Installing Casters Into Hollow Tubing

April 21, 2021

 In some cases, casters can be installed without even making a hole! There are two methods to install casters into the hollow tubing of a table, shelf, or whatever project you're working on: with a socket or threaded adapter, or by pressing a caster into the tubing directly.

Use this handy guide to see which method of installing casters will work for your hollow tubing!

Sockets and Threaded Adapters

Sockets and threaded adapters are designed to fit at the end of a hollow tube to allow you to attach a caster to your project. They come in all sorts of shapes and sizes to accommodate circular and square tubing of all kinds. 

Sockets and adapters are installed by pressing or tapping the end of the socket/adapter until it's flush against the end of the hollow pipe. It presses against the walls of the hollow tubing and uses friction to stay inside.

One main benefit of using sockets and adapters is that they are cheaper and allow casters to be easily removed and replaced.

Sockets, Grip Ring and Grip Neck Stem Casters

Sockets provide a cylindrical hole for a stem caster to be pressed into. They are typically plastic, though some are made of metal. 

Depending on the socket, sockets are sized based on either the inner or outer diameter of the tubing that they're inserted into. Metal sockets use a flower like spring clip to press against the inside of the hollow tubing walls.

Once the socket is installed into your tubing, simply press a caster inside the socket. To replace the caster, simply pull it out and install a new caster.

The down side of using sockets is that sockets can wear out and lose their ability to hold on to casters effectively over time. Below are the type of stem casters accepted by sockets.

Grip Ring Stem Casters

Grip ring stems have a split ring located at the top of the stem that presses outwards against the socket and keeps the caster from falling out. There shouldn't be any concern with the caster coming out since the weight of your object will also help keeping it in place.

Grip Neck Stem casters

Grip neck stem casters have a stem that tapers down in size and gets larger at the end that creates a bottle neck like stem. The larger upper portion of the stem is what keeps your caster from falling out. 

Just like the grip ring stem caster, grip neck stem casters are pressed into the socket and held in with friction. Grip neck stem casters are skinnier than grip ring stems to accommodate smaller areas/smaller tubing and are typically used in wooden products for its stem size.

Threaded Adapters and Threaded Casters

Threaded adapters are designed to accommodate casters with threaded stems. The adapters are designed to sit flush with the outside of the hollow tubing. Just like the sockets, adapters are designed to presses against the inside of the tubing and relies on friction to keep it in place.

Threaded adapters use a flower-like spring clip to press against the hollow tubing walls. Once pressed in, these inserts can be difficult to remove from the tubing of your project.

It's important to note that threaded adapters go by the measurement of the outside diameter of the tubing or the overall width of the pipe.

Expanding and Grip Ring Stem Casters

As previously mentioned there are two main ways of installing casters into the hollow tubing of your project: either by using sockets and adapter or simply pressing a caster into the tubing. For those who would like to simplify the process by using a caster alone, there are two main ways to accomplish this. You can use an expanding stem caster or a grip ring stem caster.

Expanding Stem Caster

Expanding stem casters utilize a barrel-like rubber applicator that's designed to be squeezed by a knurl nut. When the rubber applicator is squeezed, it presses against the walls of the hollow tubing. Despite the stem's circular shape, it can also be used in square tubing.

Typically, the correct expanding stem for your project is a bit smaller than advertised and gives you some room for play. For example, an expanding stem caster for a 1-1/2" tubing is gonna be a tad bit smaller than 1- 1/2" inches in diameter. This is to allow you to adjust the stem width during installation to make it just tight enough stay inside but loose enough to remove the stem when pulled out.

Grip Ring Casters

Grip ring stem casters can be used with a socket, but can also be used by themselves if the stem's diameter is the same as the inside diameter of the hollow tubing. There are many types of grip ring stem casters that utilize different size grip ring stem diameters. 

To install, simply press the grip ring stem into the tubing.

Which Mounting Method is Right For Me?

In order to find our which option is right for you, you can consider the details of the project you are completing, or which object you are attaching the casters to.

First, consider capacity. Of course, the caster needs to be able to carry the weight of the object it's supporting, but the caster's stem needs to be able to avoid bending under heavy loads when in use. For a higher capacity needed, choose a caster that utilizes a thicker stem like an expanding stem caster, or grip ring stem caster without a socket, because thinner stems may bend under heavy loads.

Next, consider the overall height that you need this project to sit at. If we need to keep the project close to the floor, you might be limited to sockets and adapters, because expanding stem casters and larger diameter grip ring casters rarely use smaller wheels. Keep in mind that smaller sized casters will more likely have a lower capacity.

Consider longevity of the caster. Over time, sockets lose their ability to hold tight onto the casters, and will let the caster loose when the object is lifted. You can replace the socket, or consider options. Threaded inserts tend to last longer, and expanding stem casters will last as long as the rubber applicator or ball bearings don't deteriorate. A grip ring caster alone will last as long as the caster does. Of course, longevity varies case by case, and the amount of use and the environment the caster is in plays a large role in its service life.

Finally, consider your budget. Out of the options, sockets are the cheapest, typically less than a dollar and fitting light duty casters which are also often cheap. Threaded adapters are typically around a dollar, and can fit all kinds of casters, from cheap to higher-end casters. The expanding stem casters and grip rings stem casters (with larger diameter stems) will typically cost you more because it's everything you need in one package. Keep in mind that cost is primarily dominated by caster selection.

Installation and Tips

Next we need to observe the depth of the hollow tube and make sure that you have enough room for installing a socket, adapter or caster's stem inside. When installing a caster into hollow tubing, there are two different measurements that can matter:

• Inside diameter: The diameter of the inside of the tube, not including the tube's walls' width.
• Outside diameter: The diameter of the entire tube, including the tube's walls.
  

The most accurate way of measuring either of these diameters are calipers, though a measuring tape will do as well. The exact measurement is crucial depending on the method used to attach the casters.

Once you have the steps above done and your caster picked out, go ahead with installation. Here are a few tips to help assist with installing your casters:

• Use a mallet to install a socket/threaded adapter to evenly distribute the force when tapping it into place.
• Make sure that your socket/adapter is pressed into the tubing as far as it can go. The caster must be seated all the way inside of the socket, adapter or hollow tube. The stem will not be visible if the caster is installed correctly.
• When installing expanding stem casters, tighten the rubber applicator just enough where it won't fall out when your project is lifted up, but still can be pulled out when it's time to replace your caster.
• If you're not able to find the correct plastic socket size for your tubing you can get a wider socket and sand it down to size.
• Be mindful of socket size measurements when selecting one. Sometimes the product listing will tell you specifically they're for 1" (outside diameter) tubing and sometimes it will tell you it fits a certain inside diameter tubing.
• Threaded adapters and metal sockets go off the outside diameter measurement of your tubing instead of the inside diameter measurement of your tubing.
• Kitchen/restaurant equipment that commonly use expanding stem casters must have a minimum of 6 inches between the ground and the equipment to be compliant with NSF standards. 

Final Thoughts

There are a few different ways that casters can be installed into the hollow tube of a table, shelf, or other project. By picking the right one, you can significantly improve the efficiency of the object.

If you need any assistance with your project or need a suggestion. were here to help. Contact us or give us a call at 713-227-1144 (Mon-Fri 7:00AM - 4:30PM CST) and a caster expert will assist you.

View our Sockets and Threaded Inserts View our Expanding Stem Casters View our Grip Ring Casters

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