12. Drop Edges & Downturns

HIMACS offers exceptional machining capabilities, empowering fabricators to fully explore their design creativity when shaping edges. With a wide variety of router bits available and the use of high-quality adhesives, the possibilities for edge design are virtually limitless.

The expertise of the fabricator plays a critical role, particularly when executing intricate or advanced edge profiles. Furthermore, a high level of craftsmanship is essential for producing seamless joints, which are fundamental to achieving superior edge finishes—whether the design is straightforward or complex.

1. Consideration Between Design & Fabrication

Design and Fabrication of Drop Edges and Downturns

Drop edges and downturns offer a range of design possibilities. Certain styles may be more appropriate for specific HIMACS colours, particularly those featuring veining, pearl or glitter effects, large chips, or translucent properties.

The fabrication techniques outlined in this section are generally best suited to solid colours and granite finishes with small to medium-sized chips. Using incorrect or unsuitable fabrication methods can result in structural failures such as cracking due to stress. In some cases, improper techniques may lead to stress concentration or an increase in internal stress.

Correctly fabricated drop edges and downturns contribute to the structural integrity of the HIMACS sheet assembly. Therefore, it is essential that the design and fabrication methods are appropriately matched to ensure long-term durability.

Fabrication Risks in Drop Edges and Downturns

Proper fabrication of drop edges and downturns is essential to ensure the structural integrity and aesthetic quality of HIMACS surfaces. Failure to adhere to recommended methods can result in various issues, some of which may compromise the durability and performance of the final product.

2. Fabrication Of Straight Components

The fabrication of straight components requires precision and adherence to recommended procedures to ensure structural integrity and aesthetic consistency. Straight parts are typically easier to manufacture than curved or complex profiles, but attention to detail remains essential

Key considerations include:

Proper fabrication of straight components contributes to the overall durability and visual quality of HIMACS installations.

One of the most straightforward techniques for producing a drop edge involves stacking layers of HIMACS material beneath the primary sheet. This method is particularly suitable for the Solid and Granite colour ranges.

Typically, for a sheet with a thickness of 12 mm, either two layers (resulting in a total thickness of 24 mm) or three layers (36 mm) are stacked to achieve the desired drop edge profile.

Fabrication Process for 12 mm HIMACS Sheets

1. Preparation of Strips

• Cut the required strips slightly oversized.

• Sand the underside of each strip using 120-grit abrasive paper.

• Clean thoroughly using denatured alcohol and a lint-free white cloth.

2. Adhesive Application

• Apply an adequate amount of HIMACS joint adhesive to each strip.

• Spread the adhesive evenly using a wooden or plastic spatula to ensure full coverage.

3. Clamping and Curing

• Secure the strips using “A”-type spring clamps, spaced at intervals of 70 mm to 80 mm.

• Allow the adhesive to cure for approximately 45 minutes at a temperature of +20°C.

• Ensure that a visible bead of adhesive is expelled from the joint upon clamping, indicating sufficient adhesive application and proper bonding pressure.

4. Finishing Process After Adhesive Curing

• Level the surface using a circular table saw.

• Machine the desired profile using either a portable hand-held router or a table planer.

• Complete the process by sanding and polishing the surface to achieve a smooth, refined finish.

Limitations of the Stacking Method for 20 mm Sheets

• The stacking method is not advised due to inherent thickness tolerance, which may result in noticeable discrepancies when layers are stacked, potentially compromising structural and visual integrity.

Rebating for Extended Skirts and Aprons

• Depth and Width of rebate: Ensure the rebate dimensions are appropriate for the thickness and type of material being joined.

• Tool Selection: Use suitable routing or rebating tools to achieve clean, consistent cuts.

• Adhesive Application: Apply HIMACS-approved adhesive within the rebate to ensure strong bonding.

• Alignment and Clamping: Carefully align the components and use appropriate clamping methods to maintain pressure during curing.

• Finishing: Once bonded, sand and polish the joint area to achieve a smooth, uniform finish.

• Proper rebating enhances both mechanical strength and visual quality of long skirt and apron assemblies.

Application of Drop Edges for Deep Downturns

• Drop edges may be applied directly to the sheet edge, particularly for deeper downturns.

• Rebating the underside of the sheet to a depth of ~1–2 mm before assembly is most effective.

Advantages of the Rebating Method Over Boot Seam Fabrication

• Enhanced bond strength.

• Reduced impact of particle irregularities.

• Improved surface quality.

