Small Craft Building - 2.Building A Jig

Jig is a bench(work bench) where mold(temporary frmes) and boat are placed. It is a ladder-like shape and must be boat-long length. Its height depends on your height, the height with which you coud work comfortably.



With its length direction(longitudinal way, maybe), you use 2*4 plank and must be smoothly flattend.(Dressed through buzzer). Also for stability, it is recommended that Jig legs should be fixed onto floor and strong enough to support weight of Jig, frames and the boat to be built.


One important thing in building & setting Jig is that Jig must be leveld. We still have a way to compensate the unleveled Jig but leveled Jig gives much less work to do.

  

1.Extending Jig

As I mentioned before, Jig must be as long as the lenght of the boat and our Jig was about 1meter short. So we had to extend it as below.

  



Then we planed the 2*4 plank where cross spall will be positioned and checked whether it is proper or not as below.


I think if we could, we'd better build a new jig rather than fixing used one. By fixing used jig we could learn too, but it causes many more work to do than building a new jig.


2.Measure & Marking

Measure center point and set the center line with a string along the Jig. Then with a long tape measure, mark each station and then, mark each station again measuring distance between stations to avoid measuring error.

And when you set the center line, you set it, so that it doesn't tocuh any part of Jig. So, sometimes, you need to chisel or carve out to avoid direct conatct.



3.Cross Spall

Now that we have leveld Jig with station marking, it's time to attach cross spall to which frames are fixed.
When you set a cross spall behind station line, all the cross spall should be behind each station line. Or all the way ahead of station lines.

Also there's another way to do it.
Once you set crorss spall behind station line(or ahead of sation line), you set it all the same way before the station after the widest beam and from the sation(after the widest beam), you can do the other way.
So in this case, if you set the cross spall behind station line from station 0 to 3, then from station 4 to 5, you could set cross spall before station line.


4.Frame Joint
Since we need to learn how to utilize resources we have with maximum efficiency, we need  to think before. We used particle board as a frame and it was not big enough to accommodate all the frames in one piece. So we had cutting plan that some of frames are in two pieces and needed to be jointed for efficient use of material.

We glued with PVA on each side edge of frame and add gusset on the frame with PVA glued.

5.Frame Setting
When frames ready, we started to set up frames. First we fixed frame to cross spall and make sure it's plumb with level. Since JIG itself is already leveled, we didn't need to check the level across.

As we're setting up frames with plumb ensured, we used diagonal braces to maintain its plumb rightness.

6.Transom rest.
Making transom rest on the jig was quite tricky.
I didn't do the whole setting for that,,If I were doing it,,,

First, from the CAD drawing, draw extended transom line to jig level and measure the distance from the last frame. Now all we need to do is make this imaginary 10 degree transom line real. To do this, get a wood stick one of which angle is 10 degree and level, we fixed transom rest.


7.More.
Stem and transom are parts of the boat but they also act as frames too. So when frames are done, the first thing we need to build the hull is to make stem and transom done and fixed.