repair assistance

[steve bittner]

I have an older plane that the top and turtle deck was made out of blocks of wood butted together. Over time has cracked at the but joints and im thinking of refinishing and putting the plane back in service. I don't want to refinish and have crack again or cut the whole top off and use one solid piece front to back. Does anybody have a known proven method rather than should work. What bothers me is the joints are end to end so its not the smoothest joints to begin with. Joints were covered with a strip of cloth or silk originally and glued with Ambroid.
Thanks for your help

[Clint Ormosen]

Lay a bit of glass cloth over the turtle deck area and brush on some long cure epoxy. Heat it to get the epoxy to flow. Sand smooth and refinish as usual. Probably never crack there again.

[tom hampshire]

Hi Steve - You might want to look at cutting away the butt joint with a bevel on each side, and adding in a new filler piece sanded to match the bevel on the original work.  Glue it in, let fully dry, and block sand to shape.  This might save a translucent finish.  It's going to depend on the thickness of the original block.  Also, if it's at the front end, can you add epoxy glass to the inside?  The fiberglass will certainly work strength wise, but it will be hard to get it in a trench and fill it to maintain the original contour.

[Tim Wescott]

Steve, you have my sympathy.  In your shoes I'd be juggling between Clint's suggestion, Tom's suggestion, and whacking the whole thing off and redoing it all in one piece.

Assuming that there are no other problems that point toward a rip-up and replace I'd probably end up following Tom on this one.  If you do so, make your bevel very carefully and spend a good long time on fitting it all up to minimize gaps.  Then glue it with something sandable (Ambroid is my choice; others will no doubt disagree).

[steve bittner]

It is a one off plane, the crack is one inch back from the canopy. Top block half inch thick by two inches wide, turtle deck two inches tall by two inches wide solid blocks. Plane has sentimental value to me. Thought about cutting down thru crack with saw blade then fill in with epoxy, or replace top deck with 30 inch long solid block?

[Tim Wescott]

It is a one off plane, the crack is one inch back from the canopy. Top block half inch thick by two inches wide, turtle deck two inches tall by two inches wide solid blocks. Plane has sentimental value to me. Thought about cutting down thru crack with saw blade then fill in with epoxy, or replace top deck with 30 inch long solid block?

If you just cut down through the crack and epoxy then sooner or later you'll just end up with two cracks, one on each side of the epoxy.  If you're going to do that, do Clint's suggested repair instead.

I'd do Tom's bevel thing.  If there's enough meat the easy way is to make two 45-degree cuts that meet at the bottom of the crack.  Then find a nice light block, cut it to match the hole, glue it in, shape, sand, and cover with silkspan or other strengthening material.

There's harder ways to do Tom's bevel thing that cut out less wood -- basically you either make multiple shallow straight bevel cuts, or you make one grand curved bevel cut.  For the multiple shallow cut approach, start at the bottom, glue in material, finish, then bevel-cut into the previous splice higher up until you're at the top of the fuselage.  For the grand curved bevel cut make one cut all the way around, then try to fit something into it.  Again, cover with silkspan or glass cloth or whatever when done.

[tom hampshire]

Steve, can you post a picture?  If something in the configuration prevents bevel cuts, then you might try adding a balsa doubler wetted and formed in place underneath the repair.  That could furnish the added strength you need.  If the repair site is anywhere near the flap horn, then the bending moment on the fuselage is huge.  You will need to make the repair very stiff.  Many Noblers, with the canopy right above the flap horn, had hardwood sticks glued to the  inside top of the fuse side, say 8 inches long, inlaid in to the formers.  This seemed to stop the cracking at the base of the canopy.