Face-jointing a big plank with a router bridge

[Jamie Buxton]

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.

[Jamie Buxton]

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.

[Jamie Buxton]

Here’s the end product.

[Chris Padilla]

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!

[Jamie Buxton]

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.

[William OConnell]

Beautiful :D:D:D:D

[Tim Thomas]

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?

[Jamie Buxton]

.. How did you joint the edge where the top pieces meet? ..

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. :eek: 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.

[Alex Shanku]

Awesome! Thanks for posting this!

How did you remove the router marks after flattening the faces? scraper?

[Jamie Buxton]

Awesome! Thanks for posting this!

How did you remove the router marks after flattening the faces? scraper?

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.

[Chris Padilla]

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. :eek: 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.


What?! You didn't muscle those babies on your J/P??? :eek:

[steve jay]

wow very nice and simple

[Larry Rasmussen]

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

[Maurice Ungaro]

Jamie,
I learned that technique at a Highland Woodworking class, however, their example was for flattening a workbench. Nice use of the method!

[Doug Shepard]

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.

[Gary Herrmann]

Beautiful work, Jamie. I like the way the boxed in legs contrast with the natural edge top.

[Rob Cunningham]

Jamie,
Nice looking table. Thanks for posting your procedure. I have a live edge slab of ash that I want to turn into a coffee table but wasn't sure how to machine it. I think you just gave me a solution:).

[Anthony Whitesell]

What bit did you use in the router?

I'm thinking of building a 2x4 glued-up workbench and using a large dish carving bit for the flattening step. I was wondering how to get the rails in the same plane, thanks for the info/idea.

[Chris Padilla]

I think Jamie's idea for getting the rails in the same plane is cool but wouldn't a level have worked? I must be missing something here....

[Jamie Buxton]

What bit did you use in the router?


On this project, I used a 1 1/2" diameter straight bit. That's a size which is generally available and competitively priced. There are "planing bits" which are larger diameter, but they're rather spendy.

[Anthony Whitesell]

I haven't seen a straight bit that large! That's why I was looking at the dish carving bits. The large ones were 1 1/4" diameter with a flat bottom area.

[Jamie Buxton]

I think Jamie's idea for getting the rails in the same plane is cool but wouldn't a level have worked? I must be missing something here....

A level could do the job, but it is over-specifying the task. You first have to get everything level. If you work in a garage (whose floor is sloped, by building code), or on a patio, getting everything level is extra effort. The crossed strings, in contrast, measure exactly what you need: whether the rails are in the same plane.

[Prashun Patel]

Beautiful work and thanks for planing tip. Lots of work, but worth the results. Don't you also have to make sure the top of the workbench is perfectly parallel to the rails? When you flip the top, if the bench isn't flat, the two sides won't be parallel... Or does your technique account for that?

I notice you have a couple splits; how did you reinforce those?

(edit: Nevermind; I see the rails are joined with cross pieces, which act like a sled and are probably perfectly perpendicular to the rails, so if you make the rails coplanar and level, the bottoms will necessarily be level and parallel.)

[Jamie Buxton]

I haven't seen a straight bit that large! That's why I was looking at the dish carving bits. The large ones were 1 1/4" diameter with a flat bottom area.

I bought mine locally, but online try www.mlcswoodworking.com or www.eagleamerica.com

[Jim Becker]

Thanks for that, Jamie! 'Gonna be a wonderful table, too.

[Jamie Buxton]

I notice you have a couple splits; how did you reinforce those?



The planks had some splits. They also had some knots which had shrunk and split during the drying process. I filled them with pigmented epoxy resin. I wasn't attempting to make the defects invisible; there's no way to make plastic look like wood. Instead, I was trying to make it possible to live with the defects, and make them not stand out too much. If you look closely at the top view of the finished table, you can see a knot or two with epoxy-filled cracks. The epoxy is System Three, which I bought from West Marine. I got the pigment there too.

[Prashun Patel]

No way was I implying they should be hidden! I think those are FEATURES, not BUGS!

I even like the way Nakashima style furniture focuses attention to those beauty marks with dutchman keys.

Your table is beautiful. I'm saving the jpeg for future ref.

