Beginning shaper... brace yourselves

The stringer is making it difficlut for me to create a deep single concave. What is the best method/ tool to grind the stringer down, while not disrupting a consistent curve throughout the concave? I have tried using my .5in diameter curved surform, disk sander, block plane, and trim plane… The stringer always seems to either form a ridge/ double concave, or I grind too far and create a squared channel that can’t blend into the original curve of the concave.

…the shaping is done with an electric planer, no other tool (driven by hands) have that accuracy; so you cut the concave with that too; the channels (if you are good) are done with the planer too; all is done with the planer except some shortboards that have too much flip on the nose, or things like wings, etc; the other tools are to get rid of planr marks, or fine tune the tip of the nose or some corner, etc

If you do not have an electric planer (better a modified one) you can use an angular sander/polisher (the one that you should use to sand the board) to cut the concave and then clean it with the block plane and sanding block.

You can cut it with the hand block planer too; needs a sharp blade, then check (depending on the density and consistency of the foam) the depth of the blade and adjust it as you see the results; then use sanding block.
In all the methods you finish passing a trimmer plane very shallow and sharp on the stringer; every time after you use a tool on the stringer. In this way you ll not have that protrude and will have a the foam besides without any scratches.

because the tools shown, when properly sharpened, will trim a stringer below the surface of the foam, I often use them when shaping a concave, bringing the stringer down first, then shaping the concave in the foam, thus avoiding the problems you mention in the original post.

NICE manicure there Huck!


Paying attention to Reverb will get you where you want to go

“the shaping is done with an electric planer, no other tool (driven by hands) have that accuracy” Thanks for the wise words, makes alot of sense. I have a modified hitachi. I will practice getting more comfortable with it. Sounds like I need to build good habits early.

haha funny John.  I searched internet for some images of the tools in use, (mistakenly it appears) thinking the op would appreciate it, and thats what came up.

here’s a less feminine version…

It can be done either way.  The planer is quick and accurate.  Some Pros lay out the template of the concave using masking tape along the rail or outside perimeter of the concave.  As Huck mentioned;  a good sharp hand plane can also get your stringer to the proper depth, then the foam can be blended using a small Surform, sanding block and a foam pad.  Either way;  planer or by hand;  take the stringer down First and then blend to the stringer from the outside rail.  Lowel

Hi Pendulum-

The video clip Huck used above is from our site at

Here is the link to the actual video Click Here

Best of luck!


A small, convex handplane works wonders.