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Craftsman Extra Board - November 2012

Laser-Cut Structures

Special: An Introduction to Laser-Cut Structures

by George Riley and Chris Lane /photos by the authors

This guide has been developed to introduce you to the exciting and varied category of laser-cut craftsman kits. Our goal is to provide the modeler with a number of tried and true tips and techniques used to successfully assemble and finish laser-cut kits. In addition we will showcase the latest offerings from some of the many manufacturers that specialize in this rapidly growing class of models.

The advent of affordable, desktop laser cutting machines coupled with easy-to-use computer drawing programs has been a boon to the model builder and model railroader alike. Manufacturers of laser cut structure, rolling stock and detailing kits are now providing a seemingly endless array of products that not only enhance our modeling options, but also allow us to build on a level that was until recently unobtainable. Priced from less than twenty dollars to a few hundred dollars, there are a wide array of subjects available to meet nearly everyone’s interest and budget.

The inherent precision afforded by laser cutting assures an almost perfect fit between the various parts thereby allowing for more complex and realistic models to be attempted by even the most inexperienced builder. As a rule, construction is easy and proceeds quickly on all but the most complex projects. Once the basic techniques have been mastered most laser-cut kits are as easy to assemble, if not easier, than their equivalent in other mediums since most of the tedious cutting and fitting has been eliminated.

While most laser-cut kits are made of wood featuring micro plywood and basswood components, card stock, acetate and Plexiglas are also commonly used. Any material that can be successfully burned (cut) by a laser is fair game. So, structures constructed from various materials and styles commonly used by most railroads are available in kit form in addition to commonly seen regional examples of non-line side buildings. This very abundance of subjects allows us to quickly and easily populate our railroads with buildings that are unique to our period and location, therefore reinforcing the realism and look of our chosen subject.

Though not as abundant, rolling stock in a variety of unique prototype railcars are also now available. As a rule, the prototypes for these kits are from a unique era or railroad that would not normally be available from the larger railroad model manufacturers. These build up quickly and easily with a level of detail not previously available from earlier craftsman kits.

For those looking to enhance or customize their models a wide range of affordably priced detail and conversion kits can be found that are designed to use with commonly available proprietary models from a number of manufacturers. These cleverly designed additions will not only easily improve an off-the-shelf model, but also are a great jumping off point for those not yet ready to make the plunge with a full blown laser-cut kit. A variety of individual detailing and construction items are also commonly available from a number of sources. These are a real aid for scratchbuilders, since their use greatly streamlines any building process and reduces a lot of the repetitive and monotonous tasks that slow down construction.

Laser-cut kits have categorically changed the face of model building for the better. The techniques for their construction are easily mastered and the finished results are impressive. They have opened a completely new avenue for modelers to develop new skill sets and enjoy the hobby.

Carstens Laser-Cut Structure Guide

Your Tool Box

As with all human endeavors, collecting the necessary tools for kit building can be taken to its ultimate. One of the greatest advantages of laser-cut kits is that of being able to successfully assemble them with a minimum of tools. To this end listed below are two lists of tools to be used for construction of laser-cut kits. The first, ‘The Basic Tool Kit’, list features the absolute minimum tools that one should have on hand. None of the items listed are specialized and should be available from a number of sources common retail outlets.

The second list is for the ‘Deluxe Tool Kit’. It features a number of specialized tools that are useful but are not necessary. This list has been assembled for those whose main focus in the hobby is kit construction and scratch building models. The items listed will improve accuracy and speed of construction. Needless to say, there will be a number of tools that are not included on this list that you may use frequently. The list is only a guide line and suggestion as any tool or technique that yields satisfactory results should be considered.

The Basic Tool Kit:

• Sharp modeling knife w/ disposable blades or a pack of single edged razor blades: These tools are used to remove the parts from the carrier frets as well as to trim items to length.

• Round tooth picks: Tooth picks are useful for applying small amounts of glue to small parts as well as to remove excess glue that has leaked from the joints.

• Cotton Swabs: These are used for spreading glue as well as to remove excess glue

• Masking Tape: Buy a roll of low tack masking tape to hold various pieces together while the glue dries.

• Spring Loaded Clothes Pins: Clothes pins are inexpensive and make great clamps.

