Monday, February 24, 2014

Handling a Delicate Situation in Model Building

When I show many people the delicate balsa and tissue model airplanes I build, the response I often get is that they could never build something so delicate that requires so much patience. With experience you learn how much pressure you can use when handling delicate structures and then you still break the balsa wood at times. In one of my current projects a Guillow’s PC-6 Porter rubber powered model airplane I thought I had done everything in advance correctly before gluing a certain piece but still managed to break several balsa pieces. 

Broken Structure Caused by Mistake While Building

Side Keel Before Placing in Slots

The significance of this situation goes way beyond model airplane building as I see it. These are some of the general ideas that I see that are important:

*  Learn the properties of what you were working with and get a good understanding of the risks when performing a delicate operation.
*  Perform small subtasks and test as much as possible before attempting the major operation.
*  If there is a failure in what you are trying to do, know how to remedy the situation.

Grain of the Wood Appears in Direction of Dark Lines

Balsa Breaks Easily Along the Grain

Back to the model building, I needed to glue a side keel into many bulkhead slots, the grain on the bulkheads was running in a direction that would make it very easy to break the balsa along the grain. For my first subtask I took a balsa strip the same thickness as the side keel and made sure it would fit into each slot in the bulkheads. Next I did a test fit of the entire side keel in the slots just like it would be placed for gluing, the fit was good.

Broken Parts Repaired

After pulling the side keel out, I applied glue into all the slots and again put the side keel in place.  This time the keel did not slide into place as easily and I applied too much pressure. In an instant I heard that awful sound of balsa snapping and pieces were displacing in several directions. One of the bulkheads had broken along the grain and then the side keel broke in that same region of the airplane. With plenty of experience fixing broken airplanes, the repair was easy.

Kit Box for PC-6 Porter

What will I do next time in a situation like this?  Maybe I could grip each bulkhead closer to the slot as I press the side keel in. A CYA (super glue) could be used and the glue would wick into the joints after the pieces were fitted.  Ideas to think about and this is what keeps me interested.

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