After you are finished with the spokeshave it is a good idea to sand the rails with a flexible fairing board to even out the highs and lows. Fairing Boards are a necessity to get a truly fair surface, and the more surface area they cover, the finer the fairing will be. A good board will be somewhat flexible in order to conform to the shape of the rail but still have enough rigidity not to fall into low spots.
While there are several sources of commercially manufactured fairing boards, building your own board is really simple. I built this board out of 1/4″ hardboard and a couple of spare plane knobs that I had in my drawer. I originally planed on using epoxy to fill the recessed bolt holes and then cover the bottom with a strip of FormicaTM but never bothered as it works fine as is.
Commercial boards have an elongated hole on both ends allowing the strip to “walk” as necessary, depending on the flex of the board while in use. I achieve the same result by elongating the hole in the sandpaper. I use strips of cloth backed paper as I it is the paper I use for the drum sander. Most homebuilders will not want to purchase a 100′ rolls of cloth paper so you will be better off making your own strip.
You can make your own strip with 1.5 sheets of standard sized sand paper and some craft paper. Cut the sand paper sheets in half lengthwise. Then use spray adhesive to coat the backside of the sand paper, and one side of the craft paper. Allow the adhesive to cure a few minutes, and then set the first sanding sheet on the craft paper. Butt the remaining 2 sandpaper strips forming your strip.
If you don’t foresee a use for a fairing board in the future you might consider just spray-gluing the paper directly to the bottom of the board. You will not have to change paper to do only one board as cedar sands really quickly.
The Fairing Board is used lengthwise to fair the rails.
About $60 less than a commercial fairing board!
I am using knobs with internal threads that I bought from Lee Valley for 50 cents each. I believe they were originally the front knobs from their bench planes. Any large cabinet knob will work.
This spacer was required for the treads to tighten but it also serves nicely as a support for the knob.
Not much to this just a strip of 1/4″ Hardboard with a threaded stud for the handles.
I usually fair the rails with 100-grit paper as my first sanding step. I follow this fairing by sanding the whole board with 100-girt and then 150-grit with an orbital sander. It is important to not sand the transition from top panel to the skin with the orbital, as you will quickly destroy the fair transition line.
Bottom is a 1/4″ 20 insert and a cut off bit of 1/4″ 20 all thread. This bolt was locked into he insert with epoxy.