Attaching fins question

[KILTED COWBOY]

Not sure if I am in the correct forum.
Will you get a strong bond if you are gluing the fins to the body tube after filling the spirals.
I know some folks just fill and sand the area around the spirals,in that case guess no problems. But some folks recommend filling and priming the whole tube, that’s what I wonder how the adhesive bonds to primer paint
Thanks
KC

 

[JohnCoker]

I think if you're just filling spirals, you should be OK doing that first. (The area of the spirals is small.) However, if you're priming first, I suspect you'll get a poorer bond. I generally fill everything last, because for me filling includes smoothing the exterior fillets as well.

 

[BABAR]

IIRC carpenters wood filler is fine, glue will bond right through it. For priming and painting, either mask the attachment points first, or use a Dremel or other tool to strip the contact surface after priming.

 

[opcon]

I used a 100 grit to sand the fin attachment areas (very gently) to break through the clear outer layer and scuff the cardboard, but not to the point of damaging it. I didnt mask off the area, just drew my lines and went to town (very gently). I used 30 minute 2 part Bob Smith epoxy. When I taped off for the fillets the epoxy ate right into the sanded area and greatly stiffened the body tube. I know epoxy is heavier and harder to work with but I'm not going to use wood glue anymore, epoxy is a far superior mechanical joint. My fins are 1/8" plywood so might be different with balsa or bass wood.