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Fin airfoiling jig

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TRFfan

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Does anyone know of a jig out there that is easy to operate and get very even airfoils?
 

TopRamen

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If you use a foam core then you can just use a hot wire cutter on a template of whatever profile you like.
The RC plane folks are coming up with some really nice methods nowadays, just look for "Airfoil Foam Wings" on youtube and there are plenty of videos. Obviously you want fins, not wings, so make the airfoil wing, then cut from it the desired fin design, and the airfoil will still be there.
There's a guy that does not even use a hot wire, as he can make perfect airfoil wings with foamboard, razor knife and hot glue gun. He has a method for folding the foamboard that works well, and could be tweaked just a little to get a symmetrical foil, as you don't want an airfoil that generates lift on one side.
Here you go:
[video=youtube;qJZoqGHAIDE]https://www.youtube.com/watch?v=qJZoqGHAIDE[/video]
Again, make the wing, and remove whatever shape you need from it. Then paper, glass, cf or "other" it.
 

dford

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Dude. Book. Tape. Sand paper. Wall.

Tape book to floor.
Stick sand paper next to wall.
Place fin angled on book to sand paper.
Sand.
Doesn't get any easier or simple than that.
 

Micromeister

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Sorry:
There is no jig I know of that will do the work for real airfoils. Shot most of the model buider here don't know what a true airfoil is LOL!
The only way to sand near-perfect airfoils is to do it by Hand on a Glass base, using double faced masking tape to hold the blank down with yellow frog tape or Tamiya tape along the high ridge. Sand the leading edge first with 220 to 400grit sand paper, Flip it around to do the tailing edge not quite to a knife edge, for True airfoils on rotors and Wings. Tear drop fins are a bit harder as you have 4 surfaces to sand symmetric leading and tailing edges.

To produce a matching set of Tear drop fins for a single 3 or 4 fin model might take as many as 12 count them "1 dozen blanks" to get 4 suitable fins.
I was fortunate to learn these techniques from Denis Cryway and Art Rose years ago. Art is the only man I've ever known who could sand symmetric Airfoils in balsa fins or wings by hand without anything but a sanding block and his knee.

Just keep in mind any slight imperfections in a single fin will cause the model to spin at a rate that negates the effect of all that sanding, reducing achieved altitiude by more then it would by simply rounding the leading and tailing edges of the fins instead.
Sanding TearDrop fins is as much Art as it is Science. Which is why most BTC's do not bother sanding teardrop fins anymore.
Hope the pictorial below helps a little.

1a_12in x 24in x .75in. Plate Glass & D-F masking tape_01-28-09.jpg


1b_apply & cut D-F tape on Glass edge_01-28-09.jpg


1c_De-Tac with finger oil_01-28-09.jpg


1d_Attach piece to be shaped_01-28-09.jpg


1e_Square up with 1inx1in sanding block_01-28-09.jpg


1f_Begin on hi side of airfoil_01-28-09.jpg


1g_Continue to finsh shaping_01-18-09.jpg


1h1_Plastic Artist pallet knife_01-28-09.jpg


1h3_Work down length and pop loose_01-28-09.jpg
 

hcmbanjo

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It takes one of these -

Great Planes Block.jpg

Great Planes Sanding Block with 220 grit
Patience, practice and a little time.
 

BDB

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Then you are actually wanting beveled edges, as airfoiling generally involves the entire fin.
Yea. I just want a precise way to bevel FG and CF fins. I've been looking for a 10 or 15 deg router bit for months.
 

samb

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Reading between the OP's lines I think he's looking for the ACME XFJ-1000 Universal Turbo Fin Jigger. I don't think such a beastie exists. A lot of good solutions offered here, all require varying degrees of DIY, power tools, elbow grease, time and practice. Also, fin material would dictate your choice of weapons; I don't see putting 3/32 balsa on a router table.
 
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TopRamen

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I'm designing a knife sharpening jig right now, and I am going to make it with the ability to do double duty as a beveling jig.
I intend to share it in the Watering Hole and in the Jigs and techniques sections.
It will only do bevels, not airfoils, but I only just thought to make it this morning and already have tons of pieces parts of various things that I can use, since I'm part hoarder and anytime I see free stuff on the side of the road or at garage sales, I grab it and stash it in the shed in case I may eventually need it.
 

Marc_G

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I've often wanted a good jig to do fine / shallow bevels on LPR fins. Most of the jigs I've seen are great for quarter-inch-thick stock but not helpful on my 3/32" or 1/8" fins...
 

NateLowrie

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I just built a variation of the Coker jig to do the fins on my 4" Patriot and Forumula 200. Holds the fin at a 10 degree angle for beveling. I then pass it through my router table and using a simpler 1/4" straight bit. The following pics show the jig construction.
IMG_7253.jpgIMG_7252.jpgIMG_7251.jpg

Here are some shots of the jig running. We clamp the fin down and them feed it though the bit. The jig is on one side and the fence is on the other. There is a hole in the fence for the router bit to sit into and you control the depth of the bevel by moving the fence off the bit. You need the fin to be sandwiched between the fence and jig because if you run the other way the router has a tendency to pull the fin away from the jig resulting in an uneven cut.

Note that the last picture is still the stock bevel on the Formula 200. We had to clean it up on the router because the end of the bevel was slightly sloppy and the bevel left a .93 edge. With this router jig, I was able to hold 0.005" on the edge. We beveled the Partiot fins from .093 to .030 and the Forumla 200 fins from 3/16" to 0.50

IMG_7192.jpgIMG_7193.jpgIMG_7194.jpg
 
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