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

The post Removable Engine Installation appeared first on Model Airplane News.

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..

The post 4 Simple Shop Tips appeared first on Model Airplane News.

Here’s the Starting Point of the ARF Corsair

The Corsair comes with a molded-in floor allowing for only a pilot bust but I cut it away to installed a full-depth depth cockpit. I used the parts from a Ty’s Models cockpit kit, available from VQ Warbirds, to add a little extra detail to Pappy’s “office.” With all that taken care of, it was time to work on the canopy.

SLIDING CANOPY

I felt it was a shame to hide my scale Pappy under a full canopy so for this project I wanted the canopy to be functional. In the past I have only ever made canopies open manually, but for the Corsair, I went the extra mile and make the canopy open with my transmitter.

The canopy alone is very flimsy and brittle and running it under warm water before cutting helps ease trimming. I wasn’t confident that it would hold up so I ordered a replacement from VQ Warbirds which is identical in size and shape. I needed to stiffen the canopy frame so it would hold its shape while opening and closing. Using the original, un-cut ESM canopy, I taped it to the fuselage and made a simple external balsa frame to keep the canopy’s shape once I removed it from the fuselage.

External Bracing in place

I then removed the balsa cradle and canopy from the fuselage and sprayed the inside with some universal mold release. I then laid in two layers of carbon fiber cloth and allowed the epoxy to cure overnight. After popping it out of the canopy, it was trimmed to shape and became the perfect internal frame for my sliding canopy.

A little spray of mold release inside the canopy prevents the layup from sticking in place.

After the resin cures, the carbon fiber molding pops right out.

Nice and smooth and it fits the canopy shape perfectly.

Carbon fiber framework cut to shape.

For the guide rails, I used some slotted square brass rails and carefully installed them in the fuselage sides and along the inside edge of the cockpit opening. Ball links are used to capture canopy inside the rail and allows it to move with the use of a single, long-stroke air cylinder located forward of the instrument panel.

Guide Rails made from K&S Square Brass Tubes slotted with a Moto-Tool and Cutoff disk.

Guide Rails in position.

This arrangement gives a “push to open” and a “pull to close” operation. I cut the carbon fiber frame to shape with a Moto-Tool and a cut-off disc and then I glued the clear canopy to the inside of the frame. The canopy be removed from the rails by unscrewing the ball links which pass through the frames.

Operation

If I had more channels on my transmitter I’d put the canopy function on its own switch.  At the time I built the model, I only had an 8-channel radio so I slaved the canopy function off the flap channel with a Y-harness.

Internal Drive setup to open and close Canopy.

I set it up so canopy does not open during landings (with one notch of flaps dialed in.) The model doesn’t need full flap to land. After landing I add another notch of flaps and the canopy sides open. The flaps do move down a little bit more but it only on the ground and does not affect anything else. With a 10-channel radio, it would be simple to assign the canopy function to its own channel and open it on command.

Which way to the front!?

Having this bit of animation added to any scale plane greatly increases it realism and sends the “Wow Factor” right off the charts. For a little bit of work, you get a lot of attention. Give it a try, you’re buddies will be amazed!

Canopy all buttoned up, ready for takeoff.

Doesn’t look like an ARF anymore! Weathering helps a lot too!

 Article and photos by Sean McHale

The post Install a Sliding Canopy appeared first on Model Airplane News.

The post The First Fokkers! appeared first on Model Airplane News.

Featured Photograph courtesy of Ken Isaac (RCKen)

“Since the WOTR is a flying event, I expected some polished, stand-out performances and I wasn’t disappointed. Some of the nicest, most consistent RC formation flying I’ve seen lately came from Model Airplane News contributor and owner of Best Pilots, Lyle Vasser and his buddy and wingman, Steve Forrest flying a pair of Top Flight giant scale Mustangs. They’ve been doing this for a number of years, mostly at meets and shows west of the Mississippi.

They are really good and impressive to watch. This isn’t two guys just flying similar models in the same chunk of sky, they really do join up, matching speed and altitude throughout their routine. As many of you who have tried it already know, it ain’t easy and takes lots of practice. They seem to have pretty much nailed it. Maybe they’ll make their way East so the other half of the country can appreciate their skills!

And of course, these amazing Mustangs also have the ultimate detail inside the cockpits–Best Pilot figures at the controls!

Post photos by John Dussold

The post RC Warbird Formation Flying appeared first on Model Airplane News.

