I used my CAD program to draw up a simple box structure with an attachment rim and then I had my buddy Pat at LaserCutUSA.com cut the parts for me. Of course you can just as easily make a similar design and reproduce similar the parts with a band saw and a drill press. The assembly is very easy to install and it took me about an afternoon to hang the engine.

I am using a Fuji 43cc with electronic ignition to power the Skyraider so I made the engine mount box/tank shelf long enough to accommodate the tank and throttle servo, with the idea that I would attach the ignition module and battery pack in front of the firewall.

I started by placing the engine over the side-view of the plans. The engine fits nicely in the cowled area of the reduced plans.

After aligning the prop hub position so it would clear the front of the cowling, using the engine’s attachment tabs I marked the new location for the firewall in the front of the mount box.

For strength, I made the sides of the box from 1/4-inch ply and the top and bottom from 1/8 inch lite-ply. I added notched the fronts of the four sides to key the 1/4-inch firewall face into place. Alignment tabs on the firewall and the aft bulkhead fit the slots as shown.

I made the firewall just wide enough to fit the engine attachment bolts, and you see here the blind nuts have been ground back to clear the sides. I also doubled up the firewall with a second layer of 1/4-inch plywood to properly seat the blind nuts. The total thickness of the firewall is 1/2 inch and the two layers are laminated together with Zap 15 Minute Epoxy. The firewall is also glued to the plywood sides with epoxy.

Once the box was glued together, I placed the box on the plans to mark the front of the main firewall.

Here are the two main parts of the engine box ready to be epoxied together.

I also had a new F-1 firewall cut with the required rectangular opening to clear the tank support section.

I then epoxied the new F-1 firewall to the front of the fuselage with slow setting epoxy and clamped it into place until the glue had cured.

I left off the bottom fuselage sheeting aft of the firewall so I could clamp the new F-1 firewall to the F-1 bulkhead.

Test fitting the box through the firewall, it  slides easily into place. The fuel tank fits snugly inside with some thin foam placed between it and the box.

I also added triangular balsa stock around the attachment rim to increase the gluing surface.

Looking through the cockpit opening, the two aft attachment points will use blind nuts and bolts to anchor the box to the fuselage’s vertical side structures. The bolts can be easily accessed through the wing saddle should you want to remove the engine and fuel system for maintenance.

Using scrap 1/4-inch ply, I set all the blind nuts so I could glue them into place for each of the six attachment bolts.

So the bolts installed, the engine is finally attached to the firewall and the engine mount box is attached to the main firewall for a solid installation.

TEXT & PHOTOS BY GERRY YARRISH

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SMOOTH THAT OLD IRON

Have you ever noticed the slick surface on a new covering iron after you first pull it out of the box? The iron seems to float on top of the plastic covering, giving you a beautiful finish. However, after time goes by and the iron gets a little older, the smooth Teflon feel on the surface just goes away. Here is a simple way to rejuvenate that old iron. When the iron is cool, add a little baby powder to the surface and rub it in with your fingers. This will give the contact area a new surface that will glide much more easily over your covering. You can reapply powder as needed to keep the iron gliding smooth.

PAPER TOWEL SHIM

I always have a problem with getting the socket-head bolts into those hard-to-reach spaces. Even though the socket-head bolts do hold on better than a Philips or screwdriver head, they tend to let the bolt fall off just before you can get it started. That’s where this trick is really going to save your day! Add a little piece of paper towel to the end of the ball driver and press it into the socket head of the bolt. You will find that this holds better than a magnetic head driver.

RECYCLE THAT OLD BIKE

Many bicycle spokes have the same thread size as a standard-size airplane pushrod, which means you could have 25 to 50 pushrods from an old bicycle wheel. First remove the tire and inner rim tape to get to the spokes. Now just cut the spoke near the center hub and slide it out. Cut it to length when needed. Many of the newer spokes are made of aluminum and are very light.

