Laser Cut Balsa, Love or Hate?

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Woody's Workshop

Woody's Workshop

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Hey guys,
I have to tell ya, the way I do things I do not like the Laser Cut balsa fins that come with kits these days. I guess you'd have to understand my methods to understand, but I would rather just have a sheet of balsa and a fin pattern like in the olden days (Old School?). And I will try to explain; Agree, or Disagree?
One of the very first things I do is take the balsa, unless it's unuasally rough or has saw marks in it, and don't bother to sand. I take it and start coating it with TiteBond II Thinned down with water. Being a cabinet maker, I know it adds strength as well as weight. My theory is if your adding weight, it should also add strength. Anyways, the laser cut fins are too loose to do a good job at what I do to the balsa. I thin the glue about 20 to 30 percent, depending on how thick it is. Put on 3 or 4 coats to both sides. Dries pretty quickly and it soaks into the pours so it really adds strength, plus it is flexible. Now when its all dry, if the pieces are not flat and all even with the sheet, it makes it really hard to sand without breaking threw, or adding more than required coats. I take my ROS (random orbital sander) to the sheet at low speed and it makes it as smooth as a baby's behind. If I need to add a few coats then so be it. But before the fins are even removed from the sheet, all but the edges are ready for primer.
I don't know about the rest of you, but this is a whole lot easier than trying to fill the pours and get them smooth rather than after they are mounted like the instructions say.
So... I'd rather have the pattern and an uncut sheet of balsa. Or what ever material is used if it needs filled and smoothed out.
Opinions, concerns, comments...
I'm I crazy? Different? Is there a better way?
Since I've been using glue instead of wood putty or sanding sealer I've NEVER had a fin break or split, even if the recovery system failed. Take it I have not launched HUGE rockets, but I don't think I will ever change the way I do things because it works for me and results are excellent.
So let me have it, good or bad, I can take it.
John, aka Woody
 
I started out in rocketry when the only way was to cut your own fins, and since the vast majority of my builds now are either clones or done from free plans, I still mostly cut my own. I don't have a power saw, so it's all done by hand, including the 3/16" plywood fins on my Javelin XL. With that being said, I do greatly appreciate laser-cut parts when they are provided. It saves me from having to deal with one more thing and it enables me to use components that realistically I could never fabricate myself. Having balsa or basswood fins be laser-cut does not in any way affect how I seal, fill and finish them because I always do that on each individual component anyway, regardless of whether I have cut it out of a raw sheet or separated a laser-cut one from its stock. I greatly prefer parts that have been laser-cut to those that were created using the earlier die-cut method. Building kits such as those from the FlisKits Micro To The Maxx series will definitely give you an appreciation of the value of laser-cutting technology. Less than 20% of the rockets that I have built since 2004 have been from kits, so I don't see myself as being overly dependent upon having precut wood parts, but I am hardly dogmatic about the issue. I will readily use laser-cut parts when I can obtain them. It doesn't bother me either way.
 
Woody's Workshop said:
I'm I crazy? Different? Is there a better way?
Click to expand...

No, you are not crazy. Lots of people would rather cut their own fins. Hence, the reason for companies like The Launch Pad for being around. Also, loads of folks would rather scratch build (like me) for similar reasons. Sometimes, I don't mind the laser cut fins so I could go either way on this topic.

IMHO, unless you are really going to push the rockets performance (like make it fly on a G when the recommended motors max at a D) reinforcing the balsa is not needed for flight stresses. You are far more likely to damage the fins from handling & transporting rather than flying. Maybe try wood filler instead. So long as you are not adding copious amounts of weight just focus on making it look good. Another method that I am not familiar with is laminating the balsa with office paper to fill the gaps in the grain.

The only thing I've used is 2 oz. fiberglass tip to tip not only to fill the grains but because I wanted to skip using the chute and use a streamer and I also upped the MMT from 18mm to 24mm. That was on a Quest Full Moon by the way. It's a hoot on D12's and AT D21's.

Any new method you try I would recommend trying out on scraps before using it on a project. Use what works for you. Not everyone does it the same and that's rocketry for you.
 
