Bowl Drain, Overflow and Installation Components

Gruber supplies all necessary components for setting up lavatory bowl drain systems and overflow systems (shown in the following diagram). We also supply a number of installation aids – such as bowl clips and others that are set into the matrix during casting to provide an integral bowl mounting system. These components are used to manufacture cultured marble or solid surface vanity bowls.

faucet hole rings

Faucet Hole Rings

Our silicone-coated cardboard Faucet Hole Rings are a real time saver for manufacturers, since they provide a fast, easy way to create 1.25″ (3.2 cm) diameter faucet fixture holes in a vanity top. Faucet hole rings are positioned and set in place on the vanity mold to create holes in the finished product where the faucets will be installed, saving drilling time later. Installers need only to pop out holes prior to faucet installation. Available in five different heights to accommodate different thicknesses of marble.

Order Information
Sold in boxes of 1,000 (Approximately)
3/8″ (0.95cm) – #000016C
1/2″ (1.3cm) – #00001C
5/8″ (1.6cm) – #00002C
3/4″ (1.9cm) – #00003C
7/8″ (2.2cm) – #00004C

bowl clips

Bowl Clips

Bowl clips are used with the floating unit assembly for firmly attaching undermount bowls to marble vanity tops. The screw of the floating unit assembly fits through the slot of the bowl clip, resulting in a firm, solid attachment of undermount bowls to cultured marble vanity tops. Packaged in quantities of 100 or 1,000.

Order Information
Box of 100 – #000061
Box of 1000 – #00006

floating unit assembly

Floating Unit Assembly (FUA)

Known at “T-Nuts” to many, they are placed into the ungelled matrix. When the marble cures, they provide a solid anchor for attaching undermount bowls to marble vanity tops and bases to marble table tops. The paper tab on the “T-Nut” assembly prevents it from sinking too far into the matrix and also serves as a spacer for the proper positioning of the “T-Nut” when used with speedy plugs. It also serves as a spacer for the proper positioning of the FUA when used with speedy plugs. Available in quantities of 100 or 1000.

Order Information
FUA, Box of 1000 ASSEMBLED Kits – #00005
FUA, Box of 100 ASSEMBLED Kits – #000051

Overflow Tubing

Overflow tubing is used to create an overflow system in a cultured marble or solid surface vanity bowl. The components are installed prior to casting.

oval overflow tubing

Oval Overflow Tubing

The Overflow Tubing connects directly to the polycollar at the drain end and to the overflow stem at the overflow outlet. The Overflow Pipe becomes a permanent part of the finished bowl. The Overflow Pipe connects directly to the oval polycollar at the drain end and to the overflow stem at the overflow outlet. In addition, it features an integral, calibrated scale that permits quick and accurate trimming to achieve a proper fit on any size and shape of bowl. Like the polycollar, the overflow tubing becomes a permanent part of the finished bowl. They are available in boxes of 100 and 500.

Product Details

round plastic tubing

Round Plastic Tubing

Flexible, pliable 1/2” clear vinyl tubing is used to provide a germ-resistant permanent bowl overflow. Fits snuggly onto the round polycollar. Use with a round stem to create a clean outlet hole. Boxed plastic tubing is preferred if it is being shipped via UPS, since shipping boxed items is relatively less expensive.

Order Information
1/2” Round PVC Tubing – 100’ Roll – #001010
1/2” Round PVC Tubing – 100’ Roll (Boxed) – #001010B


Polycollars are available either Trimmed, or Untrimmed. Trimmed polycollars have the top cut off, and untrimmed polycollars are not trimmed.

round overflow polycollars no overflow polycollars oval overflow polycollars Product Details

Round Overflow Polycollar       No Overflow Polycollar            Oval Overflow Polycollar

Drain Boss

These durable, high quality machined aluminum drain boss assemblies eliminate the need for polydomes, captive nut assemblies and suction cup assemblies. They are highly recommended for use with modular vanities and floating bowls – especially when using Extrudable Tooling Wax such as GruberCare Ex-Wax Extrudable Tooling Wax.

standard drain boss

Standard Drain Boss Assembly

  • 1-9/16″ Diameter Drain Boss with 5/16″ Diameter Drilled Center Hole
  • Bolt
  • Washer
  • Nut

Order Information
Standard Drain Boss – Ea – #191045

hollow core drain boss

Hollow Core Drain Boss Assembly

This drain boss is an alternative to the standard Drain Boss shown above. This product utilizes the same 1-9/16″ diameter drain boss, but with a larger 1/2″ center drilled hole. This product also includes a slightly larger bolt with a drilled center “hollow core” that some cultured marble manufacturers prefer. This bolt is drilled all the way through the bolt, which serves two functions – it allows pressure to be equalized from the mold surface to the backside of the mold and allows the operator to blow air down into the mold cavity during demolding to assist in mold release.

  • 1-9/16″ Diameter Drain Boss with 1/2″ Diameter Drilled Center Hole
  • “Drilled core” 1/2″ Bolt (drilled through the entire length of the bolt)
  • Lock Washer
  • Nut

Order Information
Hollow Drain Boss – Ea – #R-01132

suction cup stem assembly

Suction Cup Stem Assembly

The Suction Cup Stem Assembly is used to firmly attach the polydome, overflow components and floating bowl mold to a vanity top mold. Individual components may be ordered separately. Fits all sizes.

Order Information
11.5″ Stem Assembly – Ea – #011271

Order Information (Components)
Stem Only 3/8 x 11-1/2” – Ea – #01127
Suction Cup – Ea – #01122
Wing Nut 3/8”-16 – Ea – #01123
3/8” Washer – Ea – #01123-1

captive nut assembly

Captive Nut Assembly

A real time saver, Gruber Captive Nut Assembly fits directly onto the modular bowl mold. Then, an eye bolt fits through the polydome and screws directly into the captive nut holding the polydome securely in place. This eliminates the need to bend over and reach under the mold to hold the bolt while you tighten down on the wingnut above the polydome. The Captive Nut portion of the assembly, once tightened into place, becomes an integral part of the mold. Simple. Because this assembly is permanently affixed to the drain end of the mold, there is no need for a stem assembly. The polydome attaches with an eyebolt for easy removal. Time and materials are saved for a more efficient production process. We’ve got plenty in stock, so call and order a supply.

Order Information
Captive Nut Assembly – Ea – #01131

Order Information (Components)
Bolt – Ea – #011311
Jam Nut – Ea – #0113212
5/16″ Flat Washer – Per lb – #0113213
Lock Washer – Ea – #0113214

Reusable Overflow Stems

These reusable overflow stem products create a overflow hole in the casting of a cultured marble or solid surface lavatory vanity bowl, and are removed after casting.

reusable round overflow stem

Reusable Round Overflow Stem

The new round stem is angled 90° for easy insertion, so that round tubing can be attached without crimping. Creates a cleaner, more attractive outlet that is easier to finish, and eliminate the need to redrill when adding a round beauty ring.

Round Overflow Stem – Ea – #001015

reusable oval overflow stem

Reusable Oval Overflow Stem

The oval stem was designed to fit Gruber’s Oval Overflow Pipe and Oval Beauty Rings. It is easily removed for reuse and eliminates costly refinishing of the overflow hole.

Oval Overflow Stem – Ea – #01124

Reusable Oval-To-Round Adapter Stem

Reusable Oval-To-Round Adapter Stem

The adaptor stem allows manufacturers to connect round overflow tubing to a mold with an oval overflow hole already cut.

Adaptor Stem – Ea – #001017