[OP]
Contributor
This is the beginning of a big dining table. The rough-sawn planks in front of me are over 9 feet tall, 22” to 27” wide, and 2 ½” thick. They will become the top of the table. The planks behind me will become the table base.
The first major milling operation is to face-joint and thickness-plane the planks for the top. I did it with a router bridge, and the process is detailed in the next few posts.
[OP]
Contributor
The first photos shows one of the planks sitting on my workbench. Running parallel to it are two rails. The other photo shows the router bridge. It spans the two rails, with a slot for the router bit to stick through. To mill the plank, I make a cross-grain pass with the router, bump the bridge over approximately one bit-diameter, make another cross-grain pass, and repeat until I’ve reached the end of the plank. If the router tip has touched the entire plank, I’m done. If it hasn’t, I lower the bit and do it again. After one face is flat, I turn the plank over and do the other side.
If the rails are straight and in the same plane, the planed surface of the board is flat. The challenge is to make the rails straight and in the same plane.
These rails are made from 2x4s fastened together in an L shape. The L’s flange provides a spot for the clamps without getting in the way of the bridge. I used green lumber for these rails. It is likely to move as it dries, so I made them in the morning and used them in the afternoon. I edge-jointed the top edge on my jointer. Its bed is 54” long, so outboard roller stands help manage the 10’-long rails. It is convenient that two rails are necessary, because I can test them against each other to confirm that they are jointed straight. I test the jointed edges face-to-face, and then side-by-side. If they match in both tests, they are straight.
To get the two rails in the same plane, I use crossed strings. They run from end to end of the rails, forming a big X. You can barely see them in the photo. I tension them with weights hanging from one end. Put lots of tension on them to avoid sagging, or if you have a sense of pitch, pluck them like a guitar string. If they have the same tension, they play the same note. If they have the same tension, they sag the same. I measure the thickness of the string, and put shims under the upper string. If the strings just kiss, the rails are in the same plane. You can see the shims in the photo – a credit card on top of a business card. (I’ve used mason’s twine for these photos, but I often use monofilament line. I can more accurately measure the diameter.) Shims underneath the rails make the adjustment of the rails.
It is probably obvious, but the strings are only for setup. They come off for the milling operation.
The bridge is pretty stiff. Those sides are 2”x3” oak. When I’ve made flimsier bridges, they’ve flexed in the middle when I’ve been pushing the router back and forth. That leaves a little more work when it is time to sand out the machining marks.
This router bridge technique can be used to produce parts which are not flat. Curved rails produce curved pieces. Using this technique, I’ve milled the rails for curved frame-and-panel doors, and made bending forms for bent lamination.
Just for calibration, it took me a day to build the rails and bridge and to surface both planks top and bottom.
[OP]
Contributor
Here’s the end product.
Moderator
Walnut, Jamie?
That is one SUPERSWEET table and I love the simplicity of the legs.
Everything is big and beefy and I bet it weighs quite a bit!
Last edited by Chris Padilla; 11-19-2008 at 3:01 PM.
[OP]
Contributor
Yes, it is walnut. Yes, it is way heavy. It breaks into four pieces for transport: the two base pieces, and the two top planks. The top planks each weigh 120 pounds. The top planks have registration pegs between them to align them, and draw bolts to pull the seam closed. The base pieces bolt to the underside of the top, into holes tapped directly into the walnut. The holes through the base pieces near the middle are tight, but are elongated near the ends.
Member
Beautiful
William
http://woodworkers.us
I never lost money on a job I didn't get
Member
Awesome table, and I like the fact that you can break the top into two pieces to move it. You can't tell at all from looking at it, that joint between the top pieces looks permanent/glued from where I sit. How did you joint the edge where the top pieces meet? Do you have a big power jointer, or did you go with a hand plane or something else?
If I could ever finish working on my shop, maybe I could find the time to start working in my shop.
[OP]
Contributor
There was no way I could horse those big planks through a power jointer; I can barely pick one up, much less do anything precise while I'm holding it.Originally Posted by Tim Thomas
I straight-lined the planks with a guided circular saw (the bigger Festool in this case). That was good enough to use, but I did clean up the saw marks with a jointer hand-plane.
Contributor
Awesome! Thanks for posting this!
How did you remove the router marks after flattening the faces? scraper?
[OP]
Contributor
A scraper would work. However, that's lots of acreage to do by hand. I used a 6" random-orbit sander. IIRC, I started sanding with 100 grit.
Last edited by Jamie Buxton; 11-19-2008 at 4:30 PM.
Moderator
There was no way I could horse those big planks through a power jointer; I can barely pick one up, much less do anything precise while I'm holding it.
What?! You didn't muscle those babies on your J/P???
Member
wow very nice and simple
Member
Two projects coming up where it will help- an irregular shaped corner desk out of walnut probably 1 3/4" thick after jointing. I've been looking at the walnut 2X6 pile I've accumulated wondering about my muscle power for machining. Had forgotten all about this approach.
And the tip on curved surfacing- super cool!
Larry R,
Seattle
Member
Jamie,
I learned that technique at a Highland Woodworking class, however, their example was for flattening a workbench. Nice use of the method!
Maurice
In Memoriam
IIRC Alex was the one that pointed me to that method on Highland Hardware's site and I used it to do my workbench top. I just used short pieces of the same string though instead of the shims. It seemed to work out OK.
Use the fence Luke
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