Sequoia Aircraft Corporation F.8L Falco, Construction Manual

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F.8L Falco Construction Manual D–13 Revision 4, March 1, 2002
After mating, the surface pressure should be applied as soon as possible, however some time is
allowable for the spreading of other adhesive surfaces, the arrangement of pressure jigs and clamps
and the mating of other bonds.
Again, the allowable closed assembly time before pressure is applied is very dependent upon the
conditions of the wood and environment and the following table is given as a guide to be used
with “good judgement.”
Temperature of Wood and Area: 70°F 80°F 90°F 100°F
Maximum Open Time: 75 mins. 45 mins. 30 mins. 20 mins.
Pressure. In general, for the best results, sufficient pressure should be used to reduce the glue line
thickness to 0.005 inches. In all cases the pressure should be adequate to provide thin glue lines
and close contact of the surfaces being joined. However, high pressure must never be substituted
for well machined, accurately fitted joints.
When all other requirements are met, pressures of 25-75 psi should be sufficient. Multiple glue
lines between thick or dense wood laminates may require pressure of 150-200 psi, or more.
In all cases, sufficient adhesive should be applied to provide squeeze-out when pressure is applied
to insure uniform adhesive contact and eliminate voids.
Set Time. The length of time that this pressure must be maintained is determined by the texture
of the wood, the stresses present in the construction and the temperature at which the assembly is
maintained during the initial curing period. The recommended minimum time under pressure for
stress-free joints is shown in the following table:
Minimum Time Under Pressure at Various Glue Line Temperatures
Temperature: 70°F 75°F 80°F 90°F 100°F
Low Density Woods: 8 hours 6 hours 4 hours 2-1/2 hours 1-1/2 hours
High Density Woods: 10 hours 8 hours 6 hours 3-1/2 hours 2 hours
The rate of cure of Resorcinol is accelerated when raised to intermediate (95-190°F)
temperatures. The following schedule is furnished as a guide only and may require modification,
depending upon the bonding circumstances (e.g., increase the time if the joint in under stress).
Also, there are glue line temperatures which may vary from the temperature of the room or press
assembly.
Recommended Curing Periods For Glue Lines at Elevated Temperatures
Temperature : 110°F 120°F 130°F 140°F 160°F 170°F 130°F
Time: 60 mins. 50 mins. 35 mins. 22 mins. 12 mins. 9 mins. 7 mins.
Cleanup. Weldwood Waterproof Resorcinol Glue cures to an insoluble substance which cannot
be easily removed from clothing, tools, working surfaces or other unwanted areas. Thus,
Resorcinol must be used with care against spills and spatters, and should not be allowed to contact
surfaces where its presence would be objectionable. There are no satisfactory solvents for
softening a cured Resorcinol glue line.
Mixing equipment, glue spreaders, glue brushes and all containers should be cleaned thoroughly
and immediately after use, with scrub brushes and cool or warm (but not hot) water. Faster
cleaning may be obtained by using caustic soda solution (Caution: caustic may cause burns; do not