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Extended Round Threaded Inserts

Extended round threaded inserts feature a longer insertion body for a deeper, more secure press-fit in Ø 35 mm thin-walled round tubes. When a standard-depth round threaded insert does not grip firmly enough to support a leveling foot under load, the extended body reaches deeper into the tube for more surface contact and a stronger hold. Same PA body and zinc-plated steel M8 nut as standard round threaded inserts. Deep grip round threaded inserts for Ø 35 mm tubing where standard depth is not enough. Black. Sold in multiples of 4.

$3.16

4 = 1 chair · 8 = 2 chairs · 24 = 6 chairs

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Not sure what size? See the size chart ↓

📦 Sold in packs of 4 — quantity adjustable at checkout

Overview

Extended Round Threaded Inserts

Standard round threaded inserts hold firmly in Ø 28, 40, and 50 mm tubes at 1 to 2 mm wall thickness. But Ø 35 mm tubing sits between those sizes and is often manufactured with walls at the thin end of the 1 to 2 mm range. At thinner walls, a standard-depth insert can work loose under the sustained compressive load of a leveling foot, especially on heavy furniture that gets moved or adjusted frequently. Extended round threaded inserts solve this with a longer insertion body that reaches deeper into the Ø 35 mm tube for more grip surface and a more secure anchor for the leveling foot.

Same PA body, same zinc-plated steel M8 nut, same press-fit installation as standard round threaded inserts. The only difference is the body length. Extended round threaded inserts are deep grip round threaded inserts for Ø 35 mm thin-walled tubing where standard depth is not enough to support a leveling foot reliably. Black. Sold in multiples of 4.

Available Size: Extended Round Threaded Inserts

Extended round threaded inserts are currently available in one size, thread, and color combination. The Ø 35 mm dimension with M8 thread covers the specific tubing specification where extended depth is most needed.

Ø 35 mm / M8 / Extended Depth

Wall: 1 to 2 mm. M8 zinc-plated steel nut. Extended insertion body for deeper grip in thin-walled Ø 35 mm tubes. Weight: 13.9 g. Black. Accepts any M8 leveling foot from the adjustable leveling feet range.

Need a different diameter or thread?

For standard-depth inserts in Ø 28, 40, and 50 mm with M6, M8, M10, and M12 threads, see round threaded inserts. For square tube legs, see square threaded inserts. For rectangular tube legs, see rectangular threaded inserts. For custom extended sizes or threads, contact Business Solutions.

When to Choose Extended Round Threaded Inserts

Not every Ø 35 mm tube needs extended depth. The decision depends on wall thickness, furniture weight, and how much the leveling feet are adjusted or stressed during use. Extended round threaded inserts are the solution when standard depth cannot support the leveling foot reliably.

Choose extended when
  • The tube wall is at the thin end of the 1 to 2 mm range (closer to 1 mm)
  • The furniture is heavy enough that the leveling foot transfers significant compressive load through the insert
  • The furniture gets moved, adjusted, or relocated frequently
  • Standard-depth inserts in similar applications have worked loose or shifted
  • The application is commercial or institutional with daily use and periodic leveling adjustments
Standard depth may be sufficient when
  • The tube wall is at the thick end of the range (closer to 2 mm)
  • The furniture is lightweight and the leveling foot carries minimal load
  • The furniture stays in place and the leveling feet are rarely adjusted
  • Residential use with gentle handling
  • Note: standard-depth round threaded inserts are not available in Ø 35 mm. For this diameter, extended is the only option with a threaded insert

How to Measure Your Tube

Two tube measurements plus the thread confirmation. Extended round threaded inserts require Ø 35 mm outside diameter and 1 to 2 mm wall thickness. The thread is M8 only.

Step 1. Measure the tube diameter

Use calipers across the outside of the round tube. The diameter must be 35 mm. If your tube is 28, 40, or 50 mm, use standard round threaded inserts in those sizes instead.

Step 2. Measure the wall thickness

Use calipers at the tube end. The wall must be between 1 and 2 mm. Check the interior clearance: the extended body inserts deeper than standard, so confirm no welds, brackets, or bends obstruct the interior for at least 25 mm from the tube end.

