General · December 2, 2025

How to Fix Matrix KI Stacking Chairs (Patent D246813)

Guide to replacing broken stacking connectors on Matrix KI chairs. 3D-printed replacements for a discontinued OEM part.

By Nathan Robb · 4 min read

A Complete Guide to Replacing the Broken Stacking / Ganging Connector

Matrix KI stacking chairs are extremely common in churches, schools, auditoriums, and event spaces. They’re durable and lightweight — but one small plastic part consistently fails: the stacking/ganging connector located under the seat.

And because KI no longer manufactures this part, finding a replacement online is almost impossible.

This guide will help you:

Identify your exact Matrix KI chair model
Understand why the connector breaks
See what the part looks like
Learn how to replace it
Get access to a custom-manufactured replacement part

How to Identify a Matrix KI Chair (Patent D246813)

Flip your chair over and look for molded markings or a sticker label that includes:

The Matrix KI branding
A patent marking: D246813
A molded plastic shell with welded wire frame

If your chair looks like this, this article and the replacement part below are exactly what you need.

Matrix KI chair underside showing seat labels and patent number D246813 — Matrix KI chair underside showing seat labels, patent number D246813, and mounting position for the stacking / ganging connector that commonly breaks.

Original 1978 design patent D246813 for the Matrix KI stacking chair — Original 1978 design patent (D246813) for the Matrix KI stacking chair manufactured in Green Bay, Wisconsin.

Why the Matrix KI Stacking / Ganging Connector Breaks

The small connector under the seat is responsible for:

Stabilizing stacked chairs
Helping chairs align when nested
Keeping tall stacks from shifting
Connecting (“ganging”) chairs into a row

But after years of use, the original connector often:

Cracks at the screw holes
Breaks completely off
Becomes brittle
Falls off during stacking
Causes chairs to lean or collapse when stacked

Unfortunately, KI no longer sells this part, and there is no OEM replacement.

Broken Matrix KI stacking / ganging connector showing common failure under the seat — this is the part most often needing replacement on Patent D246813 chairs.

The Solution: A Custom 3D-Printed Replacement Connector

To help facilities avoid throwing away an entire inventory of chairs, a precision 3D-printed replacement connector has been engineered that fits all Matrix KI chairs under Patent D246813.

This upgraded connector:

Matches OEM dimensions
Uses the original screw holes
Fits securely on the frame
Is printed with durable engineering-grade materials
Is stronger than the original plastic part

These are manufactured in the USA and available in single units or multi-packs. Bulk pricing is available upon request.

Get the part — Matrix KI Replacement Stacking Connector (2-Pack), $29.95 →

Made in the USA, ships fast. For volume orders (10+ chairs), email Nathan for a quote.

3D wireframe model of the replacement Matrix KI stacking connector — The replacement connector was reverse-engineered from measurements of the original OEM part and printed in PETG for higher heat tolerance and premium durability.

3D-printed replacement connector installed on a Matrix KI chair — A custom 3D-printed replacement stacking connector installed on a Matrix KI chair (Patent D246,813). Fits the original footprint and screw pattern exactly.

How to Install the Replacement Connector

You only need a screwdriver. Installation takes about 2 minutes.

Step 1 — Flip the chair over

Place it on a table or clean floor.

Step 2 — Remove the three screws

These hold the old connector in place.

Underside of a Matrix KI chair showing the connector and three mounting screws — Underside of a Matrix KI chair (Patent D246813) showing the original connector location and the screws that must be removed to replace the broken part.

Step 3 — Position the new connector

The replacement part aligns exactly with the original footprint.

Step 4 — Reattach the screws

Tighten firmly but do not overtighten.

Step 5 — Test the stack

Stack multiple chairs to ensure even spacing and stability.

Does This Fit My Chair?

This replacement stacking/ganging connector is compatible with:

Matrix KI chairs
KI Matrix branded chairs
Chairs manufactured under U.S. Patent D246813
Models with two-piece molded shell + welded wire frame

If your chair looks similar to the images, you have the correct part.

Matrix KI stacking chair in use — this style is commonly found in churches, schools, and auditoriums and often requires connector replacement after years of stacking.

Why We Created This Replacement Part

The connector was reverse-engineered because a facility had dozens of chairs with broken connectors. After contacting KI, searching online, and checking resellers, it became clear:

The part is no longer made
No third-party replacements exist
No repair kits are available

A stronger, more durable replacement was produced that fully restores the stacking capability of Matrix KI chairs. Now, through ReplacementPieceFinder by Crazy Amazing Designs, these parts are available nationwide.

Need a Custom Replacement Part?

If you have a broken or missing part from furniture, equipment, staging, rigging, or anything that needs repair, custom designs and manufacturing are available.

Services offered:

Custom 3D modeling
3D printing with engineering plastics
CNC machining for metal, wood, and composites
One-off or multi-part production

#Chair Repair #3D Printing #Matrix KI #Replacement Parts #Furniture