Caster T-nuts and metal sockets for threaded stem casters — replacement parts when your existing T-nut is stripped, missing, or you need to add stem casters to furniture, retail fixtures, or industrial equipment. 4-prong zinc T-nuts in 1/4", 5/16", and 3/8" sizes for wood furniture, plus Shepherd zinc metal sockets for 5/16" grip-neck stems. Stocked at our Mansfield, TX facility. (Plastic sockets temporarily out of stock — check back soon.)
Caster sockets and T-nuts are how a threaded stem caster attaches to equipment that doesn't have factory-threaded holes. The socket or T-nut presses or threads into the equipment leg, and the caster stem screws into the socket. This is the standard installation method on office chairs, retail fixtures, and most furniture casters.
| Part Type | Stem Size | Material | Best For |
|---|---|---|---|
| Plastic Stem Insert / Sleeve | 7/16" socket bore | Nylon / Polymer | Office chair replacement, retail fixtures |
| T-Nut | 3/8-16 thread | Steel | Furniture legs, light industrial |
| T-Nut | 1/2-13 thread | Steel | Heavy furniture, industrial equipment |
| Caster Socket (press-fit) | 7/16" stem bore | Nylon | Office chair legs, hollow tube fixtures |
| Caster Socket (threaded) | Various thread sizes | Steel / Brass | OEM industrial equipment, custom builds |
If your caster has a threaded stem (you can see threads on the rod), you need a matching threaded socket or T-nut. If your caster has a smooth grip-ring stem (no threads, often with a small ring near the top), you need a friction-fit socket or insert.
Common stem diameters: 7/16 inch (most office chairs), 3/8, 1/2, and metric. Mismatched sockets won't grip properly and the caster will fall out under load. Measure the existing stem with calipers before ordering.
Press-fit sockets hammer or press into a hollow tube and grip via friction or barbs — used on office chair legs, hollow metal furniture, and retail fixtures. Threaded T-nuts screw or press into a drilled hole in solid material like wood, plywood, or solid metal legs.
Nylon/polymer sockets are quieter, won't scratch metal tube interiors, and are the OEM standard on office chairs. Steel T-nuts are heavy-duty for industrial and high-load furniture. Match the material to the load and host material.
Not sure which socket fits your existing chair or equipment? Contact CasterHQ with your caster stem measurements and we'll match it.
CasterHQ stocks 11 caster socket, T-nut, and insert configurations — covering 7/16, 5/16, 3/8, and 1/2 stem sizes — at our Mansfield, TX facility. These are the most common replacement parts for office chairs (matching standard OEM bore), retail fixtures, and industrial threaded-stem applications. 99 percent of orders ship same or next business day.
A caster socket is a tube or sleeve that installs into an equipment leg to give the leg a place to accept a threaded or grip-ring caster stem. The socket creates the "hole" the stem mounts into. Most office chairs have factory-installed nylon caster sockets in each leg.
A T-nut is a threaded insert with a flat flange shaped like a "T" when viewed from the side. It's hammered or pressed into a drilled hole in solid material (wood, plywood) so a threaded stem caster can screw into it. The T-flange prevents the nut from pulling through the hole under load.
The U.S. office chair industry standard is a 7/16-inch bore socket, made of nylon or polymer, accepting a 7/16-inch grip-ring stem caster. About 90 percent of office chairs sold in the U.S. since 2000 use this standard.
Check the existing caster. If the stem has visible threads, you need threaded. If the stem is smooth with a small grip ring near the top, you need press-fit. Mixing the two won't work — threaded stems won't seat in press-fit sockets and vice versa.
No — while the 7/16 nylon socket is the office chair standard, we also stock steel T-nuts for furniture, retail fixtures, hollow metal tubes, and industrial equipment. The threaded variants work on any solid-material installation.
Yes — missing or stripped sockets are the #1 reason these parts are sold. Order the matching bore size, remove any remnants of the old socket, and press the new one in. Use a rubber mallet to seat it fully. The caster stem then installs as usual.
Metric caster sockets (M8, M10, M12 typical) are less common but available. Most U.S. equipment uses imperial sizes. If your existing caster has a metric stem, contact us with the exact size and we'll source it.
For most installations, no — press-fit sockets grip the host tube via friction barbs, and T-nuts grip via teeth or claws on the flange. For loose-fitting installations or high-load applications, threadlocker or epoxy can be added but isn't typically required.
The socket itself isn't the load limit — it's the equipment leg material and the caster spec. A nylon socket in a steel office chair leg supports the chair's full rated capacity (typically 250-300 lb). For heavy industrial use, steel T-nuts in solid material support up to the caster's rated capacity (1,000 lb+).
99 percent of caster socket and T-nut orders ship same or next business day from our Mansfield, TX facility via FedEx Ground. Small parts often ship USPS for smaller orders. Cutoff 2pm Central.