• Sanding Block with Fine Sand Paper: While most of the time parts fit perfectly, occasionally you will need to true an edge or create a bevel on a corner.

• Nail Boards: Usually sold in the cosmetic department of most drug and department stores, these boards are indispensable for removing the ‘nubbins’ from parts. Make sure to get several grades; fine, medium and coarse.

• 0000 Steel Wool: Steel wool is handy for polishing the various pieces to remove fuzz from the wood and smooth grain that has been raised in the finishing stages.

• Small Square: This common tool is useful for trueing corners to assure that the structure is square.

• Metal Straight Edge: In addition to lining up edges, this will allow you to make straight cuts. When looking for a metal straight edge try to find one with a cork backing since this minimizes movement when cutting.

• Two Foot Square Building Board: A square of ¾" thick birch ply wood is perfect for this and will ultimately save a piece of furniture and the subsequent repercussions associated with its destruction.

• Pin Vice and Assorted Bits (* Optional) : This simple tool willallow you to either drill or clean out holes needed for the installation of detail parts and grab irons. Depending on your scale three or four different size bits are all that you will normally need. #76, #72, #66 and #60 are the ones that are used most commonly for HO and O scales.

Carstens Laser-Cut Structure Guide

Deluxe Tool Kit:

•NWSL or Equivalent ‘Chopper’: The ‘Chopper’ allow you to squarely cut strip wood to uniform lengths. This is an important tool to have if you are building some of the more complex kits or if you are kit bashing and scratch building.

• Razor Saw & Miter Box: For cutting framing pieces or thicker sections of wood.

• Micro Reamer Set: These small reamers will allow you to open and resize small holes to accept detail parts and handrails Swiss File and Rasp Set: These handy tools allow one to quickly resize parts as well as adjust parts for better fit. They are a must for cleaning the flash off of metal and plastic detail parts.

• Aluminum Angle Stock: Various size pieces of extruded Aluminum are available from most home improvement stores. These are handy for clamping and aligning corners and sides.

• Wood Angle: This fixture is quickly fabricated from ¼" or ½" wood set at a 90˚ angle.

• Dremel® Motor Tool with wire brush and cut off wheel: In addition to cleaning an trimming metal parts the motor tool with a wire brush can be used to distress wood pieces.

Adhesives:
There is a vast array of glues and adhesives available to the model builder. All have specific uses and benefits as well as some short comings. When constructing laser-cut kits you will probably want to use one or more of these products. When used properly they will yield a neat, durable and well constructed model. As a rule, you are safe following the kit manufacturers recommendations.

• White Glues: These types of glue are readily available from most retail outlets. They are easy to use, clean up with water, have long term flexibility and dry clear, however, they have limited strength and resistance to moisture. These glues are best used for applying shingles and roofing materials since their slow drying time allow plenty of time to adjust and line up the materials. Be aware that when using paper shingles there may be a problem of the shingles buckling. If white glue is used for this or other applications the finished model should be sealed with a clear lacquer. There are two commonly available types in this family of glue:

• Caseinate Glues: These glues are derived from milk with the most common brand being Elmer’s White Glue. While easy to use and clean up, they have a long ‘grab’, set and drying time so parts should be clamped and allowed to dry for at least eight hours. In addition this type of glue does not work well on non-porous and dissimilar materials.

• PVA Glues: As a rule these glues have a thicker consistency than the caseinate glues and a faster ‘grab’. They will glue dissimilar materials where there is limited stress and therefore work well when laminating items as well as attaching clear glazing in windows. Aleene offers a broad spectrum of PVA glues that are formulated for various applications. For our use the best is Aleene’s Tacky Glue since it secures pieces quickly.

• Aliphatic Resin Glues: Commonly know as Wood Working or Carpenter’s Glue, these products provide strong, moisture resistant joints. They clean up with water and are readily available and easy to use. The only minor draw back is that they do not dry clear and therefore should be cleaned off of visible surfaces before they set. While marketed to woodworkers and home repair, Aliphatic Resin Glues when carefully applied are a key adhesive for building laser-cut kits. Common brands are Franklin’s Titebond and Elmer’s Carpenter’ Glue. A new formulation designed for model use is becoming available from Great Britain. Marketed by Deluxe Materials, Super ‘Phatic glue is designed specifically for the model builder and possesses all of the virtues of its commercial kin as well has having a faster ‘grab’ and thinner body.

