A mortise and tenon assembled lacquered furniture

Abstract

A mortise and tenon assembling lacquered furniture, comprising a seat plate and a chair leg, characterized in that: the bottom corners of the seat plate are respectively provided with chair plate bottom mortises, the chair plate bottom mortises are connected and fixed with one end of the chair leg, the upper surface of the seat plate is provided with a connecting notch on the side of the backrest, and an assembled seat backrest structure connected and fixed through mortise and tenon is arranged in the connecting notch; the surface is treated by adopting a traditional Chu type lacquering process; the application has a reasonable structure, can realize the individualized quick disassembly of components, has structural stability and aesthetic property, is stable during use, has high space utilization, is stable after assembly, and can well meet the diversified and individualized use requirements of modern users on furniture.

Description

Technical Field

[0001] This application relates to an assembled furniture, and more particularly to a mortise and tenon assembled lacquered furniture, belonging to the field of furniture technology. Background Technology

[0002] In the furniture manufacturing and daily life sectors, chairs, as commonly used furniture, have structural designs that directly affect ease of use, space utilization, and the satisfaction of personalized needs. Currently, most mainstream furniture chairs on the market adopt a non-removable, one-piece structural design. This type of structure has significant technical defects and user pain points in the production, transportation, use, and storage processes.

[0003] From the perspective of ease of use, one-piece seats cannot be quickly disassembled and assembled, and need to be moved as a whole during transportation. This not only makes them poorly adaptable to narrow spaces (such as corridors and elevators), increasing the difficulty of transportation and labor costs, but also makes them difficult to operate flexibly when it is necessary to temporarily adjust the indoor layout or reorganize the space, thus failing to meet users' needs for flexible use of space.

[0004] In terms of space occupancy, the fixed structure of the integrated chair means that its volume cannot be compressed during idle or transportation, occupying a lot of storage and transportation space, increasing logistics and storage costs. This space waste problem is even more prominent in small living environments or scenarios where furniture layout needs to be frequently adjusted.

[0005] From the perspective of meeting personalized needs, the existing integrated chairs have a fixed structural form, and users cannot freely assemble and modify them according to their own aesthetic preferences, usage scenarios (such as family gatherings, personal rest) or functional needs (such as increasing the number of chairs or combining them into different forms). They lack the flexibility of use and personalized customization space, and are difficult to adapt to the diverse and personalized use needs of modern users for furniture.

[0006] Furthermore, existing detachable chairs mostly rely on metal connectors such as screws and bolts for assembly. This not only requires specialized tools and is cumbersome, but also makes the metal connectors prone to corrosion and loosening over time, affecting the structural stability and lifespan of the chair. Additionally, exposed metal parts reduce the overall aesthetic appeal of the furniture, failing to achieve a balance between practicality and decoration. Based on these shortcomings of existing technologies, the industry needs a furniture and chair structure that allows for quick assembly and disassembly, high space utilization, personalized assembly, and combines structural stability with aesthetics. This would solve the technical challenges of current integrated chairs and traditional detachable chairs, meeting users' core demands for ease of use, space adaptability, and personalization. Summary of the Invention

[0007] The purpose of this application is to address the shortcomings of existing furniture and chairs, which mostly adopt a non-removable, integral structure design, resulting in a fixed structural form, lack of flexibility and personalized customization. Furthermore, existing detachable chairs require specialized tools for assembly, are prone to loosening at joints, and suffer from poor structural stability. This application provides a mortise and tenon joint assembled lacquered furniture with a reasonable structure, enabling rapid disassembly and assembly, allowing for personalized assembly, high space utilization, and good structural stability after assembly. This furniture effectively meets the diverse and personalized needs of modern users for furniture.

[0008] To achieve the above objectives, the technical solution of this application is: a mortise and tenon assembled lacquered furniture, including a seat panel and chair legs, characterized in that: the bottom four corners of the seat panel are respectively provided with mortises on the bottom surface of the seat panel, the mortises on the bottom surface of the seat panel are connected and fixed to one end of the chair legs, the upper surface of the seat panel is provided with a connecting groove on one side of the backrest, a first assembled backrest is installed on one side of the connecting groove, a second assembled backrest is installed on the other side of the connecting groove, a mortise and tenon is provided between the first assembled backrest and the second assembled backrest, a silver ingot tenon is installed in the mortise and tenon, the first assembled backrest and the second assembled backrest are assembled together and locked together by the silver ingot tenon.

