In 2006, as a member of the Yokohama Sailing-ship Modelers Club, I developed and published a method for drawing structural model frames using graphics software. In the past, it took a great deal of effort to learn how to make a structural model, as well as to prepare drawings of the parts that make up the model, especially the frames, each of which has a different shape. This resulted in a huge amount of grinding and shaping work and material waste by cutting out several adjacent pieces in approximate geometry. 

I believe that this method has contributed to removing a major barrier for builders who want to create structural models by making it possible to create such drawings quickly and accurately.　

  Twelve years later, in 2018, it was discovered that the data drafted by this method could be used to produce parts by laser machining. Although it has become quite common in recent years to provide laser-cut parts for commercially available bulkhead kits and the like, I had no idea that I would be able to create the data ourselves and even process the parts ourselves. However, I thought that if this became possible, it would contribute to reducing the labor and cost of machining a substantial number of parts, which was the next barrier to structural model making.

As a result of the trials, I was faced with the fact that while laser cutting has great advantages, weaknesses, and issues unique to laser cutting became apparent when applying it to structural models. After much trial and error to resolve these issues with the cooperation of several members of the association who support the practical application of the system, I was able to establish a new system that will be an epoch-making support tool for structural model making.

  I would like to make this system available to a wide range of modelers, including beginners in structural modeling, and will soon release a DVD entitled "Drawing Designs and Making Parts for Structural Models".

This procedure manual describes the process in over 170 pages of detail so that you can put the entire system into practice. Once you understand the basic operation of the software, you can reduce the time required for the preparatory stages of model making, such as drawing and cutting out parts, and concentrate on the actual model building process. In addition, this DVD contains not only the operating instructions, but also a set of explanatory drawings created in the process, actual designed drawing data, and data for laser cutting, all in various formats for reference. Shade and Illustrator files can be opened and operated by yourself while referring to the manual, and JPG and PDF format files can be opened on a PC without special software and referred to on a large screen or printed and kept at your seat. Of course, the design files can also be used to build the actual GRANADO model. There are few instruction manuals like this that consistently provide everything from the contents of the system to the design data, and I hope you will enjoy using these. Prior to the public release of the system, here is an overview of this system. 

  This method organically combines 3D graphics software, 2D graphics software, and a laser cutting machine to produce design data and process physical parts quickly and accurately at high speed without compromising the accuracy of the original data.

  The software used in the method is a combination of domestic "Shade" as 3D software and Adobe's "Illustrator" as 2D software. I have used CorelDRAW for 2D software in the past and there are laser processing machines that can also be used with CorelDRAW data. However, I have decided to use Illustrator this time as my standard, which has the great advantage of direct data transfer between software. In addition to this, Illustrator also has a wide range of other operating functions that are effective in correcting data to compensate for weaknesses in laser cutting, resulting in shorter processing data creation time. CorelDRAW can also be used for laser processing by adding some conversion processes. Please try it out if you prefer.

  This method has the following features in addition to the existing ones.

(1) The 3D software "Shade" can be used to draw a smooth and accurate 3D hull shape from the body plan data of the ship to be built.

(2) The hull shape can then be generated as a line shape of the frame by slicing cross section of the shape at the desired position, and the Shade-Illustrator combination can output these line data directly as Illustrator data, eliminating the need to redraw (trace) the shape that was done in CorelDRAW.

(3) Since not only shape information but also its dimensions and coordinate information can be shared, 2D software can also accurately place parts together, enabling accurate drawings of not only single-part drawings but also hull assembly drawings. Furthermore, it is possible to produce undrawn parts drawings from the assembly drawings. All geometry dimensions can be controlled by numerical input, so drawing accuracy is the same as with CAD.

(4) Laser cutting based on this data is much more accurate and faster than conventional band saws, etc. Furthermore, as the layout distance between parts can be reduced to about 1 mm, which significantly improves the material yield. Actual processing can cut all the frame parts (futtocks) for one ship in a few hours once the machine is set up according to the data and material.

