I saw a prog the other day that showed a shaper using a tool that had a flexible plastic rod, attached to a flat rod that had bolts coming down from it. Has anyone seen such a thing - can it be bought anywhere?
In one of the last Surfer’s Journal there is picture of Stan Pleskunas in his shop. He has one laying on his workbench. I’ve also seen one in Joe Blair’s shop. Where to buy one?..I don’t know. But you could make one easy enough. Doug
I agree, anybody with access to a saw and a drill or mortising machine could make a very nice one quite easily. The bolts are a nice touch, but either dowels ( drill for a tight fit ) or square pins would do the job well enough instead and probably be easier/faster to use. What’s more, if you really wanted to get cute, you could mark the pins/dowels so that you’d get a reading for amount of rocker directly off the measuring device instead of having to set it on a table and laboriously measure here and there. Ten minutes with a ruler and a pencil could save hours later. doc…
Seems to me you might have some problems if there wasn’t some sort of ball joint and the interface of the pins and the flexable strip that lays across the board. Maybe not a problem on longboards, but shortys with a lot of nose rocker could create a problem… you need those dowels/pins to remain parallel to get a good measurement. You would also have to get used to measuring rocker from the center, unless you always make boards in lengths of the same increment that you set the dowels at.
Well, yeah, it immediately seems like swivel joints and such would be desirable, but…, if they get a little out of perpendicular to the base stick, that’d be ok, as the friction would hold it all in place, no swivel joint necessary. A couple of brads and a bit of resin or glue would probably work just fine. I’d use hardwood for the base stick and something soft and straight grained like pine for the rest. Measurement accuracy…well, close enough, you know? While the angle might throw things off a little, I doubt it would be enough to make a real difference: you’re just looking for a ‘repeatable standard’; precision, not necessarily accuracy. I’d be surprised if the measurements vs ‘true’ would vary by mire than 3/16 or so. doc…
It depends on what you are trying to achieve, if you just want to measure a basic rocker ie: nose and tail height, then get a straight edge and place a ruler on one end perpendicular to the straight edge, now place the s/edge on the board and but the ruler up to the nose, l always use the same start height (5") as it is the only true way to see the differences between rockers, if you just balance the s/edge and measure you will never get a true reading because it can change pending on how the board is balanced on the racks, l then tape the ruler in place at the desired height and from there l can take as many measurements as l want. Now if you want to copy a rocker you have to make a female curve so that the rocker fits into it (sexy hey)to do this get hold of some 1/8 ply and use the method l described above to draw a close rocker line of the curve that you want to copy, on you peice of ply use some 2 by 1 pine ond place about an inch above the apex of your rocker, then place the ply on the curve, get a sharp pencil and tape to it a flat block of timber 1/2" thick and atleast an inch square near the leaded end, then run it along the bottom curve and bamo there’s your copy, once you cut it out you place it back on the curve and clean it up so that it is a perfect fit, as you work on your shape use your female (lets call her “Gidget” the gadget)to keep it true. l have seen what you described and Lenny from the shapers tools.com sells them but l tried it and beleive that it is not that accurate and if you are going to the effort of measuring or copying a curve you might as well do it right. KR
K.R., that sounds good but your looseing me.It would be great if you could post a drawing.Thanks.
You can make the same tool in the website by taking a peice of 1 x 3 x 8ft pine white wood and ripping 5/8 deep x 3/4wide inch dado every 6 inches. Then take the 1 x 3 x 8ft with dados in it, and rip it in half length wise and glue the two peices (dados facing each other) together. Now you have a 1 x 1 1/2 x 8ft board with perfect parallel morse that will accept 3/4 x 3/4 sticks. Now take some left over 1 by whatever wood left laying around and rip it to 3/4 x 3/4 x 8 inch lengths. Now just put those sticks in the morses. If you cut then right and tight you won’t need screws or pins. If you got the tools it should take about 20 mins. once your set up to finish. Total cost about $5.00 -Jay
i like resinhead’s take on the rocker jig. however i was thinking of two thin strips (no dados) with a bolt and wingnut every two feet. just slide your dowels or sticks up and down to adjust rocker, and they don’t really have to be perpendicular. you can tighten the screws so that you can take a router along your bottom edge and cut your rocker into a piece of wood to preserve it. i watched some sailboard guys do this one time. this is especially handy for the hot wire foam cutters as you can replicate your rocker all day long, although you only need to rocker jigs to cut your foam.
