My Fin jig

[SaskAlex]

Well, with all of the talk about fin designs lately (and because I'm bored and don't want to study for a midterm), I thought I'd share my thoughts on fin jigs.

When it comes to making fins, I think the most difficult part is not what material or shape to use, but how to attach them to the rocket. I used to use bent tabs and two-sided tape, but it's hard to get them aligned perfectly. Finally, last spring I broke down and made an alignment jig. I strongly recommend making one, because once you have one, making an awesome pairs of fins is a piece of cake.

I just cut a piece of 1/2" pvc down the center for a few inches, and cut one side off. Then I bolted it to a piece of OSB (similar to plywood) which had the rough shape of a rocket cut out. All you have to do is slide a rocket over the pvc pipe, clamp a fin to the OSB, and glue the fin to the rocket. I use PL premium and laminated particle board fins, and the result is light, very low drag, and almost indestructible. I haven't even bent a fin yet.

You can't tell from the picture, but the PVC pipe actually has a splice in it. I can remove the top part if I want to put a single bottle on the jig. If you are making a four-finned rocket, you can glue one fin on either side at the same time. For three fins, it takes three separate steps.

It's a little bit of work initially, but well worth it in the long run.

[RaZias]

Good idea, indeed gluing the fins is a hard part of making the rocket

[rockets-in-brighton]

When it comes to making fins, I think the most difficult part is not what material or shape to use, but how to attach them to the rocket. I used to use bent tabs and two-sided tape, but it's hard to get them aligned perfectly. Finally, last spring I broke down and made an alignment jig. I strongly recommend making one, because once you have one, making an awesome pairs of fins is a piece of cake.

Now that is timely. I just spent part of an afternoon's fabrication session trying to glue fins using a PU adhesive for the first time.

I normally use card fins which are easy to fix with contact adhesive: instant grab, and good holding power on card. They tend to split though, so I am looking at alternatives including PET fins. Contact adhesive works best when at least one of the surfaces is absorbant.

So using PU, which as I was quickly reminded, has no grab at all and needs to be supported while it sets up. Utter failure to improvise a support on the fly. I definitely need a jig, and I have been trawling for suitable devices. I like the way your design requires so few components.

The other route I'm trying, incidentally, is to add fillets of silicone or acrylic caulk to the root of card fins to give them support and resilience.

[millermw2]

That is a really nice jig. Like the earlier post said "timely" as I am building a new rocket and hope to launch next weekend. Thanks for sharing the pictures of the jig.

Mike

[millermw2]

Thanks again for sharing your jig. I made one and it worked perfect for attaching my fins.

Mike

[SaskAlex]

Thanks again for sharing your jig. I made one and it worked perfect for attaching my fins.

Mike

Good to hear! I'm glad it helped.