AILERON ALIGNMENT JIG

When setting up the aileron linkage, it is helpful to have a third hand holding the aileron in the center position. The next best thing is to make this simple alignment jig out of a clothespin and two pieces of balsa. Just put the two pieces of balsa above and below the aileron centered on the gap between the aileron and wing trailing edge. Attach the clothespin to hold the aileron in place. The soft balsa will help prevent the clothespin from marking the surface. Just be sure to remove it before operating the servo when testing the throws..

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1 Charged Battery ID
If you have a bunch of battery packs you use over and over, knowing which ones are charged and which are not can get confusing. An easy way to identify packs is to place a small ID sticker on the packs after you charge them. Once you’ve used the pack for a flight, peel the sticker off so you’ll know it’s in need of a recharge.

2 Propeller Safety Tips
To prevent accidents, full-size aircraft are equipped with propellers that have brightly colored tips. Do the same with your model airplane propellers. Mask off the tips and spray on some bright yellow or white to make the prop tips more visible while it’s spinning. The finger you save might be your own!
 
3 Small Parts Sticker
When building (or repairing) a model, it is sometimes hard to place a wooden part properly inside a narrow fuselage. An easy way to do this is to use a sharp awl as a “part sticker.” Now, simply add glue to the part, stick it with the “part sticker” and guide it into position.

4 Emergency Screwdriver
It never fails that whenever you need a specific tool for the job, you’ll find that tool anywhere but where you need it. If you find yourself in need of a common, straight-blade screwdriver, you can always take a modeling blade and place it backwards in its handle. The exposed part of the blade can now be used to tighten that screw.

5 Throw-away Epoxy Mixing Pad
While mixing epoxy, use a pad of Post-It notes for the mixing surface. Then after applying the adhesive to the model, simply throw the used note away and you’re ready to mix some more adhesive. No clean up required.

6 Easy Control Surface Alignment

When you install and adjust your pushrods, it is better and easier to do if you lock your control surfaces in their neutral positions. Use a pair of coffee mixing sticks and a couple of clamping clothespins to keep the surfaces from moving.

7 Easy Clevis Keepers
If a clevis were to pop off one of your model’s control horns, you could lose control and crash. A simple and cheap way to prevent this from happening is to add a clevis keeper. Simply slice a thin section from some model fuel tubing and slip it over the clevis. It will act like an O-ring and keep the clevis securely in place without binding.

8 Handy Clamp
There are a hundred tasks in modeling during which you simply need a third hand. Soldering connectors to wire leads is a good example. In a pinch, you can use a pair of pliers with its handles wrapped with a rubber band. The pliers are heavy enough to act as a steady base and the rubber band provides enough clamping force to hold delicate items without damaging them.

9 Simple Building Board
You don’t need a complete building bench or table to build model airplanes; just use a straight piece of pine board. But to make it easier to insert pins to hold the wood parts in place while the glue dries, get some cheap Peel-n-Stick cork sheeting from a hardware store or a convenience shop and stick them to the building board. Place your plans on top and protect it with some clear kitchen wrap or wax paper. Should the cork get damaged or you get some glue on it, simply peel the cork away and replace it with a new piece.

10 Sheet Separator
If you build from plans or kits, you have to cover your model. Often, it is very difficult to separate the covering film from its backing sheet so you can iron it into place. The easiest way to do this is to apply strips of masking tape to each side and use them as pull tabs to separate the two thin layers of plastic.

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Simple Crush Plate

Purchase Lucite at the hardware store and pick up a 1 1/4-inch hole cutter.  Use the hold cutter to cut out some Lucite 1 1/4-inch disks. Then use a drill press to cut out a 1/4-inch hole in the center of the disk. This large Lucite disk can be used with the wing retention bolt and it will not crush the trailing edge of the wing. Because the disk is transparent, it will be hardly visible when installed.

Cheap And Easy Wheel Chocks

A quick way to keep your plane in one spot is to use these wheel chocks made from 1/2-inch PVC pipe. You can vary the length of the side pieces to accommodate different sizes of wheels. Before gluing the final pieces, fill the assembly parts with sand.  You can make several of these for about $4 or $5 and a few minutes of your time.

Looking Good
Protect your aircraft’s cover scheme! Before you fuel it up, apply a thin coat of clear dope to the trim surfaces. This will also keep the trim from coming loose when you clean your aircraft.

