Chapter 5: Frame-Related Preprocessing

This section describes sub-assemblies and preprocessing of frame-related components that make up the hull.

The main frame is made up of several individual parts called futtock, which are used to make the frame. In addition, the frames have different futtock configurations for odd and even frames so that the joined part of the futtock is not in the same position in adjacent frames [Fig. 5-01].

That is, the odd-numbered frame consists of six futtocks with the first, third, and fifth futtocks arranged symmetrically, while the even-numbered frame consists of five futtocks with the second and fourth f futtocks arranged on either side of the floor futtocks in the center.

The joined parts are tar caulked, so this model uses the laser burn mark remain to imitate it.

In such a case, the design is to invert the middle futtocks, specifically the second and third futtocks, to compensate for the non-perpendicularity of the joint. These are also shown with their names inverted in the layout drawings. Remember that odd-numbered frames (frames with a first futtock) also require the joint between the first futtocks to be inverted, so one of the two sets assembled on one side of the frame is inverted and joined [Fig. 5-02]. For this reason, two identical futtocks are prepared for each odd-numbered frame.

On the other hand, the outer and inner surfaces of the frames need to have burn marks removed. To achieve both conditions, the offset of the futtock is added while changing it for each futtock as shown in [Fig. 5-03] (red line). Please understand these points when assembling and shaping.

A frame component disassembled into a futtock becomes a collection of many similarly shaped parts, making its identification by shape alone impossible. To ensure that this can be assembled correctly without mistakes, each individual part is assigned a unique part ID by convention, as shown in [Fig. 5-04].

The first half of the part ID of the orthogonal frame is accordingly

Fore frame F00 to F24, twenty-five single frames (12 double frames + 1 single frame)

Aft Frame A01 to A30, thirty single frames (15 double frames)

The futtocks that make up each of these are prefixed with this ID, so they can be easily identified.

Also, the cant frame is followed by a square frame.

Fore cant frame F25 to F32, eight single cant frames

Aft cant frame A31 to A38, eight single cant frames

However, since the cant frames no longer correspond to the station line, the second half of the ID is simply numbered consecutively as C1 to C8.

(1) Assembly of square frames

* First, fifty-five single frames are assembled. Based on the frame number, detach the same-numbered futtocks that comprise it from the board. There are about three hundred futtocks in the square frame alone, and since the individual futtocks are a collection of similar shapes, once they are mixed up, it will be impossible to identify them again. However, it is not very efficient to detach each frame by one frame. As shown in [Fig. 5-05], it is a clever idea to put the parts used per frame in a small plastic bag, and then separate several pieces at a time. Remember to indicate a part of the frame number (e.g., F00) on the bag. 

Note: Each number is skipped by one. Also, the 5th futtock is divided into two boards.

* In fact, if you do it this way, the futtock on both sides is the same when you turn one side over. Correct placement is possible by adhering to the rules of facing or reversing. You will quickly learn how to do this, but until you get used to it, it is a clever idea to turn the inverted futtock over and then mark f, p, s, etc. on the front side of the surface.

* For single frames, place the futtock on the drawing as shown in [Fig. 5-06] and firmly check that there are no gaps in the joint surfaces before gluing the scarf sections. I use a tape called "non release paper double-sided tape" (Scotch 667-1-19D) for positioning and temporarily fixing the futtock in this work [Fig. 5-07]. If this is applied directly to the futtock joint position on the drawing and adhesive is used on top of it, the overflowing adhesive will not stain the drawing, and the futtock can be fixed until it dries [Fig. 5-08]. In addition, the tape does not damage drawings when peeling it off, and the fact that the tape itself does not have release paper is another advantage that does not impair workability.

This tape is available at the stationery section of Tokyu Hands and other stores.

* A partially assembled single frame is shown in [Fig. 5-09]. Although I have not yet removed any glue or other material that has protruded into the adhesive area, you can see that the scarf maintains a clean gap. You can also see frame numbers (e.g., A01s) marked on the top edge of the surface side to align the surfaces after assembly.

* Next, these are assembled into a double frame. Adjacent odd and even frames are glued together except for F00. Here a double-frame drawing is used as a template.

* The mating surfaces of the two single frames are also painted black with a pencil or similar tool to simulate tar caulking before gluing them together. Before doing so, sand the surface of the side to be bonded with about 400-grit sandpaper to remove adhered dust and surface roughness well. This process allows the hull surface to be nicely accented after the final oil treatment [Fig. 5-10].

