Epoxy vs. CA Glue
11-21-2002 | 01:23 PM
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From: Shenfield, UNITED KINGDOM
Epoxy vs. CA Glue
Epoxy is heavy & should be used sparingly on flying models to save weight. Never use it at the tail end for this reason. Main use is for glueing high stress items like engine bulkheads and undercarriage blocks also for joining foam items such as wings. Also useful if joint does not fit accurately.
CA (cyanoacrylate) should also be used only when necessary (for quick joints to enable work to proceed without waiting) Should be used sparingly because fumes are unpleasant and a health hazard if used for prolonged time -ventilation is essential. Joints are more brittle than PVA glue. The thinnest and fastest CA is the most useful. Only tight fitting joints can be glued with CA. Opened bottles of CA do not last long. Another use of CA is to soak into wood to harden it- e.g. use on wing bolt threads tapped direct into a ply plate or use to harden vulnerable edges such as tailplane corners.
Most aircraft construction should be done with PVA glue which sinks into wood and seems stronger with slight elasticity when crashed and therefore does not fail so easily as CA. PVA is cheaper, odourless, clean to work with and allows time to position parts accurately also spills are easily cleaned up with water.
All excess epoxy or PVA glue squeezed out from joints should be scraped off to minimise weight and give neat appearance.
It is instructive to use some scrap balsa and hardwood to make test joints with different glues and curing times. These parts should be tested to destruction and the balsa should fail before the glue. If the glue joint fails before the balsawood fibres fail then there is something wrong with glue process.
No doubt experienced modellers will have their own views on which glue to use and where, so its somewhat a matter of personal preference.
CA (cyanoacrylate) should also be used only when necessary (for quick joints to enable work to proceed without waiting) Should be used sparingly because fumes are unpleasant and a health hazard if used for prolonged time -ventilation is essential. Joints are more brittle than PVA glue. The thinnest and fastest CA is the most useful. Only tight fitting joints can be glued with CA. Opened bottles of CA do not last long. Another use of CA is to soak into wood to harden it- e.g. use on wing bolt threads tapped direct into a ply plate or use to harden vulnerable edges such as tailplane corners.
Most aircraft construction should be done with PVA glue which sinks into wood and seems stronger with slight elasticity when crashed and therefore does not fail so easily as CA. PVA is cheaper, odourless, clean to work with and allows time to position parts accurately also spills are easily cleaned up with water.
All excess epoxy or PVA glue squeezed out from joints should be scraped off to minimise weight and give neat appearance.
It is instructive to use some scrap balsa and hardwood to make test joints with different glues and curing times. These parts should be tested to destruction and the balsa should fail before the glue. If the glue joint fails before the balsawood fibres fail then there is something wrong with glue process.
No doubt experienced modellers will have their own views on which glue to use and where, so its somewhat a matter of personal preference.
