Hollow Block Balsa Wing Tips

[Casey]

Are there any videos on how to hollow out a block balsa wing tip?

[Dan McEntee]

    I'm sure there are many. I have been working with Kevin King on uploading old Windy Urtnowski Pro Stunt Product videos to the Walt Brownell Channel on YouTube. The channel is growing quite large now as we have been working on digitizing and up loading at least 4 videos a day. Find the channel on YouTube and then go through the different play lists.  On almost any construction series of any model he built there is a clip on doing solid balsa wing tips. I'm sure there are others posted by other guys also s o it's worth a look around there to see what is available.
  Type at  you later,
  Dan McEntee

[Avaiojet]

Are there any videos on how to hollow out a block balsa wing tip?

Casey,

Solid? How about two halves instead of one solid piece.

You can "spot" Epoxy the two halves together for shaping then, with a bit of heat, the halves will literally separate from each other and the tip rib. Hollow each half separately.

Working with two halves is much easier. Also, you'll probably have an adjustable lead out and working with two halves should make this task easier. You'll have a centerline from the two halves.

Good luck!

Charles

[Paul Smith]

I've always considered this a waste of balsa and the source of a lot of dust & chips.

The two halves idea is good.  Simple put the temporary glue in a part of the tips that will be cut away.

[Brett Buck]

Are there any videos on how to hollow out a block balsa wing tip?

    I don't know of any, but its pretty simple - form the outside shape to very close to the final dimensions, with it just tacked on with dots of Hot Stuff. Then pop it off. As long as you don't later mess up where the dots are, you can just put it back on in exactly the same position and the dots index it perfectly.

    Use 1/2 or 3/8 sharpened brass tubes, or the various "ring gouge" that comes in the Exacto router set to "core sample" out the majority of it.  Be careful not to split it or break it  Then, there are a variety of methods. I would probably use the Dremel sanding drum when it get close - the carving tools just cut down on the massive amount of dust. You can also split it  horizontally to make it easier to get to the ends. I mostly use my fingers to judge how thick it is, but also, use a light source to "candle" it, looking through to see how much light comes through it, because its pretty easy to get a thin spot. Splitting it also makes it a bit easier to get a good platform to mount the adjustable leadout system. Glue it back together when you are done.

   You want the interior to be nice and smooth, because if it is rough it is prone to breaking at the thin spots.

     My suggestion is that you shouldn't try to get it too thin - probably no thinner than 1/8". Light will go through that pretty well, medium orange. You can make it thinner but if you are using appropriate wood (dead soft) it will be prone to cracking. Any thinner and you also have some chance of going through when doing the final sanding with it all in place.

    Brett

[John Carrodus]

You only need to hollow out one wingtip- generally. The outboard one can be made up of block scraps glued together and roughly carved then finished to size. Do your numbers right and little wing weight is needed, if any. If there is more weight needed. I put in extra beef eg corner braces, or extra bracing. If it's gotta be heavier, may as well get it to work for it's keep!

[FLOYD CARTER]

Back long ago, when balsa was cheap, balsa block tips looked good.  I dislike using gouges or sharp things while holding a block of balsa in my hands.  So a Dremel tool with a sanding drum is quick.  And it hurts less than a knife if you zing on your hand.

[Motorman]

https://www.amazon.com/Kutzall-Extreme-Sphere-Shaft-3-1mm/dp/B072N1MN7S/ref=asc_df_B072N1MN7S/?tag=hyprod-20&linkCode=df0&hvadid=312316005242&hvpos=&hvnetw=g&hvrand=6106640490065925700&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9003887&hvtargid=pla-569427398864&psc=1&tag=&ref=&adgrpid=63836851802&hvpone=&hvptwo=&hvadid=312316005242&hvpos=&hvnetw=g&hvrand=6106640490065925700&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9003887&hvtargid=pla-569427398864

[Brett Buck]

Back long ago, when balsa was cheap, balsa block tips looked good.  I dislike using gouges or sharp things while holding a block of balsa in my hands.  So a Dremel tool with a sanding drum is quick.  And it hurts less than a knife if you zing on your hand.

  It certainly works and is very easy to control. I only use it for the last bit of stock removal because of the God-awful mess it makes.

    Brett

[Dwayne Donnelly]

It might take awhile to find it , but there is a bunch block shaping and  hollowing in Windy's B-25, the techniques used will be the same for wing tips.
https://www.youtube.com/channel/UCQLZOloDrMlE4LDcTwc1wvw/videos

[Brett Buck]

https://www.amazon.com/Kutzall-Extreme-Sphere-Shaft-3-1mm/dp/B072N1MN7S/ref=asc_df_B072N1MN7S/?tag=hyprod-20&linkCode=df0&hvadid=312316005242&hvpos=&hvnetw=g&hvrand=6106640490065925700&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9003887&hvtargid=pla-569427398864&psc=1&tag=&ref=&adgrpid=63836851802&hvpone=&hvptwo=&hvadid=312316005242&hvpos=&hvnetw=g&hvrand=6106640490065925700&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9003887&hvtargid=pla-569427398864

      I have a "medium" version of this, and if you want to remove stock fast, this is the way to go, it flies out of there like a snowstorm!

