Anyone who flys mini R/C helicopters breaks blades. My blades were running around $10 or more per pair, and the local hobby shop never seemed to have them.
To save money, I build new ones from the stubs of the broken ones. In this Instructable, I'll show you how to do that.
In addition to saving money, I found my new blades to be both more durable and to lead to a more stabilized hover (at the expense of high rotor speeds).
Step 1: What's Needed?
Basically you will be taking the stubs of broken commercial blades and creating new ones from them.
You need the stubs, because they have the mounting hubs formed in them and they help set the correct pitch of the blades. Once the new blades are cut and shaped, we'll cover them with Monokote for a sleeker finish and to add additional strength.
(2) Plastic blade stubs, cut to the same length (about 1" or so of blade remaining)
(4) Pieces of 1/16" balsa wood (or 3/64" if you can find it)
Glue - CA or Gorilla Glue
Monokote covering or similar material
Covering iron or a small household iron
Step 2: Cut Everything to Size
For my heli, I used stubs that were 1" to 1-1/2" inches long and balsa sheets that were 9" long by 2-1/4" wide. You may need to adjust these sized based on your own helicopter.
Step 3: Glue and Clamp Sheets to Stubs
Now just glue the sheets to the stubs, making a sandwich with the stub in the middle , using two bals sheets per blade.
It's important the the blade be glued securely and clamped well, especially at the stub end to get good adhesion of balsa to the stub.
You should end up with a nice curvature at the stub end, that becomes less curved at the tip end.
Step 4: Cut Balsa Blade Down to Original Blade to Size
Using one of your store bought blades as a guide, cut the balsa to size.
I cut my new blades a bit shorter than the originals, but left the chord (width) of them be a bit wider. I found that the design resulted in requiring high rotor speeds for hovering, but was more stable in the hover as well.
You will need to experiment for your particular helicopter. For first blades you can cut them larger and longer and mount them uncovered. You can then adjust the size down until you reach optimum size for your machine and flying style.
Step 5: Sand to Make an Airfoil Shape
You'll want to sand the blade so that you have a rounded off shape and the leading edge with a tapered, thin trailing edge (sorry, no good way to show this). You can also sand in a slight rounding at the tip like the commercial blades.
During this step, you'll also want to make sure that you end up with two blades that have the same weight and balance. If not, you'll get a disturbing vibration when flying.
Step 6: Cover Your Blades
I used white Monokote to cover mine, but any of the typical R/C covering will work. Of course, the lighter the covering is, the better it will perform.
Using your iron, follow the directions with your covering, but make sure the covering is absolutely smooth. Also, make sure you keep the amount of covering used consistent, else you will affect the balance of your blade pair.
Step 7: Finished!
Now just install the blades as normal and you are ready to fly!
I hope you enjoyed this Instructable and found it easy to follow.