Thanks

[Jamie Buxton]

No way was I implying they should be hidden!


We have the same view. To my eye, those checks and splits are part of the tree, the way nature made it. If this weren't a dining table, I might not have filled them at all. However, for a practical dining table, you have to be able to spill food and mop it up. Hence the epoxy.

My finish choice was made on the same basis. When I'm making furniture which will be a long way from water and oil and such, I generally use a thin wiped-on varnish. That wouldn't work for a dining table. This one has one brushed-on coat of alkyd solvent-borne varnish, followed by two coats of sprayed-on waterborne alkyd varnish (Target's Hybrivar). I get a better surface quality with a spray than a brush.

[Chris Padilla]

A level could do the job, but it is over-specifying the task. You first have to get everything level. If you work in a garage (whose floor is sloped, by building code), or on a patio, getting everything level is extra effort. The crossed strings, in contrast, measure exactly what you need: whether the rails are in the same plane.

"I see!" said the blind hobbyist woodworker! :D Yes, that makes perfect sense...just level what you have to and not everything else. I'll remember this....

I see you've learned much from living on steeply sloped hills! :)

[John Stevens]

Beautiful, Jamie. Just one question though: why move the router from side to side instead of along the length of the planks?

Regards,

John

[Jamie Buxton]

... why move the router from side to side instead of along the length of the planks?....

Either would do the job. However, with a nine-foot-long plank, there would be a lot of walking back and forth to do it your way.

[Chris Padilla]

I would have written my name in the plank and had fun with it but you guys just want to go in nice, even, BORING straight lines.... ;)

[Joe Petersen]

I've been milling my own lumber in slabs like this to try to build furniture in the same style (god willing). I see these are close to being quarter sawn and that helps, but will still have the tendency to cup.

How do you ensure no cupping on the boards? Is making sure they are completely dry enough?
Also, I cant tell how you joined the legs to the table. How was this done?

[Jamie Buxton]

I've been milling my own lumber in slabs like this to try to build furniture in the same style (god willing). I see these are close to being quarter sawn and that helps, but will still have the tendency to cup.

How do you ensure no cupping on the boards? Is making sure they are completely dry enough?
Also, I cant tell how you joined the legs to the table. How was this done?

The planks were not cupped very much at all from the drying process. They were 2 1/2" thick, which might have had something to do with it. They were air-dried for about six years, according to the miller I bought them from. My moisture meter says they're about 7% moisture content. That seems very dry to get from air-drying, but that's what it reads.

The base subassemblies are basically rectangles made with 2"x7" lumber. There's finger joints at the corner. There are through-holes bored through the top piece of 2x7. The holes are round near the middle of the table, but oval near the edges. 3/8" bolts go through the holes into holes tapped into the underside of the top planks. The tapped holes are about 1 1/2" deep, so there's lots of thread.

[Derek Stevens]

gorgeous wood. nicely done.

[Jon Banquer]

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.



What would others suggest as an alternative for making the rails out of?




Shims underneath the rails make the adjustment of the rails.



Could someone describe the process of how one would go about adding shims so that the strings just touch. How do you know where to add the shims?

Does the work also have to be shimmed?

Jon Banquer
San Diego, CA

[Norman Pyles]

Wow, that is way cool. :cool::cool:

[Heather Thompson]

This is a great thread and beautiful work, but this a two year old thread so it may not come up on the radar of many.

Heather

[Jon Banquer]

This is a great thread and beautiful work, but this a two year old thread so it may not come up on the radar of many.

Heather

I thought it would be better to comment and ask questions on an existing topic before starting another thread on a topic that had already been discussed so I did a search first and found this thread.

If the response is poor to the questions I asked I'll start a new thread.

Thanks for pointing out that I might get a limited response because of the age of the thread. From what you wrote I take it there are some posters don't look at older threads.

[David Epperson]

I thought it would be better to comment and ask questions on an existing topic before starting another thread on a topic that had already been discussed so I did a search first and found this thread.

If the response is poor to the questions I asked I'll start a new thread.

