Chapter 8: Mortar-related Assembly

With the main deck completed, the structure will be assembled around the mortars, this ship's greatest feature.

(1) Mortar pit assembly 

The first is a mortar pit, with the same one attached to the front and rear in two locations, but each of the front and rear can be accented by putting the mortar in use and stowed, respectively. Structurally, only part of the structure is removable, but here I decided to make everything from the pit deck removable so that the internal structure can be viewed at any time. A commercially available circular cutting compass is used to cut the general shape (this will ensure a circular shape), but another method is to mark the circular shape with the compass and drill a hole inside it with a thin drill. The finish is shaped by hollowing out the inner circumference with a 30-degree blade cutter [Fig. 8-01].

* Glue these two decks together. Secondary planks are thin and may warp due to moisture in the glue.

Mortar pit deck

 * Prepare the following parts.

* Primary plank PP is a caulking process in which the prepared parts are glued next to each other with the burned surface slightly sanded (parallel to the burned surface, not perpendicular) and the sides of the parts are alternately flipped front to back to represent caulking. As a result, the finished design dimensions of the PP alone are 46 x 58 mm, but the overall dimensions are slightly larger than this, so the overall width (= 52 mm) is adjusted with the Boundary Timber BT to be assembled later.

* The secondary plank SP should be assembled in the same manner as the primary plank. A round cutout for the turntable that rotates the mortar is needed here. Press down firmly on the entire surface of the deck to dry. The sidewall BT is then glued to the sides. The overall finished dimensions will be 52mm x 58mm.

* Drill a 2 mm hole in the center and embed the metal rod of the spindle. Make two sets of the same one [Fig. 8-02].

Mortar pit

* The mortar pit is an octagonal frame with the four corners of the square cut at 45 degrees. The frame consists of two tiers, and each part is assembled to make up the structure.

Outboard bulkhead             OB                   16                    3mm

Angled bulkhead     AB                   16                    3mm

These are assembled based on MortarPit drawing. As a guide to machining parts, 

Long boundary (OB)     32mm long                   End face angle 22.5°

Short boundary (AB)     14.1mm long           End face angle 22.5°

Now, when the parts are assembled, the external dimension is 52 mm and the joining angle is 45°. The 45° can be easily assembled by placing a 45° ruler on one reference plane as shown in [Fig. 8-03].

* If you wish to add housing covers to both sides of the pit housing (to be made by yourself, see below), you must make a rabbet to the corresponding parts according to the MortarPit drawing before assembly. Once assembled, shape the pit perimeter to fit snugly between the deck beams [Fig. 8-04].

Hereafter, rabbeting (groove shape) will appear in several times. This is an easy process if you already have power tools, but on the assumption that you do not yet have such an environment, it is conceived so that it can be done by hand at the time of the component itself, all in an L-shaped processing by plate distribution. In the extreme, processing can be done with a cutter alone, but it can be done more beautifully by using an engraving knife, a chisel, or a sanding block. The key to a good appearance is to keep clear edges to entire surface.

* The mortar pits are to be fixed to the pit deck, but as mentioned previously, these all can be removable, so they will not be glued, only aligned, and fitted together.

* The pit deck assembled earlier will move freely in the front-back direction as it is, so a small stopper is attached to the back side to make it fit into the mortar pit beam.

Note: In Version 2.0, a laminated structure of parts equivalent to rabbeting was added.

Mortar pit housing

* The mortar pit housing is a combination of removable plates used to cover the mortar by canopy etc. when it is stowed away, but in the model, these plates are integrated and made removable at once. Its assembly is illustrated in the MortarPit drawing along with the mortar pit.

* The arrangement of each is shown in [Fig. 8-05].

* Rabbeting is performed on the upper RHU1 of the housing based on the MortarPit drawing. The side rabbets are not necessary if the housing cover is not attached, but the top rabbet is for canopy attachment and should be processed.

* Glue the housing lower RHL in two layers and then glue the housing upper 1 (RHU1) on top of it.

* The housing upper 2 (RHU2) will also be rabbeted for the canopy. The design length is 23 mm but adjust the length so that there is no rattling in the width direction when assembled and fitted into the mortar pit. If there is rattling, the inserted housing cover may come off.

* Glue RHU2 in line with the protrusion at the top of RHU1. Allow it to dry while maintaining the verticality of the sidewalls due to the small adhesive area [Fig. 8-06].

　 Note: In Version 2.0, a laminated structure of parts equivalent to rabbeting was added.

Canopy and housing cover

When the mortar is not in use, its upper part is covered by a cover called a canopy.

Only the canopy transom (CT) is included as a component, so the planking is done with about 0.8 mm planks. To make it, cut a board slightly longer than the total length of the two combined (52 mm), place CTs on both ends of the board, and glue them together. After completion, the center is cut at right angles with a thin-bladed saw and shape the edges [Fig. 8-07].

There is a space between the mortar pit and the pit housing for stowing small items, which is covered. The cover is divided into four sections [Fig. 8-08]. Work with the scraps of wood you have on hand to fit each space. The cover also comes with eye bolts for lifting, which can be machined with wire on hand. Black dye solution is not available these days, so black paint is applied with something called "AZ Black Dye Spray".

(2) Mortar bed assembly

The mortar bed is a platform on which the mortar is mounted and operated such as rotation. The mortars come in two sizes, and the smaller size (10") is mounted in the rear of the actual ship, but I have replaced it with the larger size (13") for better appearance and changed the mortar bed to a corresponding one. Do arrange it as you like. The structure consists of four stages, including the turntable section, which are assembled one after the other according to the MortarBed13 and MortarBed10 drawings. The only difference is the component configuration of the second stage, so I will describe the steps using a bed for 13" here. 

* See [Fig. 8-09] for the arrangement of each stage.

* In the first stage, the turntable base TTB is glued to the center of the turntable TT. After drying, drill 2 mm hole to match the hole in the turntable [Fig. 8-10].

* For the second through fourth stages, glue each designated component then glue each stage on top of the other.

* After assembling the entire bed, the rear part is shaped into an arc following the shape of the baulk Bk. The overall finished outline is 19x35x11mm high for 13" and 18x29.5x11mm high for 10" [Fig. 8-11].

* The mortar mounted on the bed is the one drawn using the functions of the software used in this method and fabricated by 3D printing [Fig. 8-12].

* The area around the mortar is now complete. Its status is shown in [Fig. 8-13] to [Fig. 8-15].