[0009] Furthermore, the bottom ends of the first and second assembled backrests are provided with straight tenons, and the bottom of the connecting groove is provided with a mortise corresponding to the straight tenon, and the straight tenon is assembled in the mortise.

[0010] Furthermore, mortises and tenons are provided on the mating surfaces of the first and second assembled backrests, with the mortises and tenons on the first and second assembled backrests respectively provided.

[0011] Furthermore, the silver ingot tenon is narrow in the middle and wide at both ends, and is made of wood or metal.

[0012] Furthermore, one or more arc-shaped backrest pieces are installed on the connecting slot via a mortise and tenon structure.

[0013] A type of mortise and tenon assembled lacquered furniture includes a seat panel and chair legs. The seat panel has four mortises at its bottom corners, which are connected and fixed to one end of each chair leg. A connecting groove is formed on the upper surface of the seat panel on one side of the backrest. A bottom crossbar is horizontally installed within the connecting groove. One upper end of the bottom crossbar is connected to the bottom end of a first backrest upright, and the other upper end is connected to the bottom end of a second backrest upright. The top end of the first backrest upright is perpendicularly connected to the first backrest crossbar, and the top end of the second backrest upright is perpendicularly connected to the second backrest crossbar. The first and second backrest crossbars are connected by a wedge tenon structure. Alternatively, the upper end of the bottom crossbar is connected to the bottom end of a middle backrest upright, and a tenon-jointed backrest piece is assembled to the top of the middle backrest upright, with a backrest crossbar installed on the tenon-jointed backrest piece.

[0014] Furthermore, the wedge tenon structure includes a first wedge tenon groove, a second wedge tenon groove, and a wedge. The first backrest crossbar has a first wedge tenon groove, and the second backrest crossbar has a second wedge tenon groove corresponding to the first wedge tenon groove. A wedge is fitted in the joint groove between the first wedge tenon groove and the second wedge tenon groove, and the small end of the wedge faces inward.

[0015] Furthermore, the middle parts of the first backrest crossbar and the second backrest crossbar are connected by a connecting crossbar, and the upper end of the tenon backrest piece is connected to the backrest crossbar by a mortise and tenon structure.

[0016] Furthermore, the two ends of the middle upright of the backrest are respectively provided with connecting tenons, and the middle upright of the backrest and the tenon backrest piece are connected by connecting tenons.

[0017] Furthermore, the bottom crossbar and the backrest crossbar are connected by a first backrest diagonal bar and a second backrest diagonal bar that are arranged in a cross configuration. The middle intersection of the first backrest diagonal bar and the second backrest diagonal bar is provided with a cross brace groove, and the first backrest diagonal bar and the second backrest diagonal bar are assembled and connected through the cross brace groove.

[0018] The beneficial effects of this application are: 1. This application adopts a mortise and tenon joint structure originating from ancient China, which has been practically designed. Combined with the unique shape of the seat, it can not only realize the personalized and quick assembly and disassembly of each component, but also has both structural stability and aesthetics. The overall structure is stable when used after assembly.

[0019] 2. This application uses traditional Chu-style lacquerware for surface treatment, which is hard and wear-resistant, can maintain the integrity and gloss of the surface for a long time, is simple and elegant, and is friendly to people and the environment. When used with mortise and tenon structures, it can achieve a very good effect.

[0020] 3. This application has a reasonable structure, is aesthetically pleasing and practical, and can also play a role in the inheritance of traditional craftsmanship and culture, and can well meet the diverse and personalized needs of modern users for furniture. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of Embodiment 1 of this application.

[0022] Figure 2 This is an exploded view of Embodiment 1 of this application.

[0023] Figure 3 yes Figure 1 Perspective view of the center seat panel.

[0024] Figure 4 This is a schematic diagram of Embodiment 2 of this application.

[0025] Figure 5 This is an exploded view of Embodiment 2 of this application.

[0026] Figure 6 yes Figure 1 A schematic diagram of the structure of the crossbar of the backrest.

[0027] Figure 7 This is a schematic diagram of Embodiment 3 of this application.

[0028] Figure 8 This is an exploded view of Embodiment 3 of this application.

