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Member Projects => Ken N's Project Board => Topic started by: Model Maker on November 20, 2016, 06:14:06 PM

Title: Dehavilland DH 88 Comet Chidren's Toy
Post by: Model Maker on November 20, 2016, 06:14:06 PM
I promised myself that I would make a wooden model as a Christmas gift. However, I need to expand my repertoire, so I've developed a set of plans for a 1/32 scale toy DH 88 Comet. I must admit, I am very impressed with Gordon's and Jeff's models of the Comet and so I thought maybe a young child might also be impressed by the sleek lines. Once the model is complete and any kinks worked out, I'll post a set of PDF plans underneath photo 1 for anyone who is interested. The fuselage is true to standard plans. However, I have beefed up the wings and stabilizers to minimize any breakage. For added safety, I've also widened the wing tips so they are not as pointed.

Photo 1 shows the the various shapes laid out and ready for cutting. I've opted for the tang on the fuselage and nacelles to facilitate clamping while shaping is in progresses.
Title: Re: Dehavilland DH 88 Comet Chidren's Toy
Post by: Model Maker on November 20, 2016, 10:10:19 PM
Roughing out in progress.

Photo 2 shows the wing being started. The dihedral angle was rough cut using a bandsaw and planed smooth using a small block plane and a chisel. Since it's a toy, the dihedral can be omitted and the wing kept flat to make things simpler.

Photo 3 shows all the parts cut out. I find cutting kerfs for the wing dado makes chiseling out the waste material very easy. A few strokes with a sharp chisel and all the pieces are removed. I then tidy up the back surface of the dado using a 3/4" or 1" chisel. The wide chisel allows me to "float" the back of the chisel against the back of the dado allowing the chisel edge to shave the high spots.

Photo 4 shows the fuselage parts dry fitted.

Photo 5 shows the wing shaped and sanded. I used the bow sanders to shape the edges and the velcro sanding blocks (see tools section if interested). Both worked great to remove material quickly, especially when using the courser sanding papers and provided a very smooth surface with the finer sandpaper grades. Since this is intended to be a child's toy, I opted to modify the wing by replacing the pointed wing tips with a wider straight wing tip to prevent possible eye injuries, etc. I also made the wings thicker along the entire length to minimize the chance of breakage.

Next step - on to the nacelles
Title: Re: Dehavilland DH 88 Comet Chidren's Toy
Post by: buccfan on November 21, 2016, 10:26:34 AM
Nice work Ken, it's always interesting to see the step by step progress of a project making it easier for others to follow, as in yours  and Lou's models,and to see your tooling ideas making things easier. Thanks for posting. Regards Paul J.
Title: Re: Dehavilland DH 88 Comet Chidren's Toy
Post by: Model Maker on November 23, 2016, 01:59:59 AM
Thanks Paul for the positive feedback. I'm never sure if I am posting too much detail.

Nacelles are almost complete. They have been fitted and rough sanded. I'll finish sanding and detailing to ensure final symmetry once I have glued them in place.

Photo 6 shows the nacelle in the carving vice, with the wing profile filed to shape using a rat tail (round) file and a flat file. It takes a little patience to fit the wing contour. - File, test fit, file, test fit, etc., etc. I used the bandsaw to rough cut the wing profile, but a coping saw can also be used. Remember to cut conservatively (ie leave lots of material for filing). I had to throw away my first set of nacelles as I did not adequately account for the dihedral and sweep angles of the wing which resulted in a very loose fit on the leading edge. If I was painting the model, I would have simply filled the gap with wood filler. But as I will be using a natural finish I opted to start over and obtain better fit.

Photo 7 shows the nacelle clamped and shaped using a flat file and a bow sander

Photos 8 &9 show the nacelle dry fitted to the wing.

Next step on to shaping the fuselage.

Title: Re: Dehavilland DH 88 Comet Chidren's Toy
Post by: lastvautour on November 23, 2016, 04:31:14 PM
Marvelous toy Comet.

Lou
Title: Re: Dehavilland DH 88 Comet Chidren's Toy
Post by: Boomerang on November 24, 2016, 06:16:40 PM
Looks great Ken.