• Precise edge termination without additional guides or alignment templates.

Rebating and Bonding Procedure for Drop Edges

• 12 mm sheet: rebate ~13 mm × 2 mm

• 20 mm sheet: rebate ~21 mm × 2 mm

Pre-Bonding Inspection

• Inspect all edges for broken chips, saw marks, or whitening.

Surface Preparation

• Sand the internal edges of the rebate and corresponding downturn edges using 150/180-grit abrasive paper.

• Clean thoroughly with denatured alcohol and a lint-free white cloth.

Adhesive Application and Clamping

• Apply enough HIMACS-approved adhesive.

• Secure the edge using screw clamps spaced at intervals of 70–80 mm.

• Confirm continuous adhesive beads along internal and external edges of the joint.

Finishing

• After curing, invert the sheet and remove any excess adhesive using a portable hand router fitted with a straight cutter and nylon bearing.

• Sand and polish the surface to achieve a smooth, professional finish.

Rebating Guidelines for 12 mm HIMACS Sheets

When working with HIMACS sheets of 12 mm thickness, the required rebating depth varies depending on the colour family to ensure optimal visual consistency and edge quality:

• Large Chip Colour Families (Volcanics, Lucia): Increase rebate depth to 5 mm.

• Veined and Glittering Colour Families (Marmo, Perna, Sparkling): Increase rebate depth to 9 mm for better visual consistency and edge quality.

Boot Seam and V-Groove Edge Techniques

The boot seam method (non-rebated) and the v-grooving technique (45° cut) are alternative approaches for edge fabrication in HIMACS sheets.

• Boot Seam (Non-Rebated): Joins edges without a rebate. Simpler but less structural and visually consistent.

• V-Grooving (45° Cut): Forms a mitred joint. Effective for precise corners and concealing colour variations. Requires careful alignment, adhesive coverage, and finishing.

Note:

Both methods require careful execution to ensure proper alignment, adhesive coverage, and finishing quality.

Boot Seam Drop Edge Fabrication Procedure

When fabricating boot seam drop edges, it is essential to inspect the underside of the HIMACS sheets for any defects prior to bonding. The underside of both the sheets and the buildup strips should be sanded using 120-grit abrasive paper to ensure proper surface preparation.

Wooden stop blocks secured with hot melt adhesive can be employed to assist in the accurate alignment of the buildup strips during assembly.

Note:

While this method is functional, the rebating technique is generally preferred, as it offers superior structural integrity and visual consistency.

The V-Grooving fabrication method is effective for concealing colour variations in certain shades that exhibit veins and/or glitter.

Without drip Edge

No-Drip Front Edge Fabrication

A no-drip front edge may be specified for any horizontal surface fabricated from 12 mm material.

Process:

1. Cut a rebate 6 mm deep and 6 mm high at the top of the front edge of the countertop surface.

2. Cut a corresponding groove in the apron material so that, when joined, the apron projects approximately 12 mm above the horizontal countertop surface.

3. Use joint adhesive to bond the apron to the countertop.

4. Once the adhesive has cured, use a router to round over the top edge and sand the surface as required.

3. Manufacturing Internal Corners

Recommendations for Internal Corners of Worktops

• A minimum radius of 5 mm must be maintained for any internal corner in HIMACS sheets; a larger radii are preferable.

• The vertical joint line between the edge and the top seam should be at least 25 mm apart.

• All jointed sections of the edge must be reinforced with a HIMACS back block. The worktop should be fabricated 1.5 mm oversize to allow for precise edge trimming.

Fabricating an Internal Corner – Stacking Procedure

Begin by preparing blocks from HIMACS sheet. For the following conditions, a minimum block size of 130 x 130 mm is required:

• Edge depth: 50 mm

• Internal corner radius: 5 mm

• Distance from corner to seam line: 50 mm

• Distance from seam line to block edge: 25 mm

  (Total: 50 + 5 + 50 + 25 = 130 mm)

Steps:

1. Sand the underside of the blocks using 120-grit abrasive paper. Clean thoroughly with denatured alcohol and a white cloth.

2. Stack and bond the blocks and strips for the edge material on the underside of the internal corner, using a sufficient quantity of HIMACS joint adhesive.

3. Secure with “A” style spring clamps and allow to cure for approximately 45 minutes at +20°C. Ensure that a reasonable amount of adhesive is expelled from the joint once clamped.

4. If the corner structure is not sufficiently robust, reinforce the vertical joint line formed by the corner blocks and strips with a 50 mm wide, 12 mm thick HIMACS back block.

