Fin Can

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Well-Known Member
Sep 20, 2003
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This forum has proven to be a veritable cache of great construction tips. Especially those surrounding fin can construction where the assembly is "slid" into place via slotted
BT. What does one use to "fill in" the slots at the aft end?

Stewart, I've never tried this technique, but you might try Elmer's Carpenter White wood Filler in the tube. It's very easy to work with.
There are a couple of options as usual to answer your question.

A short section of tube coupler glued inside the aft end up to the first centering ring. than fill in the slots with short pieces of the tube you cut out for the fins...Ya saved em didn''t ya;) or fill and sand will work if you didn't.

Depending on your model you could also add a short section of the "fincan" size outside tube to the bottom of the model or cut the fin can a little longer to begin with.

Another method I use regularly is attaching the fins to the can with epoxy rivits, sanding the inside smooth again after fillets have been applied doing away with the slots all together.

All three methods have worked will for me in standard, Micro and LMR size models.
hope this helps.
that the 'fincan' is a structure that has a short section of body tube with fins attatched, usually made from composite materials, i.e. carbon fiber/fiberglas/kevlar, etc. the motor mount is installed into this unit, or minimum diameter fincans can double as a motor mount with minor modification.

what you are describing sounds like through-the-wall fin attatchment.
with ttw fins, you can run a bead of epoxy along the inside fin-body tube joint, then install a centering ring to seal the area. some people use expanding foam on higher powered models to fill the area and add strength.
I use the term for both. But a true fincan would be what you have shown Elapid.

But I also call the part of my rocket that has the fins the fincan section and then the payload section for the rest.

Whatever floats your boat.

I've always though of a fin can as the unit which comprises of the fins and MMT. Whether or not it has solid piece of BT (ie - Estes Alpha) it makes no difference to me. ie - see picture of what I consider a <a href="">fin can</a>.
Yep you've got the idea!Well done! Can I ask what epoxy you used to glue the fins in place ?
I've always been confused about the terminology myself

seems like it could be better to describe them as 2 different assembly types? like, external fin can, internal fin can