Fin alignment: jig, sight, or ?

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Jon Craig

Well-Known Member
What's the best way people have found to align fins on a rocket? Have you build (or bought) a jig of sorts? Do you just eyeball it? Or ... ?

I'm getting better, using eyeball method, but I think it's still not perfect, and I always strive for perfection.

stantonjtroy

Well-Known Member
I always use my military issued, laser straight, NASA calibrated eyeball.

FWIW

blackjack2564

Crazy Jim's Gone Banana's
TRF Supporter
Jon, you haven't mentioned what size rockets.....for airframes 2in and up I use homemade jigs made from foamboard or heavy cardboard modeled after this jig.
https://www.vatsaas.org/rtv/construction/finjig.aspx

Simple and easy to make. For estes type rockets I still just eyeball them

It's more of of thrust thing for me. If I do make a smaller high power rocket, like a minimum diam 29mm 0r 38mm I will use a jig.

Jon Craig

Well-Known Member
Jon, you haven't mentioned what size rockets.....for airframes 2in and up I use homemade jigs made from foamboard or heavy cardboard modeled after this jig.
https://www.vatsaas.org/rtv/construction/finjig.aspx

Simple and easy to make. For estes type rockets I still just eyeball them

It's more of of thrust thing for me. If I do make a smaller high power rocket, like a minimum diam 29mm 0r 38mm I will use a jig.
Wow - very nice jigs. I haven't the tools to construct one however. I wonder if anyone sells them?

e42

Well-Known Member
Wow - very nice jigs. I haven't the tools to construct one however. I wonder if anyone sells them?
While I have not personally used this product, I am told it works extremely well.

Standard Rockets Assembly Tool

Someday I hope to pick one up.

--- Ron

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GuyNoir

Well-Known Member
Art Rose fin jig, hands down. Your fins will be on perfectly straight using that puppy.

Bravo52

Well-Known Member
Art Rose fin jig, hands down. Your fins will be on perfectly straight using that puppy.

The high power one is almost 1k... :y: Anyway, I just use my eyes and the estes yellow ruler. It helps out with getting it in line. FatBoy Random Part-time Hobbyist The Standard Rockets Assembly Tool (www.standardrockets.com) is the best way to go. It is so simple to set up all fins at one time.... set them up, glue them and forget about them. Its extremely versitile no matter how many fins you have or how thick they are. It even has cradles to lay your rocket flat while doing fillets. troj Wielder Of the Skillet Of Harsh Discipline, Potent Hundreds of dollars.... for a fin alignment jig? Wow. Me? I eyeball 'em. I can rebuild a lot of rockets for what a400+ jig would cost.

Unless you're a perfectionist, or you have real problems with hands that shake a lot, learn to eyeball 'em and save yourself a lot of money.

-Kevin

AKPilot

Well-Known Member
You know, there looks like a tremendous business opportunity here (Vatsass Fin Jig) for anyone that wants to pursue it.

Could make them in all sorts of BT sizes and 3 or 4 fin configurations.

powderburner

Well-Known Member
You would also need them (potentially) for different fin thicknesses.

One suggestion: it might be "better" to make the fin guides out of foamcore instead of masonite---it would be much lighter to mail. Foamcore also has a little springy-ness to it, and it grips the fins snugly if you cut it just right.

And foamcore might be compatible with laser cutters?

I can see it now--sets of jigs (for BT20, BT50, etc), with pairs of guides for 3 fins 1/16th thick, 3 fins 1/8th thick, 4 fins....

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Pat_B

Well-Known Member
I have the Art Rose fin jig and am extremely satisfied with it. However, it is expensive and I've noticed that the price has increased quite a bit since I bought mine.

The mandrel cost is way out of line considering that you can buy dimensioned metric rods that would just need to be cut down and center drilled. The mandrels supplied with mine were made out of Delrin which is pretty inexpensive stuff (~$1/ft in 2" diameter). Nonetheless, it works really well and I'm glad I have mine, but it is high priced. Adrian A Sponsor TRF Sponsor TRF Lifetime Supporter Here's what I do to glue on my fins straight. The granite/marble floor tiles cost about about$3 each at Home Depot.

