Using a Router Table

[dusty]

If I route a groove the length of a work piece and while doing so I ascertain that the work piece is always tight against the fence, am I guaranteed that the groove is parallel to that reference edge?

[Gene Howe]

As long as the ascertainment is well clamped feather boards and the fence doesn't move, then yes.

If I route a groove the length of a work piece and while doing so I ascertain that the work piece is always tight against the fence, am I guaranteed that the groove is parallel to that reference edge?

[BuckeyeDennis]

To pick nits, both the fence and the workpiece reference edge must also be straight.

[dusty]

To pick nits, both the router fence and the workpiece reference edge must also be straight.

So if I rip the work piece to its intended width on a table saw with a slightly bowed rip fence and I then take that work piece to the router table, are you telling me that the error in the rip fence will be transferred to my routed groove?

[BuckeyeDennis]

If the bow in the workpiece is convex, then yes, assuming that you keep the workpiece pressure against the fence near the bit.

If concave, the workpiece will contact the fence only at the outermost points, and the curvature will be reduced. But you will likely get some "snipe" when the ends hit the gap in the fence (at the bit).

[JPG]

So if I rip the work piece to its intended width on a table saw with a slightly bowed rip fence and I then take that work piece to the router table, are you telling me that the error in the rip fence will be transferred to my routed groove?

Sorta. The resultant lack of linearity of the ripped workpiece will not directly match the shape of the fence, but rather the shape resulting from the non-linear motion of the workpiece as it traversed the rip fence. The shape of the routed part will be the result of the non-linearity of the work piece traversing the router fence. The 'shape' of the side riding against the rip fence will also affect the resultant shape of the opposite ripped edge.

That's the 'generic' answer. It all relates.

[dusty]

[quote="JPG"]Sorta. The resultant lack of linearity of the ripped workpiece will not directly match the shape of the fence, but rather the shape resulting from the non-linear motion of the workpiece as it traversed the rip fence. The shape of the routed part will be the result of the non-linearity of the work piece traversing the router fence. The 'shape' of the side riding against the rip fence will also affect the resultant shape of the opposite ripped edge.

That's the 'generic' answer.]

I am not absolutely certain but I think that was a "yes".

[Gene Howe]

Use a jointer. Anything but flat edge against the fence, as you described, scares the He!! outta me.

[forrestb]

Since we are 'picking nits,' what has been said is true UNLESS the ripped piece is narrow enough to be flexible and the feather board is strong enough to hold it against the fence just before and after the bit. If so, the work piece will bend against the fence be it convex or concave.

The routed edge will be consistent end to end - barring other unforeseen circumstances.

But that is a situation to be avoided if possible.

Forrest

[charlese]

In addition to pressure against the fence, remember DOWNWARD pressure. Nothing is more frustrating than a groove that is too shallow in places.

If a bowed board, with the middle part of the board elevated above the table, then a groove can be made if downward pressure can temporarily level the wood.