Painting your model is the last bit of finishing and it’s the part most noticed. For great results use the same paint as used on full size airplanes. stits.com is the place to get the stuff. Poly Tone paint works great and is designed to work with the heat shrinkable Poly Fiber covering.

That big radial engine cowl reaaly benefits from a dummy engine installation. If you don’t have the cash for a Robart 4-stroke 7-cylinder radial engine, there are plenty of resin cast dummy engines that will hep cover up your RC gas engine. And the finer details like proper color, lifter rod tubes and spark plugs and wiring all add to the appearance.

So, you do have to get inside the airplane to work with and maintain the radio gear and linkages, so why not add functional cabin doors. These work great and give easy access to the internal parts. A removable cabin interior helps hide the RC hardware.

For the various RC radio gear and engine ignition switches placing them in a secluded area like here between the fuselage firewall and the engine cowling, greatly improves the model’s looks. They are just as accessible as they would be if you had just cut holes in the side of the fuselage and installed there there. Of course that ruins the scale looks of any airplane.

As with most Ziroli designs, the Staggerwing is designed to use the custom made Robart Staggerwing gear. Besides saving a ton of time and effort, the Robart gear work great and are very scale in appearance.

Those wheel also look great and are machined from aluminum.

The post Super-Scale Beechcraft Staggerwing appeared first on Model Airplane News.

While reading through an old issue of Model Airplane News, I came across an article about float-flying off water. It started me thinking about how much fun it would be to fly off snow with skis. First on my agenda was to pick some suitable subjects to modify for ski installation. That was the easy part, because my Stinson L-5 Sentinel and Cessna L-19 Bird Dog were just begging to get out of winter storage and be drafted back into service. They are both 1/4-scale tail-draggers and are very suitable for trudging through snow. After working out a few logistics, I cleared a spot on the drafting table and got started. My intent was to come up with a ski design that was simple, easy to build and would use up some of that “leftover” material we all seem to have lying around the shop.

SKI DESIGN
To get a better feel for the design requirements for skis, I took a quick look through some full-size aviation magazines for possible articles on winter flying. I came across an issue of the EAA magazine Sport Aviation. This particular issue had a short article about winter flying with skis. The article contained some neat color photos of two Piper J-3 Cubs on a snow-covered runway at a grass field. The J-3 is probably the most common aircraft that’s outfitted with different brands of skis, and this supplied me with a few ideas on designing a simple, yet effective, set of skis for my own 1/4-scale models.

After measuring the skis and fuselages of the Cubs in the photos, I calculated their comparative lengths, and used these figures to plan the dimensions of my skis. I then generated a rough draft of the full-size drawings for the 1/4-scale skis following the tried-and-true “That looks-about-right” formula (here’s to good old eyeball engineering!). The length of the skis would be approximately 50 percent of the fuselage length, and the axle pivot point would be at 30 to 40 percent of the ski length aft of the ski nose. For the width, I just picked a number that felt right.

MATERIALS
The materials I used for the skis are well-known by all modelers and, depending on the weight of your model, the skis can be made of 1/18, 3/16 or 1/4-inch-thick lite-ply or luane (the plywood material used to skin interior household doors). For models that weigh up to about 15 pounds, use 1/8-inch thick material. For models of 25 pounds or more, I recommend 1/4-inch-thick material (both the L-5 and L-19 are in the lower 20s, so I chose to use 1/4-inch thick lite-ply). I’ve found that metal skis generally mean trouble because snow really likes to stick to cold metal. Wooden skis seem to work better; but just be sure you sand the bottoms silky smooth, seal them well with polyester resin, polyurethane, or epoxy and then apply a good grade of wax. We’ve successfully used beeswax, as well as high-grade automotive paste wax. The wax will prevent the snow from sticking and also will allow the model to really slide across the snow.

Lay out the patterns on a flat piece of material and cut the outlines to shape. To get the nose of the ski to bend up and match the curve of the stiffener, a series of cuts is made across the skis top surface. These cuts are only 1/2 the material thickness deep and are only required in the nose area that needs to bend. This process is called “kerffing‚” and I simply used a utility knife to score these cuts. Just prior to bending this kerfed area, I also fill the cuts with glue so that when all the glue sets, this area will be nice and strong. The center stiffener and the two axle mounts are made of various types of plywood. For 1/4-scale models, the center stiffener is 1/2-inch thick, exterior grade, house-construction plywood, and the two axle mounts are 1/4-inch thick, aircraft plywood. I also like to add spacers to each side of the axle supports so that the final thickness is the same as the wheels that I use on that model. This makes the process of switching from wheels to skis and back again, very easy and fast.