    Brett

[Dan McEntee]

It might take awhile to find it , but there is a bunch block shaping and  hollowing in Windy's B-25, the techniques used will be the same for wing tips.
https://www.youtube.com/channel/UCQLZOloDrMlE4LDcTwc1wvw/videos

       There are several construction series on the Walt Brownell Channel. I just digitized the 50 tapes that Walt had on the B-25 but don't remember which one. It should have been pretty early in the series. There is another on the main play list that has wing construction and shows tip carving:

   

   The tips get carved about 3/4 of the way through. I meant to make note of the minute mark but forgot!! In some of Windy's earliest videos he goes through making custom sanding tools. Anything that you can glue sand paper to can be a sanding tool if it will help you do the job. After you get the blocks shaped on the outside and split them to do the inside, even various grits of sandpaper folded up in your hand will help you get to the final thickness you are looking for. No matter how you do it, it's all about controlling what you are using and easing into the final steps.

   Type at you later,
   Dan McEntee

   PS to add; The tip carving starts at about the 1:25 mark.

[Avaiojet]

Are there any videos on how to hollow out a block balsa wing tip?

Casey,

I took this photo just for you. Sure, it's not a video, but a photo of a great tool for hollowing out or to just quick shape.

The other photo is the results of the tool at work. Works great! Others my know where to get one?

Good luck!

[Brett Buck]

Casey,

I took this photo just for you. Sure, it's not a video, but a photo of a great tool for hollowing out or to just quick shape.

The other photo is the results of the tool at work. Works great! Others my know where to get one?

Good luck!

   That is the "ring gouge" I mentioned earlier. They work pretty well and leave *much less mess* than the rotary tool methods, but you have to be a bit more careful because the want to follow the grain of the wood. I find I can control the brass tubing a lot easier, because you can turn it as you push it in, which cuts better with less tendency to split something out. Either tool is good to remove the bulk of the material, but rotary tools are much easier to control when you get close to finished.

    Brett

[Scott Richlen]

Check out WindyUMaster 945 or 946.  He does a hollowed balsa block wing-tip for his Big-Job.

[Ken Culbertson]

I priced the block Wendy used to make those tips.  4 x 3 x 36 - $87 and I doubt that was contest grade either.  Time that we learn more about making built up tips.  It won't be long before the last Ring Gouge is gone.

Ken

These are from my Tirfecta and Engame.  Very light and easier to make than hollowing.  Front is still a block or, in most cases, laminated 1/4" scrap.

[Avaiojet]

I've used this tool from time to time but I'm not all that comfortable with it. it can get away from you

I have used it to drill holes. Rotary Rasp.

Charles

[Jim Hoffman]

I find hand carving and hollowing solid wingtips a fun and satisfying task.  It’s pretty darn fast compared to the myriad of tasks needed to build and finish a competitive stunter.

[Scott Richlen]

If you wanted, you could also mold them.

Pink foam buck carefully shaped.
Carbon fiber veil and fiberglas cloth layers vacuum bagged.
Inner wing tip components.
Mounted and ready to paint (the blue you see is NOT blue foam, it is Aeropoxy light.  I used that to smooth the surface as my "vacuum bagging system" is not professional grade.....  but it works for me... )

[Perry Rose]

I think Bob Hunt molded wing tips. 1/16 balsa or something.

[Matt Colan]

I started doing wingtips for a customer plane a way Doug Moon recommends and very similar to what Ken posted. It was much, much faster and resulted in not having to use multiple thick blocks to hollow. My stash of good blocks is starting to run low so I’m saving them for my special projects.

Start with a 1/4” hollow frame for the tip you want, glued up against a rib. Then take scrap wood to make little “riblets” to stiffen it up and keep it square. After that some 1/16” wood bends very nicely around the rib and CAed to the frame. Took me about 90 minutes to do compared to hours of carving and hollowing blocks

[Scott Richlen]

So, here is my "poor man's vacuum bagging system".

You may have to do a little searching for it because not every grocery store carries it.  Look for the Zip-Lock freezer vacuum bag system.  It is cheap and easy to use.  Of course, it is size limited as the largest bag available is gallon-size, so no wings or fuselages (unless you like building the Musciano 1/2 A stuff.  In fact, that is how I first used it - to make cowls for my Musciano planes.

First - before you run off and buy one of these, please repaet after me: "you get what you pay for!"  Yes, it works.  But if you have ever used a professional vacuum bagging system right now you are laughing.  It is not in the same league; however, it does work and if you are trying to make a small item such as wheel pants or cowls it is a cheap and easy way to make them without investing a fortune in a prefessional system.

