Beech 18 Details

[JeffH]

The engines used on the Beech 18 model (and several other 1/32 scale planes) were cast from Envirotex Lite epoxy using a master and molds made some years ago.  I once read somewhere it helps to first give the mold a shot of spray paint before adding the casting medium.  It doesn't seem to hurt.  The molds have held up well over a number of castings.  The close up shows the engines used in the Beech 18 model, suitably dressed up with wire push rods and ignition leads.

[JeffH]

The pin stripes were made using a combination of masking (the designs on the tail and nacelles), strips of Frisket film and Pactra Trim Tape.  The trim tape is relatively easy to work with (although it stretches readily), but its thickness makes it stand proud of the surface rather than looking like a painted-on stripe.

The frisket film stripes worked out okay until I sealed them with a thick coat of Johnson's Future floor polish.  It was then that I discovered one of the few substances Sharpie pen ink is not impervious to- the Future started to dissolve the ink which proceeded to run down the side of the model.  If I try that technique again, I'll first apply a thin coat of future while the film is still attached to the Plexiglas.  I would have preferred to use paint rather than markers, but found paint always flaked off the frisket film before I could get the stripes on the model.

[JeffH]

The windows were painted on using an airbrush and enamel paints.  The windows and surrounding areas were masked off using strips of masking tape. 

To mask large areas I first roll out poster putty (i.e. Blue Tack) into a rope, then apply it to the perimeter of the area to be masked.  I next place the model in a plastic bag, pressing the bag into the putty.  I then cut away the portion of the bag within the perimeter of the putty.  It helps to first trace over the putty with a marker.  The bag then protects the rest of the model from overspray and I don't have to use up a whole roll of masking tape.

[lastvautour]

It does not get any better than this. Thanks for posting.

Lou

[cliff strachan]

Holy Mackerel! Is that nice. But how did you get the original engine moulds?

Cliff.

[Oceaneer99]

Lovely model!  Thank you for the masking details.  I forget about the sharpie/future incompatibility regularly.  My R2D2 had some problems with that.  If I remember, I shoot the sharpie (or Pigma pens) marks with a light coat of spray lacquer (too much makes it run) and let that dry before the Future coat.

Garet

[JeffH]

Thanks for the tip, Garet.  I'll try applying a clear laquer overcoat before using Future if I use that technique again.  Having the ink run was the main problem I encountered.  Permanant markers come in lots of colors (including metallics), so I may try that method again at some point.

Cliff-
To make the master engine (the tan colored one with the not-cut-down cylinder heads) I first made a mold of a cylinder from a 1/32 scale plastic model kit. This was done because I wanted to preserve the kit engine.  I then cast 9 duplicate cylinders from that mold and glued them to an appropriate sized plastic ring using the guide template.  The crankcase is a blob of the same epoxy I used for the castings; just with more Durham's powder added to thicken it up.  The crankcase was then glued to the plastic ring to complete the master engine.

Next, I stuck the master onto a suitable flat surface (a piece of acrylic sheet) using double sided tape and coated it with silicone mold making material.  That's the magenta colored mold seen in the left in the photo.  For small parts like this I don't bother constructing a dam around the part-- the silicone is viscous enough to stay in place on its own.  After the silicone setup, it was simply a matter of prying out the master engine and casting as many duplicates as needed.
To fit into smaller diameter cowlings (like the Beech 18) I ground off enough of the cylinder head material to fit inside the cowling, then made a mold of that engine- that's the green mold in the upper right.  That material is intended to be kneaded by hand and pressed onto the master, and is a little easier to work with than the pourable silicone.  One tip for using the hand-applied stuff is to periodically dip your fingers into water when pressing the silicone over the part; the moisture prevents the silicone from sticking to your skin and makes it easier to force the stuff down into all the nooks and crannies.

I hope this was helpful,

Jeff

[lastvautour]

Thanks Jeff, this has to be my next challenge. First I must find the materiels.

Lou

[cliff strachan]

Thanks Jeff for the detailed description of your engine construction techniques. But I must confess that - being from that era before plastic (Models I mean. I'm not quite that old.) - it's a lot to absorb. It may be interesting to try to carve a mould of an engine from which a number of engines could then be made as required. That project I'll leave for someone else. Thanks again.

Cliff.

[dave_t]

Whatever happened to Jeff H? Earlier this year, I seem to recall a whole bench-full of primed but otherwise unpainted projects.

Just wondering...

[dave_t]

OK, whatever happened to almost everybody at SMM? 

[lastvautour]

Summer and wonderful weather.

Lou

[Oceaneer99]

Lou's got it.  I did clean off my workbench last night and put in a half hour of model work, though.

Garet