Custom fit for your wing
Looking for a less expensive, effective and truly custom wing bag? Try Reflectix foil insulation that can be found at any hardware store. It is like bubble wrap with Mylar on both sides and comes on a roll.  Start by laying your wing on half of it and fold it over the top. Then, cut off the excess but leave a few inches around and a little extra for a fold over flap. Use a regular stapler, spaced as close as you can, to seal up the edges. You can staple the edges with the wing inside to give it a sung fit. Add handles made out of flat nylon cording purchased at a fabric store.

The post Favorite DIY Advice appeared first on Model Airplane News.

Propeller Safety Tips
To prevent accidents, full-size aircraft are equipped with propellers that have brightly colored tips. Do the same with your model airplane propellers. Mask off the tips and spray on some bright yellow or white to make the prop tips more visible while it’s spinning. The finger you save might be your own!

Easy Clevis Keepers
If a clevis were to pop off one of your model’s control horns, you could lose control and crash. A simple and cheap way to prevent this from happening is to add a clevis keeper. Simply slice a thin section from some model fuel tubing and slip it over the clevis. It will act like an O-ring and keep the clevis securely in place without binding.

Small Parts Sticker
It is sometimes hard to place a wooden part properly inside a narrow fuselage. An easy way to do this is to use a sharp awl as a “part sticker.” Now, simply add glue to the part, stick it with the “part sticker” and guide it into position.

The post 3 Favorite Workshop Tips appeared first on Model Airplane News.

Let’s face it! Accidents are bound happen, and when it comes to flying RC airplanes, the chances are that you’re going to suffer some damage to your airplane. There’s no reason, however, to trash your crash. With today’s beautiful molded foam fliers, you can get back into the air with very little effort. You also can save some bucks by repairing your bent bird instead of buying new parts or an entirely new airplane.

What’s Needed

The supplies needed for any model repair are a hobby knife with sharp replacement blades, some masking tape, a sanding bar with medium sandpaper (100 to 150 grit), and some fine 220-grit sandpaper. The glue needed is 15-minute two-part epoxy, foam-safe CA adhesive, and foam-safe accelerator. Denatured alcohol is good for cleaning the surface of the foam and for cleaning up excess epoxy from repairs. We used an assortment of glue, including those by Bob Smith Industries and Flash Adhesives.

Removing Dents

Step 1: The leading edge of a foam wing can really take a beating, but dents are really only cosmetic issues. If you have a minor dent, simply apply a wet paper towel to it and heat with a covering iron. Most of the time, the steam will expand the foam and your dent will disappear.

Step 2: If the dent is more pronounced, you can quickly cut away a section of the damaged material with a razor saw and glue in some new foam.

Step 3: Cut some new foam to length, and glue it in place with foam-safe CA. The best way to do this is to cut the foam a bit oversize, and spray foam-safe accelerator to the new material. Apply the CA glue to the cutout area, and insert the repair piece. Hold it in place until the glue sets. Use your saw to remove most of the unwanted material, then use a sanding block to smooth the replacement piece.

Step 4: Apply a little hobby filler around the edges to fill in any gaps (Hobbico HobbyLite Filler is great for this).

Step 5: Once the filler has dried, use fine sandpaper to smooth the repair. If you need to, apply more filler around the repair area to feather out the repair area.

Step 6: Apply some matching foam-safe paint to complete the leading-edge wing repair. The hardest part of this repair really is finding matching paint. Usually, the instructions that come with your airplane will call out the colors used. If not, go to the hobby shop and check out the Master Modeler and Tamiya brands of acrylic foam-safe paints. You’ll be able to match the color chips and then lighten or darken the colors slightly to match. In real life, warbird repairs seldom matched the rest of the airframe, so welcome to scale weathering!

Mending Broken Wings

Step 1: In extreme cases, you might break a foam wing in two (or more!) pieces. A great trait of foam is that it is usually very easy to piece back together. Mix up a small batch of 15-minute epoxy on a plastic can lid. Run two or three lengths of each part as shown and then mix together.