Step 3. Confirm M8 thread

Extended round threaded inserts are M8 only. Confirm your leveling foot uses an M8 threaded rod. If you need a different thread on Ø 35 mm, contact Business Solutions for custom options.

How to Install Extended Round Threaded Inserts

Same press-fit installation as standard round threaded inserts, with more insertion resistance due to the longer body. A rubber mallet is strongly recommended. The extended body creates more friction during insertion because more PA surface contacts the tube interior.

What you need
  • The extended round threaded insert (Ø 35 mm, M8)
  • A rubber mallet (strongly recommended)
  • Clean, dry tube end free of burrs or debris
  • The M8 leveling foot (for installation after the insert is seated)
Installation steps
  1. Inspect the tube end. Remove any burrs, sharp edges, weld spatter, or debris from the inside. Confirm the interior is clear for the extended insertion depth.
  2. Align the extended round threaded insert with the tube opening. The M8 nut faces outward (toward the floor).
  3. Press the insert into the tube by hand as far as it will go. The extended body creates more friction than standard depth, so hand pressure alone typically will not fully seat the insert.
  4. Tap with a rubber mallet until the head sits flush with the tube edge. Apply even force to the center of the head.
  5. Screw the M8 leveling foot into the nut. Turn clockwise to the desired height. Adjust each leg independently.
Removal: more effort than standard depth. The extended body grips more surface area. Push from the opposite end of the tube if accessible, or pry from the tube edge with a flat-head screwdriver. The PA body flexes without breaking but resists pull-out by design.

What Extended Round Threaded Inserts Solve

The specific problem of insert retention under load in thin-walled Ø 35 mm round tubing. The National Wood Flooring Association (NWFA) recommends protective measures on all furniture legs, and extended round threaded inserts ensure those measures stay in place when standard depth cannot hold under the compressive load of a leveling foot.

Secure anchor for leveling feet in thin walls

The primary function. A leveling foot transfers the weight of the furniture and its contents through the M8 thread, through the nut, through the PA body, and into the tube walls. At standard insertion depth on thin-walled Ø 35 mm tubing, that load path can cause the insert to shift or work loose over time. The extended body adds grip surface that keeps the insert anchored. Extended depth leveling foot inserts that hold where standard depth does not.

All standard benefits maintained

Tube sealing, moisture protection, noise dampening, and finished appearance. The extended body does not change any of these. The PA body still seals the tube opening completely. The zinc-plated steel nut still provides a durable M8 threaded connection. Unlike leaving furniture legs unprotected, the insert stays in place and continues supporting the leveling foot because the extended body prevents the pull-out that would eliminate the threaded connection.

Reduced maintenance on Ø 35 mm furniture

Every time a standard-depth insert works loose, the leveling foot loses its anchor and the furniture leg drops to bare metal on the floor. Rethreading a loose insert is difficult without removing it and reinstalling. Extended round threaded inserts reduce this by holding more securely from the start. Fewer loose inserts. Fewer maintenance calls. Round threaded inserts thin wall tubes need for reliable long-term leveling support.

Ø 35 mm coverage

Standard round threaded inserts come in Ø 28, 40, and 50 mm. Ø 35 mm falls in the gap. Extended round threaded inserts fill that gap with a product specifically engineered for this diameter. Without the extended version, Ø 35 mm tubing would have no threaded insert option in the range. Extended insertion threaded inserts that bring Ø 35 mm into the leveling system.

How Load Transfers Through Extended Round Threaded Inserts

Understanding the load path explains why extended depth matters. When a table sits on four leveling feet, the weight of the table and everything on it divides across the four legs. Each leveling foot carries roughly one quarter of the total load. That load travels up through the foot’s threaded rod, into the M8 nut, through the PA body, and into the tube walls via the ribbed grip.

At standard insertion depth, the grip surface is limited. On thin-walled Ø 35 mm tubing, the tube wall provides less resistance per millimeter of contact than a thicker wall would. The load can cause the PA ribs to compress slightly, allowing the insert to shift downward over time. Extended round threaded inserts address this by adding grip surface. The additional body length distributes the load across a longer section of tube wall, reducing the compression per millimeter at each rib point. The result is a more stable anchor that resists the gradual shift that standard depth cannot prevent in thin-walled Ø 35 mm tubes.