[0029] Figure 9 This is a schematic diagram of Embodiment 4 of this application.

[0030] Figure 10 This is an exploded view of Embodiment 4 of this application.

[0031] Figure 11 This is a schematic diagram of Embodiment 5 of this application.

[0032] Figure 12 This is an exploded view of Embodiment 5 of this application.

[0033] Figure descriptions: 1. Seat panel; 2. Chair leg; 3. Tenon on the bottom surface of the seat panel; 4. Connecting groove; 5. First assembled backrest; 6. Second assembled backrest; 7. Straight tenon; 8. Tenon mortise; 9. Silver ingot tenon; 10. Bottom crossbar; 11. First backrest upright; 12. Second backrest upright; 13. First backrest crossbar; 14. Second backrest crossbar; 15. First wedge tenon groove; 16. Second wedge tenon groove; 17. Wedge; 18. Connecting crossbar; 19. Connecting tenon; 20. Middle backrest upright; 21. Tenon backrest piece; 22. Backrest crossbar; 23. First backrest diagonal bar; 24. Second backrest diagonal bar; 25. Cross stretcher groove; 26. Curved backrest piece. Detailed Implementation

[0034] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] See Figures 1 to 12 This application discloses a mortise and tenon assembled lacquered furniture, comprising a seat panel 1 and chair legs 2, characterized in that: the bottom four corners of the seat panel 1 are respectively provided with mortises 3 on the bottom surface of the seat panel, the mortises 3 on the bottom surface of the seat panel are connected and fixed to one end of the chair legs 2, the upper surface of the seat panel 1 is provided with a connecting groove 4 on one side of the backrest, a first assembled backrest 5 is installed on one side of the connecting groove 4, a second assembled backrest 6 is installed on the other side of the connecting groove 4, a tenon mortise 8 is provided between the first assembled backrest 5 and the second assembled backrest 6, a silver ingot tenon 9 is installed in the tenon mortise 8, the first assembled backrest 5 and the second assembled backrest 6 are assembled together and connected and locked by the silver ingot tenon 9.

[0036] The bottom ends of the first assembled backrest 5 and the second assembled backrest 6 are provided with straight tenons 7, and the bottom of the connecting groove 4 is provided with a mortise corresponding to the straight tenon 7, and the straight tenon 7 is assembled in the mortise.

[0037] The first assembled backrest 5 and the second assembled backrest 6 are provided with mortises and tenons on their mating surfaces, and the mortises and tenons on the first assembled backrest 5 and the second assembled backrest 6 are respectively provided.

[0038] The silver ingot tenon 9 is narrow in the middle and wide at both ends, and is made of wood or metal.

[0039] One or more arc-shaped backrest pieces 26 are installed on the connecting slot 4 via a mortise and tenon structure.

[0040] A type of mortise and tenon assembled lacquered furniture includes a seat panel 1 and chair legs 2. The seat panel 1 has four mortises 3 at its bottom corners, which are fixed to one end of each chair leg 2. A connecting groove 4 is provided on the upper surface of the seat panel 1 along the backrest side. A bottom crossbar 10 is horizontally installed within the connecting groove 4. One upper end of the bottom crossbar 10 is connected to the bottom end of a first backrest upright 11, and the other upper end of the bottom crossbar 10 is connected to a second backrest upright 12. The bottom ends of the first backrest upright 11 are connected to the top end of the first backrest crossbar 13, and the top end of the second backrest upright 12 is connected to the second backrest crossbar 14. The first backrest crossbar 13 and the second backrest crossbar 14 are connected by a wedge tenon structure; or the top end of the bottom crossbar 10 is connected to the bottom end of the middle backrest upright 20, and the top end of the middle backrest upright 20 is connected by a tenon backrest piece 21, on which a backrest crossbar 22 is installed.

[0041] The wedge tenon structure includes a first wedge tenon groove 15, a second wedge tenon groove 16, and a wedge 17. The first backrest crossbar 13 has a first wedge tenon groove 15, and the second backrest crossbar 14 has a second wedge tenon groove 16 corresponding to the first wedge tenon groove 15. The wedge 17 is assembled in the joint groove between the first wedge tenon groove 15 and the second wedge tenon groove 16, and the small end of the wedge 17 faces inward.

