Highland Woodworking
First Look: Woodpeckers Slab Flattening Mill
By J. Norman Reid

Click on any picture to see a larger version.

I like the looks of natural edge coffee tables and enjoy making them. And I'm fortunate to have a nearby lumber supplier that specializes in reclaimed wood, where I can find inexpensive slabs. In the past, I've flattened slabs by running them through my 16-inch planer and finishing them with hand planes. But some of the best slabs are wider than my planer can accommodate. While I can still finish larger slabs by hand, I was excited when Woodpeckers announced their Slab Flattening Mill and I was quick to put in my order for one.

I was lucky to get one of the early models. It came by FedEx in a large cardboard box. It's heavy; although I was able to carry it into the house, I was reluctant to manhandle it down the stairs to my cellar woodshop, so I opened the box and carried it downstairs piece by piece. The parts, machined from high quality aluminum, come securely wrapped to protect their fine finish. The assembly parts—and there are many—come clearly labeled in separate plastic bags. The instructions are thorough and guide the assembly step by step.

And some assembly is required! In fact, the whole sled is in pieces and must be built up part by part. This is a process that, if done carefully, will take a couple of hours. Following the instructions, I began with the sled that traverses the slabs. To build it, you need to work on a perfectly flat surface to assure the assembly is perfectly square in all dimensions. My workbench was tied up with another project, so I used my table saw infeed table. This left the 48" traversing rails overhanging the table on both ends, but that simply gave me working room to install the hex screws that hold the assembly together. I first installed these loosely, as the instructions said to do, then tightened them after assuring the ends were perfectly square. This is important; the assembly must slide over a longer set of rails and any lack of squareness will impede smooth performance later. Once the ends are square, install the end caps and safety stops. The instructions called for installing the self-drilling screws that hold the end caps in place with a screwdriver to avoid stripping out the aluminum, but I found this hard to do, so I ignored the instructions and partially inserted the screws with a Torx bit-equipped hand drill before tightening them by hand.

Photo 1 - The completed assembly consists of two rails running the length of the slab and
two that allow the router to slide over the slab. The mechanism works smoothly and,
once assembled, is easy to use.

The plate that will carry the router is next. This is a simple installation. Screw the upright handles in place and attach the router plate to brackets with hex screws and you're done.

Photo 2 - The assembly that holds the router glides on rails that traverse the slab.
Assembly is simple. Screw the sides to the base and attach the handles. The base will
accommodate a wide range of routers.

That finishes the traversing sled. Now for the longitudinal rails that run the length of the slab. These need to be mounted to a perfectly flat base. My choice: a sheet of 3/4" red oak plywood mounted on a pair of Kreg track horses. The track horses feature a track that accommodates a hold down clamp on each end and brackets on the side to support 2X4s. Since the rails are 72" long, I cut the plywood down to 84", leaving a 6" overhang on each end, enough room to screw the ends of the rails to the plywood base. I screwed the first rail into place and then installed the traversing sled, assuring that the second longitudinal rail was in perfect alignment from one end to the other before screwing it down. The sled, which rides on slick tape, moves smoothly.

For my first test, I placed a slab of Ambrosia maple on the plywood, centering it on the sled. Since both sides will be flattened, I began with the flattest side facing down. Because most slabs will be somewhat unlevel, you'll probably need to insert shims as I did. Then, take the four toothed dogs supplied with the mill and screw them to the plywood to hold the slab tightly in position.

Photo 3 - Toothed dogs supplied with the flattening mill are screwed into the plywood
board beneath the slab. They hold the slab firmly in position for routing.

Next, I installed my router on the router plate that will slide on the traversing sled. The Woodpeckers Slab Flattening Mill is designed to accommodate a wide range of routers, including the Festool 1400 EQ. In most cases, other than the Festool Router, it's necessary to remove the plate from the router base before screwing it to the sled base with the supplied screws.

It's desirable to install a dust collection system to the router to catch some of the sawdust that's produced. I didn't have one available for my garage installation, so I mounted the track horses on wheeled bases so I could do my routing in the driveway where the winds can carry the sawdust away.

Photo 4 - Flattening a slab is sure to generate a lot of sawdust. Be sure to wear eye and
hearing protection. A dust mask is advisable as well. This is not a job to be done inside,
unless you have good dust collection.

You'll want a spoilboard router bit for this job. There are a couple of options, including a replaceable carbide equipped bit, but I chose the Whiteside 1/2" Spoilboard Bit for the job. Whiteside has a good reputation for quality carbide.

I set the router at a depth that would skim the top off the highest points of the slab and slid the router across the slab, making a succession of passes that overlapped each other by half until I'd covered the entire slab. Because the first pass left some lower spots unflat, I lowered the router bit about 1/8" and passed over the whole board a second time. I repeated this practice until the whole surface was flattened. Then, I turned the slab over and flattened the second face. The result was a beautifully surfaced slab that only needs sanding or handplaning to make it ready for finishing and the construction of a base.

Photo 5 - The flattened slab needs only a few passes with a handplane or a sander to
finish the job. The router made an almost completely smooth job of it.

This is probably not a "must-have" product for all woodworking shops, unless you love using natural edge slabs for coffee tables, as I do. But if you're like me and have a stash of slabs that are crying for attention, then you'll want to give this high quality Woodpeckers Slab Flattening Mill a serious look.

Click here to find out more and purchase your own Woodpeckers Slab Flattening Mill from Highland Woodworking.

J. Norman Reid is a woodworker, writer, and woodworking instructor living in the Blue Ridge Mountains with his wife, a woodshop full of power and hand tools and four cats who think they are cabinetmaker's assistants. He is the author of Choosing and Using Handplanes. He can be reached by email at nreid@fcc.net.

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