DaveSR71

Sounds like a fairly common problem with foam cores. Sounds like you are going to sheet the cores?

If so hopefully you have the upper and lower "cut off" foam peices.
If so keep up with what went where.
Is so no problem.

Round up some heavy books.
Vacuum and wipe cores real good!

Put the bottom cut off on a flat straight, strong surface.

Glue the edges of sheets together to create sheets big enough to do one side completely and trim to about 1/2 inch bigger in all directions than your core. Make 4 big panels of sheeting.

Glue your sheeting to one surface of each wing.
Titebond is a good choice as it will loose weight over 6 weeks or so gives lots a working time and is strong.
Spread it thin with a bondo squeegee.
place one sheet in the cut off cradle and place your core into place and stack the next cut off( cradle on both sides) and do the same to the next core. stack a big pile of books on top. Dont over kill with the weight I guess an extreem would do damage.
Make sure cores are straight in cradles. Let this dry 24 or so hours, longer if you can stand it.

Now unstack all, leaving bottom core in cradle. If your sheeting is stuck to cradles leave them stuck.

Do the same for the upper skins and restack and weight.

If the cores were cut from a straight block and stayed flat on bench while cutting this should get you straight.

If your sheeting is stuck to cradles its easy enough to destroy and peel the cradle foam off finis with sanding block.

2nd method if you have no cradles or every thing is whacked out.

Coat core and inside of skin with thin layer of Titebond glue with squeegee. let dry 24 hrs

Put core on flat surface with bow up.
Place skin on core and a straight weight along spar and trailing edge so that all is held flat.
Heat up your iron to high and between the weights slowly iron from the middle of this area out to root and tip.
This will bond the 2 glue surfaces together even better bond than normal method.

Move the weight over spar area back just far enough to be on the area already ironed area.

Working from spar, center of panel out ward to tip and root until you get to the leading edge.

Now move the trailing edge weight forward enough to do the trailing edge.

Set to the side and do next core.

Then come back to first core and do other side.

Trim and finish up!

Remember to move slow so heat penetrates sheeting.
If you smell plastic/foam move a little faster. repeated fast passes will not do as much as slow penetrating passes.

This heat bonding of aphlitic(spl?) resins is very stong and can be done with titebond or Elmers carpenters glue.
IT WILL NOT WORK WITH WHITE GLUE!

Take your time!
I will work out.

Hope all this made sense.

David

If I left something out someone please add it .