Flattening Large Wood Slabs with a Router
Charlie KocourekSlabs of wood make excellent tables; the challenge lies in flatting them on the surface. In most cases, cool slabs will be too large for a planer or sander to handle; end grain slabs, on the other hand, will not be suitable for a planer. Fortunately, there is an easy way to flatten any oversized board using a shop-made jig and a router, and I’ll show you how.
For step-by-step instructions, check out our blog post: Flattening Large Wood Slabs with a Shop-made Jig and a Router
Hi, I'm Charlie Kacourek, and today, I have this really nice six inch thick piece of walnut on my bench. This is a cookie, meaning it's a slice out of a tree. So the surface is all end grain. And I think this would make a really cool end table, say, up at a cabin or something like that. The problem is that the surface is rough of course, and it won't fit through my planer.
Certainly not, it wouldn't Definitely can't use it on my jointer. So how do I clean it up? Well, there's a surprisingly quick and easy way to do that using just a few pieces of plywood and a router, and I'm going to show you exactly how to do that today. I made a simple sled out of three pieces of plywood and I bolted my router onto that, then I clamped two more pieces of plywood on the side of my bench, and those were the rails that the sled rode on. The jig requires five pieces of plywood and four small blocks of lumber.
The pieces that I clamped to the bench and the sides on the sled are all 3/4 inch plywood. The bottom of the sled is a little thinner and I made that out of 1/4 inch plywood. I glued small blocks on the ends of the side rails so that I would have a good way to clamp them down to the bench. I wrapped a piece of paper around the base of my router to make a template, and then I took a pencil and I poked holes through the paper to locate the screw holes and the collet. Then I put my template at the center of the sled and I marked the location of the collet and the screw holes.
I glued the sled together after I drilled the holes for the router mount and for the router bit to go through. Flattening a board produces a lot of dust, so I installed this four inch dust hood behind the router to help with that. Before you begin routing your work piece, you need to, well, you wanna check and make sure your bench is level, but you also want to level the work piece and secure the workpiece onto the bench. So what do I mean by leveling the workpiece? Well, our objective is to flatten one side of the board and remove the least amount of wood necessary to get that side flat.
So ideally, you'd hold a straight edge, a level of straight edge on your board and there'd be no gap between the level straight edge and the workpiece, that's what we're trying to get to. But there will be a gap. So what you want to do is you want to adjust the work piece up and down, however necessary using shims, until you've got the least amount of gap between the level of straight edge and the workpiece. And you'll be able to tell. So when you've got that, when you've adjusted it with shims and you've minimize the gap between the level and the work piece, then you're there.
You know you're there and you're ready to secure it down to the bench. Okay? Now you have your work piece leveled, and you need to secure to the bench. What's a good way to do that? Well, here is one good way that you could do it.
You need three scraps of wood. You clamp one scrap down at one end of the bench, a few clamps, clamp it on your bench. Carefully, so you don't mess up the adjustments that you worked so hard to just get. You slide your work piece up against that scrap that you've just clamped there. Then you take a second, smaller scrap, and you clamp that on the opposite end of your work bench.
And then you take the third piece, and you but that against the work piece and place it in between this scrap that's clamped and the workpiece. Now you take a few wedges and a hammer. You tap the wedges in here between these two pieces, and now, your work piece is solidly secured to your bench, and you're ready to go. When you clamp the side rails onto your bench, it's important to make sure that they're level in both directions. And if they're not, you can adjust that by putting shims underneath them.
You can use just about any router for this operation that you happen to have as long as it has a 1/2 inch column, because you will be using a larger router bit. It's also easier if you have a plunge router, it'd be easier to make your depth adjustments than with the regular router. And a variable speed is a big plus, because then you can use larger bits. With a single speed router, you'd be limited to a 3/4 inch diameter bit. As far as router bits go, they do make dedicated planer bits.
They call 'em dado planer bits. That's what I used this last time. This one is 1 1/2 inches in diameter, and I've used regular straight router bits, they work fine. This planer bit worked a little better, went a little faster, slightly cleaner surface, but straight bit really works just fine. The big consideration with the router bit though is the length.
You want a minimum of a 2 1/4 inch length, and preferably, something that's even up to maybe three inches long, because as you make your subsequent passes, you're going further and further down, adjusting your router further and further down. And if your bit isn't long enough, you'll run out of length and then you'll have to adjust the side rails on the jig to make your next pass. Which isn't a big deal, you can adjust the side rails. It's just another consideration. You can remove up to a 1/4 of an inch on each of your initial passes with the router.
You'll get a cleaner finish though if you reduce that to an 1/8, of an inch or even less than an 1/8 of an inch on your final pass. So I hope you like this video. And if you'd like more detailed information on flattening large boards with a router, I wrote an accompanying article on this that you'll be able to find on the Guild's website.
Such a simple cheap alternative to expensive commercially made sleds. Well done.
It is imperitive to wear dust mask when doing this operation.
That was a very good way of doing the flatting of a round of wood. My problem with that is that I do not use power tools only hand tools. How would you all suggest that I do the flatting using say a hand plane would you suggest that I go in a circle so as not to gouge the wood. I understand that you are most power tool advocates and only use hand tools on occasions, well I am the other way around and only use power tools occasionally. So, how would you suggest I tackle the problem.
How is the "gap" between the level and the work surface reduced by shimming the bottom of the workpiece?
I would use a chain saw to level the piece and then sand it smooth. I would use an Festool MFT table to secure the piece to the table and not require the elaborate plywood jig to secure to the table, which seems far too nice to mess up. All in all, I suspect doing it my way would save a lot of time and plywood.
This is the best info on a router sled i have seen so far. The router bit and speed info was excellent.
Great idea. I wonder if a small window (cut out a square and cover with plexiglass) on each side of the router would give you a better view of that has been cut and what remains?? I also see this being useful on more than a cookie. What about a rough-cut mantel piece from a log?
Nice! I plan to build a sled!
Great video!
I was really interested to watch how the operation can be carried on, but video could not opened.