I used the centering rings to make a fin alignment tool. I screwed two centering rings together then using my mill I cut slots through one of the centering rings. The slots were just as wide as the fins. There was an alignment tool at each end of the fins.

I used vacuum tape to hold the fin alignment tools in place while the epoxy holding the fins to the motor mount cured.

Here is the first fin being glued to the tube using my fin alignment tools.

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My wife hates my rockets. I took over the kitchen. Opened the leaf in the table so one of the glued fins could face down while the 3rd fin cured.

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Here the fins are all attached to the motor mount tube. The next step was to remove the fin alignment tools. Since I didn't glue the centering rings on I can just slide them off and remove the tools with a screw driver. Then I can glue on the centering rings.

Here the alignment tools have been removed from the assy.

I am removing the alignment tools from the good centering rings. Then I will glue the good centering rings to the MM tube and the fins.

Alignment tool removed and now gluing centering rings to motor mount tube and fins.

Ready to slide the centering ring on the AFT end.

Finished gluing on the centering rings. The next step is to put the kevlar pulp and epoxy fillets on.

Just finished adding the epoxy and Kevlar pulp fillets to fin roots, fin edges and centering rings. These fins will never come off.