Hi Gil

Here is a procedure that I've used successfully for over 40 years when building and joining foam cores together. I've included a series of photographs to help. That old saying a picture's worth 1000 words is so very true.

Using a sanding bar and straight edge, these two tools will give you the results you want. Basically after sanding the trailing edges and the root of the foam cores you are ready to vacuum the surfaces clean. Then epoxy(I mix micro balloons and epoxy into a putty consistency) the cores at the root, wipe excess off, set the cores together against the straight edge as you see on the worktable, take a 10 inch or so strip of packing Tape and carefully attach it around the leading edge of the cores. Now check the alignment along the full trailing edge to see that it is up against your straight edge that has been clamped on the table. I may use a second strip of straight wood to just push against the backside of the trailing edges.

This procedure will give you true and straight alignment of your trailing edge and allow you to adjust and fit the leading edges to get perfect alignment. I hope the pictures help you, any questions let me know.

Regards
Dave

ama 41041

A few more

I still use single edge razor blades at the LE and TE for alignment.

Charles

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KT

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Single edge razor blade aligning both wing halves on center line of the airfoil. Actually,  a center line should be drawn along the LE and TE also. Some guys go so far as to put a center line on each rib!

Look carefully you can see the razer blade.

Charles

Single edge razor blade aligning both wing halves on center line of the airfoil. Actually,  a center line should be drawn along the LE and TE also. Some guys go so far as to put a center line on each rib!

Look carefully you can see the razer blade.

Charles

Wasn't the original question about FOAM wings?  Those pix show your "razer" [sic] blades with a built-up balsa wing.

Dave, I see those are foam wing cores.   Did you discard the bucks they came in?   I hope you also had your bellcrank assembly ready to go in place.  Each of us has a different way of doing things and I do not like holding a core vertical and trying to sand it.   Another reason for the bucks. 

John

To answer your questions.   The bellcrank/leadouts were epoxied into the left panel earlyer.  All  sanding of wing panels was done in the bucks before the wings were to be joined. After the epoxy has set next step is to wrap the center section with a 3/4" band of glass tape.  The bucks are now used to house the wing until assembly into the wing.  Over the years I've found this vertical alignment works well for most  stunt type wings.

Regards.
Dave
ama41041