Author Topic: Cessna 340 1:32  (Read 2451 times)

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JeffH

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Cessna 340 1:32
« on: October 06, 2009, 07:32:41 PM »
I didn't find much time for model building during the summer of 2009, but I did manage to start a 3/8" = 1' Cessna 340 and will post some in-progress shots.

The fuselage and engine nacelles are constructed from clear aspen (the fuselage is laminated from 3/4" stock).  The tip tanks are basswood and the tail parts are pine.  The wing is mystery wood from a discarded dresser found while dumpster diving some time ago.  The model is based on a tiny drawing found in a library book on Cessna aircraft.
« Last Edit: October 06, 2009, 08:42:37 PM by JeffH »

JeffH

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Re: Cessna 340 1:32
« Reply #1 on: October 06, 2009, 07:35:38 PM »
This view shows the disassembled parts.  The wings and tip tanks are held on with metal pins.  The tail pieces fit into slots cut into the fuselage.

JeffH

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Re: Cessna 340 1:32
« Reply #2 on: October 06, 2009, 07:42:33 PM »
This close up shows the method I used to attach the tip tanks to the wings.  The tanks were first tacked in place with a drop of Cyanoacrylate glue ("Super Glue" or CA cement).  Next, I packed the gap between the wing and tank with sawdust and blew away the excess.  I then flooded the gap with CA.  The adhesive dries quickly upon soaking into the wood to fill the gap and bond the tank firmly to the wing.  It's possible to fill enormous gaps this way.  I used the same technique to attach the other parts of the model as well. 

The old butterknife in the photo was used as a scoop to apply the sawdust and the bamboo skewer was used to tamp the sawdust down into the gap.
« Last Edit: October 06, 2009, 07:47:52 PM by JeffH »

JeffH

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Re: Cessna 340 1:32
« Reply #3 on: October 06, 2009, 07:51:23 PM »
After the model was assembled, latex based wood filler and catalyst activated auto body putty (Bondo) was used to fill any remaining gaps and gouges in the model.  The wood grain was sealed by applying multiple coats of fiberglass resin (the same polyester resin used in fiberglass construction) with sanding between coats.  

The sanding tools posed around the model are from left to right:  The device with the handle is made by 3M and was found at a local Home Improvement store.  The handle rotates and I've found it to be a useful tool for sanding irregular shaped surfaces.  Next are a couple of Applied Design Corporation Mini Sanders from a hobby shop.  Their shape makes them useful for sanding corners such as the wing-fuselage junction as well as flat surfaces.  After the original sand paper strips wore I out I replaced them standard sandpaper cut to size (save the original sand paper strips to use as a pattern for cutting replacements).  I found the paper last longer if first backed with duct tape before cutting to shape; I likewise used a strip of duct tape to secure the back of the metal ring where the sand paper strip attaches.  On the right is a sanding block from Harbor Freight Tools.  The sanding surface features a foam pad which provides some "give" for the sandpaper.  It's useful for sanding large relatively flat areas.

The fiberglass resin sets up fast, and can be sanded within a couple of hours of application.  After the last coat of resin was sanded smooth, I found a couple of small spots where I had sanded through to the bare wood.  Instead of re-coating with resin, I applied cyanoacrylate cement to the bare wood areas and then sanded them smooth.  The model was then ready for its first coat of primer.
« Last Edit: October 06, 2009, 08:50:03 PM by JeffH »

JeffH

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Re: Cessna 340 1:32
« Reply #4 on: October 06, 2009, 08:11:44 PM »
The photo below was taken after the first coat of primer has been applied.

Lately, I've been using Dupli-Color Primer Surfacer purchased at an auto parts store rather than rattle cans for the initial primer coats.  The up-front cost is higher, but one can of primer like that shown is enough to cover a large number of models.  I've also found this product can be applied in multiple coats without runs or drips, and it dries extremely rapidly (it's ready to sand down as soon as I'm done putting the airbrush away).  In the can, the primer has a paste-like consistency, so I first transfer a small quantity to the jar on the right, then add enough thinner to reduce it to the viscosity of skim milk.  That mixture is then decanted into the airbrush jar.  On a model this size, I'll spray two or three airbrush jar's full of primer in one session.  The primer sprays best at around 30 PSI (higher than I would use for applying paint).

The apparatus used for spraying primer is shown in the upper left and is another inexpensive Harbor Freight Tools purchase.  The device lacks precision for detail work, but is just fine for applying primer.  In hot weather the breather hole on top of the jar will sometimes clog with dried paint, so I keep a piece of wire nearby to clear the blockage.  Other than that, I have had no trouble with it.
« Last Edit: October 06, 2009, 08:41:19 PM by JeffH »

lastvautour

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Re: Cessna 340 1:32
« Reply #5 on: October 07, 2009, 04:23:10 AM »
Outstanding work Jeff. I admire all your modeling skills.

Lou

dave_t

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Re: Cessna 340 1:32
« Reply #6 on: October 07, 2009, 05:01:54 AM »
I like how you solved the problem of attaching those over-sized nacelles by cutting notches in the wing. That method allows you to rotate the nacelle into the correct angle in relation to the fuselage (something I've had trouble with at times).