Just get out the pink foam and start carving.

A couple of tips:
- the bags don't always hold a vacuum long-term, so don't use long cure epoxy, use something that sets up in an hour or less.
- use laminating epoxy.
- I always cover my foam buck with saran-wrap or equivalent and I always put a wrap of saran-wrap over the top of everything.  However, if you don't mind destroying the bags (they're pretty cheap) don't kworry about an over-wrap.
- pay attention to where you locate your piece in the bag as you need the little pump-down valve area of the bag unencumbered.
- once you pump the bag down, keep an eye on it as it may lose vacuum and you may need to pump it down again.

Have fun!

[Scott Richlen]

By the way, I used the Zip-lock system to mold the cowl on my Uber-Hai.  In this case I used 1/16th balsa.  So you can use it to mold some pretty complex shapes.

[John Carrodus]

Nice work all round Scott!

[Paul Smith]

I started doing wingtips for a customer plane a way Doug Moon recommends and very similar to what Ken posted. It was much, much faster and resulted in not having to use multiple thick blocks to hollow. My stash of good blocks is starting to run low so I’m saving them for my special projects.

Start with a 1/4” hollow frame for the tip you want, glued up against a rib. Then take scrap wood to make little “riblets” to stiffen it up and keep it square. After that some 1/16” wood bends very nicely around the rib and CAed to the frame. Took me about 90 minutes to do compared to hours of carving and hollowing blocks

To me, this is the best answer to the question.

[Matt Colan]

That’s pretty cool Scott!

[Scott Richlen]

John and Matt: Thanks!

I also used the Zip-Lock method to make the cheek cowls for my half-A Bonzo stunt-ship.

[Casey]

Thanks everyone for your inputs

[Motorman]

Nice work all round Scott!

+1   I tried to carve balsa block tips once and got instantly depressed. Went right back to frame tips.

Motorman

[Dennis Toth]

Another approach to the Zip-Lock freezer vacuum bag system method is the Balloon method. With this approach you carve your wing tips, cowl, tank, etc. then mount it on a support stick, if you use foam you go right to fiberglass, it wood you need to seal finish the surface and apply mold release wax. Apply the fiberglass to the mold making sure the weave is filled, now take a good size balloon and inflate it, slowly push the balloon over the mold releasing air as you get it around the shape. The balloon put pressure on the FG/mold and gives a fairly smooth surface. For the foam mold just pour in a little gasoline or other solvent and it melds out. For wood, you need to work the part free starting at the widest edge. After the part is free of the mold you can fill in any dry spots in the weave then go to primer and color.

Best,    DennisT

[KenP51]

I haven't done many hollowed out wing tips, but some (most tips I build up). I use my Dremel a lot for hollowing work of any kind. Ball mills, sanding drums, 1/2" and 1/4".

The same tools work for balsa cowls, wheel pants, fillets, what ever.

If I am carving with a knife of any sort or shape I wear a Kevlar glove on the opposite hand. The glove has saved me gallons (well maybe ounces) of red hydraulic fluid leaks. They are cheap on Amazon. You can even get some that will protect not only your hand but arm as well in case you decide that if you are going to slip do it right.

Ken

[Dan McEntee]

I started doing wingtips for a customer plane a way Doug Moon recommends and very similar to what Ken posted. It was much, much faster and resulted in not having to use multiple thick blocks to hollow. My stash of good blocks is starting to run low so I’m saving them for my special projects.

Start with a 1/4” hollow frame for the tip you want, glued up against a rib. Then take scrap wood to make little “riblets” to stiffen it up and keep it square. After that some 1/16” wood bends very nicely around the rib and CAed to the frame. Took me about 90 minutes to do compared to hours of carving and hollowing blocks

   This could be lightened up a bit more by using a laminated tip outline similar to what the free flight guys use for outlining surfaces. You can use some harder wood and still be a bit lighter than trying to find light weight 1/4 or 3/8" sheet. Make a ply wood form, soak the wood, glue it up with white glue and wrap until cured. Should sand easy also when finishing, and will probably take some hanger rash abuse also.
   Type at you later,
   Dan McEntee

[Chris McMillin]

That model is really neat, Scott.
Chris...

John and Matt: Thanks!

I also used the Zip-Lock method to make the cheek cowls for my half-A Bonzo stunt-ship.

[Scott Richlen]

That model is really neat, Scott.
Chris... 

Thanks Chris!  It is an update on the old Scientific Bonzo designed by Walt Musciano.  The old kit was a profile with a built-up wing.  My brother built one when he was in Junior High.  And still has it but a little worse for wear!

My upgrades include a molded fuselage, a lost foam "Little Legends" wing, and stretched moment arm.  I sort of lost my Mojo on it, but hopefully I'll start working on it again.