I will say I like the idea of taking a whole sheet of balsa and trying your method. I do build alot of scratchers. This would actualy save me alot of time. I could do a few sheets at once while I have the mesh going on.Clean up and then they would be all done and smooooooth and ready to cut. Filling and sanding is a DRAG (pun) and in rocketry DRAG(pun) is not good.Thanks for the post.
 
If I were building a Guillow's style rib and stringer airplane I would prefer laser cut balsa over die crushing.
I think I spent as much time repairing the crushed bulkheads together as I did flying the models.
Those balsa bukheads on a model plane or model ship are accurate cuts, better than i could ever do with a knife.

On a simple 3FNC rocket cutting balsa isn't really that big of a problem.
I'm building an Estes Klingon Cruiser right now and had forgotten how rough the die cutting can be, especially on softer balsa.

Sometimes the laser light will cut a wedge shape, the cut will be wider from the top than at the bottom. I always seem to square up the edges before gluing.
Some vendors are cutting launch lugs with a laser. I don't like the burnt brown edges on a laser cut lug.

Letramax (or the black) laser cut centering rings are strong, but the charred edges get black soot on everything.

Everything is a compromise I guess.
 
hcmbanjo said:
If I were building a Guillow's style rib and stringer airplane I would prefer laser cut balsa over die crushing.
I think I spent as much time repairing the crushed bulkheads together as I did flying the models.
Those balsa bukheads on a model plane or model ship are accurate cuts, better than i could ever do with a knife.

On a simple 3FNC rocket cutting balsa isn't really that big of a problem.
I'm building an Estes Klingon Cruiser right now and had forgotten how rough the die cutting can be, especially on softer balsa.

Sometimes the laser light will cut a wedge shape, the cut will be wider from the top than at the bottom. I always seem to square up the edges before gluing.
Some vendors are cutting launch lugs with a laser. I don't like the burnt brown edges on a laser cut lug.

Letramax (or the black) laser cut centering rings are strong, but the charred edges get black soot on everything.

Everything is a compromise I guess.
Click to expand...

LOL like me with over 30 Guillows airplanes and now rockets :smile:
 
When I use balsa I prefer to cut my own, but have no problem with laser cut especially over die cut as hcmbanjo mentioned.
On those rare times I build kits I almost alway sub Basswood over balsa so i'm usually hand knifing them anyway.
 
with my old hurtin', shakin' hands, I love laser-cut parts. I don't build many kits, but I can't make a precision fin without fixtures and jigs any more. If I'm cloning something, Semroc's robot with a raygun cutting my fins for me is a blessing these days. High power means I can use power tools at least.
-Braz
 
I prefer laser cut if it`s balsa ,but I really don`t care for balsa period ,I prefer Basswood and try switch to it when ever I can (TLP kits) or scratch when doing LP.

Balsa nosecones I don`t mind so much.

Ahhh ,that`s just me though ;)


Paul T
 
This year I have joined up with the new kids on the block and I am a 100% laser cut fan. To heck with the old school and spending all that time and money on expensive, toxic, and environmentally unfriendly Xacto blades and sanding sealer. Why, I don't even bother to sand the burned carbon off the edges anymore. Just get me some sticky label paper, slap the laser cut balsa down, trim with a dull Xacto knife, seal up the ends with some CA and done. The paper balsa sandwich is just like super light plywood, even stronger than old school doped balsa. I just whipped out all the lumber on two Interceptor E's in no time at all, looked darn good as well. When one crashed I didn't even have to go to the car and cry because I had not spent boat loads of time on the balsa. I'm building at least five rockets to the old schooler's one, lookin' as good and just as, if not more durable. They may call square fin edges the bane of the hobby but I don't care. I'm not going for altitude records nor am I standing around lamenting about how much pain and suffering I went through to achieve the perfect airfoil shape, strong and lightweight yet with smooth as glass finish.

The jars of sanding sealer just set on the shelf, the Fill-N-Finish has long dried out, the Titebond III is all crusty and brown. They may criticize my bad techniques and laziness but hey, I just launched ten rockets and they flew well without damage. Get out of the 70’s and join the 21st Century. It is the new golden age of rocketry so you better jump on the crazy train before it leaves the station. Life is too short to try to get back the glory days of your youth in the 60’s, Today you are proud to have just enough time in your busy life to just shake the box and have a finished rocket fall out. Old world craftsmanship … humbug … soon we will make anything perfectly in an instant with advanced materials fabricated by computer.

