Alpha International U321br K Series Stainless Steel Single Bowl Undermount Cutout
Description
The Alpha International U321BR K Series is a premium double bowl undermount sink designed for professional countertop installations. This 31.5" x 18" stainless steel sink features two unequal bowls, making it ideal for residential kitchens where homeowners need versatility in food prep and cleanup. Our production-ready DXF template includes four installation variants to accommodate different fabrication requirements: no reveal for flush mounting, 1/8" reveal for standard undermount applications, 1/2" overhang for enhanced support, and drop-in configuration for alternative installations. Fabricated from commercial-grade T-304 stainless steel in either 18 or 16 gauge, this sink delivers exceptional durability and corrosion resistance. The large bowl measures 17.75" x 18.5" with a 9" depth, while the smaller bowl provides 10.5" x 16" of workspace at 7" deep. This configuration is particularly popular with clients who want a dedicated disposal bowl alongside a larger washing basin. The K Series designation indicates this model is part of Alpha International's professional line with DXF files optimized for CNC cutting accuracy.
Dimensions
- Overall Width
- 31.5"
- Overall Depth
- 18"
- Bowl Width
- 17.75"
- Bowl Depth
- 18.5"
Specifications
- Manufacturer
- Alpha International
- Model Number
- U321br K Series
- Installation Type
- Undermount
- Bowl Configuration
- Single
- Material
- Stainless-Steel
- Min. Cabinet Width
- 34"
- Downloads
- 0
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The Alpha International U321BR K Series is a premium double bowl undermount sink designed for professional countertop installations. This 31.5" x 18" stainless steel sink features two unequal bowls, making it ideal for residential kitchens where homeowners need versatility in food prep and cleanup. Our production-ready DXF template includes four installation variants to accommodate different fabrication requirements: no reveal for flush mounting, 1/8" reveal for standard undermount applications, 1/2" overhang for enhanced support, and drop-in configuration for alternative installations. Fabricated from commercial-grade T-304 stainless steel in either 18 or 16 gauge, this sink delivers exceptional durability and corrosion resistance. The large bowl measures 17.75" x 18.5" with a 9" depth, while the smaller bowl provides 10.5" x 16" of workspace at 7" deep. This configuration is particularly popular with clients who want a dedicated disposal bowl alongside a larger washing basin. The K Series designation indicates this model is part of Alpha International's professional line with DXF files optimized for CNC cutting accuracy.
Installation Overview
Installing the Alpha U321BR requires a minimum 34" cabinet width to ensure proper support and clearance. For undermount installations, we recommend the 1/8" reveal variant as it provides the best balance between aesthetics and structural integrity. Begin by positioning the template on the countertop underside, ensuring the orientation matches your plumbing layout. The template accounts for the rim dimensions, so center alignment is critical for dual-bowl balance. Use a minimum 3" clearance from the front edge to prevent chip-out during cutting. The sink ships with fixing clips and a cutout template, though our DXF files provide enhanced precision for CNC routing. After cutting, test-fit the sink and verify that both drain openings (3.5" diameter) align with your plumbing rough-in. Apply a continuous bead of silicone around the cutout perimeter, position the sink, and secure with the provided clips at 6-8" intervals. Allow silicone to cure for 24 hours before connecting plumbing. For granite and engineered stone, reinforce the cutout with mesh or support bars spanning the bowl cavity.
CNC Cutting Notes
The U321BR template is optimized for CNC routers with the origin point set at the front-left corner of the cutout. All dimensions are in decimal inches, verified against Alpha International's factory specifications. When cutting natural stone, use a 1/2" diamond router bit with water cooling to prevent thermal cracking. Feed rates should not exceed 80 IPM for granite or 100 IPM for quartz to maintain edge quality. The no-reveal variant cuts to the exact bowl dimensions (17.75" x 18.5" for large bowl), so any CNC calibration errors will affect the fit. We recommend running a test cut on scrap material to verify dimensional accuracy. For the 1/8" reveal option, the cutout is reduced by 0.25" on each axis, providing a uniform lip that conceals minor cutting variations. The DXF layers include LABEL for model identification, cut paths on layer 0, and reference dimensions on DEFPOINTS. Ensure your CAM software imports all entities correctly, as the template contains 158 discrete elements including arcs, lines, and text annotations. Corner radii are minimal on this model, so sharp inside corners require relief cuts or a smaller bit to prevent stress concentrations in the stone.
Material Compatibility
This template is compatible with granite, engineered quartz, quartzite, marble, solid surface, and ultra-compact surfaces. For granite installations, the dual-bowl configuration requires additional support due to the large cutout span. Install steel mesh or wooden support bars beneath the cutout, bonded with epoxy for permanent reinforcement. Engineered quartz (Caesarstone, Silestone, Cambria) handles this cutout well due to superior tensile strength, but still benefits from perimeter support clips. Marble is not recommended for kitchen sink applications due to etching from acidic foods, but if specified, seal the exposed edge with penetrating sealer before mounting. Solid surface materials like Corian can be routed with carbide bits and bonded directly to the sink rim using manufacturer-approved adhesives. For thin porcelain slabs (6mm-12mm), this large cutout requires steel frame reinforcement spanning the cabinet perimeter. The stainless steel construction of the U321BR means it's compatible with any countertop material from a chemical perspective, unlike composite sinks that may have compatibility restrictions. Always verify that your material thickness exceeds 2cm for undermount installations to provide adequate edge strength.
Where to Buy
The Alpha International U321BR K Series is available through kitchen and bath distributors, specialty sink retailers, and online suppliers. Fabrication professionals can order directly from Alpha International at 888-255-2574 or via their website at alpha-int.com. Retail partners include specialty kitchen showrooms and plumbing supply houses that cater to trade professionals. When purchasing, verify the gauge specification (16 or 18 gauge) as pricing varies between options. The sink typically ships with mounting clips, a template, and installation instructions, though our DXF files provide greater precision for CNC workflows. Lead times vary by distributor but generally range from stock availability to 2-3 weeks for special orders. For clients seeking this specific model, we recommend confirming bowl orientation and gauge thickness before fabrication begins. Alpha International also offers the DXF files for free download from their technical resources page, making it easy to verify dimensions before ordering the physical sink. This sink represents excellent value in the professional-grade stainless steel category, with pricing typically ranging from $300-$500 depending on gauge and finish options.