Step 2: Place some waxed paper or food wrap under the wing pieces and then apply just enough mixed epoxy to cover the exposed ends of the break. Use some masking tape to hold the parts together while they rest flat against your work surface. Be sure to wipe away any excess epoxy that oozes from the repair using a paper towel and some denatured alcohol.

Step 3: After the epoxy has set, remove the tape. Using a sanding bar, smooth out the repair area.

Step 4: If your wing is more than 36 inches in span, use a piece of thin plywood that is 4 to 6 inches long and ½ inch wide as an internal brace. Using a hobby knife and a razor saw, cut a straight line all the way through the wing, as shown. Test-fit the plywood, then apply foam-safe CA and insert it into the wing. Apply some accelerator, and let the glue set.

Step 5: After the glue sets, apply model filler to the repair and let the filler dry.

Step 6: Using fine sandpaper, sand the filler smooth and flush with the rest of the wing surface.

Step 7: Apply matching foam-safe paint, and let it dry. The repair is complete, but you can also apply some decals over the repair area, if you like, to completely cover the mended area.

Repairing Foam Hinges

Step 1: It is not possible to repair a live-foam hinge, where the hinge is molded in as part of the control surface. It is best to install new hinges in the damaged surfaces. Before removing the surface, mark the locations for the new hinges. For this rudder, three 1/8-inch Robart Hinge Points will be installed.

Step 2: After marking the hinge locations, take a sharp hobby knife and slice through the molded hinge to separate the rudder from the fin. Use some sandpaper to smooth the mating surfaces.

Step 3: Sharpen the end of a 1/8-inch brass tube, and use it as a drill to produce the holes for the Hinge Points. This produces much neater holes than a wood drill bit.

Step 4: Mix up some 15-minute epoxy, and use a toothpick to apply the adhesive into each of the holes in the rudder.

Step 5: Insert the Hinge Points into the holes, and set aside until the epoxy cures. Make sure that no epoxy gets into the pivot pins. If it does, quickly remove the hinge and install a new one. You have about 20 minutes before the epoxy starts to thicken and set.

Step 6: Apply more glue inside the holes in the vertical fin, and slide the hinges in the rudder into place. Again, wipe away any adhesive that oozes out of the holes with paper towels and alcohol. Set aside until the epoxy sets.

That’s it! Let the glue set and get your pride and joy back in the air.

Please share your easy repair tips in the comments below!

The post Easy Foam Airplane Repair Tips appeared first on Model Airplane News.

Simple Pushrod Guide

You may not always want to install a servo to operate the choke on a gasoline engine; in fact, many times you may rather have a manual choke. The issue becomes controlling the push/pullrod’s location so you can operate it when the cowl is installed on the plane. The answer is probably in your parts box: an old nylon control horn. By enlarging the hole, you can use the motor mount bolt to secure the control horn to the motor mount, and then use one of the control horn base holes as a guide for the pushrod. Since it is made of nylon, there is almost no friction and no RF noise to bother the ignition of the engine or receiver. It’s very simple to make, install, and works very well.

Cheap Sanding Files

Next time you get paint at the hardware store, be sure to get some extra paint stirrers. Glue strips of sandpaper of various grades to each side of the sticks; 3M 77 spray adhesive works great for this. You can also use sticky-back sandpaper. Now you have created a collection of useful sandpaper files! I find it’s also helpful to mark the sandpaper grit on the handle of the stick for easy reference.

After the Delivery

Don’t throw away those pizza boxes — they make great wheel chocks when transporting your favorite fuselage. Just cut holes to fit the tires —the plane size is only limited to the span of the pizza box. If you have carpet, such has the back of a car or a van, use some hook-and-loop fastener to keep the box and plane fuselage in one spot.

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Parting Trick

The protective backing on some covering films can be difficult to separate at first. A strip of masking tape applied to each side of the covering creates a handle on which to pull the sheets apart. Once you try it, you will never go back to separating them with your fingernails.

