Quickest, easiest and strongest is to do the last method you mentioned - overlap the skins onto the rail, top and bottom.
Don’t try and recess the edge of the skin, too difficult and not necessary.
Just partially shape the rail down on the deck side before the skins go on, so it blends into the deck roll (pretty obvious), but leave the rest square.
Shape the rails properly when the skins are on.
It makes quite a clean line around the board, I think it looks good.
You have to use a thick enough rail though, so you don’t thin the skins out at the join - 14 - 16mm is pretty safe for a shortboard, i’ve done some with 12mm and even 10mm, but they were really thin railed, and it was close!
Having said that, I’ve done the last couple of boards by putting the rails on last, just for a change!
Although there is and inner piece to support the skins, I wouldn’t do it without some something to strengthen it. A fillet can work, like I mentioned on the WMD thread.
I've found that the following method for putting on balsa rails works good:
1 saw out the outline of the blank
2 add the bottom skin/clean up edges
3 add the rails using the offcuts left over from cutting the outline, with clamps/elastic/spanbanden/etc. I've found that 10mm(2x 5mm balsa slaps) works good for shortboards 15mm for longboards. You don't have to cut real close tolerance but outlining the rails before adding them helps bending them on the blank. I've found that 5mm balsa bends good, thicker ones will give you trouble. Using 2 or 3 5mm slaps instead of 6 or 8 2mm slaps will cut alot of time and save a lot of glue. Besides that, it shapes loads easier.
4 shape the board and rails. Try to use the electric planer as much as possible. For the bottom side you have to be carefull with cutting of the overlap without touching the bottom skin. I use the electric planner mostly till it leafs me with say 1 or 2mm overlap. For the nose and tail I use a grinder. For finishing I use a small blue handplanner with razorblades sold bij Gamma. Great tool, I could shape a whole board with that thing. Then sandingblocks
5 add top skin, sand away edges
Downside of this method is that blending the topskin flush with the rail will make the balsa near the rail as thin as paper making it very prone to denting.
Í'm working on a new method which includes adding the rails last and not sanding the skin at all. Photo will follow soon!
I’ve done all three methods you describe. I think #2 is the easiest and best looking. I’ve never had any strength issues. Well, except the snapped “Snapper.” And that one was the one I built with the last method (attaching rails first, then skins, then shaping rails). When I posted about the breakage everyone was trying to analyze the “why?” I think why it broke is that is was a big wave and I was in the wrong spot. End of story.
I’m presently building 2 “t-flex” with, for the first time, no wood on the rails. We’ll see how that goes.
Mooks way is time consuming but well documented and gives you a clean look and according to some gives you a bit more flex. If you use this way do as KK says and take down your rails to compensate for the added top skin and you wont have the issues associated with having a skin thinned out. I have found that using 1/16" skins is more than adequate for the bottom and the top if you use a tail pad.
I've done 2 and 3 and like 2 best - looks better, gives a clean join line and seems a little less fussing around. I do find it difficult to not get a square rail on the top though - just practice.
JUst finished my second boo skin balsa railed board with this method. Feels a bit stiff though.
tell us about your build schedule if you don’t mind. I have gone to bamboo skins after 4 years of balsa skins, I am still in the discovery phase with my first one (fins etc). It is definitely not too stiff.
I don't like the idea of sanding the top skin blindly while feathering to the rail... too much risk of thin skin or even sand throughs. Adding rail material only to outside the edge of the skins possibly creates a shear line due to lack of support under the skin edge.
Here is a diagram I did showing the method I prefer. Some guys claim it may be too stiff. I'm OK with that. It minimizes sand throughs and the internal perimeter stringer supports the edge of the skin.
I glue the internal perimeter stringer first, vacuum the skins on, then build the rest of the rail. It still involves planning and some careful rail shaping.
Here are a few pic’s of some recent boards. All bamboo. All 2 pound EPS.
The one with the cut away tail has obviously balsa rails. The other has alternating layers of 4 pound EPS and bamboo. Never again. But glad I tried it.
bag the bottom ( I usually do it while making the blank from flat sheets)
cut the outline
put on the first layer of perimeter rail
shape out the deck profile to a flat rail
bag the deck over lapping the perimeter rail
build out the rest of the rail with single strips of HD foam or multiple strips of wood
finish turning the rest of the rails
deck over laps perimeter bottom doesn’t
the rail has something solid to adhere to as you tape or bag it on
Greg Tate’s way is the fastest if you shape the boards after applying the first layer of perimeter to the outlined blank then bag on both skins at the same time sanding flush to the perimeter and then apply the solid wood rails bands and finishing off shaping the wood rails.
First one with about 20 sessions on it and holding up well...
6' x 12.75" x 19.5" x 15" x 2" thick, 2.4kg/5.28# without fins.
Deck to bottom - 4oz patch, 4oz, boo veneer, 4oz, 1.1# eps, 2oz boo veneer, 4oz, and 15mm balsa rails. Skins overlap the rails.
Feels like moderate flex - need to try the natural resonance test to rate it.
Just finishing not ridden yet (swell due Wednesday so will report back)...
6'4"x 12" x 19" x 14" x 2.25" thick, same weight as above - higher density core and less glass on inside.
Deck to bottom - 4oz patch, 4oz, boo veneer, 2oz, 1.5# eps, boo veneer, 4oz, & 15 mm balsa rails. Skins overlap the rails.
Deck feels bullet proof but on the upside down test feels a bit stiffer than the other board. In hindsight I should have made it thinner and without balsa rails.
The method that Oneula describes is probably the best. I only do it the old fashioned way because I am not such a good shaper and I need to see the full rail while I crown the deck and turn the rails. If I just do the deck without the rails and then add the rails later, I’m afraid I’ll screw it up. I should also mention that I swore off balsa rails because they are such a pain, but the buyer (a good friend) really wanted that look and I relented.
But you know, overall, attaching rail material is hard work and takes time. If you can get some HD PU in sheets, I think you can do that much more easily, but even then I’m not sure it is worth the trouble. As many have said here, just another layer of 4 oz over the rails really beefs them up. I suggested earlier, and didn’t see that anyone picked up on the idea of just saturating the EPS rail with a little epoxy to add some ding resistance.
I saw Sam Barker in the water on Saturday riding the first WMD that came out of the Resin Research skunk works. Still looks like a million dollars. Poplar skins. Zero pressure dents. I spotted it a mile away.
I like this whole veneer method thing. I believe we have advanced the science. And we build stuff that is strong and light and that the pro’s can’t/won’t build.
So I look at this to see what's going on in wouter's basement, and there's our carbon/spectra board from 2+ years ago. Thanks for remembering us! That board had a good thread of it's own.
I just cut the rails off an older board and glued on bands of balsa. The original rails were round (like 50/50) and the bottom was beveled so the board didn’t ride very well. I cut off a good chunk of the rails and plan to get a nice edge along the bottom and a better rail shape this time. I figure the glassing will help to hold the rails on and keep the rocker from changing, but I’ll have to see.
We usually have the top skin over lapping the first couple of strips of wood. Then we add the final bands and finish shaping the rails. My brother (oneula) uses blue dow foam for the final rail bands, I still like balsa or cork, or balsa and cork.
When we first started, we would wrap the top and bottom skins around the rails of a shaped blank. That made a strong board, even without a stringer, but it’s not easy to get a really hard edge.
I think something like Danny Hess’ method of starting with the rails, then adding the foam core, then the skins might be the way to go. Problem is you need jigs to make the rails.