(5) Laser cutting machines have recently become available for rent from DIY or hobbyist manufacturing institutions, allowing people to create their own originals at a low cost.

  While laser cutting has the great advantage of being accurate and fast, it also has some weaknesses that other cutting methods do not have. We have devised various workarounds for these problems and have made it possible to apply the laser cutting method to structural models. The characteristics of laser cutting, including these measures, will be explained.

(1) Laser beam irradiation can cut by very narrow cutting widths (0.1 to 0.2 mm) faithfully to shape data, dramatically reducing the time required for shaping and grinding models. The thinness of the blade (laser beam diameter) is also reflected in the material yield, allowing for high-density spacing of parts, reducing the material requirement by up to half compared to machining.

(2) The cutting speed is extremely fast, and if only cutting is required, the cutting of a single frame parts can be completed in a total of about 30 seconds. The entire project can be done within a few hours of rental time, even if considering set-up time and engraving.

(3) Graphics data at the time of design can be used as is, so there is no need to convert or recreate data.

(4) Processing functions include through-cut, half-thickness cut, and engraving, and processing can be distinguished by changing the line thickness and line color of individual data.

(5) The process uses a laser to burn through the material, leaving black burn marks on the cut surface (in the case of wood). If parts are exposed on the surface of the model, such as a frame model, these burn marks must be removed cleanly, but simply shaving them off will result in loss of shape dimensions (thinning). Since Illustrator has a function to add a uniform amount of extra wall around the shape without damaging the shape, this weakness can be avoided by using this function to correct the machined shape.

(6) Even with a laser, if the thickness of the material to be cut is thicker, the cutting width will be different on the front and back sides of the plate, resulting in a non-perpendicular cut surface. When joining cut parts, this can reduce the strength of the joint or prevent the joint surface from being flat (horizontal). As a workaround, one of the adjacent parts can be cut inverted in shape, and then inverted and joined again when assembled, so that the inclination of the cut surfaces can be aligned, and the bonding surfaces can be secured and leveled. Please refer to the following section 5 for specific details of these corrections.

(7) Parts are usually left with a 1 mm or so cut-off area so that the part is retained in the base material after the work is done. However, because the width of the cut is so small, if the thickness is several mm, as in the case of frame materials, the tool to cut it off will not fit through the gap, making it difficult to separate the part. Therefore, except for the parts smaller than the honeycomb of the processing machine base, the entire circumference is cut without this leftover portion. If it is assumed that the parts will be processed by yourselves, it is possible to avoid that the parts will be scattered and indistinguishable by temporarily fixing the detached parts with masking tape after processing. Since there are many similar shapes in futtock, great care must be taken to identify them. Layout drawings with ID numbers of the parts are available separately.

Note: Subsequent studies have resulted in all parts having a cut-off to allow them to be retained on the plate.

(8) One of the difficulties at present is the lack of consistency in size when procuring boards for cutting. There were several shingle suppliers in the U.S. that were able to procure shingles in fixed dimensions, but recently there are now some in Japan that can handle them as well. The data on the DVD is laid out on this basis on a size of 500mmx100mm. For other sizes, you will need to re-layout according to the size. Re-layout is not a complicated process, but you will need to operate the software yourself or have it done by us.

  To take full advantage of the special characteristics of laser cutting, we use Illustrator functions to correct the original design drawings.

(1) Add fleshing of only the inner and outer edges of the frame

Specifically, 0.3 mm was added on each side relative to the design value as an allowance for burn mark grinding. Since the laser is expected to wear away about 0.1 mm of the outer surface, at least another 0.2 mm is needed for grinding to remove the burn mark. The bevel section will cut more of this surface at an angle, but keep in mind that the minimum allowance for this cutting is only about 0.2 mm.

The joint surfaces of the edges, except for the inner and outer edges of the futtock, are conceived to be glued together, leaving the burn marks as they are, to imitate the tar filling in a real ship. In this way, it is easy in Illustrator to make corrections according to the part of the shape.