[0042] The first backrest crossbar 13 and the second backrest crossbar 14 are connected by a connecting crossbar 18 at their middle parts, and the upper end of the tenon backrest piece 21 is connected to the backrest crossbar 22 by a mortise and tenon structure.

[0043] The two ends of the middle upright post 20 of the backrest are respectively provided with connecting tenons 19, and the middle upright post 20 of the backrest and the tenon backrest piece 21 are connected by the connecting tenons 19.

[0044] The bottom crossbar 10 and the backrest crossbar 22 are connected by a first backrest diagonal bar 23 and a second backrest diagonal bar 24 that are arranged in a cross configuration. The middle intersection of the first backrest diagonal bar 23 and the second backrest diagonal bar 24 is provided with a cross stretcher groove 25, and the first backrest diagonal bar 23 and the second backrest diagonal bar 24 are assembled and connected through the cross stretcher groove 25.

[0045] As attached Figures 1 to 12 This application creatively designs a set of mortise and tenon assembled chairs, combining modern lifestyles with the design trend of quick disassembly and assembly of furniture. In addition to the chair's unique shape, it incorporates practically designed mortise and tenon joints from ancient Chinese wooden structures, including straight tenons, silver ingot tenons, wedge tenons, clamp tenons, and cross stretchers, and uses traditional Chu-style lacquer for the surface treatment. It is not only easy to disassemble, store, and assemble, with high space utilization and personalized assembly capabilities, but also aesthetically pleasing and practical, and plays a role in the inheritance of traditional craftsmanship and culture.

[0046] Most components of the seat kit in this application are interchangeable. The components are connected and locked together using a uniquely designed mortise and tenon joint structure, ensuring stability and reliability after fixing, and facilitating quick manual disassembly and assembly. Furthermore, the structural components of this application undergo surface treatment using traditional Chu-style lacquer, resulting in a hard, wear-resistant, waterproof, and acid / alkali-resistant finish that maintains surface integrity and gloss over a long period. This application can employ various structural forms; the following describes five typical structural forms from the kit in detail, with specific structures and principles as follows: Example 1: The bottom four corners of the seat panel 1 are provided with mortises 3, which are blind holes used to connect and fix the chair legs 2. The mortises 3 are connected and fixed to one end of the chair legs 2, which can be connected and fixed using a straight tenon joint. A connecting groove 4 is provided on the upper surface of the seat panel 1 on one side of the backrest. The connecting groove 4 does not penetrate the seat panel 1. A first assembled backrest 5 is installed on one side of the connecting groove 4, and a second assembled backrest 6 is installed on the other side. The first assembled backrest 5 and the second assembled backrest 6 are assembled together to form an integral backrest.

[0047] A mortise and tenon 8 is provided between the first assembled backrest 5 and the second assembled backrest 6. One part of the mortise and tenon 8 is located on the first assembled backrest 5, and the other part is located on the second assembled backrest 6. The mortise and tenon 8 is the same size as the tenon 9, which is installed inside the mortise and tenon 8. The tenon 9 is designed to be narrow in the middle and wide at both ends, and is made of wood or metal. After the tenon 9 is installed and embedded in the mortise and tenon 8, it can effectively lock and fix the first assembled backrest 5 and the second assembled backrest 6. In addition, straight tenons 7 are provided at the bottom of the first assembled backrest 5 and the second assembled backrest 6. A mortise is provided at the bottom of the connecting groove 4 corresponding to the straight tenon 7. The straight tenon 7 is fitted into the mortise, realizing the connection and fixation between the assembled backrest and the seat panel 1, ensuring the stability and reliability of the assembled seat.

[0048] Example 2: The bottom four corners of the seat panel 1 are provided with mortises 3, which are blind holes used to connect and fix the chair legs 2. The mortises 3 are connected and fixed to one end of the chair legs 2, which can be connected and fixed using a straight tenon joint. A connecting groove 4 is provided on the upper surface of the seat panel 1 on the backrest side, and the connecting groove 4 does not penetrate the seat panel 1. A mortise is provided on one side of the connecting groove 4, which is connected to the bottom end of the first backrest upright 11 via a straight tenon. A symmetrical mortise is provided on the other side of the connecting groove 4, which is connected to the bottom end of the second backrest upright 12 via a straight tenon. Alternatively, a bottom crossbar 10 can be used as an intermediate connecting structure. The bottom crossbar 10 is horizontally installed within the connecting slot 4. One side of the upper end of the bottom crossbar 10 is connected and fixed to the bottom end of the first backrest upright 11 via a tenon joint, and the other side of the upper end of the bottom crossbar 10 is connected and fixed to the bottom end of the second backrest upright 12 via a tenon joint. Furthermore, the middle sections of the first backrest crossbar 13 and the second backrest crossbar 14 are connected by a connecting crossbar 18, and the upper end of the tenon-jointed backrest piece 21 is connected to the backrest crossbar 22 via a mortise and tenon joint.

