How to Keep a Slab Flat

Live edge slabs make beautiful tables and countertops; however, they are susceptible to warping and cupping. The best way to keep a slab flat is to properly prepare the surface and install a c-channel. Our CNC shop has the tools and knowledge to expertly flatten slabs of all sizes and species.

Expect Expansion and Contraction

All wood has moisture in it, and as the moisture evaporates, the wood will physically change shape. Many woodworkers leave their slabs and other lumber to air-dry (sometimes for years) before using it. But, even if you take the time to let your wood dry out, the slab can still warp or cup over time because of changes in temperature or air moisture levels.

Installing a c-channel can help prevent this type of cupping and warping.

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Flatten Live Edge Slab

Before a slab can be used in furniture, it needs to be perfectly flat and level. While this can sometimes be done with a commercial drum sander or planer, many of the large slabs we work with are too big for standard equipment, so we use our CNC table instead.

The router moves across the slab, carefully cutting down any high spots until the surface is completely level. Once one side is finished, the slab is flipped and the process is repeated. The final step is a thorough hand-sanding, giving the slab a smooth, ready-to-finish surface.

Install C-channel

Once the slab has been flattened, the next step is installing the C-channel. A C-channel is a high-strength steel bar shaped like the letter “C” and fitted into a recessed groove on the underside of the slab. Screws fasten it through slotted openings along the channel, securing it firmly in place.

These slotted openings are key, they allow the wood to expand and contract naturally as its moisture content changes. By giving the slab room to move, the C-channel helps prevent warping and cupping over time, keeping the surface stable and true.

This live-edge waterfall tabletop was manufactured from one slab. After flattening, and installing the c-channels, we mitered the inside corners to create a seamless waterfall edge. This piece was professionally finished before delivery to the customer.

Slab Flattening Services

We offer professional slab flattening services in our CNC shop for live edge wood slabs, custom furniture projects, and other woodworking applications.

Many furniture makers and custom builders bring their slabs to us for precision flattening and C-channel installation, then go on to build their own custom furniture from the prepared material.

We can work with your supplied slabs or help you source domestic or exotic species such as walnut and mappa burl shown in these videos.

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Taking the time to flatten a slab and install the correct number of c-channels will go a long way to prevent the wood from warping and cupping.

You could finish the surface and router out the channel yourself – but if you’d rather leave the precision work to us, reach out.

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    Our manufacturing center is located in Ottawa, Ontario and can provide local delivery on our trucks to most of Eastern Ontario and Western Quebec. 

    We also work with customers Canada-wide and internationally and can work with you to find the best shipping options. 

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