Getting the fins on straight?

[jqavins]

it's one thing to have the tool, it's another to know how to use it!

(like, people who get a jeep, then get it stuck.. "But it has 4-wheel drive!")

Same reason I do quick sketches in MS Visio. Sure there are better tools for it, but that's the too I know.

 

[JLP1]

Hey XL I sent you a PM, well I took the angles to work and we put them on the granite slab and use the precision squares and one was dead on and the other was like 88.5 degrees. Also on the that one the slots were almost a 1/4" shorter that the other. Those angle are 1/8 x 1-1/2 x 1-1/2 I'm going to order some 3/16 x 1-3/4 x 1-3/4 and make some new ones see if that helps. So in the meantime I downloaded a template from payloadbay.com mounted it on the foam board, cut it out placed it on the rocket and boom fins lined right up. I think I'm going to put the Macklin back on the shelf and come back later with fresh eyes.

 

[XrayLizard]

Good report !

 

[Joshua F Thomas]

I have the Estes' fin alignment tool, as well as the ones from Qualmann Rocketry. Both work well.

 

[jahall4]

There is know one best way to attach fins, but every good way starts with holding the rocket's airframe securely. IMO the best “tool”, for doing this is the Macklin Jig. You’ll notice I left out the word “fin” intentionally. That’s because attaching fins is probably the least of what you will use it for. Now it does it very well, but really how much time do you spend attaching fins? In fact, if you own one and it’s not on your bench most of the time, then you are not putting your investment to good use. Here are just a few examples of use in just the last few days…

Simple cradle to sand inside the airframe.


To quote Mona Lisa Vito "Dead-on balls accurate" alignment and installation of rail guide weld nuts.



... and oh yes, fins, but because these fins are "thru-wall" and have a tapered profile, a laser cut fixture provides tip-to-tip alignment to a fraction of a millimeter. Again its about holding the rocket securely.


Sometimes its about holding the "tool", that holds the rocket. When one Mackling Jig is not enough.

 

[RocketTree]

Aluminum angle to draw a straight line down a tube.

Then I use this paper target for fin alignment after they are glued on, for any minor tweaks.

https://www.rocketshoppe.com/info/fin_guide.pdf
Works fine up to 4" rockets if you add the larger diameters to the sheet.

 

[jrap330]

Does no one here use the PayloadBay Fin Guide Tool? Mark fin locations, draw lines using aluminum angle, print out template based on your fin parameters, glue to foamboard, cut out template, glue on fins using rubber band to apply pressure. Couldn't be easier or cheaper, especially compared to a commercial jig. You can even make a second guide to help keep them aligned. In any case, this tool didn't exist when I was younger and even back then, eye-balling it was close enough and yielded rockets that flew just fine.

Where do you get Form Board...just save it from packaging materials or Insulator boards from Home Improvement stores used in basements and attics.

 

[BABAR]

Where do you get Form Board...just save it from packaging materials or Insulator boards from Home Improvement stores used in basements and attics.

Office supply, in fact you will usually find it at both Walgreens and Walmart.

 

[lakeroadster]

I use a door jamb to mark the longitudinal line down the tube (I think back in the 60's the Estes Instructions said to do this?)


And a scrap piece of plywood to align the fins (if there's an even number).


That being said I love all those wiz-bang fixtures. I'm just to frugal - tight to buy one when I have stuff laying around I can make do with.

 

[Spitfire222]

Where do you get Form Board...just save it from packaging materials or Insulator boards from Home Improvement stores used in basements and attics.

The Dollar Tree foamboard is perfectly sufficient, and is what I use.

 

[Senior Space Cadet]

I can't believe this is still getting posts. Not that I'm complaining. I'm not. It's great.
I've come to the conclusion that, yes, I'm using the tools I have correctly (they aren't complicated), and I'm probably getting my fins on as straight as anyone else that is not using a jig.
From the videos I've watched at Apogee, it would appear that he usually doesn't use a jig for smallish rockets, so I'm in good company.
I've started using my Estes jig. I hadn't used it before because some fin sizes and shapes didn't fit on it very well, it isn't very rigid, and I was afraid of gluing the whole thing to the jig.
So what I've been doing is, using spacers under the body tube (if needed), leaving a gap between the jig's fins and the body tube (so I don't glue the rocket to the jig), make sure all three fins are in good contact with the body tube, then gently brushing some Super Glue along the joint to hold the fins in place. After it dries, I take it out and start making my fillets.
I suppose I lose some strength by not using white glue under the fin edge, but a good fillet seems to do the trick.
For me, one of the attractions of rocketry is the simplicity. I can whip up a design and see it come to fruition in a couple days. Launching is just a matter of sticking a motor in, hooking it up and pushing a couple buttons. I really don't want to spend weeks and hundreds of dollars building some huge, complex rockets with all sorts of electronics. Just doesn't appeal to me.

 

[Alan R]

I print my own 3D jigs. I have grown a small collection of them now. Sometimes I even get to re-use them.
Surprised no one has mentioned these: https://qualmanrocketry.com/Fin_Guides.html
There are some cool tools on that site.
As for that angle iron, I found one of those old triangular drafting rulers at the goodwill for 99 cents. Works great on most things.

 

[Bill Hanson]

Here's a parametric 3D printed fin jig: https://www.thingiverse.com/thing:2424931

Can do any number of fins, you define fin height and thickness, diameter only limited by the size of your build plate.

Printed one out for my 38mm Go Devil and it worked like a champ