Bonding Bulkheads - with Worms

[kramer714]

Quick day job trick,

Ever have something like bulkhead plates that need to be bonded, concentrically, without messing up the hole and without squeezing out too much adhesive? Great example are bulkheads for av bays. you know, you have the smaller one that fits IN the coupler and the other one fits ON the coupler. They already have a center hole or multiple holes in them. it is pretty hard to get them to line up and worse keep the holes clean from adhesive. Plus it is hard to clamp them together without squeezing out too much adhesive. Clothes pins, binder clips...

Simple solution, use worms. These are disposable rubber parts (I have used ordinary o-ring stock but the pre made worms are easy to install). Available at McMaster. We use LOTS of these at the day job for masking holes in parts that get painted bonded or plated.

The way this works is,

1. have two parts with one or more holes that align them (they don't need to be in the center).
2. Buy a worm with the proper ID, NOTE the actual worms are a little bigger than the hole diameter on the big end, and smaller than the hole diameter on the small end
3. Prep the parts, for bonding, apply adhesive, position the pars together, put the small diameter through the hole and gently pull the small diameter until the large diameter stretches into the hole - DON'T pull it all the way through. When you let go they want to 'un-strech' and expand filling the hole and clamping the parts. The stretch fills the holes and aligns them plus LIGHTLY clamps the two parts. you can rotate the parts a little relative to each other to get the adhesive 'flattened out'.
4. wipe off any squeeze out, allow to cure
5. After it is cured, pull the worm out, it will stretch and come out, leaving a clean hole

2 parts

add adhesive


Align them


Small end of the work in the hole

Pull part way through