Materials and Construction

Same two-material construction as standard round threaded inserts. PA body for tube grip and load transfer. Zinc-plated steel nut for the M8 threaded connection. The body is simply longer to provide deeper engagement in the Ø 35 mm tube.

Extended PA Body Deep grip + load transfer

The PA body extends deeper into the tube than standard round threaded inserts. This additional length provides more contact area between the PA ribs and the tube interior. At 13.9 g, the extended insert is heavier than the lightest standard size (Ø 28/M6 at 9.3 g) because of the additional PA material. The PA compound is the same: high tensile strength, chemical resistance, and temperature stability from -40 °C to 85 °C.

  • Extended insertion depth for Ø 35 mm tubes
  • More PA surface area for stronger friction grip
  • Same PA compound as all threaded inserts in the range
  • Black
Fe HDG (Zinc-Plated Steel) M8 Nut Threaded connection

Identical M8 nut to the standard round threaded insert. Same thread pitch. Same zinc plating. Same corrosion resistance. Same load capacity through the threaded connection. The extended body affects tube grip, not thread performance. Any M8 leveling foot that works with a standard insert works with the extended version.

  • M8 thread: standard furniture load capacity
  • Zinc-plated: corrosion resistant for indoor use
  • Pre-installed in the PA body during manufacturing
  • Compatible with all M8 leveling feet

Extended Round Threaded Inserts vs. Other Options

If your Ø 35 mm round tube furniture needs adjustable leveling, here is how extended round threaded inserts compare.

vs. Standard Round Threaded Inserts

Standard round threaded inserts are available in Ø 28, 40, and 50 mm but not Ø 35 mm. For Ø 35 mm tubes, the extended version is the only threaded insert option. If your tube is Ø 28, 40, or 50, use standard depth with the thread size that matches your leveling foot.

vs. Adding Adhesive to Improve Grip

A drop of adhesive inside a standard-depth plug body can improve retention. But adhesive makes the insert harder to remove for replacement, can fail under chemical exposure, and adds an assembly step. Extended round threaded inserts achieve stronger retention mechanically without adhesive. Cleaner, removable, no chemical dependency.

vs. Using a Standard Ø 28 or Ø 40 Insert in a Ø 35 Tube

A Ø 28 insert is too small and will not grip a Ø 35 tube. A Ø 40 insert is too large and will not enter a Ø 35 tube. Tube plugs and threaded inserts must match the tube diameter exactly. Extended round threaded inserts are the only option for Ø 35 mm.

Where Extended Round Threaded Inserts Work Best

Extended round threaded inserts are designed for one specific scenario: Ø 35 mm hollow round tubing that needs a threaded M8 connection for adjustable leveling feet.

Ideal applications
  • Tables and desks with Ø 35 mm round tube legs on uneven floors
  • Commercial furniture with Ø 35 mm legs that needs adjustable leveling
  • Any Ø 35 mm hollow round tube where a leveling foot with M8 thread is required
Not ideal for

Where People Use Extended Round Threaded Inserts

Anywhere Ø 35 mm hollow round furniture legs need adjustable leveling feet with secure, reliable retention in thin-walled tubing.

Commercial and institutional

Tables, desks, and fixtures with Ø 35 mm round legs in restaurants, offices, conference centers, and institutional environments. In commercial settings where furniture gets moved and adjusted frequently, the extended grip ensures the insert stays anchored through repeated use. The M8 thread handles standard commercial furniture loads. For restaurant tables that get repositioned for different group sizes multiple times per day, extended round threaded inserts paired with quality leveling feet provide the stable, wobble-free surface that customers expect. For office desks on uneven raised floors, the precise M8 adjustment eliminates the wobble that affects typing, writing, and monitor stability. Available in bulk for manufacturing runs. For commercial pricing, visit Business Solutions.

Residential

Dining tables, desks, and workstations with Ø 35 mm round tube legs on uneven residential floors. Less common than commercial use since Ø 35 mm is a less standard residential tubing size, but it appears on imported furniture and custom-fabricated pieces. When the tube matches, extended round threaded inserts provide the same leveling capability as standard inserts on other diameters. For residential floors with minor unevenness, the M8 leveling foot provides enough adjustment range to eliminate wobble. For significantly uneven floors, the leveling foot’s adjustment range rather than the insert depth becomes the limiting factor. Browse adjustable leveling feet with M8 thread to find the right adjustment range for your floor conditions.