The idea of fleshing is the same for other parts except for the frame, but unlike the frame, the fleshing is applied evenly around the entire circumference. The amount of fleshing thickness varies depending on the thickness and shape of the part and is indicated on the layout and offset drawings for each part.

(2) Inverted joining of futtock

As mentioned in the previous section, when the plate is thick, the cut surfaces are not perpendicular, so adjacent futtocks are flipped front to back and joined. For this reason, a futtock shape is prepared in which the cut shape is drawn inverted so that it can become a regular shape when it is inverted again.

Specifically, the second and third futtocks, as well as some of the cant frames, are drawn in reverse. These are easily identifiable because they are shown with their ID numbers also reversed in the layout diagram.

In actual joining, these futtocks are aligned in the layout orientation and then turned over to form the proper joining state, making the joint surfaces parallel to each other. The scarf lengths at both ends are also changed, so there is no danger of incorrectly assembling the top and bottom, but please keep this in mind when assembling the frame.

(3) Odd-numbered frames

For odd-numbered frames which start from the first futtock, the same measures as in section 2) must be taken not only between futtocks but also at the left-right joints (between the first futtocks) that touch each other on the keel.

For this reason, two sets of one-sided frames are made first, joined in the same orientation regardless of port side or starboard side, then one of them is turned over and the first futtock section is joined. In the layout drawing, two sets of futtock IDs are drawn for the s-side (aft frame) and p-side (fore frame) respectively. This is not a mistake, so please do not be confused.

(4) Guide holes

The center of the frame (where it straddles the keel) and both ends have 1mm holes for alignment when assembling the double frame, but the diameter of these holes will be changed by laser cutting if they are left as they are. Therefore, the odd-numbered frames are expected to have smaller hole diameters after assembly, so they should be scraped with a pin vise to the specified diameter (1 mm).

On the other hand, even-numbered frames (frames with floor futtock) and both ends are pre-set with smaller hole diameters, so they will be at the specified diameter after laser cut.

When assembling the double frame, the three guide holes can be easily aligned by inserting a 1 mm brass rod or similar object into the holes.

(5) Laminated structuring of beams, etc.

The deck beam has a brined notches on each side of it to hold the carling, and such a shape cannot be easily produced by laser cutting. Therefore, we divided one beam into three layers, notch depth thickness part on each side and the center part without the notch and cut each layer separately to create a laminated structure. In addition, guide holes have been added on both sides of the beam, based on the same idea as in section 4), so that the notches will not be misaligned during assembly. These holes are not visible after assembly covered by the knee.

This laminating method is also applied to the assembly of bits and catheads that have hollow holes for sheaves inside.

(6) Mating with assembly jig

As described above, parts that can be handled such as joints between parts are corrected, but parts that straddle the keel and parts that fit into assembly jigs are cut to the design dimensions. As a result, the assembly accuracy needs to be ensured by grinding the parts in case they are tightly fitted, and by adding a retainer to the loose parts, as necessary.

  Laser cutting techniques can be applied not only to create accurate parts, but also to create jigs that ensure assembly accuracy during assembly.

The assembly of a structural model requires the assembly of many parts in a neatly aligned state, and we have found that the positioning jig plate that guides the assembly can be easily produced by laser cutting using an assembly drawing.

In the assembly of the frame section, which is the most difficult part of hull assembly, the jig design can incorporate more and more necessary ideas, including not only the machining of the notch shape for positioning and fixing the top edge of the frame, but also reproduction of the cant frame angle, addition of various reference lines necessary for hull machining after frame assembly, and ensuring reproducibility of fixing positions during hull attachment and removal. They are also easily fabricated, revolutionizing the ease of hull assembly.

After several trials, the latest design uses the following method.

(1) Cutting out the outer circumference of the jig plate

At first, the outer circumference of the plate was used as it was, but because the center position could shift due to variations in setting the plate on the machine, we eventually decided to cut the outer circumference to a certain dimension. This allows for precise alignment of the relative positions of the posts and upper and lower fixing holes, thus facilitating the assembly of the jig.

