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Tools/techniques for profiling balsa sticks?

#1
What tools do you use to turn a 1/2" square stick into a leading edge or a 1x1/4 stick into a trailing edge?

I've been trying to do it with a hand plane and hand sanding and do not like the results at all.

Is there some kind of system that can hold a 36" stick in place and move a blade along it lengthwise?
 

Turbojoe

Well-known member
#2
What tools do you use to turn a 1/2" square stick into a leading edge or a 1x1/4 stick into a trailing edge?

I've been trying to do it with a hand plane and hand sanding and do not like the results at all.

Is there some kind of system that can hold a 36" stick in place and move a blade along it lengthwise?
You've already tried what most of us would suggest. It's all about learned technique. None of us are born with this stuff in their head. It's trial and error. Depending on what final dimensions you need you MAY be able to find what you need from one of the balsa suppliers. If not exact then something close could be final shaped to what you need. Over 40 years ago I was privy to seeing a Marks Models/Jim Miester collaboration being die cut. I don't know what it was and don't know if it even made it to production. I do know they were using a router system to shape some parts. One of those parts was a leading edge.....

Give us more info as far as what plane/kit/plan etc and at what scale and maybe one of us can help point you in the right direction.

Joe
 

PsyBorg

Wake up! Time to fly!
#3
Look into a luthiers radius block for sanding guitar fret boards to certain curvature. They wont be as tight as you want for an aircraft leading edge but they are longer and have a curve in them to be able to sand very evenly. You just replace the sand paper on it depending how much wood you need to remove or smooth out.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#4
I'd suggest sticking to tools that are known to work well, and pick up some extra balsa to practice with. A good balsa plane with sharp blade and long sanding bar work great. Multiple sanding bars are even better - with different grits from 80 to 400 will get the job done. For the plane, an adjustable blade will let you take fine cuts without gouging deep into the wood. It's also very beneficial to know the direction of the grain so you can work WITH it, and not AGAINST it.
 
#5
Yeah, I've been using a cheap plane and wasn't really sure which way I was supposed to be going. Is there a good plane you like? I've never had a bar sander... I usually just lay a full sheet of paper on my bench and pretend like the wing is a big knife I'm sharpening on a stone.

The plane I'm building is nothing fancy, basically just a balsa FTTT. I'm sure Sig has LE/TE stock about that size but I kinda like making it myself.
 

Joker 53150

Mmmmmmm, balsa.
Mentor
#6
Master Airscrew makes what is probably the most common planer. It works well, although I think mine is getting worn out and should be replaced. I've also 3D printed a planer which works well and uses common razor blades.

For a sanding bar I picked up a couple from Great Planes. It's their "Easy Touch" bar, available in a few different lengths and even a couple profile designs for doing things like leading edges.
 

Hai-Lee

Old and Bold RC PILOT
#7
For complex curves along a LE or similar I often use a small length of the balsa to be shaped and then carve/sand the required profile.
Next I apply a little petroleum jelly to the sample, put it curve side up on the workbench, and cover it in modelling clay. Let it set or dry properly.
Next is to remove the sample stick clean up the dry clay to remove all of the jelly, (I sometimes give it a light sand as well).
Now I glue some sandpaper into the clay LE profile.
Now I place the LE piece to be shaped on the workbench top and do the sanding of the long length that is to be the LE.

Once the job is finished you should keep the clay block in case you damage the LE and need to rebuild the wing in the future.

With a little care and expertise you can make any profile you choose and even do TE pieces as well.

Old school but it works!

Have fun!
 

rockyboy

Skill Collector
Mentor
#8
An alternative to buying sanding bars is to use a construction level from the hardware store and put double sided carpet tape to stick sandpaper to the edge. This can be a really cheap option if you already have a couple levels hanging around the workshop! :D

But yeah, I'm another of those "use the Master Airscrew plane with fresh razor blades to rough in the shape, and then a sanding bar (uplifted construction level) to get the final shape by hand.

For best results, go slow, and don't listen to speed metal or political podcasts while sanding. :p