Canadian Woodworking

More live edge slabs

Blog by Rob Brown
router bits

In my post two weeks ago (“How beautiful are live edge slabs?”) I received a few comments about some of the details of how I flattened the slab for the bar top.

Bit type

Mark Salusbury asked about the size and style of bit I used. I have a lot of flat-bottomed router bits, but because of the large surface area of the slab I was working with, I wanted to use a bit with a large diameter. Although I’m guessing other types of bits may have left me with a smoother surface (maybe not, I’d need to experiment to see for sure) I knew I was going to hit the surface with my belt sander equipped with a 60 grit sanding belt, so I wasn’t overly concerned with how nice the surface was.

I reached for my Freud mortising bit, which is 1-1/4″ in diameter. At about twice the width as most of my other straight bits, it sped up the process quite a bit. And in reality, the surface it left was very smooth and only needed a small amount of work with the belt sander to even it out. This bit isn’t a true plunge bit, as the centre section of the end of the bit doesn’t have any cutting edges on it. If you wanted to plunge with it, I would recommend moving the bit sideways while slowly plunging, as that will ensure the bit can safely ramp down into the material, as opposed to plunging directly into the material. When I was levelling the slab, I was able to start the cut at the edge of the workpiece.

Not a Plunger – Although this bit isn’t a true plunge bit, I was able to use it to flatten the slab without problem.

A Wide, Flat Bit

Wanting to use the widest flat bit I have to speed up the process of flattening this large slab, I reached for my Freud mortising bit. It’s 1-1/4" wide and likely cut the time it took to level this slab in half.

router bits

Cookie time!

Rick MacDonald asked if I had any tips for levelling some spalted maple cookies. In case you’re new to this whole sub-genre of woodworking, cookies are cross sections of a tree or branch that are usually vaguely circular, tend to have a live edge around the perimeter and are end grain on both faces.

Levelling cookies involves pretty much the same process as levelling a live edge slab. The main difference is that cookies are often smaller and weigh much less than slabs, so they should be kept in place while being machined. Unless the cookies are very small, the best approach for this would be to first ensure they’re sitting flat on a surface. Some shims might be needed so the cookies don’t rock while being machined. The next thing you can do is extend a few lengths of solid or sheet goods that will press against the edge of the cookie and ensure it doesn’t move. You’d need at least three of these pieces, though four or more would be best.

It’s all in the sawdust

The other thing that you don’t realize until after you’re done working with cookies is that the sawdust you create is much different. I’ll try to explain the differences, though it’s much easier to explain this sort of thing face-to-face.

First, picture machining a slab with standard face grain, like the one I discussed machining a few weeks ago. The sawdust comes off in shavings, as it would if you were using a hand plane to dress the face of a board, though the plane would produce longer shavings (often as long as the workpiece), obviously.

When flattening a cookie with a router, the shavings you take off will be like short toothpicks. This is because the grain is oriented parallel to the bit. Wood fibres are hollow and aligned like a bunch of drinking straws sitting together, side-by-side. If you were to cut into the ends of the straws, as in the first example of the face grain slab I machined, you’d end up with very short bits of straws, though there would still be numerous straw ends still joined together. This is the type of wood chip we’re most familiar with.

The type of chip you’re going to produce when you rout end grain cookies will be more like you’re removing one single wood fibre from the workpiece, and it will be equal to the depth of the cut you’re making. For example, if the cut you’re making is 1/4″ deep, the resulting chips are going to be very similar to a 1/4″ long straw. This chip will have a lot more structural integrity and, as I mentioned above, will be more like a toothpick, in that it’s strong and pointy.

This is where the difference will be more obvious to the woodworker. When I machined the large end grain cookie years ago my socks ended up filled with a million tiny, sharp splinters, tickling my feet and pricking my skin with every step I took. It was also hard to get them out. A few cycles through the washing machine helped, but I still had the odd tickle on my ankles for a few weeks.

The moral of that story is to wear long pants, high-cut work boots and make sure your pant cuffs are over your boot cuffs while you’re machining the cookies.

Rotary planer head?

Another commenter mentioned how the company he works with uses a 10″ diameter rotary planer head to machine slab faces up to 60″ wide x 8′ long in about 20 minutes or so. Naturally, I asked them for a few photos so I could share them with you. Now that’s a setup I’d love to see.

A Microscopic Look at Wood Chips – The wood chips produced from an end grain cookie are different than those produced from a face grain surface.



Published:
Last modified: May 25, 2023

Rob Brown - [email protected]

Rob is a studio furniture maker and the editor at Canadian Woodworking & Home Improvement. Instagram at @RobBrownTeaches

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