(2) Preparation of support stanchions

At first, we assumed that the users would individually prepare the upper and lower jig plate fixing supports, and only the drilling positions for fixing were indicated. However, since the jig accuracy may be affected by the length of the stanchions and the accuracy of the drilling, we decided to prepare these stanchions in advance. In addition, we have made it possible to achieve positional accuracy only by fitting them together.

When we tried it, simply fitting the six stanchions into their respective positions is sufficient to assemble the frame, as the relative positions of the upper and lower boards can be secured without gluing them together. If you are concerned about the jig sticking, fix the front and rear parts of the jig with a rubber band or string to make it more rigid.

The reason for not fixing the stanchions in this way is to avoid some of them getting in the way when measuring the outer surface of the hull or machining holes, etc., and to make it easier to remove the entire hull while it is fixed to the top plate for shaping and grinding.

(3) Clarification of reference position

The hull design is based on a ship design standard that allocates the midship position to the front and back with zero position, but we found this to be difficult to measure in the actual assembly process. Therefore, the reference position for assembly was changed to the end of the hull, and to enable accurate measurement from either the front or the rear, a zero position was set at both front and rear, from which representative dimensions are displayed on the jig board. The specific zero position is at the top of the stem in the forward direction and at the top of the sternpost in the aft direction, and the hull (keel) supports in the front and rear are also supported at this position.

(4) Reasonable reinforcement and measurement guides

While the above concepts we have provided are sufficient to use the jig, there are also options such as using aluminum or other materials to attach reinforcing feet or rails to guide instruments that measure the interior of the hull from the top. Please refer to the images in the "Jig" folder and devise your own.

  Based on the overview described above, the procedure manual "Design Drawing and Parts Fabrication in Structural Models" describes each operation procedure in detail. After reading the previous introductions, this is an essential procedure for anyone who wants to design a ship that he or she would like to build, or to laser-cut a ship with the desired materials. The extensive software operation screens and easy-to-understand step-by-step instructions on how to edit blueprints for laser cutting make it easy to master the methods. An overview of the explanations follows.

Chapter 1): Introduction

It introduces the selected software and explains the basic knowledge of 3D shapes necessary for drawing curved surfaces.

Chapter 2): Preparation

It explains the preparatory work before design, such as how to collect the basic data necessary for drawing, determine the reference position for drawing, and determine the scale and frame structure as a model.

Chapter 3): Creating Templates

Basic Illustrator operations are explained through the creation of template (rough sketch) figures necessary for drawing hull surfaces.

Chapter 4): Creating hull surface

Shade operation is explained through the procedure of creating specific hull surface. This is one of the most unique parts of this method.

Chapter 5): Creating Frame Curves

The procedure for specifically generating individual frame curves from the generated hull surface is explained. This is the highlight of the method, and you will be surprised at how accurately and instantly subtle differences between adjacent frame shapes can be generated.

Chapter 6): Creating frame drawings

This chapter describes the procedure for drawing the generated frame curves as part drawings for fabrication. The shape of the futtocks and joints are determined, and identification numbers are assigned when the parts are made.

Chapter 7): Creating futtock exploded drawings

It explains how to break down the frame drawing into individual futtocks.

Chapter 8): Creating various assembly drawings

Using the rich functionality of Illustrator, this chapter explains the procedures for creating the various assembly drawings necessary for model making, and how to create them as accurate drawings.

Chapter 9): Creating various parts drawings

In addition, we have developed what used to be only frame drawings to include drawings of most of the parts necessary for model making, thereby we can maximize the advantages of laser cutting.

Chapter 10): Expansion to laser cutting

It explains how to edit drawings that specifically reflect how to avoid some of the issues that were raised when adopting laser cutting, and how to create data for laser cutting based on these methods.

If you would like to request this procedure manual, please contact us through the Contact page.