* Even if you think you have assembled a single frame carefully, there are individual assembly errors, and when you combine two such frames, it is difficult to know which one to use as a standard. In this case, three small holes were drilled in the center of the frame and at both top edges using the precision of laser cutting. By passing a 1 mm guide pin (brass rod) here, the relative positional relationship between the two can be automatically secured [Fig. 5-11]. The state of assembly as a double frame is then placed on the drawing to check for any major opening deviations. Some misalignments can be corrected by gluing the top edge of the frame to the jig during hull assembly. In a beveled frame, the two are slightly misaligned at this point, but this is not a mistake [Fig. 5-12].

* After all the gluing work is completed and the frame is dry enough, rough grinding of burnt marks on the inside and outside perimeter of the frame is performed. The final finishing touches are made after the frame is assembled to the hull as part of the overall shaping process.

* Regarding sanding, after the hull is assembled as a hull, it will be very difficult to finish the inner surfaces, especially at the bow and stern. Grinding concave surfaces whose curvature varies from place to place is not easily handled by ordinary shaped sanding blocks, and routers with cylindrical sanders are not good at grinding this area. Recommended here is the micro belt sander introduced in [Fig. 2-03]. The reason for this is that the tip is thin and can face the grinding surface, so it can freely cut narrow areas and areas with varying curvature, and the angle and speed of the neck can be changed, so work can be performed while avoiding obstructions. Of course, it can also grind freely on convex surfaces, and is recommended as a minimum power tool for hull shaping, especially for structural models.

* Keeping in mind that the grinding allowance is minimal due to laser cutting, grind each double frame to the point where a few burnt marks remain [Fig. 5-13], [Fig. 5-14]. The trick is to grind as if you were drawing a thin line with a brush. I think you can get the gist of it soon if you do a test with scrap wood. Sanding belts are rather too sharp when new, so adjust the sander speed slower. I grind the workpiece while holding it by hand without fixing it to a vise, etc. This is to serve as a buffer when force is inadvertently applied to the sander, and to prevent inadvertent over sharpening.

* A frame with bevels will have more standing on one side, resulting in a parallelogram shape in the frame cross section.

* Even though the amount of grinding is small, a considerable amount of dust is generated during this grinding process. Even if it is simple, use a vacuum cleaner or other device for dust suction.

* After the rough shaping is completed, the double frame is cleaned of residual adhesive on the flat surfaces according to the next column, and then the flat surfaces are finished ground with about 400-grit sandpaper. Also, write the frame number (A01, A03, etc.) on the upper vertical extension, etc. as identification.

Removing residual adhesive

* In many cases, structural models are not painted with coloring but are given an oil finish (Watco oil, oil stain, etc.) to show the original texture of the wood. In this case, if adhesives remain on the surface, oil will not be applied to those areas and will remain as bright stains, so they must be detected and cleaned off beforehand. As a detection method, wipe the area around the adhesive with a cloth dampened with water and grind the area where the adhesive remains bright [Fig. 5-15].

* As for grinding, since sanding can remove even the wood, here I recommend scraping with a round-bladed blade (such as a Feather disposable scalpel). Do not use straight-blade cutters, etc., as they will surely damage the substrate [Fig. 5-16], [Fig. 5-17]. Disposable scalpels have thicker blades and blades that are integrated with the body, so they transmit the feel of the hand more reliably than ordinary cutters. No.21 is especially recommended. (Tokyu Hands Engraving Corner)

* Use a light rubbing action on the surface without too much force. If you practice with scrap wood in advance, you will quickly learn how to apply force. Any thick adhesive residue can be easily removed by wetting the area with water and waiting a brief time for the adhesive to soften.

* This completes the double frame with twelve front and fifteen rear.

* On the cut model, the gun ports and other hull openings were processed here at the time the frame was a single piece. In the full model, the shape of the opening, especially in the cant frame area, may vary depending on the state of the cant frame assembly. So, this time I decided to do it after all the frames were assembled into the hull.

(2) Cant frame assembly

Continue to assemble the cant frame. Cant frames are frames attached to the front and rear of the hull with a fixed angle, not perpendicular to the keel. Also, each port side is independent of the other.

Note: Each number is skipped by one. Also, the 5th futtock is divided into two boards.

* Detach the eight sets of futtocks for the front and rear cant frames and sort each set into small bags, as you did for the square frames.

* Cant frames have secondary processing required. One of these is to add grinding to the bottom edge of the frame for the angle of contact with the keel (the deadwood section). This kind of machining is easy if you have a disc sander and measuring instruments, but most of you do not yet have such an environment, so we will proceed with the machining while making various efforts based on this premise.