The entire assembly is glued together with 20-minute epoxy and clamped in place to cure. After curing, all the areas are sanded and then coated with epoxy and sanded again. Next, they are painted with a couple of coats of paint and topped off with some clear polyurethane or epoxy.

FUSELAGE CONSIDERATIONS
 One of the neatest things about this design is the ease with which you can switch from wheels to skis. This is very important when you get that unexpected snowfall and last-minute calls from your flying buddies to meet them at the field. It will take only a few minutes to change from wheels to skis.

There is only one modification needed for the fuselage; two pairs of eyehooks need to be installed to act as attachment points for the cables. Install two in front of the landing gear, one on each side. Attach the skis, nose bungee and safety cable (more on these later) to these eyehooks ahead of the landing gear. The other two eyehooks go aft of the landing gear, (again, one on each side of the fuselage), the rear-extension limiting cables will be attached to these. To make these attachments sturdy, I simply epoxy some hardwood blocks inside the fuselage and permanently screw the eyehooks into place (see photos). I leave these in place all year long, so I do not have to make any changes when the weather makes an unexpected turn. I painted these eyehooks to match the fuselage and this way, they just get camouflaged and disappear very nicely.

SKI SETUP
To set up your skis properly, there are two basic, yet very important alignments to maintain.

Toe-in: The skis must be parallel to each other, as well as to the fuselage centerline (a function of the landing gear-axle toe-in adjustment).

Angle of attack: The skis’ angle of attack must be approximately 10 degrees positive while the aircraft is in flight (a function of the bungee and aft limiting-cable adjustments).

The nose bungee is big rubber bands that lift the tips of the skis. To limit how high the ski noses rise, you have to adjust the lengths of the rear-limiting cables. I like to make these adjustments on the workbench with the skis mounted on the axles (held in place with wheel collars) and the airplane’s tail propped up. To get the required 10 degrees of ski nose-up attitude, I keep the skis flat on the bench and then raise the tails that the plane’s nose is set at a flight attitude of negative 10 degrees. A stack of paint cans works very well here! If you’ve set everything up properly, when you lift the model off the bench, the bungee cords will lift the noses of the skis and make the aft limiting cable taut. When the model is placed on the ground, the aft cables should slacken and the skis should lie flat. It’s important that they also be able to pivot freely on the axles. As an added safety measure, I suggest you run a safety cable alongside the nose bungee. This cable is adjusted when the model is sitting on the ground in the normal “at rest” attitude. The safety cable is attached at the same spots as the bungee, yet at this attitude, this cable should be taut. The idea here is that in the event of a bungee failing, you do not want the ski to turn nose-down on you in flight as it makes for a very messy landing. To make it easy to attach the bungee cords and cables, I install line connectors or some other form of “quick-disconnect” device at the fuselage attachment points. Old control-line connectors work well and you might also find similar connectors in a fishing-tackle store.

To make it easier to remove the wheels from my models, I replace the usual wheel collars with cotter pins that go into small holes drilled through the end of the axles.

TIPS ON SNOW FLYING
 With all the shop work finished, now it’s time to head to the field. The toughest part is waiting for the snow and then having it arrive at just the right time, like on a Friday night so that Saturday can be a day at the field with nice fresh snow. I live on Long Island, NY, and we don’t usually get much snow, but last winter we had so much snow that it was difficult to get to the field! Regardless of how much snow we get, when we get an opportunity like this, the “Snow Bird Squadron” gets together and makes it to the field for some really great, off-ski flights.

When flying off snow, remember these tips:

• You’ll need to apply slightly more power to taxi. If you have no ski attached to the tail wheel, the rudder will also need a blast of power for turning.
• You’ll need more power for takeoff, and the skis will have to “plane” on the snow before you’ll be able to build up air speed. To overcome torque, apply the throttle gradually and smoothly and feed in the rudder as required (just as if you were flying off a green runway). You may need a bit more elevator to prevent the model from attempting to nose over, but once the speed builds up and the skis are “on plane” you’ll be able to release the elevator. When it’s equipped with skis, your model will not fly as fast because skis increase drag. When flying with wheels, don’t expect to pull up as steeply.
• Increase power during landings and use a slightly nose-high, three-point, or wheel-landing approach to keep the tips of the skis up. For short-field operations with my L-5, I particularly like the “I have arrived, three-point, plop-type” of landing. The fun part for me is just shooting touch-and-go’s one after another.

