Wondering if 1/16" basswood is heavy enough

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JRThro

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I have some 1/16" basswood that I'm using for fins on a BT-50-based rocket, and I'm concerned if it'll be strong enough. It seems very flexible to me when I bend it 'with' the grain.

Any comments? What's been your experience with basswood?
 

rocketsonly

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How many plys is it? 1/16" birch wood is perfect for LPR. Just make sure you put the grain parallel with the leading edge.
 

JRThro

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It's single-ply basswood, not plywood. And I cut the fins with the grain parallel to the body of the rocket, because they are long in that direction. I know that's not the usual right way to do it, though.
 

vjp

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Originally posted by JRThro
It's single-ply basswood, not plywood. And I cut the fins with the grain parallel to the body of the rocket, because they are long in that direction. I know that's not the usual right way to do it, though.
If the grain is parallel to the BT, then they'll be prone to snapping off. Grain should be parallel with the leading edge of the fin, so that end grain is glued to the BT.

Anywhere a line of wood grain is unsupported at both ends, it's easy to snap the wood along that line. That's what makes plywood so incredibly strong - the planks are glued cross-grained to each other in alternating layers, making it impossible for a crack to form or propagate along a grain line.
 

North Star

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Originally posted by JRThro

Any comments? What's been your experience with basswood?
Basswood isn't common here in the UK except on some imported kits but I've always found it stronger than balsa, much easier to clean up and finish too.Trouble is - it's heavier and it sits at the end of the rocket where heavy isn't good. You've cut it the wrong way (as already pointed out) so those fins will be very weak.
Plywood at this size of rocket is usually far too heavy and I have found that lite-ply (balsa ply) is actually very brittle - not at all as strong as you'd think where fins are concerned (excellent for CRs though)
 

phil

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I've found Basswood quite good for fins. It seems to take bashes and hard landings better than balsa. My experience is that it's better than balsa for thin fins.

If you want to get it the UK try "Hobbycraft" shops - they sell it in 3ft planks at a range of useful thicknesses.
 

astronboy

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Basswood is fine for fins. It is tougher than balsa, and heavier. However, it has a deeper grain, and is a bit more time consuming to fill the grain than balsa. Basswood will flex with the grain, just as balsa does. Be sure to cut the fin so that the grain supports the strength of the fin once it is glued to the body tube. This usually means that the grain should follow the leading edge.

Phred
 

DynaSoar

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Originally posted by JRThro
I have some 1/16" basswood that I'm using for fins on a BT-50-based rocket, and I'm concerned if it'll be strong enough. It seems very flexible to me when I bend it 'with' the grain.

Any comments? What's been your experience with basswood?
I use it almost exclusively over balsa of the same thickness. It's stronger. If 1/16" balsa would work, so will 1/16" basswood.

If you're concerned about strength, laminate it with paper and wood glue. Fold a piece of paper and place the leading edge in the fold. Trace the shape on both halves, paint glue evenly within the lines and slightly over, fold it and cover it with something heavy. It'll not only make it very strong, but now it requires no filling prior to priming.
 

JRThro

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Originally posted by DynaSoar
I use it almost exclusively over balsa of the same thickness. It's stronger. If 1/16" balsa would work, so will 1/16" basswood.

If you're concerned about strength, laminate it with paper and wood glue. Fold a piece of paper and place the leading edge in the fold. Trace the shape on both halves, paint glue evenly within the lines and slightly over, fold it and cover it with something heavy. It'll not only make it very strong, but now it requires no filling prior to priming.
What I've done is to glue a piece of typing paper slightly smaller than the outer edges of the widest part of the fins to each side, with white glue. I didn't place a heavy object on the fins, but I did squeeze out the excess glue from under the paper with my fingers.

Here's a picture:
 

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