what do you mean by level? most of the thickness should be taken out of the bottom for strength reasons. use a planer on a shallow cut for doing rail bands. i always have had problems with a surform. it seeems to rip the foam instead of cutting it

Teddy i meant to say …how do you keep the bottom even on both sides of the stringer . Cal

a simple low angle block plane- a lumber store or a dixieline will carry what you are looking for.

I think lots of garage shapers just make equal planer passes on both sides of a blown blanks. I like block sanding on the bottoms of my wire-cut EPS blanks. I check for twist with the bottom up, laying two boards across the bottom. I eyeball them to make sure they are level with each other. This would be a good way to check for twist in a blown blank as well.

use a level across the bottom. if its a little off use your sanding block to take a little off and then see if its level i do this all the way down the board and make little pencil marks on the side i need to take a little off of. seems to work for me at least. try it.

Blanks usually are twisted to some degree.They may also be thicker on one side,a pair of calipers will show the truth.Shaping stands should be level (right on the bubble) crosswise.I your stands aren’t level the board will look twisted.Usually the first thing I do is cut the nose and tail off.Next I look for twist and remove it with light planer cuts.I guess you would call this “truing” the blank.From that point on the shaping begins and thats another page or two. R.B.

start by skinning the bottom. Look for obvious bumps, dips, twists. Take them out anyway you know how, flat stiff sanding block with heavy grit, light (shallow) planer passes, surform then sanding block, dragon screem on stiff block…etc. Then use calipers on boths halfs (each side of stringer) of the blank, measuring frequently.

I start completely opposite from Dave. I true up the deck on the raw blank. getting rif of twists and obvious flaws first. Then a very light skinning of the deck, this gives me a level playing field to start with, the bottom gets the most work done on it, so I leave truing the bottom for last. After I have put on the top and bottom bands and rolled them into the deck and bottom, I have band sawn out a variety of paneling templates that are off the curves of decks and bottoms where they become rails. I’ll make a soft/dark pencil line across the blank at midsection and with a small spring clamp, connect a pair that fit, match up these templates to the rail curve. Then it is a matter of checking left to right

Thanks for the advice dave mahalo 1 Aloha , Cal

Thanks for the advice also jim ! mahalo Aloha , Cal

Follow up. I started truing the bottom after one of my friends at Clark informed me that the glue up proses usually leaves a truer bottom…but I am not too sure of that now…so I may strart with the deck. But though the bottom does get a lot of planing to thin the blank I like to true up the blank as I described earlier. ANd then I take as full of a depth passes on the bottom, as I can make to get to the close to desired thickness. TRy both methods as see which one works for you. All in all, I am trying to say that I like to tru up the bottom because it is a good flat datum and the deck has more curves laterally as well as from nose to tail.