Wobbly Rocket Assembly

Not sure how to describe this, but my 6" diameter 11' long FG rocket, which uses shear pins and rivets to hold the 4 pieces together (including NC) is a bit wobbly when it's all assembled. When I hold it vertical, if I lean it one way or another, I can feel a bit of a wobble as the pieces settle at different angles, even with the shear pins and rivets installed.

1. Is this fine/normal? Or,
2. Is the solution just to use masking tape to get closer to a friction fit, then install the shear pins?

This is the rocket https://wheelerl3.wordpress.com/ I'm very nervous for this weekend and just checking over everything! Site's not quite done yet.

Thanks,
Brian

In and of itself, wobbly is not an issue. The real question is: is it going to stay together until apogee? Did you do shear pin calculations? You will be relying on them 100% for drag-retention. Is your coupler too short?

Using tape is fine, but keep in mind that the amount of tape you use in the cool basement may be the wrong amount out on the field. But you know that already.

As with anything L3-cert-related, run it by your TAP/L3CC well before launch.

+1 on tape. Tape is your best friend

Many ways to deal with this based on source of wobble.

1. If you have shear pin holes that are too big, you should fill and redrill or go to next size up if that fits your charge calc ranges and flight plan
2. Ditto for plastic rivets; and again, another possible option here is a slightly bigger size
3. If you use binding screws they are a bit more forgiving since you have the screw to hold the airframe, although I have filled and redrilled these also if I really screwed something up
4. If you are pretty close on your drilling, but the fit of the couplers are wonky, then a wrap of tape top and bottom of coupler area helps stabilize the joint.

Thanks, makes sense. I think the couplers are a bit small because the #4 shear pins go into a #4 tapped hole, and the plastic rivets use the appropriately sized hole.

I'll add a ring of tape before I do the ground test today to get the wobble out.

Sincerely,
Brian