[0049] The top of the first backrest upright 11 is vertically connected to the first backrest crossbar 13, and the top of the second backrest upright 12 is vertically connected to the second backrest crossbar 14. The first backrest crossbar 13 and the second backrest crossbar 14 are connected by a wedge tenon structure. The seat backrest crossbar is formed by splicing and fixing the first backrest crossbar 13 and the second backrest crossbar 14. The wedge tenon structure includes a first wedge tenon groove 15, a second wedge tenon groove 16, and a wedge 17. The first backrest crossbar 13 has a first wedge tenon groove 15, and the second backrest crossbar 14 has a second wedge tenon groove 16 corresponding to the first wedge tenon groove 15. The wedge 17 is fitted into the splicing groove between the first wedge tenon groove 15 and the second wedge tenon groove 16, with the small end of the wedge 17 facing inward. The wedge 17 is used to tighten the first wedge tenon groove 15 and the second wedge tenon groove 16 to achieve fixation.

[0050] Example 3: The bottom four corners of the seat panel 1 are provided with mortises 3, which are blind holes used to connect and fix the chair legs 2. The mortises 3 are connected and fixed to one end of the chair legs 2, which can be connected and fixed using a straight tenon connection. A connecting groove 4 is provided on the upper surface of the seat panel 1 on the backrest side, and the connecting groove 4 does not penetrate the seat panel 1. The upper end of the bottom crossbar 10 is connected to the bottom end of the middle upright bar 20 of the backrest. The top of the middle upright bar 20 of the backrest is connected to a tenon-jointed backrest component 21, and a backrest crossbar 22 is installed on the tenon-jointed backrest component 21.

[0051] Example 4: The seat back adopts a cross-stretcher fixing structure, and the connection structure between the seat panel 1 and the fixed seat leg 2 is the same as in the above embodiment. A connecting slot 4 is provided on the upper surface of the seat panel 1 on one side of the backrest, and the connecting slot 4 does not penetrate the seat panel 1. A bottom crossbar 10 is horizontally installed in the connecting slot 4, and a backrest crossbar 22 is provided at the uppermost end of the seat back. The bottom crossbar 10 and the backrest crossbar 22 are connected by a first backrest diagonal bar 23 and a second backrest diagonal bar 24 that are arranged in a cross configuration. Cross-stretcher slots 25 are respectively provided at the intersection of the first backrest diagonal bar 23 and the second backrest diagonal bar 24. The first backrest diagonal bar 23 and the second backrest diagonal bar 24 are assembled and connected through the cross-stretcher slots 25 to form an assemblable integrated structure.

[0052] Example 5: The seat back uses a detachable arc-shaped backrest component. The connection structure between the seat panel 1 and the fixed seat leg 2 is the same as in the above embodiment. A mortise is provided in the connecting groove 4, and one or more arc-shaped backrest components 26 are installed on it through a tenon and mortise structure. The two arc-shaped ends of the arc-shaped backrest component 26 are provided with straight tenons, which are connected together with the mortise.

[0053] The above description is a further detailed explanation of this application in conjunction with specific embodiments. It should not be considered that the specific implementation of this application is limited to these descriptions. For those skilled in the art, there will be various simple substitutions, improvements and changes to this application without departing from the concept of this application. All such simple substitutions, improvements and changes should be considered to fall within the protection scope of this application.