 

Replace broken dowels and screws

By using a hollowed-out drill bit, you can remove a broken dowel such as one used in the leading edge of the wing. First, find a piece of metal tube that can slide over the broken dowel. File cutting teeth in one end of the tube and then insert the other end in your drill. Use this to “core out” the broken stub. Use this same method to remove broken-off screws. Now just glue in a larger dowel and adjust the mating size hole or sand the dowel flush with the surrounding area and re-dill for the same size dowel you removed.

 

Little screws, big trouble

Tiny screws are the worst. You can use a pair of tweezers, but the screws are hard to handle and will often drop and fall off the bench onto the floor. Solve this by placing the screws into the holes and put a piece of clear tape over them. This will hold them there while you place the hubcap down onto the tire. Now you can easily start the screw by poking the screwdriver through the tape and turning them. This works very well and will work on any little screws that need to be put into a pre-drilled hole.

Transparent labels

You never know when your model might get away from you, and per AMA rules, you need to have an address label inside the plane. You also want a label near your charging jack with the size and type of flight battery you have installed. If you don’t have a label maker, here is a simple way to make a transparent label. Using a ballpoint pen, write on the adhesive side of the tape. The trick is to write backward, which is not as hard as you think. When you attach the label to the model, every word will read correctly and be protected from the elements.

 

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This 1/3-scale kit includes the front of the engine as well as four cylinder back halves as well as induction intake pipes, cylinder heads and valve rocker details all resin casted in white. Overall this kit is nicely detailed with lots to look at but it does need to be painted before installing it in your airplane. Being 33% scale it fits all sorts of Fokker designs including Glenn Torrance Models, Ron Weiss and Balsa USA kits.

Prep work

After removing the engine cowling, I placed the main engine piece over the Zenoah GT-80 to check the fit. It fits nicely over the front housing and propeller hub, and I added some stick on foam strips to make a snug fit. I also painted the bottom of the engine compartment area black to add some depth behind the engine.

As with all resin cast parts, before you can paint the engine, you have to wash all the parts in warm soapy water. I used dish detergent in an old pot and an worn out toothbrush to really give it a good scrubbing. If you do not do this important step, your paint will easily chip and peel off.

Be sure to really get into all the nooks and crannies with a good scrubbing to remove any mold release material that may still be on the parts.

After washing the parts I use a covering heat gun and speed the drying process. Now is a good time to also remove any rough edges and flashing left over from molding the parts. Fine sandpaper and a sharp X-Acto blade does a good job.

To get a good glue joint between the parts, I sand the parts with a belt-sander to produce a smooth flat surface between any mating parts. This includes the front and backs of the cylinders, and the tops of the cylinders and the cylinder heads.

For this project, I used the new ZAP “Brush-On” CA adhesive and applied the glue with the built-in brush applicator. It is very easy to apply a nice thin layer and avoid drips and excess adhesive dripping over the edges.

Here the back halves have been glued in place. Some fit perfectly while others need a little trimming to produce a smooth and flat surface. It is important to match up the cooling fins on the sides of the cylinders.

Once the surfaces have been sanded flat, GLue on the cylinder heads and then the rocker arm details. Medium CA works best for a good bond and for filling in seams.

Once the cylinder heads have been glued in place. You have to add the induction intake tubes. You can either trim the tubes to fit between the cylinders or you can trim away a little cylinder material to produce the clearance so the tube ends can be glued flat to the backside of the engine case. A Robart grinding bit makes quick work of the job. Here you can also see the foam strips I added to the center opening to fit around the model’s engine.

After the parts are all glued together I couldn’t help but put the engine in place and see how it would look with the cowl in place. The fit is perfect.

Aging with Paint

The process of making a model part look real, is to detail it layer by layer and do the same thing as is done with scale pilot figures. You start with a base coat, apply highlights and undertones and avoid solid colors. The steps are as follows.

Since the back of the engine has to painted too, I start with the back and check the coverage of the base flat black paint. I used flat black primer from Krylon applied with a rattle can. Be sure to spray square to the cylinders so you get the black in between and deep into the cooling fins. Also shown here is the lifter tubes I added made from brass wire and glued to the backs of the lifter arm details.

Once the back is dry, paint the front of the engine as well. be sure to cover all the parts and recesses, you don’t want to see any white.