This way, you use the nice uniform thickness of the floor tiles to ensure that the fins are parallel to the body tube, which is the most important part to get perfect. To make sure that the fins stick straight out from the tube, I set the tube on end over a piece of paper with 120 degree markings, and adjust while the glue is soft. I also like to save time by taking the fins using this jig with CA, and then I go back with epoxy for fillets.

foose4string

Well-Known Member
I usually just eyeball 'em. A jig would be nice but I get along pretty well without.

However, if I were to spend dinero on a jig, I think it's hard to beat Lyle Merdan's, Standard Rockets Assembly Tool. Very clever design and solid. Cost a fraction of the Rose jig.:2: I think you can pick one up through Sirius-Standard Rockets Jig.

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JRThro

TRF Supporter
I use the gray plastic Estes Fin Alignment Guide that someone gave me a few years ago. Works like a charm for most single-engine model rockets.

Stymye

Well-Known Member
annother vote for the estes fin alignment guide.

FatBoy

Random Part-time Hobbyist
However, if I were to spend dinero on a jig, I think it's hard to beat Lyle Merdan's, Standard Rockets Assembly Tool. Very clever design and solid. Cost a fraction of the Rose jig.:2: I think you can pick one up through Sirius-Standard Rockets Jig.
This is worth every penny.

BobH48

Well-Known Member
The Standard Rockets Assembly Tool (www.standardrockets.com) is the best way to go. It is so simple to set up all fins at one time.... set them up, glue them and forget about them. Its extremely versitile no matter how many fins you have or how thick they are. It even has cradles to lay your rocket flat while doing fillets.
I saw these at NARCON last year and I'm kicking myself for not picking one up.

jeff_in_AZ

Well-Known Member
BMI CAD also used to make and sell a machined Aluminum fin jig:

https://www.bmibay.net/finjig.html

I'm not sure what their status is right now, the fin jig is not

I think the answer to what is needed for fin alignment
depends a lot on what the rocket is used for. If it is
a contest rocket, fin alignment will be important. If it is
for park flights with your kids, then line of sight alignment
is fine.

jeff

Well-Known Member
I always use my military issued, laser straight, NASA calibrated eyeball.

FWIW
In the RAF they call it the Mk. 1 eyeball.

j.a.duke

I saw these at NARCON last year and I'm kicking myself for not picking one up.
Bob,

You can order one still-it's never too late! And you get the newer version to boot.

Cheers,
Jon

Moldie

Well-Known Member
Eyeball and lots of double checking.

rocketsmith

Well-Known Member
You know, there looks like a tremendous business opportunity here (Vatsass Fin Jig) for anyone that wants to pursue it.

Could make them in all sorts of BT sizes and 3 or 4 fin configurations.
Anyone interested, contact me : dynocaster@msn.com. I have been making acrylic fin alignment jigs and they work great. I will include instructions on use and I can make any size body tube/ fin thickness/ number of fins you want. I will post a picture when I can. Cost is pretty minimal as the material is less than 10 dollars a square foot. Epoxy doesn't stick either.
David B. Smith (tra #11892)

Viperfixr

Born Again Rocketeer
Anyone interested, contact me : dynocaster@msn.com. I have been making acrylic fin alignment jigs and they work great. I will include instructions on use and I can make any size body tube/ fin thickness/ number of fins you want. I will post a picture when I can. Cost is pretty minimal as the material is less than 10 dollars a square foot. Epoxy doesn't stick either.
David B. Smith (tra #11892)
Would really like to see this for HPR application, like on a 38mm min diameter build I am about to start. Any pictures? \$?

luke strawwalker

Well-Known Member
As most rockets I build have four fins, I usually put them on in opposing pairs and clothespin a scrap piece of balsa (usually "L" shaped) or a steel ruler across the two fins to keep them straight...

Works like a champ... I may need to come up with something with a 120 degree angle for 3 finned rockets though... OL JR

Scott Evil

Well-Known Member
For LPR-ish sized rockets, I've been known to round up some choice LEGO's from my sons extensive selection and make jigs out of them. It actually works fairly well with a little creativity.

(It's also a great excuse for a grown man to play with LEGO's a bit :blush: )