Basswood

I bought a kit that I am very excited to build (Vagabond) and I was thinking about picking up some sheets of basswood from Michael's and replacing the balsa wood fins before I built it for a couple of reasons.

I realize this will add weight, though I'm thinking not much.

Is there any reason not to do this ? Is there anything different I have to do to the basswood ?

How do you plan on cutting it??

Why bother? Balsa fins are plenty strong, and you'll be adding weight to the worst place you could possibly be adding weight to.

The only time I replace the balsa fin stock from a kit is when building a TLP kit.

Cutting basswood is pretty easy....just need a straight edge (ruler works fine) and a new x-acto blade.

paul.nortness said:

The only time I replace the balsa fin stock from a kit is when building a TLP kit.

Cutting basswood is pretty easy....just need a straight edge (ruler works fine) and a new x-acto blade.

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I tried cutting a 3/16" thick piece of balsa...and it took some work. I never tried cutting basswood. When you get down to it a ruler and xacto is the best way to cut anything...you are sure to get a straight cut...with a saw not so much.

With basswood, you can generally go to a thinner stock in most cases and not have as much of a weight penalty as you might imagine.

Also, basswood is very easy to get to nearly glass smooth finish-ready condition (one coat of high-build auto primer, sand, done).

It's also a lot easier to shape if you want tight angles, since it takes more effort to remove material when sanding. I botched some Praetor fins once; replaced them with thinner basswood that was very easy to make the tapers with.

Some folks report it is more likely to splinter on hard landings than balsa. Never had this problem myself.

Marc

If you want to beef up the fins, save the money and a little bit of effort and just laminate them with either copy paper or card stock. I generally use 110lb for larger models with 1/8" bales and white glue.

I tried to laminate using copy paper and glue...what a mess.

I have since switched over to self adhesive labels. So easy. Perfect laminated fins in no time, and no mess!

I like using basswood for fin material. It's so much easy to finish, and a lot more dent resistant. You can go thinner, but for most models the weight pick up is minimal.

So with basswood it makes sense to go with thinner fins...so if originally the kit came with 3/16" you could go down to 1/8" and from 1/8" to 3/32"?

I should try it out...thinking about building a Snarky kit and upgrading to basswood. So I decided to make the changes in ROCKSIM. I kept the thickness the same 1/8" and the CP and CG stayed the same and the flight characteristic were identical. So based on the information if there isn't much change I would use basswood...because it is stronger, but more importantly is the fact that as others have mentioned it's easier to prep for paint.

I never cut basswood with an Xacto knife, but it is probably harder to cut? Maybe a razor saw would do the job too based on the fin design?

RocketManDan said:

How do you plan on cutting it??

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My first thought was to use a little jigsaw I have, but I hadn't really gotten to the planning stages until I heard whether or not it was a good idea. My second thought was dremel tool.

cjl said:

Why bother? Balsa fins are plenty strong, and you'll be adding weight to the worst place you could possibly be adding weight to.

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Because the fins on the Vagabond are in three pieces. I am new to rocketry and I have a hard enough time getting one set of fins straight without having to worry about a putting three separate pieces to each fin in line.

No problem cutting it with a hobby knife.

Marc_G said:

No problem cutting it with a hobby knife.

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OK I am sold....LOL

While balsa is just fine for most Mod-Roc uses over the years I've foundI use alot more basswood over balsa for several reasons. we can usually use a bit thinner basswood ie 3/32" instead of 1/8" on sport models or 1/32" or thinner over 1/16" on micros without worry about strength.

Basswood sands well and holds finer shapes, fin Bevels, sharp angles and surface detail then any grade balsa can.

Basswood generally take far less filling the balsa so the trade off in initial mass works out to almost a push by the time the fins are fill and painted.

Finally Basswood is not as subject to minor dents,dings and fingernail gouges as balsa.

Cutting Basswood is not much harder then balsa with a sharp X-acto blade or razor. or can be cut well on a Jig or band saw with fine tooth blade 18T or higher.

Micromeister said:

While balsa is just fine for most Mod-Roc uses over the years I've foundI use alot more basswood over balsa for several reasons. we can usually use a bit thinner basswood ie 3/32" instead of 1/8" on sport models or 1/32" or thinner over 1/16" on micros without worry about strength.

Basswood sands well and holds finer shapes, fin Bevels, sharp angles and surface detail then any grade balsa can.

Basswood generally take far less filling the balsa so the trade off in initial mass works out to almost a push by the time the fins are fill and painted.

Finally Basswood is not as subject to minor dents,dings and fingernail gouges as balsa.

Cutting Basswood is not much harder then balsa with a sharp X-acto blade or razor. or can be cut well on a Jig or band saw with fine tooth blade 18T or higher.

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It would probably make sense to change the blade of the Xacto after each fin is cut from the stock. I know the blades can dull rather quickly. Would you use a #2 or #11 blade?

RocketManDan said:

It would probably make sense to change the blade of the Xacto after each fin is cut from the stock. I know the blades can dull rather quickly. Would you use a #2 or #11 blade?

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If you start with a sharp one, you should be able to cut at least a couple of sets of basswood fins (or more) without needing to change the blade. I usually keep using the same blade throughout even when I am cutting plywood. When the blade becomes too dull, you'll know it. (It will require much more work to make cuts.) Basswood is a soft wood; it isn't that hard to cut.

MarkII said:

If you start with a sharp one, you should be able to cut at least a couple of sets of basswood fins (or more) without needing to change the blade. I usually keep using the same blade throughout even when I am cutting plywood. When the blade becomes too dull, you'll know it. (It will require much more work to make cuts.) Basswood is a soft wood; it isn't that hard to cut.