Now that I am all riled up I think I need to start in on that Fliskit laying there in the box, boy I sure do miss the smell of sanding sealer in the morning!
 
Last edited:
with my Flame Master 3000 Protection suit on:
Woody's Workshop said:
.... I take it and start coating it with TiteBond II Thinned down with water. ...
Click to expand...
that seems a little of an overkill. Balsa should be strong enough on its own for most rockets. If it isn't, then it is better to go to basswood, lite ply, birch ply, or other materials depending on the flight. These products also come in different thicknesses.

As for the laser cutting, it has already been mentioned it is much better than the die cut. End are crushed, and it gets worse as more units are produced as the die edge is not as sharp.

In comparison to cutting with a pattern, it is one of convenience. The parts are already cut with just some tabs to be cleaned up. For complicated patterns (such as the Penguin) or in kits where there are a lot of fins ( 8 large one in the Solar Eclipse), it cuts down on mistakes and hand injuries.
 
Nothing really wrong with Laser cut production balsa.
I just prefer the old school method of drawing, measuring, cutting, and forming by hand.

More effort = better experience.
 
One of these days I'll get my own laser cutter. It's just a matter of time before they get cheap.
 
Go get a FlisKits Intergalactic Man Of Space kit and a Tumbleweed and build them. Then tell me that you would have preferred to cut out those parts yourself! There are situations in which having laser-cut parts isn't a matter of convenience, but of necessity. It makes certain kits possible that wouldn't otherwise be marketed if the builder had to craft those tiny parts with close tolerances by hand. I enjoy scratch-building, but I don't want to have to learn watchmaking in order to create rockets that I can fly.

In cardmodeling, I have crafted and assembled surface details that were smaller than the head of a pin and I don't shy away from challenges. But if laser-cut versions of those parts had been available, I would have gladly used them instead!
 
I am fine with the laser cut fins as well as cutting them myself. I do 2 coats of sanding sealer then prime and paint. Comes out pretty good and it doesn't take too long to do.
 
Hey guys, thanks for the imput.
Couple things I need to point out I forgot to mention.
I don't use sanding sealer for anything. It's always TitBond II. Even on the body tubes.
When I do this on either laser or die cut fins, you basically close the cut with glue.
Now you assume I'm using a hand knife of some sort to recut the fins out of the sheet which is inaccurate.
I use a scroll saw, different blades for different things. Their kerf is the same or less than a laser cut. When doing cuts, like on the Rock-It kit I just finished, I used a round cut blade so didn't change the direction of the stock, just the direction of motion. Could do this as they were all different shapes and none of them had mating edges in the cuts. The round cut blade leaves about 2-1/2 times the kerf of a straight cut blade.
I've yet to try lamination of paper, but I think I will try on a re-build I'm doing because this old thing has thin balsa for the size of fins, and there is sanding sealer on them. After probably over 25 years, is still sands gummy. So the best is probably just cover everything up before re-attaching the fins.
But keep leaving your thoughts. I might just learn something.
 
Woody's Workshop said:
Hey guys,
I have to tell ya, the way I do things I do not like the Laser Cut balsa fins that come with kits these days. I guess you'd have to understand my methods to understand, but I would rather just have a sheet of balsa and a fin pattern like in the olden days (Old School?). And I will try to explain; Agree, or Disagree?
One of the very first things I do is take the balsa, unless it's unuasally rough or has saw marks in it, and don't bother to sand. I take it and start coating it with TiteBond II Thinned down with water. Being a cabinet maker, I know it adds strength as well as weight. My theory is if your adding weight, it should also add strength. Anyways, the laser cut fins are too loose to do a good job at what I do to the balsa. I thin the glue about 20 to 30 percent, depending on how thick it is. Put on 3 or 4 coats to both sides. Dries pretty quickly and it soaks into the pours so it really adds strength, plus it is flexible. Now when its all dry, if the pieces are not flat and all even with the sheet, it makes it really hard to sand without breaking threw, or adding more than required coats. I take my ROS (random orbital sander) to the sheet at low speed and it makes it as smooth as a baby's behind. If I need to add a few coats then so be it. But before the fins are even removed from the sheet, all but the edges are ready for primer.
I don't know about the rest of you, but this is a whole lot easier than trying to fill the pours and get them smooth rather than after they are mounted like the instructions say.
So... I'd rather have the pattern and an uncut sheet of balsa. Or what ever material is used if it needs filled and smoothed out.
Opinions, concerns, comments...
I'm I crazy? Different? Is there a better way?
Since I've been using glue instead of wood putty or sanding sealer I've NEVER had a fin break or split, even if the recovery system failed. Take it I have not launched HUGE rockets, but I don't think I will ever change the way I do things because it works for me and results are excellent.
So let me have it, good or bad, I can take it.
John, aka Woody
Click to expand...

