Like
@tsmith1315 mentioned, I for one, have been using 1/16 inch styrene rod shear pins on my dual deployment rockets since the 1990's when I learned about it, probably on the RMR news group.
And when I am flying cardboard tubes and/or plastic nose cones, I use aluminum soda can blades to reinforce plain cardboard or soft plastic materials that are liable to 'waller out' over time.
I have only ever used a single polystyrene pin for each joint, one for the nose and one for the the av-bay on my traditional dual deployment rockets.
Align the holes, shove a styrene rod thru the holes and trim them flush with the surface of the airframe with side-cutters or an Exacto knife.
Styrene rod pins have worked fine for me on flights to 12K feet to keep my low mass, empty nose cones connected to the main chute bay during drogue descent.
And they have also worked fine on flights up to Mach 1.4 to keep my mid-body recovery section coupler attached to the booster during the coast-phase.
After recovery, I generally find a the holes blocked by the sheared off polystyrene material which I can push thru with the cylindrical tip of my Pentel mechanical pencil.
I could see that the rods are cut cleanly without any distortion when I bothered to look back when I first started using them.
And after numerous flights, there is no notable wear on the aluminum blades or the cardboard tubes or plastic nose shoulder on my cardboard LOC Vulcanite or even on my 4-inch cardboard Iris.
One note. If you install a blade on your coupler or nose cone shoulder, be sure to install a matching blade on the inside of your cardboard tube.
I did suffer a wallered hole on an unbladed, glass-wrapped cardboard tube of my 1.9 inch Vulcanette scale model when I thought the outer wrap of glass was good enough -- it wasn't -- the interior of the airframe hole was distorted by the styrene rod so I added a blade to the inside arc of the airframe and drilled a new hole.
Note that the thin aluminum blades work fine with styrene shear pins but I
MIGHT go with brass blades if I ever feel like I need to change over to nylon screws, say when I start flying a tracker in the nose.
I would definitely want to test the effectiveness of the soft-ish aluminum blades -vs- nylon machine screws.
This is a Mach 1 'kit' I've gathered for an upcoming BT-55 fiberglass rocket that I am building to replace my cardboard 'La Pequeña Vulcanita 34' which was damaged due to an AV-Bay brown-out at apogee and then landing on an asphalt road on a streamer:
Note the Mach 1 polystyrene nose cone with the band of sanded, HEB Original Cola can material CA'd to the shoulder ( there is a matching band on the opposite side ) to keep the nose cone square with the air frame.
I have not drilled the holes yet -- I usually drill the holes after the rocket is finished and assembled, just before I prep for primer.
HTH and have fun !
-- kjh