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I'll have to pick up a piece at Michael's and practice some cuts on it just to get a feel for it before I place an a larger order.

My very first BAR build used a combination of basswood for the lower fins and balsa for the upper fins. Primarily this was to try out basswood (have never used it before).

Pros: Definitely easier to finish...only took one coat of Elmer's Wood Filler to finish out to a nice, smooth surface (balsa usually takes 2 coats with sanding in between). Stronger and more rigid overall than balsa.

Cons: Harder to cut and sand (not insurmountable, just more work)...easily doable with an XActo knife.

Personally, I think the weight addition is negligible, especially for anything powered by more than an 'A' motor.

I'd recommend it for items where strength is a priority.

FC

I got a perfect example of the benefit of basswood today.

I was test flying my TLP Phoenix missile and it straightened out and flew in a soft arc instead of going up. The parachute deployed about 50 feet of the ground and it came down fast.

Normally, this would spell disaster for those big rear fins on the Phoenix made out of balsa. But the basswood didn't even get a stress crack. Ready to fly again.

RocketManDan said:

It would probably make sense to change the blade of the Xacto after each fin is cut from the stock. I know the blades can dull rather quickly. Would you use a #2 or #11 blade?

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Depends on the thickness:
very thin to 3/32" (.093") I generally grab my #1 handle with #11 stropped blade.
Thicker stuff I'll generally go with a #2 Stropped shape blade.

Absolutely no need to change blades unless your cutting on a steel plate under the basswood LOL!!! Once you get in the habbit of keeping your blades stropped each time you pick it up, You just don't have to worry about changing blades Unless you snap off a tip or something.
I think i'm still using the #11 & #2 blades I put in the handles when I bought them more then a dozen years ago.

paul.nortness said:

I got a perfect example of the benefit of basswood today.

I was test flying my TLP Phoenix missile and it straightened out and flew in a soft arc instead of going up. The parachute deployed about 50 feet of the ground and it came down fast.

Normally, this would spell disaster for those big rear fins on the Phoenix made out of balsa. But the basswood didn't even get a stress crack. Ready to fly again.

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Just a quick sidebar ... I am also an F14 and Phoenix missile fanatic. I was an AQ (Aviation Fire Control Technician) in the Navy back in the 80's. I have passively kept my eyes open for a Phoenix kit while I'm learning to build.

Look at The Launch Pad's 2.6" Phoenix. A really nice kit, will test your building skills...but turns out really nice

Back to the basswood, I assume it matters which way the wood grain is going on the fins ?

Yep. Same as balsa, really. You want the grain parallel to the leading edge (in 99% of cases).

paul.nortness said:

Look at The Launch Pad's 2.6" Phoenix. A really nice kit, will test your building skills...but turns out really nice

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Thanks for the pointer Paul, I think I might order the 1.6 version and try it out.

cjl said:

Yep. Same as balsa, really. You want the grain parallel to the leading edge (in 99% of cases).

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Thanks, I'll do my best to keep it parallel.

I bought a small sheet of 3/32 Basswood that turned out to be the perfect size for my fins. I found that cutting the Basswood with my Xacto knife was easy and precise. I found the 3/32 Basswood to be similar in weight and strength (by my novice estimation) to the 1/8 balsa while I found it to be smoother, less porous and easier to work with (I find balsa *too* easy to sand, etc).

On the downside, I discovered that I suck. The fins came out looking like garbage and I'm going to use the stock fins anyway.

Practice makes perfect. Don't rule out laminating. It costs about $.05 per rocket, is incredibly strong and light. I'm building two 4" upscales for my kids with 3/16 balsa fins laminated with gift box material and 1/8" centering rings laminated with either gift box or 110lb card stock. They will have 1,2,3,4x 24mm interchangable mounts as well as a 1x 29mm mount and will take an H-128 or H-165 without thinking twice and come in at just over a pound.

My point is, try different techniques more than once and you will find what works for you.

El Cheapo said:

Practice makes perfect. Don't rule out laminating. It costs about $.05 per rocket, is incredibly strong and light. I'm building two 4" upscales for my kids with 3/16 balsa fins laminated with gift box material and 1/8" centering rings laminated with either gift box or 110lb card stock. They will have 1,2,3,4x 24mm interchangable mounts as well as a 1x 29mm mount and will take an H-128 or H-165 without thinking twice and come in at just over a pound.

My point is, try different techniques more than once and you will find what works for you.

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Must Correct an OLD and incorrect (while Often used) saying..."Practice does not make perfect...Practice makes Permanent!" If you continue to practice a technique you'll generally come back to do it the same way again, if we practice the task correctly..that's fine.. but if we were not.. we well continue to do whatever incorrectly! "Practice makes Permanent!
That said; El Cheapo is absolutely correct it's very helpful to try different methods and techinques more then once to find which one or combination works best for your particular style and strengths.

Laminating is truely a great way to increase fin strength with minimal additional mass. fins can be laminated with anything from onion skin tracing paper to 3/64th" liteply depending on the size of the fins your making.

Don't be discouraged that all your fins didn't come out exactly the same as your pattern...I've been cutting fins for 40 years and the STILL don't all come out the same Once they are cut out, the next technique is to learn to stack sand all 4, 6, 8 or however many fins you have all at the same time and square. This can be done simply by holding the stack between the fingers while rubbing the edges along a Sanding block or T with 220 to 240 grit sandpaper. Takes a little practice to learn to hold them tight enough not to slip and square to the sanding block but it works.
A bit easier is to stick the stack together with a little double faced masking tape. Trick with this is not to use so much you can't get the fins apart again after shaping without snapping them.
Hope the hints help