• Glue Sticks: Available from most office and school supply outlets, this wax based glue works well for applying shingles, signs and similar items. It is clear, easy to use and seems to be durable. Since we have only recently begun using this glue we cannot report on its long term durability. If you try this product make sure that you buy the variety that is ‘permanent’.

• Alpha Cyanoacrylates: Commonly know as ‘Super Glues’, CA glues have revolutionized model building. They ‘grab’ quickly, cure clear and are great for bonding dissimilar materials. Available in various viscosities, CAs can solve a number of bonding problems. For our uses, thick body CAs and CA Gels work the best when bonding porous materials such as wood and cardstock. Never use CAs to affix clear glazing since there is a tendency for the glue to fog the window. If you use this glue for general construction make certain that the glue has fully cured before adding windows or storing the model in a sealed container since the out gassed fumes have a tendency to raise any finger prints on a surface as well as frosting any clear material. For our uses these glues are best used to bond detail castings and parts to our models.

• Solvent Based Glues: Glues such as Ambroid, Duco and the like have a use in model building even though most people consider them to be ‘Old School’. They ‘grab’ quickly while still allowing time for alignment and usually set without clamping. If not used carefully they will mar a finished surface and need solvent to remove. They are moisture resistant; however, their joints may become brittle over time (measured in decades).

• Gorilla Glue: This glue uses the ambient moisture of the bonded materials to cure. Gorilla Glue is exceptionally strong, moisture resistant and in model building applications difficult to use since it ‘foams’ up as it cures. Use this for your bench work or to fix a kitchen cabinet, do not use it on your models.

• Model Master Clear Parts Cement & Window Maker: This formulation was developed by Testors for attaching clear canopies to model aeroplanes. The cement dries clear and is easy to use. It appears to have more moisture resistance than standard PVA glues.

Carstens Laser-Cut Structure Guide

Quick Tips for Laser-Cut Kits

Seal and paint all of your parts on their carrier frets prior to assembly where possible. Make sure that all parts are sealed on both sides. This may not be possible on parts that have peel and stick tape applied. This step will minimize warping of the wood and cardstock as well as speeding up the assembly of the model. Allow all the parts to dry overnight.

Spray the walls that will have decals applied with Testors Glosscote prior to assembly. Apply the decals per the manufacturer’s instructions and once dry seal with Glosscote. Recoat with Testors Dullcote after the second gloss application has dried. Your decals will look like they were painted on and the wood will not warp due to the moisture from the decal application process.

Build all of the walls completely before assembling the overall structure. This includes all windows, clear glazing and trim. Paint under the eves of your roofs. This often overlooked area left unpainted detracts from the finished model.

Keep a supply of 1/16", 1/8", 3/16" and ¼" square strip wood on hand to brace the interior walls and corners. Since many models do not include an interior floor or corner bracing a few pieces of added strip wood will greatly improve the strength and alignment of the finished model.

Once the model is finished, mask off all clear parts with masking tape and apply a light coat of Dullcote, particularly to the roof. For passenger cars sides and cabooses, a thin mixture of polyurethane spar varnish applied to the sides and ends will replicate the varnished paint commonly used during the 1850s to the 1950s.

Carstens Laser-Cut Structure Guide

Sealing, Painting, and Finishing

Successfully building laser-cut kit models is in large part a function of the time spent in preparation and painting the model. A substantial portion of this process should be completed prior to beginning construction. We have found three systems that yield very satisfactory results. The key step of each system is sealing the wood prior to painting and final finishing. Each works the best for a certain type of finish.

Airplane Dope/Sanding Sealer: Clear model aeroplane dope or lacquer or a commercial sanding sealer is applied to both sides of each part. We prefer ‘aeroplane dope’ since it dries faster than most other products. If you use a commercial sanding sealer let the filler settle to the bottom of the can and only use the top portion. Once dry, use 0000 to polish each piece. This step will remove any raised grain and gives the sealed part ‘tooth’ that allows your color coat of paint to adhere properly. Any type of paint can be used for this. This system works best for models that represent either new or well maintained structures and rolling stock.

