Silver Pencils

[Tin Falcon]

A decade or so ago when I was learning Aircraft Sheet metal trade at Pensacola Florida I was taught that the silver pencil was THE only acceptable marking device for Aircraft sheet Metal work. Anything else leaves a residue that can cause metal fatigue at the mark. A scribe leaves no residue but a hair thin line where stress can concentrate .A scribe line is a cut line that is it. . Sharpies were used in the classroom.
We had one or two of these precious and rare tools when I reached my home station . Not a tool that I have seen available at the local Home Depot, Lowe's , Sears etc. of course anything can be found on line.
But these are readily available from Tractor supply in the welding section under the Hobart Label Not cheap but not ridiculous either. for $10 US you get a 2 mm lead holder and IIRC 5 leads. IMHO this is a handy addition to ones tool box for metal work.

Tin

 

[modelman1838]

One of the problems with aircraft sheet metal is that the material is known as Alclad and is produced by sandwiching the stress bearing material between two sheets of pure Aluminium which is heated is a soaking pit and then rolled to the gauge size leaving a .005 coating of pure Aluminium on each side to protect from corrosion and it is this coating that must not be damaged as well as creating a stress raiser by a scratch.

Hugh

 

[cheepo45]

I have one of these pencils at work. I use it often-it makes nice visible marks on steel. I'm glad to see they are available at Tractor Supply-now I can get one for home!