Woody

I don't believe there's a wrong or right way of doing things. It just boils down to what works best for you and what you feel comfortable with. For as far as I know there are 3 methods to treat balsa fins that I use. First is FnF...next Aero-gloss sealer and then skinning the fins with paper. I have had much success with all methods. I agree with you on the dye cut fins today. I think depending on the company it seems the quality of the balsa-wood has got worse and it seems to be weaker/more flexible then some wood that you may have bought from years ago.

I never tried your method with wood glue, but if works.... great. I know there are other hobbyist that use wood glue and I know BSI make a finishing sealer too, that you can use on balsa-wood...

I don't have the time to try a dozen methods..I find a few that I am comfortable with and perfect those...
 
I like laser cut balsa as long as it is cut decently.

When I built my Estes Vagabond, it felt like I was going to break my hands trying to cut out the fins. My exacto knife just wasn't up to the task so I actually used my work provided box cutter (a razor blade encased in a handle) to cut out the parts and even with that, it still put up one heck of a struggle!!!

On the other hand, the Semroc PSC Infinity I built (still needs a paint job), the fins practically fell out of the sheet just by handling it.

Now THAT is how laser cut balsa should be cut.
 
Have to say, I'm a fan of laser cut as well if I'm building a kit.

BUT, I tend to do something similar to the OP as far as prepping sheet wood in that I do the majority of the filling/sealing long before a fin ever gets cut. I use the ol' Fill and Finish, sanding on a flat surface, making sure it's smooth...doesn't matter if it's a laser-cut, die-cut, or uncut balsa or basswood sheet. By doing most of the fill work before cutting, it helps achieve a consistent surface (no inadvertent ridges, troughs, etc). Edge finishing becomes much easier, either needing very little or no filler, just using primer to fill in the remaining leftover grain.

Takes a little more time before you reach that magical moment where a bunch of wood and paper tubing starts looking like a rocket, but it's an acceptable compromise between speed and finished appearance.

FC
 
The only rocket I ever built with laser cut fins was my Semroc Mars Lander. Ok, they were good to work with but I almost never build kits anyway. I have nearly 50 rockets in my present fleet and all were built with hand cut fins. My whole approach to building rockets is about the craft. Laser cut fins takes some of that crafting away. I actually prefer to make my own because I have to hand pick my balsa (which I prefer to do) and with kits / pre-cut fins, you don't have that option. You could end up with old balsa or something too light weight. I like my balsa dense. I would say your approach if just fine if it works for you, but when you do laser cut fins, Go to plan B. (that would be an alternative approach)
 
I grew up building airplanes/rockets with die crunching in the 70's and 80's. Laser cutting is far better in every way.
 
MarkII said:
Go get a FlisKits Intergalactic Man Of Space kit and a Tumbleweed and build them. Then tell me that you would have preferred to cut out those parts yourself! There are situations in which having laser-cut parts isn't a matter of convenience, but of necessity. It makes certain kits possible that wouldn't otherwise be marketed if the builder had to craft those tiny parts with close tolerances by hand. I enjoy scratch-building, but I don't want to have to learn watchmaking in order to create rockets that I can fly.

In cardmodeling, I have crafted and assembled surface details that were smaller than the head of a pin and I don't shy away from challenges. But if laser-cut versions of those parts had been available, I would have gladly used them instead!
Click to expand...