Using scale-snow skis is a really easy way to extend your flying season. Before heading out, make sure all your radio gear is up to snuff. Cold weather wreaks havoc with batteries, as well as people. Just dress warmly, you don’t want frostbitten ears, toes or flying thumbs and be sure to take along some hot coffee or hot chocolate. Oh yes, and sunglasses are definitely in order. Enjoy!

Here are all the wooden parts cut out for one set of skis (see text for details).

Closeup view of the kerf cuts and how they help to bend the nose up to match the curve of the center support.

All the parts glued and clamped in place to cure. Lead bars and clamps (and anything else that is heavy) aid the process.

Another means of  “clamping”  the assembly is to use anything from around the shop that is heavy such as a can of Bondo or old car parts.

Close up of the axle attachment area with filler pieces between the uprights and on the outsides to make the attachment area the same width as the wheel originally used. Note the cotter pin and washer. Very easy installation.

With fuselage propped up so the nose is slightly down you can see the rear attachment cable is taught and the front bungee stretched.

Same as photo 6 but fuselage attachment points can also be seen.

Roy Vaillancourt designed and built this 1/4-scale Stinson L-5. It weighs 21 pounds and is powered by a US-41 engine. Latex paint (but of course).

Roy Vaillancourt designed and built this 1/4-scale Stinson L-5. It weighs 21 pounds and is powered by a US-41 engine. Latex paint (but of course).

The post Easy Scratch-built Skis (fly off the snow!) appeared first on Model Airplane News.

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 kit comes complete in one larger box and it contains everything you need to build the machine.

Lets take a closer look.

All the well packaged parts are German-made and they are of the highest quality.The system when fully assembled and running is well suited for producing all sorts of model aircraft parts with the highest quality and tolerances. The 2/420 along with its optional accessories, is perfect for making parts from wood (balsa, lite-ply, plywood and other hardwoods), various plastics and foam such as polystyrene, Styrofoam, EPS, Depron, Selitron, ABS, polyethylene, polypropylene (EPP), PVC, Lexan, Polyamide, Plexiglas, as well as fiberglass and Carbon Fiber sheet material. It is also perfectly suited for machining non-ferrous metals like aluminum, brass and copper.

All the parts and pieces required except for the spindle (power head) are included. Being a 3D milling machine, the system includes all the moving parts for the X, Y, and Z axis gantries including stepping motors, lead screws, and precision-machined tracks made from extruded aluminum channel. All the hardware is top notch and includes all the screws, nuts, washers, bearings, bushings and track rollers. The frame panels, gantry uprights and the end plates are all made of thick, powered-coated aluminum and all the fastener holes come machined into the parts. All the electronics including the main control circuit board, limit switches and wire harnesses are also part of the package. The main work surface is made from 3/8-inch laminated medium-density fiberboard (MDF) which slides easily into place for quick replacement.

There’s no soldering required and all the wiring easily plugs into place on the main control board which screws into place.

All Stepcraft CNC systems come with the required “CNCDrive” motion control program on a CD, as well as a nicely-illustrated assembly manual. The manual shows every step in detail and calls out all of the required parts and hardware for each task. Stepcraft also provides online tutorial videos which are divided into separate steps corresponding with those in the printed assembly manual.

Combining all of this with the company’s excellent Connecticut-based customer service makes putting together one of the Stepcraft kits very easy. In total, I was able to build the 2/420 desktop CNC system in about 8 to 10 hours, but I was also taking photos along the way. The tasks for the assembly are made very easy as the instructions are very well illustrated and all the hardware and parts are well identified and easy to find as everything is well packaged. The instruction booklet also identifies every single piece in the first 6 pages so you see what each piece is and where it goes.

The frames, end plates, guide tracks and the stepping motors all fit together amazingly well and there are only a hand full of tools required.

Being a 3-axis milling system, there are three stepping motors, one for each axis. The frames, end plates and gantry uprights are sturdy machined aluminum that comes powered coated for protection.

The lead screws that are attached to each motor are precision made and they mate to the lead screw nuts that are attached to each moving part.

The Tracks are made from precision-made extruded aluminum and they provide smooth travel.

The first part you assemble is this Z-X Combination plate which supports the vertical Z-axis track and connects it to the X-axis cross track.

Here is the vertical Z-axis track and stepping motor attached to the X-axis cross track.

