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For those of us who purchased a CNC for solid surface, seaming material became a whole lot simpler. I can remember trying to fit 10-ft.-long seams together. We started with what we thought was the best straight edge and the sharpest router bit. Then, we set up the material so we could do a mirror cut because, like we all know, that straight edge isn’t really straight. You get the idea: The setup and execution of creating nice tight seams is difficult using hand tools.

So, about five years ago we finally purchased a CNC for solid surface fabrication. Besides all the wonderful shapes, cutouts, speed and accuracy, the biggest improvement can be seen in the seams. I have gotten pretty creative over the years and want to share four of the most common seams we use for everyday kitchen countertops.

CURVED SEAM

The curved seam is pretty simple to work with. Unlike some of the others, it is the easiest to fit after cutting. As you know, after cutting a seam, it doesn’t always go together without gaps. Sometimes a quick sanding with a block sander can get you a perfect fit. With the curve, it is simple to sand the convex side to clean up any unwanted gaps.

DOG LEG (FRENCH MITER)

The “Dog Leg” seam, also known as a French miter seam, is predominately seen in the stone industry. It is a bit tricky, especially if the inside corner has a radius as required by most solid surface manufacturers. As you can see in the pictures to left, my options were limited because of the placement of the sink.

This style is more complicated because it is difficult to see the fit of the inside angle when glue is applied. You have to trust that you have it tight. A wood block on each side of the seam toward the front angle, along with a large spring clamp, can ensure a better fit. (Hint: If you make the inside corner larger, the pieces will match better.)

PRECUT ONE PIECE

This seam is as easy as it gets, but can be really useful when using expensive or patterned material. It will work on any size seam, but where it really comes in handy are for 8-ft. and longer seams.

As you know, the longer the seam, the more difficult it is to achieve a tight fit through the entire length. This seam gives you the opportunity to cut, fit and finish the seam before you cut your final shape. You may wonder what’s the big deal. The picture above shows a large island more than 10 ft. long and 4 ft. wide using a veined material. Matching the two sheets together prior to cutting the final shape gives me the ability to line up the seam and even inspect it after the initial sanding. If the results are not acceptable, I can recut.

I like to cut, fit and finish right on the CNC for those large seams. If you do not use the CNC full time, this is perfectly fine. If you are in full production, it would probably be better to seam away from the machine.

SERPENTINE SEAM

My first introduction to the serpentine seam was when DuPont introduced its Venaro line. The pattern was a heavy, veined material that was almost impossible to achieve inconspicuous seams with.

This is by far the most complicated. If the initial fitting is tight, it goes well. If it doesn’t, then you will either have to have perfectly matched seam adhesive or a steady hand with the block sander. The results are excellent though. I have yet to have a customer be able to spot a seam.

But be prepared to triple your fabrication time. Results vary based on color and the sharpness of the tooling in your CNC. I would recommend a triple flute bit that can achieve a mirror finish and nice gentle curves.

With a little practice and a little imagination, anything is possible. All the seams discussed here come out better with a larger diameter router bit. The larger diameter tends to deflect less, creating a more accurate fit. Test these ideas on some scrap material. The more comfortable you are with seams, the more likely you are to make them work to improve the quality of your fabrication. I hope these ideas help and good luck.

About the author: Andy Graves is the owner of Olive Mill, a solid surface fabrication company, and runs www.TheFabricatorNetwork.com, an online association of countertop fabricators. He has been a solid surface fabricator since 1986 and can be reached at andy@thefabricatornetwork.com.