Good point and one that helps explain when/where we (FlisKits) use laser cut parts. Many of our kits do NOT use them. The reasons include:
  • Cost
  • The kit has simple fins that are easy to cut
  • An effort to teach the next generation of rocketeer HOW to cut fins (can't design your own models if you don't know how to fashion parts)
  • Freedom (to make changes to the stock design)

Interesting thread :)
jim
 
MarkII said:
Go get a FlisKits Intergalactic Man Of Space kit and a Tumbleweed and build them. Then tell me that you would have preferred to cut out those parts yourself! There are situations in which having laser-cut parts isn't a matter of convenience, but of necessity. It makes certain kits possible that wouldn't otherwise be marketed if the builder had to craft those tiny parts with close tolerances by hand. I enjoy scratch-building, but I don't want to have to learn watchmaking in order to create rockets that I can fly.

In cardmodeling, I have crafted and assembled surface details that were smaller than the head of a pin and I don't shy away from challenges. But if laser-cut versions of those parts had been available, I would have gladly used them instead!
Click to expand...

You are absolutely correct and that is something I never really considered. Kinda funny especially since I recently built a Semroc Mars Lander...I woulda gone nutso (well, MORE nuts that is) if there were no laser cut parts.
 
I don't mind LCB, I just don't like the smell when I open a box or pkg. I just can't get use to that smell. I like burning wood smell, just not balsa.
 
jflis said:
Good point and one that helps explain when/where we (FlisKits) use laser cut parts. Many of our kits do NOT use them. The reasons include:
  • Cost
  • The kit has simple fins that are easy to cut
  • An effort to teach the next generation of rocketeer HOW to cut fins (can't design your own models if you don't know how to fashion parts)
  • Freedom (to make changes to the stock design)

Interesting thread :)
jim
Click to expand...
Very true. Laser-cutting isn't a standard across-the-board policy on your kits by any means. As I said previously, I started when every kit had cut-your-own fins. I mentioned those two kits in particular because both of them include very tiny parts that would be a challenge to cut with precision if they were done by hand. I did build a pre-laser Tumbleweed. Great rocket, BTW. It remains my most-flown rocket to date. I struggled to cut out those fingernail trimming-sized fin caps, but with persistence and several tries, I did it and I was proud of my accomplishment. The TW is a simple build otherwise; laser-cutting can help to unify a kit that is overall a Skill Level 2 but which has a couple of Skill Level 4-5 steps.

I love your laser-cut MTTM centering rings, and I had to laugh when I got my latest set. In the BT-2.5 (MicroMaxx motor tube) to BT-4 centering rings, there is a tiny, nearly microscopic, laser-cut mark on the face of the ring, right near the inside diameter opening. You have to look closely to see it, and using a magnifying glass (or a microscope!) helps a great deal here. What is it? At first glance it appears to be just a tiny speck, but with a bit of magnification, its actual purpose is revealed. Why, it's a perfectly round, partially-cut perforation that can be used to create a port to pass the shock cord (26 lb. Kevlar, thinner than common sewing thread) through the upper ring when you want to anchor it to the motor tube. It needs to be knocked out to use it; otherwise, the ring can be used as is as a typical CR. I had to find a pin that was thin enough to do the job, and I eventually employed a fine embroidery needle to open it up. I was truly impressed when I looked at the needle tip after it poked through and found an extraordinarily small, absolutely round fiber board chad stuck to it. This is a perfect example of the kind of precision that laser-cutting adds to a kit or a component.

More than a few FlisKits feature cut-your-own tubes, too, which is a neat and very handy skill to learn.
 
Last edited:
Laser Cut Balsa, Love or Hate?
None of the above, I just accept that it is.
There is enough of the craftsman in me to not mind if it were merely blue lines printed on sheet. Am also fine with die-cut.
Looking at laser cut sheets for "intakes" on Estes QCC Explorer I am happy they saved me a couple hours and a few broken #11 tips.
 
I often shape my fins so filling and sanding before cutting them out would be a bit counter productive.
 
MarkII said:
More than a few FlisKits feature cut-your-own tubes, too, which is a neat and very handy skill to learn.
Click to expand...

Oh yeah... If I am looking for a specific look or (more commonly) doing a scale model, it is impractical to have every length needed in stock (I don't have the warehouse space for it...) so for some kits we have the builder cut the body tube.

For other kits, the body tube cutting is for a special look (like angled cuts and such). Learning THAT particular skill really opens up the possible design ideas :D
 

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