved me some problems if I would have known about it last month. I had marked my ribs with the engraving pencil but when I drilled the spars for the electrical conduit it was all gone, ( yes the marks were exactly where I drilled ) and YES I did mix number 1 and number 3 when I riveted them to the spars.... no big deal just on hole to drill.