Fettling or Tuning Planes to produce shavings less then 25 micron/1 thousandth inch thin.
Not only old Planes need to be Fettlted, new Planes are never ready to use when purchased - even the higher priced Planes can need some work, at least honing.

The process includes:

General cleaning of the Plane

Flattening the Sole

Filing the Mouth

Setting the Frog square to the Mouth

Tune the Back Iron including polishing the front edge

Sharpen the Iron: Polish the Face, hone at 30 degrees for Bench Planes, 25 for Blocks.

Rust prevention treatment

Notes:

1. The face of the iron is polished on a #6000 grit Japanese Waterstone. When refreshing the edge, it should not be necessary to use anything coarser than #6000, the finer the better.
2. The Frog is set parallel to the Mouth with an opening of about 0.010” (10 thou.) between Blade and front of Mouth. This should be OK for general purpose and most fine work but may need to be reduced for extra cranky grain – may need to be increased for heavier cuts. The shavings with the Plane are about 0.001” (1 thou.) or 25 micron.
3. The Plane parts are coated with rust preventative – G15 from Australian Inhibitor, which I prefer to other to other products such as Inox , Lanox, CRC Longlife or Lanotec, all spray cans with an oil base. A light oil such as 10W sewing machine oil is good but leaves an oily film. The G15 seems to leave a firmer film than other products with dust less likely to stick to the tool. Apparently Moth Balls or Naphthalene Flakes work – the fumes given off by these products create a film on Cast Iron and Steel which assists in rust prevention. I am not sure whether the steel has to be perfectly clean, i.e. free of any other preventative coating, but I would assume that if a protective coating wore thin or off on an area of the steel, then the Naphthalene would take over and provide protection.
4. Please do not use your Lever Cap to loosen/tighten the Cap Iron Screw – do they make Screw Drivers from Cast Iron?
5. Always keep the Knob and Tote screwed firmly down to the base. If loose, Studs can bend, Totes can crack and premature wear can occur under the Brass Nuts. Check the Frog Screws as well.

Finally the Plane is tested and some shavings (Hoop Pine) included.