Stain and Seal: Minwax® Stain and Seal provides the basis for this system. The product is available either in tins for brushing on or in spray cans. The tins are more economical, while the spray is faster. Each yields good results. The Golden Oak stain is the variety that we use most frequently for our models, however, chose the color that you are most comfortable with. Allow the stain to dry overnight and then polish each of the parts with 0000 steel wool. This system is best used for heavily weathered and derelict structures and rolling stock.

Gray Primer: Inexpensive gray spray primer is available from most big box and discount stores. This product is an excellent model maker’s finishing product since due to its inexpensive nature it covers with a very thin coat that does not obscure detail like the ‘better’ more expensive brand name primers on the market. Simply spray the primer on both sides of each of the parts and once the primer dries polish the pieces with steel wool. This system makes a good base for models that represent a well maintained but weathered subject.

Once the parts are sealed you can apply your preferred type of paint. Once dry the 0000 steel wool comes in handy for abrading and distressing the painted finish. The best models have their weathering and aging built in as they are constructed. Obviously the amount of wear at this point is in direct proportion to the level of use and wear that you impart on your model.

Carstens Laser-Cut Structure Guide

Toning & Weathering Finishes

When constructing a model for our railroad we not only try to replicate the actual dimensions and proportions of the subject, but also the environment that it inhabits. To this end we need to concern ourselves with maximizing the visual impact presented by our small version of the real world. Two main events conspire in the real world that we must artificially replicate in miniature. The first is the effect of light and shadows or toning on both the real world and then on our models. The second in the wear and tear produced by the elements or weathering.

To capture the light and shadows that we see on the prototype requires a bit of modeling slight of hand. We need to create artificial shadows and highlights on our models to capture the right look. In addition to this we need to tone down our colors which appear over bright when compared to the actual subject of our models. The process of toning is entirely separate from the weathering process and should be used on projects that are presented in a like new condition as well as ones that reflect age.

Carstens Laser-Cut Structure Guide

Toning is easily done by using Payne’s Gray Artist tube oil or acrylic colors applied directly from the tube with out thinning. The color is rubbed into the cracks and crevices with cotton swabs and shop towels. You want to wipe off any excess that remains on any of the flat reflective surfaces on the model. The goal is to accentuate the depth and detail on the model.

Follow the toning by dry brushing a lighter color on the areas that would normally reflect light. This step is done by loading a soft bristle brush with a small amount of paint. Most of the paint is the wiped off on a towel to leave just a bare minimum. Next scrub the brush over the model to deposit a very light coat of you highlight color. You want the base color to show through and want to pick up the highlighted details.

Weathering is in itself an art form and for the most part well beyond the scope of this supplement. However, we would be remiss if we did not touch on some of the basics of this process. The natural aging and weathering of any item left out of doors occurs in three stages. Dirt and dust is deposited on an item over a period of time. This is an additive process that is easily replicated by the use of chalks or thin washes of color sprayed onto the model.

Paint and Coatings failure usually occurs some time after dirt and dust begins to accumulate. Usually the first stage of this failure is the dulling or chalking of the finish. At this point the finish becomes dead flat and the pigments begin to come loose from their carriers. These free pigments create streaks down the sides of a structure or vehicle. In nature this is a subtractive process. We can replicate this process in several ways. One is to give the model several coats of flat finish and use chalks and dry brushing to replicate the deterioration of the paint.

Another is to use our steel wool to wear off the color coat on our model down to the base coat or primer. This latter method is more controllable than the former and allows for the differential weathering seen in different areas of an item. Each technique is not exclusive so a mixture of the two can be used.

Usually, but not exclusively, the final stage of aging is materials failure. This needs to be planned for at the onset of construction and entails more than a few loose pieces falling off a structure. The first stages of this failure manifested by rotting and loose trim pieces; gutters and metal rusting through as well as loose shingles. A metal brush or Dremel Tool with wire brush bit can be used to distress various parts on a model to simulate this aging. Gray paint and a black wash made from alcohol and India ink can serve to highlight the decay. Various rust colored paints with chalk applied while wet for texture can simulate rusty metal.

Carstens Laser-Cut Structure Guide

Special Finishes: Special paint effects can be obtained using some unusual and interesting techniques. We have included several for your consideration. Hopefully, these will provide a starting point for your further experimentation as you strive for better, more realistic and creative models.