5. Once adhesive has fully cured, trim the blocks to match the shape of the internal corners and remove any excess adhesive using a router.

6. Complete the process by sanding and polishing the surface as required.

Internal Corner of Jointed Worktop

Begin by fabricating blocks from HIMACS sheet. For the following conditions, a minimum block size of 125 x 125 mm is required:

• Internal corner radius: 50 mm

• Distance from corner to seam line: 50 mm

• Distance from seam line to block edge: 25 mm

  (Total: 50 + 50 + 25 = 125 mm)

Steps:

1. Sand the underside of the blocks using 120-grit abrasive paper. Clean thoroughly with denatured alcohol and a white cloth.

2. Stack and bond the blocks onto the edge strips for the underside of the internal corner, using a sufficient quantity of HIMACS joint adhesive.

3. Secure with “A” style spring clamps and allow to cure for approximately 45 minutes at +20°C. Ensure that a reasonable amount of adhesive is expelled from the joint once clamped.

4. If the structure of the corner is not sufficiently robust, reinforce the vertical joint line formed by the corner blocks and strips with a 50 mm wide, 12 mm thick HIMACS back block.

5. Once the adhesive has fully cured, trim the blocks to match the shape of the internal corner and remove any excess adhesive using a router.

Internal Corner with Extended Skirt

Steps:

1. Begin by fabricating a thermoformed corner block.

2. Sand the underside of the block using 120-grit abrasive paper. Clean thoroughly with denatured alcohol and a white cloth.

3. Bond the thermoformed block and edge strips to the underside of the internal corner using a sufficient quantity of HIMACS joint adhesive.

4. Secure with “A” style spring clamps and allow to cure for approximately 45 minutes at +20°C. Ensure that, once clamped, an adequate amount of adhesive is expelled from the joint.

5. If the structure of the corner is not sufficiently robust, reinforce the vertical joint line formed by the corner block and strips with a HIMACS back block measuring 50 mm in width and 12 mm in thickness.

6. Once the adhesive has fully cured, trim the blocks to match the shape of the internal corner and remove any excess adhesive using a router.

7. Complete the process by sanding and polishing the surface as required.

4. Fabricating External Corner

• External corners may be fabricated using either the stacking method or the thermoforming method.

• The procedures and recommendations are identical to those for internal corner fabrication.

• If a small-radius external corner is required, the corner may be reinforced by cross-stacking the edge strips.

External corner by stacking method

If a small-radius external corner is required, the corner may be reinforced by cross-stacking the edge strips.

Reinforcing a Small-Radius External Corner by Cross-Stacking Edge Strips

Steps:

1. Preparation: Cut the required number of edge strips from HIMACS sheet, ensuring suitable width and thickness.

2. Sanding: Sand the bonding surfaces of each edge strip with 120-grit abrasive paper. Clean thoroughly with denatured alcohol and a white cloth.

3. Positioning: Arrange the edge strips so that each layer is oriented perpendicular (crosswise) to the previous layer. This cross-stacking increases structural strength.

4. Bonding: Apply a sufficient amount of HIMACS joint adhesive between each layer.

5. Clamping: Secure the stacked strips using “A” style spring clamps. Allow adhesive to cure for approximately 45 minutes at +20°C. Ensure that excess adhesive is expelled during clamping.

6. Shaping: Once cured, trim the stacked edge strips to match the required small-radius external corner profile.

7. Finishing: Remove excess adhesive with a router. Sand and polish the corner to achieve a smooth, uniform appearance.

Minimum Recommendations for Fabricating Corners with HIMACS Sheets

• Always create the largest possible corner radius; never fabricate a square corner.

• Ensure adequate distance between the corner and the seam line on the worktop and minimize the number of joints at the corner.

• Employ sufficient reinforcement methods at the joints where possible.

• Provide additional structural support to ensure the stability of the corner.

Impact on Durability

Adhering to the recommended fabrication practices for corners—such as providing a generous corner radius, maintaining adequate distance between the corner and seam lines, minimising joints at the corner, and reinforcing with suitable support—significantly enhances the durability of the finished product.

Sharp or square corners are more susceptible to stress concentration, which can lead to cracking or failure over time.

Sufficient reinforcement and support help distribute mechanical loads more evenly, reducing the risk of structural weaknesses.

By following these guidelines, the likelihood of premature wear, damage, or failure is minimised, thereby extending the service life of the installation.