Once the base flat black undertone has dried, spray on the silver base coat. Do this at a shallow angle to the engine to minimize the amount of silver that gets in between the cooling fins, then let dry.

Here’s one of my tricks so to speak. I then apply a light mist of Master Modeler “Burnishing” Aluminum over the Krylon silver. I mist onto all the smooth larger areas and then when dry, I use an old tee shirt to buff the parts to a smooth, new appearance. The is done to the engine case and the bottoms of the induction tubes. The difference is subtle but noticeable.

Again, I placed the engine on the Triplane to get a feel for how the engine is starting to look. The rest of the detailing is mostly done on the lower 4 cylinders that will be visible below the cowling face plate.

I now take Master Modeler flat black and thin it with mineral spirits for form a thin wash and I just paint it on and wipe it off over and over until I get the look I am after. You want it to fill recesses and seams and build up slowly with less color on the outer surfaces. This really brings out the fine details like the bold heads around the engine case and the spring details around the lifter arms. You can also add a wash of light brown to add oil residue here and there.

You really can’t make a mistake. If you apply too much, just wash it away with more mineral spirits before it dries. Next since this is a German rotary engine, it differs from the LeRhone engine in that that the induction tubes were made of steel and not brass or copper. So, they heated up a lot and produced a black and worn look that I reproduce with gloss black, flat black and Rub-N-Buf silver paste. Again, no solid black paint coats. Apply thin washes and scrub the parts with your brush. Flow it on and let it dry then flow on more. In a few areas like around the neck, apply blotches of glossy black to make it look baked on. Also add more black washes around the base of the cylinder and around the bolt heads.

The post Install a Scale WW1 Engine appeared first on Model Airplane News.

The original engine casting is available from Nick Ziroli Plans and just like all other parts of a scale model, the finer details are what make it look realistic. So the first step is to produce a master part to cast. Of course, if you want to save time and effort, the Evolution 1/4-32 spark plugs ($13) for the Evolution gas engines from Horizon Hobby are perfect for a 1/3-scale part.

At the very least, it can be used as a guide for making your own less expensive copies.

So I started with an old burned out O.S. #8 glow plug and turned down the unneeded threads and I drilled out the coil. This is easy to do with any small shop machine lathe.

I then used a piece of acrylic plastic rod (from Michaels Craft Store), and I turned the top insulator to shape. I used a jeweler’s file and 400 grit sandpaper to smooth it and then I flipped it around in the lathe chuck and drilled out its base with a 3/32-inch drill bit so it would fit over the top of the glow plug.

With a couple drops of medium ZAP CA glue, I glued the insulator to the glow plug. Looks pretty convincing to me. Now it’s time to make a silicone mold of the master part.

Everything needed for making resin cast parts and silicone molds is readily available online. Check on www.Amazon.com. I prefer to use Amazing Casting Resin (www.moldputty.com), and Alumilite HS3 Silicone molding material. If you prefer to make a 2-part mold, you also need the mold release spray. For this simple technique, we’ll make a single piece mold, since the HS3 is very strong and flexible so it can really be stretched to release your part after it cures.

The Base of the silicone is thick but pourable and it has to be mixed with its catalyst. You mix it 1 part catalyst to 10 parts base (by volume or weight,) with the included measuring/mixing cups.

I use a digital gram scale to make the ratios precise. so for 28 grams (1 oz. of base) you would then pour in 2.8g of catalyst. The base is white and the catalyst is pink. Mix it very well so that there are no swirls of color in the mixture.

To make my mold making container, I simply use a drop of thick ZAP to tack glue the master to the center of one of my mixing cups. This makes for a quick and easy setup. You could also use smooth sheet plastic and a base and glue a box around your master.

Once your mold mixture is completely mixed through, gently pour it into the container. Do this with a steady stream poured in from high above. This helps eliminate bubbles in the silicone as it flows around and over your master.

