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  #1  
Old 04-20-2006, 10:42 AM
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Unhappy Balsa vs. Basswood

First post here. I have been using basswood instead of balsa on some recent scratch builds.
Basswood seems to be a bit stronger and has a tighter grain than balsa. The fins are easy to sand and finish, not requiring much filler. Basswood maybe a little heavier than balsa, but I am willing to sacrifice a little weight for added strenth. Have not flown a rocket with basswood fins yet, but will soon. Any thougts??
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Old 04-20-2006, 12:17 PM
stefanj stefanj is offline
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Basswood has one fault:

Because it is heavier and tighter-grained, surface-mounted fins made of it are more apt to snap off during hard landings and rough handling.

This is much less of a problem with through-the-wall mounting.
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Old 04-20-2006, 01:26 PM
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I have no problem with basswood fins snapping off even when surface mounted: I mount them the durable way; with good ol' EPOXY ala HPR construction. Heavier than titebond, but VERY strong.
I use this method for ANYTHING 24mm "D" power and above & never have fin breakage.
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Old 04-21-2006, 08:27 AM
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This is a great discussion. I have tried both over the years, and here is my 2 cents for what little it is worth:

For a while I used basswood exclusively for my model rockets, but I have moved back to balsa for the ease of sanding, and the low weight. I have found basswood to be too brittle for my tastes, and have suffered not only the above mentioned fin 'snap off' on tough landings, but also a tendency to split along the grain.

I am picky about my Balsa however, and scour all of the hobby shops I visit (even while on vacation and business) for ' C grain' balsa. I find C grain balsa to provide the best of both worlds: strength, low weight, and a certain toughness due to the swirly grain. (My wife says: "You fingered every piece of balsa in this case and you are buying just two sheets???")

Lately I have been building BT-70 and BT-80 mid power models, and I have been using 1/4" balsa for the TTW fins. I typically will taper sand the fins to 1/8" at the outer edges, and then begin rounding the leading and trailing edges. What I am left with is an attrractive, tapered fin, with a 1/4" root that goes TTW, and is really strong.

My only problem is... I hate, hate HATE sanding...

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Old 04-21-2006, 02:24 PM
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Phred:

Do you have a Demel and/or a belt/disc sander?

I got a nice sander for under $100.

If you are really careful, and use extra-fine paper /drums, you can use these to work with balsa. Takes some practice, though.

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Old 04-21-2006, 02:31 PM
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Hi Stephan,

Yes, for 'big' sanding jobs like the fins for a BT-80 sized Screamer upscale, I use my belt/drum sander... but I still hate doing it!!

Thanks for the suggestion!

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Old 04-24-2006, 10:08 AM
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Interesting feedback. I hate sanding as well, but I find that I get a much better finish on basswood with a lot less hassle. I have tried using a Dremel tool to sand balsa, what a disaster, I try not to swear but on that particular day, if you would have written it down I would have signed it.
Actually flew my newest 2 scratch builts with surface mounted basswood fins Saturday, one under "D" power and the other under "E" power. Great flights with no adverse recovery effects. Ground softened by recent rain may have helped, but no sheared, cracked, or chipped fins.
This maybe a topic for another thread, but how do you cut a body tube for through the wall fin mounting? How do you keep the cuts at the correct locations on the tube? How do you keep the cuts straight? I just see piles and piles of worthless "swiss cheese" looking tubes on my bench.


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Old 04-24-2006, 11:35 AM
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You consistenly make the cuts in the correct location on the tube by using an automated machine using a laser ! (not practical for MOST)

Any other method I see as being extremely tedious at best.
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Old 04-24-2006, 01:38 PM
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I see, being that my laser is on the blink, maybe I should just stick to surface mounting for now. I just got the impression for earlier posts that cutting your own slots was common practice. Thanks for your input. Didn't mean to ask a stupid question. Ignorance is no excuse, but it is the only one I have.
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Last edited by DaveR : 01-25-2011 at 09:40 AM.
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Old 04-24-2006, 01:51 PM
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Quote:
Originally Posted by Sadmug
I see, being that my laser is on the blink, maybe I should just stick to surface mounting for now. I just got the impression for earlier posts that cutting your own slots was common practice. Thanks for your input. Didn't mean to ask a stupid question. Ignorance is no excuse, but it is the only one I have. That is why I am the saddest of all mugs.

People cut their own slots all the time (although not myself). Someone will pipe in with an answer for you on tube-slot cutting I'm sure. No question is a stupid one here!
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