Gordon
Title: Re: Dehavilland DH 88 Comet Chidren's Toy
Post by: Model Maker on November 27, 2016, 03:47:34 PM
Thanks Gordon and Lou for the compliments. Dare I say still lots for me to learn from masters such as yourselves!

Rough out of fuselage shaping is complete.

Photo 10 shows the centre lines and station lines penciled in. I haven't developed the knack yet for working without a detailed set of templates to shape the fuselage.

Photo 11 shows the fuselage clamped in the carving vice using the tang at the impeller end as the clamping block

Photo 12 shows the completed roughed out fuselage. Since this model will have a natural finish, I've left a perimeter around where the wings will be attached proud of the fuselage. Once the wings are glued in place, I'll use a couple of small diameter gouge chisels to form the fillet.

Photo 13 shows the roughed out fuselage with the tools used for shaping. I used the chisels for bulk material removal in some locations such as around the wing fillet projection, thinning down the tail thickness and shaping the fuselage taper at the the tail end. The files were used for for rounding and smoothing the rough surface from the bandsaw blade on the flat sections. I find the files a little more forgiving when rounding. They are not sensitive to grain direction like the chisels, which can lift and gouge the wood if going against the grain.

Photo 14 shows a gravity dust collection set up which I experimented with to capture the shavings and filings. It's simply a 14"x14" plastic table saw dust collection tray sitting on top of a  20 liter waste bucked under the carving.  The benefit is it collects the dust before hitting the floor and being tracked over the shop as I move around. A few quick brush strokes to the middle disposes all collected debris into the waste bucket. It can also be made form a piece of hardboard or thin plywood with a 3" or 4" hole in the middle and framed sides. Nothing magical, but it does help to eliminate dust travel.

Next step - On to glue up
Title: Re: Dehavilland DH 88 Comet Chidren's Toy
Post by: Model Maker on November 29, 2016, 09:25:10 PM
Almost finished

Photo 15 shows a little trick I use to scribe the back of the propeller hubs. To ensure a concentric scribe, I first wrap some tape around the nacelle as a guide. Then I use the sharp side of a triangular shaped file to file a groove to represent the gap between the hub and the nacelle.

Figures 16 and 17 show the final carving with the tang removed, ready for finishing.

Figure 18 shows the carving with the first coat of Tried and True varnish oil. I'll apply two more coats over the next couple of days and then it will be ready for donation. Hopefully someone will have as much fun playing with it as I had making it. I certainly learned about the complexity of fitting nacelles. I didn't quite get the fits the way I wanted. But practice makes perfect. My next endeavor will be a Halifax with 4 nacelles so I'll get a little more practice.
Title: Re: Dehavilland DH 88 Comet Chidren's Toy
Post by: lastvautour on November 29, 2016, 09:27:21 PM
Beautifully done.

Lou
Title: Re: Dehavilland DH 88 Comet Chidren's Toy
Post by: Boomerang on November 30, 2016, 05:46:27 AM

I'm impressed. Looks great !

Gordon
Title: Re: Dehavilland DH 88 Comet Chidren's Toy
Post by: Model Maker on December 05, 2016, 02:22:05 AM
Thanks Lou and Gordon. Your encouragement is greatly appreciated. The grain of the pine certainly adds character. One day I'll have to try my hands at a laminated model using walnut and basswood or another contrasting combination of woods.

The toy now has 3 coats of Tried and True varnish oil applied and is ready for wrapping. Hopefully Santa will find a child who has a much fun playing with it as I had carving and finishing it.
Title: Re: Dehavilland DH 88 Comet Chidren's Toy
Post by: lastvautour on December 05, 2016, 06:24:02 PM
I hope Santa picks me. Magnificent Comet will make someone very happy this Christmas.

Lou
Title: Re: Dehavilland DH 88 Comet Chidren's Toy
Post by: buccfan on December 05, 2016, 08:47:59 PM
Very nice indeed Ken, the grain certainly shows up well, particularly on the fuselage.  Re your mixed wood model idea,finally managed to find some basswood for my stash in Hobbycraft, they were selling mixed bundles. Regards Paul J.