Spindle Choices

Shown on the Stepcraft website, there are several choices for spindles that you can ordered with the 2/420 system. For this review I chose the Kress 800W spindle. Priced at $309.00 the Kress 800 FME is a milling and grinding motor with full wave electronics providing consistent power and speed control. It has a soft start-up and start-current limitation, carbon brushes and a stainless steel motor flange with dual bearing for high speed milling performance. Other spindle choices are the Dremel 4000, Dewalt DWP611 Trim Router, and the 500 watt Stepcraft HF-500  brushless DC spindle. When you order your spindle, the kit comes with the proper tool holder bracket to fit your spindle of choice.

What to do with the Stepcraft CNC?

We will be continuing to add posts to the MAN website with additional information and photos on the assembly of the kit and the use of the CNC desktop system. I will be producing RC airplane parts from plywood, carbon fiber and G-10 filled Fiberglass Glass sheet material, including step by step details for using the required software to produce the tools paths and making the G-code to operate the system.

The post Desktop CNC — DIY System for RC Modelers appeared first on Model Airplane News.

We used the landing gear itself as a spacer for the rails and plywood ribs, so we know they will fit perfectly into place after the wing panels have been sheeted. I even added an extra 1/8 inch of space so there’s a little wiggle room in case we need to tweak the gear’s position for proper toe in measured at the axles.

After getting the support ribs and rails in place, I added a lite ply support doubler to the W-6R rib which has it mid-section cut away to clear the wheel and forms the wheel-well area. Also at this point it is a good time to go over the entire wing structure and sand everything smooth and flush.

Also where the main spar is recessed to clear the strut when the mains are retracted, I added a 1/4-inch plywood doubler for additional support . This part, like the gear rails is epoxied into place

Sheeting 101

To get started, look at your plans and estimate how much sheeting you will need to cover your wing panels. For this project I am using medium-grain 3/32-inch x 4-inch wide x 48-inch long sheeting. You should have a good supply of no. 11 X-Acto blades.

I start by first truing the edges of my sheeting by cutting a small amount, (1/16- to 1/8-inch), from the side edges using a sharp blade and a long metal straight edge. This allows the seams between the sheeting to be tight and minimizes the gaps.

I start with the bottom, aft sheet which forms the wing’s trailing edge. I cut it to length, pin it over the plans and then pin the wing structure over it. I then tack glue a couple of ribs along the  length of the wing panel to the sheeting. This is the easiest piece to apply as you have full access to the wing structure. Once this is in place, I add the next piece of sheeting that is cut to cover the area from the Trailing edge piece to the main spar.

You can start anywhere, but I like to begin at the tip rib, applying Zap medium glue to the rib and sheeting, hitting with a little Kicker, then moving inboard one rib at a time. The important thing here is to not force anything while gluing the structure to the sheeting so you don’t warp the wing. The washout was built into the wing when it is assembled over the plans and supported with alignment shims. We will recheck the washout again before applying the wing’s top sheeting.

Here you see the next piece of bottom sheeting. It is made by gluing two sheets together as mentioned above to cover the area from the front edge of trailing edge sheeting to the center of the main spar. Start by taping the pieces together with painter’s tape as shown above.

Flip the sheeting over, and prop the seam up so it opens like a book, apply some yellow glue like Titebond, and scrap away any access.

Weigh the sheeting down and let the glue dry. If there is still access glue at the joint, use a damp sponge to clean it away. Once the glue has dried, lightly sand the joint with a sanding bar then cut the piece of sheeting to size.

Here the sheeting has been taped to the trailing edge sheeting piece and the front edge is glued and clamped to the main spar. Again, there should be no stress or pressure causing the wing to twist out of shape.

With the center piece of sheeting taped and clamped into place, flip the wing panel over and start gluing it to the ribs and stringers. I use Titebond at the main spar, and Zap medium CA for the rest of the rib bottoms applied from above.

At this point I added the alignment dowels to the ribs that form the separation line for the outer wing panels that will plug into the wing center section. Here the fixed end of the front dowel is secured with a square of 1/4-inch plywood.

The receiver end of the dowel is supported with a square of 1/8 inch lite plywood glued to the rib, but not the dowel.

Above you see the same treatment for the aft wing panel alignment dowel.

Here you see the two W-10 plywood ribs forming the separation line between them.

Other internal parts that need to be glued in place are the wing hold-down screw support block shown above. I made it from 3/4 inch thick poplar, cutting, and sanding it to shape so it fits flush between the upper and lower sheeting.