Maintenance and Inspection

Extended round threaded inserts require less frequent retention checks than a hypothetical standard-depth insert in the same tube because the deeper grip is more resistant to loosening. Check every 6 to 12 months that the insert remains seated and the leveling foot is tight. The extended grip means the insert is less likely to shift between inspections.

If an extended insert does come loose, it usually indicates a tube interior issue (debris, wall deformation, or corrosion) that prevents full insertion depth. Remove the insert, inspect and clean the tube interior, and reinstall. Extended round threaded inserts are sold in multiples of 4, making it easy to keep replacement stock on hand for convenient maintenance. The PA body and zinc-plated nut do not require lubrication or any chemical treatment under normal indoor conditions.

Related Products

Standard depth for other diameters

Round Threaded Inserts: Ø 28, 40, and 50 mm. M6, M8, M10, M12. Standard insertion depth for thicker-walled tubes.

M8 leveling feet

Adjustable Leveling Feet: M8 thread options including standard base, low-profile, anti-slip, ball-joint, tilt, and stainless steel rod.

 

Specifications

Specification Details
Product Type
Tube Plug with Threaded Insert (Inner) – Extended
Shape
Round Tube
Materials
PA (Polyamide) body + Fe HDG (Galvanized Steel) thread insert
Fit Style
Extended ribbed friction-fit compression with internal thread
Furniture Compatibility
Furniture legs, shelving, railings, office fixtures
Leg Compatibility
Metal and plastic round tubing
Tube Outer Diameter
Ø35 mm (1.38")
Wall Thickness Range
1–2 mm (0.04"–0.08")
Weight Capacity
80 kg (176 lbs) static load per plug
Color Options
Black
Installation Type
Press-fit by hand or rubber mallet
Key Benefits
Deep grip, internal thread, durable finish, fast installation
Indoor/Outdoor Use
Indoor | Covered Outdoor | Uncovered Outdoor

Size Chart

Tube Diameter (Ø) Tube Wall Thickness (T) Threaded Insert (M) Head Height (H1) Insert Depth (H) Static Load Capacity (SL)
35 mm (1.38")
1 – 2 mm (0.04" – 0.08")
M8 (8 mm (0.31"))
5 mm (0.20")
14 mm (0.55")
80 kg (176 lbs) / pc

Frequently Asked Questions

Why is Ø 35 mm the only size available in extended?

Ø 35 mm falls between the standard Ø 28 and Ø 40 mm sizes. Tubing at this diameter is often manufactured with thinner walls than the larger sizes, which means standard-depth inserts have less interior surface to grip. The extended body compensates by reaching deeper into the tube. The standard sizes (Ø 28, 40, 50 mm) typically use wall thicknesses that provide adequate grip at standard depth.

Is M8 the only thread available for the extended version?

Currently yes. M8 is the most common leveling foot thread for furniture in the Ø 35 mm tubing range. For other thread sizes in standard depth, round threaded inserts offer M6, M8, M10, and M12 across Ø 28, 40, and 50 mm. For custom extended thread options, contact Business Solutions.

Does the extended body change the load capacity?

The M8 nut and its load capacity are the same as in standard-depth round threaded inserts. What changes is retention: the extended body grips the tube interior more securely, which means the insert is less likely to pull out or shift under repeated loading and unloading. The threaded connection handles the same furniture weight regardless of body depth.

Can I use an extended insert in a thick-walled Ø 35 mm tube?

You can, but the extended depth is designed for thin-walled tubes (1 to 2 mm) where standard depth does not hold firmly. In thick-walled tubes, a standard-depth insert already grips securely. The extended body in a thick-walled tube creates a very tight fit that is harder to install and remove.

What leveling feet work with this insert?

Any leveling foot with an M8 thread. Browse our adjustable leveling feet range for M8 options including standard base, low-profile, anti-slip, ball-joint, tilt, and stainless steel rod variants. The M8 thread interface is identical to the standard round threaded insert.

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