The silicone takes about 18 to 24 hours to fully cure, but you have about an hour before it starts to setup. Here’s a tip for saving the relatively expensive materials. Should you not mix enough silicone to cover your master completely, (you should have at least a 1/4 inch over the top of it,) you can insert objects into the container to raise the level of the silicone. AA and AAA batteries are ideal for this. But make sure what ever you use, that it does not come in contact with your master piece. Now set the mixture aside, on a level surface and let the silicone cure fully.

So here you see the master part, which is easily removed from the mold after the mold has been removed from the container. Notice the container and the master are perfectly clean. Silicone only sticks to more silicone and to nothing else.

Even the batteries come out easily.

The casting resin is a much less critical mix. Both parts are mixed together 50:50 and you have about a minute or two to work with it. Use the included mixing cups and sticks and mix together for 30 seconds. Again mix until there are no visible swirls in the mixture.

Here the resin has been mixed together and is ready to pour into the opening in the top of the silicone mold. Notice I re inserted the batteries to ensure the mold isn’t deformed before pouring in the resin.

Very quickly, the resin with start to turn white as it cures. An unusual aspect of casting resin is that larger batches of it cure more quickly than smaller amounts. So, the left over material in the mixing cup will fire off in about 2 minutes. And the material in the mold will take somewhat longer to cure. This is because the chemical reaction is a thermal event, and the mixture gets hot to cause the resin to cure. The less resin, the longer it takes to cure.

Here you see the resin is still clear. Time in mold, 2 minutes.

After about 3 and a half minutes you see the center of the casting is starting to turn white.

Here it is after 5 minutes. It is still not opaque but getting close.

After about 15 minutes the casting is completely white and as you can see, if you stretch the mold, it easily separates from the inside of the mold. I use a pencil to tap the top of the casting while it is in the mold to see when it is hard. if the casting is still soft, you will leave slight indents on the outer surface of the casting. In about 20 minutes the part is hard enough to pull out of the mold.

(Tech Tip) Because heat is needed to cause the resin to cure, you can speed the process by preheating the mold. This can be done by placing your mold in a 175 degree heated oven for about 10 minutes. Then the resin casted part will cure more quickly.

So here is the resin casted part next to the master. As you can see it has the same smooth surface as the original part, straight out of the mold. It has the same exact details as the original part and after about a half hour, the cast part is fully hardened. You can easily drill it, cut and sand off the waste material and paint it. ZAP CA glue works great for gluing unpainted resin casted surfaces.

So here is the original resin casted part I made using an actual Evolution 1/4-32 spark plug as a master. I made several reproductions using a 2-piece mold.

Here’s the painted and detailed rotary engine with four spark plugs and ignition wires added. Subtle detailing is what scale RC is all about.

2-Parts Molds

Two piece molds are a little more involved to make but the basic techniques is the same. For 2-part molds, I recommend HS2 silicone molding material. It is slightly less stretchy and is more suited to this type of mold.

The technique requires making a molding box, (Lego Blocks work great), and then adding a 1/4 inch thick layer of modeling clay in the bottom of the box. You then press the master part into the clay so that half of it is exposed.

(Above) Here’s the finished casting with the mold haves opened.

Use the back of a paint brush handle to poke indents into the clay next to the part. These form keying nubs that help align the finished mold halves. After this you pour the first half of the silicone material into the box to cover the master. Once the silicone has fully cured, (24 hours,) flip the mold box over, and remove the clay.

Clean off any scrap clay from the master. Now spray on a healthy coat or two of mold release agent over the  silicone mold and replace the part in the mold. Make sure to completely cover the face of the silicone mold or the second half will stick to it sealing your part inside. Now mix and pour in the second half of the mold into the box and let cure overnight.

Separate the mold halves, remove the master and then, with a sharp X-Acto blade, cut in a pouring channel so you can pour in the resin. To cast a new part, tape the two mold halves together and place on a level surface with channel opening at the top. Mix and pour in your casting resin and the rest of the technique is the same as described earlier.

So there you have it, Resin Casting made, easy. Give it a try.

The post Resin Casting Scale Parts appeared first on Model Airplane News.

All adhesives from Zap Glue. The wing is from Gerry’s 1/3-scale Fokker Triplane built from a Balsa USA kit.

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