In this note, we would like to share some information with you about the expansion stem caster. Expansion stems come in various different sizes and are used to fit up into hallow tubing usually on tables or chairs. Expansion stems can have more versatility compared to using a friction ring caster and a socket with the reason being, one expansion stem can fit tubing within a certain range of sizes and a round expansion stem can fit up into round and square tubing. An expansion stem caster is a long stem caster that has threading at the top that is then covered with a rubber expansion grip that goes around the stem. The expansion stem consists of 3 parts, the plastic sleeve (spacer), the rubber sleeve (expansion) and the round nut. The nut is the gripping mechanism that allows the rubber sleeve to be compressed thus expanding its diameter to fit into the tubing snugly.
In order to make your expansion stem fit properly while holding the swivel bearing at the top of the caster, you want to turn the round nut at the top of the stem clockwise. This will start to tighten which will start to compress and expand the rubber sleeve. Continue to tighten the nut until you expand the rubber sleeve enough to have a very snug fit going up into your tubing. Insert the stem all the way up into your tubing. Once the stem is up in your tubing, turn the swivel bearing counter-clockwise to further expand the rubber sleeve inside your tubing. If you need to tighten it further and are struggling to do this by hand, with a wrench, you can turn the hex nut under the swivel bearing counter-clockwise until your stem is tight enough for your liking.