Chapter 3: Jig Assembly

The hull assembly jig is one of the key features of this method. This lightweight jig is made of 5.5 mm thick MDF board, but its accuracy and usability exceed expectations thanks to laser cutting, making it an effective tool especially for modelers with limited production experience.

Jig board                                             two sheets (top and bottom) [Fig. 3-01] [Fig. 3-02]

Aluminum channel                              16x25x1.5t Approx. 1m (divide to two)

Flat head screws, nuts, washers         M4x10mm 6 set 

The jigs are not for ornamental purposes, so burn marks will not to be removed, and no offset will be provided as a grinding allowance. The cut surfaces have just fit alignment with each other, they are glued together while maintaining the right angles to each other using a square or similar tool.

(1) Pre-processing

* Remove the outer frame from the upper and lower plates and remove any pieces if they are remaining in the screw and fit holes.

* Referring to the jig drawing, check the name of each auxiliary part on the upper board then carefully separating them.

* Legs by aluminum channels will be added to the lower board for reinforcement and maneuverability. To fix it in place, flat head screws are used to flatten the surface, and tapered counterbored holes are provided on the long side of the bottom plate, three on each side for a total of six [Fig. 3-03]. This surface is to keep the homemade square and the height gauge (described below) out of the way as they move around.

* Cut the aluminum channel to half length, drill holes to match the screw holes in the bottom plate, and fix both with M4 screws [Fig. 3-04]. If the above counterboring process is not possible, channels may be secured with a two-component epoxy adhesive. We also found that, in practice, ordinary pan head screws are hardly disturbing.

(2) Sub-assembly of supports

* Assemble the above four types of support. The assembly procedure is the same and is as follows

* Glue the vertical and horizontal plates together while ensuring a right angle by using a tool square [Fig. 3-05].

* All parts with centerlines drawn are assembled so that they are on the outside for positioning when assembling to the jig board.

* After the gluing is dry, glue each reinforcement plate to the L-shaped section, maintaining that relationship.

* The front and rear supports are similar but have different heights and notch shapes, so do not make a mistake.

(3) Assembly of jig

* For the front stanchion (stem support), place the tool square at the front-most auxiliary line intersection drawn on the lower jig plate and glue the base part while aligning the centerline at the back of the notch [Fig. 3-06].

* Do the same for the rear stanchion (sternpost support), aligning the center of the back of the notch with the intersection of the auxiliary lines at the end of the bottom plate, and then glue the base part. Since the stern support to be installed later when assembling the stern section will interfere with the sternpost support, the sternpost support should be lightly glued (only the points) to the lower plate so that it can be easily removed without interfering with the model construction. The dimensions after assembly are as shown in [Fig. 3-07], with the backs of the notches facing each other.

* Glue the six stanchions to the bottom plate. Glue them while ensuring absolute verticality by making full use of tool squares [Fig. 3-08].

* The stem and sternpost support should also be checked to ensure that their centerlines are aligned with the centerlines of the upper and lower jig plates when viewed from directly above [Fig. 3-09] [Fig. 3-10].

* Check the verticality of the key points of the jig with a square and make fine adjustments if necessary [Fig. 3-11].

* The stern support is installed when the counter timbers are assembled after the frame and other parts are assembled, so it should be stored at a certain place after the legs (spacers) are glued in place.

To no small degree, I was impressed, but the upper board mated perfectly with the posts without any adjustment, and I could hardly feel any rattling. I checked by placing a square on the reference line at key points, and the top and bottom are in line with each other with sufficient accuracy. Some parts of the photo look a little off, but this is due to the camera angle; in fact, they are correctly matched.

For this reason, I decided to make the upper plate removable for ease of subsequent work and use it without gluing to the stanchions. If rattling or misalignment is a concern, it is sufficient to use masking tape or other weak adhesive tape to hold the top of the stanchions [Fig. 3-12]. In addition, the square frames (A29-30 and F23-24) at both ends can be assembled to the keel here first for stronger integration.

The hull assembly jig thus devised subsequently proved to be more effective than expected and made a significant contribution to the assembly of oddly oriented structures, especially like cant frames at the front and rear of the hull.