Thanks for pointing out that I might get a limited response because of the age of the thread. From what you wrote I take it there are some posters don't look at older threads.
Well, I didn't see this thread before I started on my Bridge Router Planer/Jointer set up. I might have got a different route. :rolleyes:
My problem was trying to flatten warped wood that would need to be cut too small for a planer. So I just clamp the pieces onto the work table with some sacrificial shims and bridge router them when needed along with the project piece. My bit is a little different though. I modified a slotting bit to take a flat head socket cap screw - so that it fits a little under flush - and mounted that on a mandrel. Got a 2" diameter "Planing Bit" for about $15 that way.

[Steve Jenkins]

I use a bridge and router to flatten big pieces also but a slightly different method. My work table is a 4x8 foot torsion box so is nice and flat. I lay the piece to be flattened on the table and shim it so it doesn't rock. My bridge consists of two pieces of aluminum angle long enough to span the work piece. They are fastened to two short pieces of 3/4 ply that I rip wide enough to give me the height I need for the thickness of the workpiece.
This gives me good support without having to make long rails and mess with getting them even.

[Dan Friedrichs]

Could someone describe the process of how one would go about adding shims so that the strings just touch. How do you know where to add the shims?

Does the work also have to be shimmed?



You only use 2 shims for the strings. One string gets run corner-to-corner without shims, and the other string goes corner-to-corner, but at each end, sits on top of a shim that is the thickness of the string. If the two boards being used as rails are perfectly coplanar, the strings would perfectly intersect each other. Since that can't happen, shimming one string lets it sit just barely on top of the other one.

If the lines just barely touch, then the rails are coplanar. That doesn't say anything about the relationship of the board to be surfaced to the plane formed by the rails, though. You should shim the work up so that it is a uniform distance from the strings (to minimize the amount of material you take off).

[Jon Banquer]

Dan,

Do I have this right?

If one string is sitting above the other string I would start by shimming the rails at the ends that the lower string is attached to till both crossing strings just touch?

If one string is riding on top of the other string I would start by shimming the rails at the ends that the upper string is attached to till both crossing strings just touch?

If I have this right would you recommend using wedge type shims to make it easier to get the strings to just touch where they cross?

[Jon Banquer]

I use a bridge and router to flatten big pieces also but a slightly different method. My work table is a 4x8 foot torsion box so is nice and flat. I lay the piece to be flattened on the table and shim it so it doesn't rock. My bridge consists of two pieces of aluminum angle long enough to span the work piece. They are fastened to two short pieces of 3/4 ply that I rip wide enough to give me the height I need for the thickness of the workpiece.
This gives me good support without having to make long rails and mess with getting them even.

Steve,

So you don't use rails at all and instead *slide* the two aluminum angles, that are attached to the two short 3/4 plywood pieces, which sit on your torsion box table top down the length of the piece you are flattening?

Each time you make a cut you slide the bridge down so you can take the next cut?

[Dan Friedrichs]

Dan,

Do I have this right?

If one string is sitting above the other string I would start by shimming the rails at the ends that the lower string is attached to till both crossing strings just touch?

If one string is riding on top of the other string I would start by shimming the rails at the ends that the upper string is attached to till both crossing strings just touch?

If I have this right would you recommend using wedge type shims to make it easier to get the strings to just touch where they cross?

Um, I guess I've never seen it done with shims UNDER the rails. Every time I've seen it done, one rail gets securely screwed to the side of the bench, and the other rail gets one screw in one end (holding it to the side of a bench), then clamped at the other end. You can carefully adjust (by pivoting on the single screw at the far end) until the strings touch, clamp it tight, then drive more screws to hold it.

[Jon Banquer]

Dan,

I got the idea that I needed to shim under the ends of the rails because I saw this video which has the rails sitting on top of a table.

http://www.youtube.com/watch?v=8aWze4UM32U&feature=player_embedded

[Steve Jenkins]

Steve,

So you don't use rails at all and instead *slide* the two aluminum angles, that are attached to the two short 3/4 plywood pieces, which sit on your torsion box table top down the length of the piece you are flattening?

Each time you make a cut you slide the bridge down so you can take the next cut?

yup you got it

[David Epperson]

yup you got it
Less of a bridge, more of a gantry. Oughta work. :D