* As an example, the bottom-most futtock is temporarily glued to a piece of wood having reliable right angle, with the grinding surfaces aligned [Fig. 5-18].

* A part of the drawing of the lower board of the jig is accurately fixed to the right-angle shaping jig, and the wood piece is aligned to the angle of each futtock then the protruding portion of futtock is grinded. If the angle is large, grind it off with a knife, etc. before grinding [Fig. 5-19]. Use this kind of approach to adapt the method to the tools you have on hand. It is important to note that the starboard and portside are different from each other, so the direction of attaching the futtock and the drawing used should be changed. [Fig. 5-18] shows the difference between the two.

* Another secondary process is to add a trailing slope to the scarf joint. The inclination is also related to the cant angle, so a few lines near the center of the ship can be ignored, while those at the end of the ship cannot be ignored. In each drawing, the black and red lines of the scarf shape are shown misaligned, and after shaping this misalignment with a knife or other tool, the futtocks are combined. The difference in the inclination of the scarves to be joined will appear as an unsuitable gap, so it must be careful in processing the scarves. Match them to each other little by little. Also note that both ship's side are opposite angle [Fig. 5-21].

* After secondary processing, each futtock is glued together as a frame [Fig. 5-22].

* After the glue is dry, roughly shape the inner and outer surfaces. For frames with a large cant angle, the bevel will change from inside to outside to inside, so sand while carefully understanding the change between the front surface (black line) and the rear surface (red line) from the drawing. Also, be careful not to detach the adhesive part since the work is done in a single frame. [Fig. 5-23] shows the state of the glued and roughly sanded rear cant frames.

(2) Hawse timbers

A similar rib material, though not called a frame, is the hawse timber in the bow. Hawse timbers include angling where they meet the front-most cant frame, slitting for ventilation, and drilling holes for hawse holes. Detach the following parts.

Floor futtock   HT1s, HT1p                 1 ea. 6mm

HT2s to HT5s, HT2p to HT5p        1 ea.        4mm

* Hawse timbers, like canted frames, are also different from each other on both sides, so even if they have the same number, be careful of the different surfaces to be processed.

* First, adjust the thickness only on the first hawse timber HT1. Make tapers on the surface where it contacts with the apron to match the apron taper. In the HawsePiece2 drawing, the top edge is specified as 4 mm and the bottom edge as 5.25 mm, but the bottom can be 5.2 to 5.3 mm [Fig. 5-24].

* The rest of the process is the same for all five timbers, so we will proceed using the HT1 case as an example.

* Angle the bottom of the timber where it meets the cant frame. The cant frame to be contacted is C8 at the very front, and its cant angle is 24 degrees, so 24 degrees is obtained and ground in the same way as the cant frame is angled. This surface contacts the cant frame as a vertical surface when assembled to the hull, but since the area of the part to be ground is small and verticality is difficult to achieve, check the verticality by placing a square on the vertical extension at the top of the part [Fig. 5-25].

* Next, rough grinding of the bevel is performed. Since the bevels of these parts are exceptionally large and their boundaries are not marked on the parts, cut out the corresponding portions of the front and back from the drawing and affix them to the parts with spray glue or the like (Fig. 5-26). Since this is a rough machining process, rough grinding is fine. Micro belt sander is also effective for sanding here. The vertical extension at the top of the part is to be aligned with the guide notch in the jig top plate, so it is left as it is without grinding. The rough ground state is shown in [Fig. 5-27] and its cross section is shown in [Fig. 5-28].

* [Fig. 5-29] shows the finished state. This is for the starboard side.

* Next, slitting for ventilation is performed. Refer to the HawsePiece2 drawing to determine the position and cut in about 0.4 mm on each side. The holes are then drilled, but since they span adjacent timbers, if they are drilled to their final size at this point, the holes may shift due to misalignment during assembly. It is better to position and drill only small holes and finish it after assembling it to the hull.

(3) Transom

The aft transoms are also a rib material and can be assembled to the sternpost as a stand-alone component, so there is no specific subassembly process, but some shaping is required.

* Since both ends will be glued to the last cant frame side (vertical section), remove the burnt marks in this section and finish the surface at a right angle.

* Shape the area sandwiched between the sternpost and inner sternpost in the center to prevent gaps between them when assembled [Fig. 5-30].

* The wing transom (WT) and second transom (T2) will have camber, so also finish shaping them.

* The bevel amount is large, so rough shaping should be completed in advance [Fig. 5-31].

In addition to the above, there are other parts that make up the hull, but they are all single items, and pre-machining and shaping are done at the assembly stage, so it is time to start assembling the hull.