A Different Kind of Feather Board
by John Bonin
Click on any picture to see a larger version.
When making table tops that consist of a hardwood frame around a plywood center, I always use tongue-n-groove joinery to connect them. Since the plywood has only a very thin veneer, it is obviously always best to get the tongue in the frame positioned exactly with the groove in the center piece to avoid having to do much sanding later.
I have an Incra router fence in concert with a Woodpeckers router lift and Wixey digital height measurement. This combination lets me get to within .001 in adjustments between the tongue and groove pieces. (Only fine sanding required afterward.) Until recently I always used a traditional feather board to hold the pieces flat against the router table as they are being pushed-through the cut.
On my last project some of the sticks were slightly bowed to begin with. I cut the frame pieces on the table saw and readied them to cut the tongue on the router table. I was not concerned they were not perfectly flat because the feather board will hold them firmly flat against the table as the tongue is routed - or so I thought. The thinking being that the groove in the plywood will hold them perfectly flat after assembly.
I thought all was fine until it was time for dry-fitting assembly. To my dismay, the ends were perfectly flush with the plywood, but the center area was not. In fact, it was off more than 1/32nd - obviously too much to sand without the risk of going through the veneer. My only alternative (if I continued at that point) was to flip the frame pieces over so that they were 1/32nd proud of the plywood and rely on sanding to save the day - a dilemma.
So as to never have that happen again, I began designing something that would hold the pieces more firmly as they are drawn across the router bit. Here is what I came up with, using ball-bearings from Highland Woodworking, part number 485661.
The back piece that is mounted to the router fence is standard 3/4" thickness (whatever you have laying around). The piece that holds the bearings is a 2x4. Both pieces are 8" long.
I also considered using small caster wheels instead of the bearings, but that would have raised the ensemble considerably higher on the fence. This does the job nicely.
As a slight modification of what John "Hannibal" Smith used to say on "The A-Team," after cutting a tongue-n-groove frame around a center piece, "I just love it when they come together perfectly."
You can email John at firstname.lastname@example.org
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