Claims

1. A type of mortise and tenon assembled lacquered furniture, comprising a seat panel (1) and chair legs (2), characterized in that: The bottom corners of the seat panel (1) are provided with mortises (3) on the bottom surface of the seat panel. The mortises (3) on the bottom surface of the seat panel are connected and fixed to one end of the chair leg (2). The upper surface of the seat panel (1) is provided with a connecting groove (4) on one side of the backrest. A first assembled backrest (5) is installed on one side of the connecting groove (4), and a second assembled backrest (6) is installed on the other side of the connecting groove (4). A tenon (8) is provided between the first assembled backrest (5) and the second assembled backrest (6). A silver ingot tenon (9) is installed in the tenon (8). The first assembled backrest (5) and the second assembled backrest (6) are assembled together and connected and locked by the silver ingot tenon (9).

2. The mortise and tenon assembled lacquered furniture according to claim 1, characterized in that: The bottom ends of the first assembled backrest (5) and the second assembled backrest (6) are provided with straight tenons (7), and the bottom of the connecting groove (4) is provided with a mortise corresponding to the straight tenon (7), and the straight tenon (7) is assembled in the mortise.

3. The mortise and tenon assembled lacquered furniture according to claim 1, characterized in that: The first assembled backrest (5) and the second assembled backrest (6) are provided with mortises and tenons on their mating surfaces, and the mortises and tenons on the first assembled backrest (5) and the second assembled backrest (6) are respectively provided.

4. The mortise and tenon assembled lacquered furniture according to claim 1, characterized in that: The silver ingot tenon (9) is narrow in the middle and wide at both ends, and the silver ingot tenon (9) is made of wood or metal.

5. A mortise and tenon assembled lacquered furniture according to claim 1, characterized in that: One or more arc-shaped backrest pieces (26) are installed on the connecting slot (4) by means of a tenon and mortise structure.

6. A type of mortise and tenon assembled lacquered furniture, comprising a seat panel (1) and chair legs (2), characterized in that: The seat panel (1) has four mortises (3) at the bottom corners, which are fixed to one end of the chair leg (2). The upper surface of the seat panel (1) has a connecting groove (4) on the backrest side, and a bottom crossbar (10) is horizontally installed in the connecting groove (4). The upper end of the bottom crossbar (10) is connected to the bottom end of the first backrest upright (11), and the other end of the upper end of the bottom crossbar (10) is connected to the bottom end of the second backrest upright (12). The top of the first backrest crossbar (13) is vertically connected to the top of the second backrest upright (12) and the second backrest crossbar (14). The first backrest crossbar (13) and the second backrest crossbar (14) are connected by a wedge tenon structure; or the upper end of the bottom crossbar (10) is connected to the bottom end of the middle backrest upright (20). The top of the middle backrest upright (20) is connected by a tenon backrest piece (21) and a backrest crossbar (22) is installed on the tenon backrest piece (21).

7. A mortise and tenon assembled lacquered furniture according to claim 6, characterized in that: The wedge tenon structure includes a first wedge tenon groove (15), a second wedge tenon groove (16), and a wedge (17). The first backrest crossbar (13) is provided with the first wedge tenon groove (15), and the second backrest crossbar (14) is provided with the second wedge tenon groove (16) corresponding to the first wedge tenon groove (15). The wedge (17) is assembled in the splicing groove between the first wedge tenon groove (15) and the second wedge tenon groove (16), and the small end of the wedge (17) faces inward.

8. A mortise and tenon assembled lacquered furniture according to claim 6 or 7, characterized in that: The first backrest crossbar (13) and the second backrest crossbar (14) are connected by a connecting crossbar (18) at their middle parts, and the upper end of the tenon backrest piece (21) is connected to the backrest crossbar (22) by a mortise and tenon structure.

9. A mortise and tenon assembled lacquered furniture according to claim 6, characterized in that: The two ends of the middle upright post (20) of the backrest are respectively provided with connecting tenons (19), and the middle upright post (20) of the backrest and the tenon backrest piece (21) are connected by connecting tenons (19).

10. A mortise and tenon assembled lacquered furniture according to claim 6, characterized in that: The bottom crossbar (10) and the backrest crossbar (22) are connected by a first backrest diagonal bar (23) and a second backrest diagonal bar (24) that are arranged in a cross configuration. The first backrest diagonal bar (23) and the second backrest diagonal bar (24) are respectively provided with cross stretcher grooves (25) at their middle intersections. The first backrest diagonal bar (23) and the second backrest diagonal bar (24) are assembled and connected through the cross stretcher grooves (25).

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