Whitewash: Lime mixed with water was a common coating for unfinished wood until fairly recently. While not durable over a long term, it was cheap and easy to apply. This coating was very common and is easy to replicate in miniature. Beginning with a model that has been sealed using the ‘stain and seal’ technique apply a white oil based pickling stain over top of the wood colored stain. This stain is available at nearly all paint stores as well as home improvement centers. An inexpensive quart will yield a life time supply. Once the white stain has dried use steel wool to wear through some of the coat. The end goal is to have a chalky finish on your model with some of the underlying wood color showing through.

Cracking Paint: While not as common as it once was due to new paint formulas designed to be resistant to this type of paint failure, cracking paint is a sure sign of age. Begin by painting the walls of the model with a dark color of paint and allow to dry completely. Blacks, charcoal grays, dark blues, reds and greens will all yield good results since the main function of this base coat is to accentuate the crazing of a lighter top coat. Next, apply either a coat of thinned white glue or crackle finish from your local craft store. While still tacky brush on a top coat of acrylic paint that contrasts with your base coat. Try to brush on the paint in one direction. As the top coat dries a crackle finish will appear. Seal with a spray sealer.

Grits Finish: Peeling and missing paint can be replicated using grits to good effect. Yes, even hominy grits, that native American preparation and staple food of the South has a place in model railroading. Begin by soaking the grits (either regular or instant) in water. Once they are spongy and tacky brush the grits mixture over a sealed and stained wall. Allow to set until almost dry and apply a coat of acrylic paint over the entire wall, grits and all. Once the paint is completely dry wipe off the surplus grits to reveal the patchy paint.

While the preponderance of kits and details that feature laser-cut parts are of wood, lasercut kits are not limited to this material. Several manufacturers offer a range of kits that feature Plexiglas as their main material. Plexiglas is particularly effective for simulating masonry and cut stone construction.

Like their wood cousins, these kits are easy to construct and finish. Unlike wood they do not require as much intensive preparation before assembly. Anyone familiar with building injection molded plastic kit will be familiar with the construction techniques.

Unlike plastic injection molded kits Plexiglas kits are not subject to warping and build up into very strong and stable models. This medium is particularly effective for constructing large structures.

Carstens Laser-Cut Structure Guide

Going Beyond the Basics

Laser-cut kits have greatly expanded our choices and enjoyment in the hobby. Just like any other media, laser-cut kits and parts can be the basis for any number of projects. Obviously, they lend themselves to additional detailing and combining with other products to build exactly what a modeler may wish. The only limiting factor is ones imagination.

Kit Bashing: Often times when one looks at a kit one sees beyond the kit itself and more over the product becomes a reservoir of parts to be modified and used for other projects beyond that specified by the manufacturer. On such example is a quick and easy conversion in which we took a gas station and converted it into a marine supply office for use on one of our On30 narrow gauge projects. This was a straight forward conversion where the core building remained basically unchanged, however, the addition of nautical signs and details revised the overall appearance of the structure. Another project entailed the modification of a large, full sized masonry station building into a low relief structure to use against a backdrop. Both conversions were easy conversion and only a beginning to the possibilities of kit bashing.

Scratch Building: The use of laser cut trusses, shingles and various other parts used in conjunction with strip wood and more conventional scratch building materials allowed us to quickly fabricate an 1860s era covered station similar to the one currently on display at the California State Railway Museum in Sacramento, California. We feel that the results speak for themselves.

Designing your own: What if you could harness the power of your computer to knock out all the basic forms of a scratchbuilt structure, set all the basic dimensions, chose from a number of different siding materials, cut out all the window and door openings for Grandt or Tichy castings or even design your own custom windows and doors, that would be a pretty awesome scratchbuilding tool, right?

Luckily for modelers, such a tool exists. It is called Kit-O-Mat and is available from KingMill Enterprises, LLC. The software retails for under $45, works on either Macintosh OR Windows computers and is custom designed to offer the modeler a finished laser-cut kit burned to their specifications. I find it very easy to learn and use, a far cry from the complicated CAD programs that are usually used to generate laser cutting files. Another important distinction is Kit-O-Mat automatically generates all the tabs, slots and offsets needed. This software makes it so you only have to worry about the basic dimensions. I could go on, but I’d rather you just go to the KingMill website and try their demo.

 


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