A few amazingly crude sketches- First, an old boatbuilder’s trick: spiling. Good for getting smooth curves when all you have is a pencil compass and a piece of template material. For rocker reproduction, you’d place it right under the centerline ( stringer) . Swing various arcs, all the same radius, at several points, making curves on the template material. Ok, now, the thing about a circle, or a part of a circle is this: it’s a bunch of points that are all the same distance from the center of that circle or part of a circle. Placing your pencil compass ( still set at the same radius ) at some point on the circle segment, swing an arc. Put it somewhere else on that same segment, swing another arc and where the arcs cross is the point that was the center of your first arc. Keep going, then connect the centers with a batten as described in another thread, draw a line and then you have it. It’s kinda involved, but good if you don’t have the tools to do something else. Then we have Gidget the Gadget. Dadoing slots, ripping, flipping and gluing works very well if you don’t have a mortising machine. Swine that I am, I do have a mortising machine, left over from a foray into furniture making. You could also fake it by using a drill press, dowels and a drill that is the same size as the dowels for a tight fit. As resinhead says, if they tweak a little it just makes it nice and tight. Then there’s the easy way- block the blank up and use a block of wood. A variation on the templater jig (link below) would also do the job very nicely. Hope that’s of use doc… http://jfmill.home.comcast.net/temp/templater.jpg 
“Silva” (one portagee, eh?!)…just kidding. What you saw was a stan pleskunas “rocker stick”. Fiberglass Hawaii USED to have them, but they do not carry them any longer (you can give 'em a try, though). Be prepared to shell, however,… they were 450 bucks when offered as new. T.
The track that the feet fall into is slotted (extruded plastic)so the length of the track gets longer the more rocker there is. This is what keeps it from bunching up. I use scraps of balsa from top or bottom rocker to lay along the bottom or deck of the board and then trace the curve. It takes several trimmings until it is settled nicely into the curve. Once you have one of these, it is only a matter of expanding this curve on another piece to create a longer or shorter piece to make a new set of curves
A rocker stick is a good tool If you need one. The main advantage of a rocker stick is if it is robust enough and is accurate you can use it with a template guide and a router to create plywood patterns/templates for use when shaping. This is the focus of my design of this tool. It can be adjusted and used as a guide when shaping but it is cumbersome and attempting to re-set it with marks on the rods is nearly impossible to do accuratly or repeatably. That is why it needs to be used to make wood patterns that are light and easy to use while shapeing. I use a fibeglass batten and alum rods that go through a plastic dowel the dowel is drilled and tapped on the axis for a set screw and also at 90 degrees to the axis for the rod to pass through. The back bone of the stick needs to be strong enough to resist the tension of the batten and drilled on exactly the same centers as the clevises that hold the batten end of the rods. The rods must piviot at the batten and they must also pivot where they go through the back bone. If the piovting elements work smoothly the tension in the batten can be used to fair the lines you are looking for by loosening and and tighting the set screws individually once you get the stick adjusted. The batten needs to be strong enough so it doesn’t sag between the rods with pressure from the router while cutting patterns. This means that the batten needs to be fairly thick and then tapered at the nose end. If done correctly the increased tension in the batten where it goes over the nose rocker takes care of the tendancy to sag where the batten is thinned out. I use mine constantly for a lot of things other than surfboard stuff. I find it is most useful for making fair concave lines. All of our tools work great on convex or straight lines but the concave stuff is a hassel. I quit making rocker sticks because it isn’t cost effective to make them one at a time. The cost of the required machineing and materials to do it the way I think is best, requires me to build about 25 of them at a time. Even then to make it worth my while the price is beyond what most guys want to spend. With that in mind there are a lot of boards that have been shaped without them and there are other methods to achive the desired result more inexpesivally. I think the explainations here are all great and if you are looking for accuracy a stick can certainly help. However if you consider how much blanks move after they have been shaped and glassed the results are only approaching repeatability. I wouldn’t want to hazard to guess the tolerance of this repeatablity with a number, but I bet you would be surprised by how big that number is. The way to test it would be to scan a shaped blank then glass it, consider the required offsets for hot coats, glass etc. then scan it again and measure the differences. I would like to see a study that did this for ten identical CNC boards. That might take all the magic out of it though. The real question is what is an acceptable tolerance in a rocker to get the same results when in the water?
This would be very easy to modify to copy rockers off of a proven board.