Why do so many blanks have bent stringers?

Anyone care to chime in on why it’s so hard for blank manufacturers get this right on a consistent basis??..Seems like a side of quality that gets little attention.

I shake my fist angrily at god whenever I think of how not everything gets blessed with perfection.

Cheap wood?

I don’t think it has to do (much) with wood quality. Foam is flexible and so is wood. When the stringer is glued in, a bit too much pressure on the clamps here or there and everything will bend slightly. The thicker the stringer, the straighter the line (usually). If blanks were rectangular shapes, it would be easier to apply even pressure everywhere. But they are not…

(This is assuming that the cut line is straight, to begin with… Of course.)

1.Drunk or stoned employees manning the saw or they just don’t give a shit.

2.Cheap third world labor that can’t tell the difference.

If you push the trolley that is holding the blank through the saw too fast it makes the blade twist. If you push it through at a sensible rate you have a straight cut as there is no undue force on the blade. The main problem is piece rate, the more blanks you can force through that saw as quickly as possible the more money you can earn. The easiest solution is no pay for crooked cuts.

Q: Why do so many blanks have bent stringers?

A: its because they suck

suck = they don’t care, don’t have the right tools, don’t know, or have the right tools but one of the proceeding issues plagues them.

the real question is WHICH blank companies “suck” or not. and the answer to that.

Pushing the cutting trolly too fast is part of the answer, uneven clamping pressure is another part, humidity is also a problem, low humidity causes a stringer to twist. You can have a perfect cut and an even clamping pressure but as soon as you release the blank from the clamps it twists.

The timber used is a big problem, plywoods are the worst for twisting, 1/8th is best, 3/16th is bad. The grains are fighting each other in plywoods (surfboard style ply) because we need long grains for ease of cutting and finishing. Just about all plywoods are peeled off the log and have a natural curve in them from the log. Humidity has a BIG influence on stringer twist, the drier it is the more twist you get in surf plywood.

The other problem is forcing / bending the blank from its natural rocker to get the rocker curve ordered by the client, higher clamping pressure is required, the blank and the stringer are fighting each other.

Have you ever noticed that as you thin out your blank at the nose a twist develops?


i dunno

but it kinda negates the latest 5 axis u beaut techno machine

doesnt it

actually thinking about it

i guess demand for the straight ones would be so strong from shaping machine guys

that there large volume buying power would mean they would get the “A grades”

and the homeboys will have a choice of the rest

or is that a bit cynical?

if i was into building polys

my money would be going to the company that supplies straight blanks to the small custom guys

all the time!

and have a ongoing commitment to that kind of customer service

If you live in the country you get what your given, and that has not changed in 30 years.


Why not glue your own up? It is another part of the art of surfboard making. I have been doing so since I started. You have no excuse for bent stringers, and really it is quite easy.


The real bitch about this is CNC’d boards will measure wider on one side when mesured from the stringer.

If you use full size 1/2 plan templates and line them up on the stringer at the nose and tail, you can plot your n12, and WP and t12 accurately and ignore the middle part of the stringer.

The CNC machines ignore the stringer and plot their own centre line, which on a bent stringered blank is not the same, and there is the width difference measured from the stringer.

I think the only reason we have stringers is for a centre line (bad) and mainly to hold the custom rocker we put in.


All that is very true but, try to explain that to the store owner with the customer complaining that his custom board looks wider on one side and wants a refund.

Blank companies just have to get their act together.

hey atomized iv been shaping for 47 years nothings changed’’

That is about as assinine answer as I have seen,

“stoned or drunk”, the foam mfgs. are not back room businesses.

Employees are running expensive and dangerous machines, anyone coming to work toasted, would be sent packing.

Now to the real cause, like in a prior post, the foam is flexible and because of this is prone to being moved about easily.

Walker has some clamping stations where one side of the jig is stationary and the clamp heads move to it,

The fixed stops are set to particular blanks and if it is misaligned by placing it forward or rear, it doesn’t make proper contact, the result is a tweaked blank.

Clark had air actuated clamps that were self centering, but as Dick Morales showed me on a tour through the factory, any glue on the rails that hold the clamp heads and that clamp stops before center and the opposite clamp continues to travel towards it, the result, a tweaked stinger.

It is more than slapping wood between 2 pieces of foam, as long as there is the human factor and machinery, there is the posibility for error. remember, what can go wrong, will go wrong

the vast majority of misaligned or bent stringers are mainly caused from the initial splitting of the blank. the newer blank mfgrs are doing a much better job of this due to the plugs being from cnc’d cores. one of the main reasons of crooked and twisted stringers are from the “squareness” of the symmetry of left to right halves of the actual plug before spitting. the older plugs were not as true and square. if indexing from a non trued and squared surface will result in a twisted/crooked stringer.

being a shaper and running my own milling, I can’t stress how important the bottoms of the blanks are. it is the foundation. if you have an 1/8" missing skin from one half on the blank in either direction guarantee that blank will have a crooked/twisted stringer.

when choosing blank mfgrs tell tale signs I look for are the quality of the skin of the bottoms and how meticulous the glue ups are. if you have an 1/16" step off from right to left sides this will result to 1/8"-1/4" deviations.

hello, blank mfgrs are you listening? bottoms with good skins, no right/left step offs, no glue boogers. please.

That is about as assinine answer as I have seen,

“stoned or drunk”, the foam mfgs. are not back room businesses.

Employees are running expensive and dangerous machines, anyone coming to work toasted, would be sent packing.

Now if only the glass shops on the Hill would have the same employee policy.