Also before we can cover the front section of the wing panel forward of the main spar, we have to epoxy the outer wing panel attachment bolt support blocks in place between the wing tube socket tube and the bottom wing sheeting.

To keep the blocking flush with the main spar, I used an alignment piece weighted down with a piece of lead. This ensures that the pieces are securely epoxied together and that the sheeting will fit flush over the blocking. After the wing has been completely sheeted, I will drill a hole through the sheeting and blocking, into the aluminum wing tube. This will then be threaded to accept the attachment bolt.

The lower leading edge sheeting is applied in the same way as before. Cut the sheeting to length and shape and tape the pieces together, Here the short sections inboard of the landing gear area is shown.

Apply yellow glue to the top of the spar and the ribs and then tape and pin the sheeting into place. I also tape the leading edge tightly over the sub-leading edge strip and use some clamps to form a tight seam. Now let dry.

(Above) So, again the sheeting for the lower leading edge forward of the main spar, outboard of the landing gear rails, has been cut to size, glued together, weighted down to dry and then sanded smooth .

Here all of the bottom sheeting has been installed on the left wing panel. The area near the root ribs is left unsheeted so the two panels can later be epoxied together and the two plywood dihedral joiners inserted and glued on place.

Before gluing the top sheeting in place, install all the other items like hard-points for the drop tank pylons, and so forth. Once the top sheeting is in place, you won’t be able to get to them.

So now we do the same for the wing’s top sheeting. Glue and tape the pieces together, sand smooth, cut to size and glue the section of sheeting in place with Titebone yellow glue. Apply the glue to the top of all the ribs and the spar but be careful not to get any glue in the separation line between the two W-10 ribs. I added just a small amount to the every edges of these ribs as more glue can be added when the inner and outer wing panels are cut apart and separated.

Here you see the aft sheeting is cut to end at the centerline of the main spar. The sheeting is cut so the grain runs parallel to the trailing edge.

These cuts in the bottom sheeting are guides for the cut line between the main wing and the removable wing tip sections. They were cut through before the top sheeting was applied.

Also before the top sheeting is glued in place, the trailing edge of the bottom sheeting must be sanded to bevel the edge so it is flush with the wing ribs. The provides a good purchase for the top sheeting to glued to.

To keep the trailing edges straight while the glue dries, I add a straight piece of wood under it and clamp and pin the trailing edge to it. be careful not to glue this support piece in place. Wipe away any glue that oozes out.

Also before the top sheeting is glued in place, I marked the cut lines with a pen for the ailerons and the flaps. This makes the task of removing the control surfaces much easier and cleaner.

Also before installing the front top sheeting to the wing, add any pieces that will be covered up. Here you see the vertical sheer webbing being glued into place.

Here the right wing is shown with the sheeting weighed down with Scuba diving shot bag weights. As the top sheeting is applied the wing structure must be placed back onto the washout alignment shims so the wing retains its proper shape.

Here you see the tip end of the wing. It shows the shim strips as well as 1/4 inch thick shims added to raise the panel above the workbench. When we added the landing gear mount rails they protrude below the surface of the wing so the additional shims are required so they clear the work surface. The shims run along the main spar as well as the under the washout shim strips.

Once the sheeting has dried, you again prepare the sheeting for the top section forward of the main spar. Here above, you see it pinned to the main spar and taped down onto the sub-leading edge strips. Once the glue has dried, your will sand the front of the wing panel smooth and straight and add the 1/4 inch leading edge material and then plane and sand it smooth to complete the wing.

Here’s the completed left wing panel with the shaped leading edge in place. I have installed the Hangar 9 Angle Pro digital level to check the washout of the wing panel.

With the panel blocked up so it won’t move, I zeroed out the reading at the root rib.

I then moved the level to the wingtip and checked the reading. The plans call for -2 degrees of washout and this shows it is spot on. The trick however is to have your other wing panel come out with the same amount.

So here we are, both wing panels have been sheeted and and the root section as shown above has been left open on the bottom. This will allow us to glue the wing panels together and then inset and epoxy the plywood dihedral braces in place to strengthen the wing structure.

Here the plywood dihedral braces are being epoxied into place. Slow setting epoxy is being used so there is time to make sure the alignment of the two wing panels is correct before the adhesive cures.

The wing panels have been glued together and the wing is now ready to be installed on the fuselage.

Check out the Ziroli Plans website at: https://ziroligiantscaleplans.com/

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