Using a router table to joint an edge

[Bob Turkovich]

Ok, so what am I doing wrong????

I picked up two pieces of rough sawn oak yesterday. Both pieces were 1 1/2 inches thick, 3 inches wide, 30 inches long. I first ran it through the planer. Since I do not have a jointer, I used my router table to joint the edges. My router table is a Bench Dog CI (table saw extension kind) w/ a ProMAX fence. The fence has spacers to offset the outfeed fence to allow jointing.

I ran both pieces thru the table multiple times. When I placed the two "jointed" edges against each other, I had a small gap on each end. Placing each piece against my table saw fence confirmed that there was indeed a bow in both pieces.

I'm wondering if the issue is how I am pressuring the work piece up against the router fence as I pass it by the bit. If I press too much on the infeed side of the fence, I get snipe about a 1/2 inch from the end of the board.

For this particular project they will not be placed against each other so I can live with the bow but in the future I'd like to avoid it (especially if I build any panels). Buying a jointer is not feasible due to workshop space.

Any advice would be appreciated.

[Cory Hoehn]

Are you using featherboards to make sure you've got good contact with the fence? I try to make sure to transition my pressure from the infeed side to the outfeed side and keep it there until the last of the board has passed the bit.

As an alternative, you could use your table saw with a straight-line ripping jig. A 30" board wouldn't be very difficult to do at all.

[Brian Kincaid]

Bob,
My only suggestion is to use a longer fence on infeed and outfeed. If you have a gradual bow you will not be able to get it out if the fence is not long enough to hold the straight-line.

-Brian

[Dave Gaul]

Bob,

Try to measure the length of the "gap" you are seeing... is this gap's length equal to the distance from the leading edge of the router bit to the outfeed fence?

Sounds to me like you outfeed fence is set a little too far in, so that when you feed the stock, once the stock hits the outfeed fence it is actually being pulled away from the bit.. this would certainly cause a gap at the end when you join the boards...

I've used your method myself, before I had a jointer.. keep at it, practice with scrap until you get it just right... take your time in set up and you will get it right sooner than later!! HTH....

[Andrew Pitonyak]

Although I have no particular advice for jointing on your router table, if you are jointing so that you can join the two boards together, you may be able to do the following:

1. Install a straight bit in your router.
2. Lay the two boards next to each other with a small gap between them.
3. Run the router along a straight edge such that the straight bit cuts a path through the two boards.

The idea is that the router bit will remove a bit from each board as the router is pushed between the boards. If you waver a bit on one side, this is reflected in both boards so that they should match together for a glue-up.

[Johnnyy Johnson]

Make sure you have you flattest sides down on both pcs's going through the router.(since you don't have a jointer) Mark with a pencil so you don't get them reversed. Then they should match up. Before going through the router I (with flat side down) use a Emerson tool and clamp guide and run through TS and get a glue rip cut with a straight edge. Then it is not as important how long the router fence is, b/c the board is now straight. Also, I switched to using a spiral 1/2" up bit rather than a straight bit. Much smoother..

Thanks
JJ

[Johnnyy Johnson]

Bob, since you don't have a jointer, next time you may try this. A friend had a 13" wide pc of Walnut 10' long. Since my jointer is 10" I had to use my planer which is 15". (I am not skilled with hand planes) I ran the pc through my planer with the small cupped side up. I had to make many passes. Sometimes it would go through and not cut anything. I wanted for the blades to just kiss the wood. That way I was not pressing the board flat. This process worked and was worth all the extra time I spent. Once the cuped side was flat I flipped it over and hogged the other side flat.

[Myk Rian]

You need to put pressure on the outfeed side of the fence.
The outfeed fence needs to have a shim behind it to makeup for the material being removed. 1/16" is good.
When setting the fence, lay a straight edge along the outfeed side, and adjust the fence so the straight edge touches the bit flute. Lock it down.

[Bob Turkovich]

Thanks to all that responded.......here's what I've found so far.

I'm using a 3/4" straight bit (I forgot until after re-reading this thread that I, indeed, have a 1/2" spiral up bit ) with only a 1/8" gap between the bit and both fences. The Promax fence has spacers for both 1/16 and 1/32 removal. I was using the 1/32 spacer.

I first tried flipping one of the pieces (end-to-end) to see if the pieces were truly bowed in the center and not biased on one end. When I mated the two pieces together there was no change.

I then ran a 30" piece of MDF through, put it up against the table saw fence and saw the same bowing. I then ran with featherboards on both the infeed and outfeed side. No change.

I then increased the gap between the bit and the outfeed fence to about 1 1/2 inches. No change. I then removed the outfeed fence and "indexed it" so I could get about a 9 inch gap to the bit (still using featherboards) The bow went away but I had a hard time keeping from sniping once the work piece passed the support given by the infeed fence. As long as I leave enough stock length to cut off the snipe, I'll be good to go.

Didn't get a chance to test the longer fence theory. The ProMAX allows for replaceable fences and I've got a couple of 3-footers somewhere in the shop from an earlier project......

Again, thanks to all for the help.

BTW, after I had done my original "jointing", I ran both pieces through the TS with a Glue Line Rip Blade just to smooth up the other edge. When I was doing the above "flipping", I put the ripped edges against each other and saw a small gap along the entire edge. Put the Wixey gauge to the blade and saw my blade was off by 0.1". Reset the blade to 90 degrees and got a good match. Who'd thought that small of an angle error could make such a difference?

[Greg Wease]

One more thing to check is that the faces of the infeed and outfeed fences are parallel. If they are at a slight angle to each other you can get bowing.

You might also try using a pattern bit so you can be sure the outfeed fence is aligned exactly with the bearing. This is a little easier than triying to align the cutting edge.

[pat warner]

Graphic shot of jointing on the router table.

[Stephen Cherry]

The relation of the outfeed table to the bit is critical

On a jointer, the blade at its highest point of travel should be in the plane of the out feed table, so if you place a straightedge on the out feed table and rotate the cutterhead, the blades will imperceptibly touch the straightedge. The problem with this is that imperceptibly touching is imperceivable.

So the effect to look for is bowing. If the outfeed table is too low, the board bows one way. If it is too high, it bows the other way.

And the in feed must be paralell to the out feed or that will cause bowing also.

The easy way would be to route along a straightedge.

[Myk Rian]

I then ran a 30" piece of MDF through, put it up against the table saw fence and saw the same bowing. I then ran with featherboards on both the infeed and outfeed side. No change.

MDF will wear your bits down quickly. Use wood similar to what you will be jointing.

I then increased the gap between the bit and the outfeed fence to about 1 1/2 inches. No change. I then removed the outfeed fence and "indexed it" so I could get about a 9 inch gap to the bit (still using featherboards) The bow went away but I had a hard time keeping from sniping once the work piece passed the support given by the infeed fence. As long as I leave enough stock length to cut off the snipe, I'll be good to go.

Opening the gap is the wrong way to go. Keep the fence gap as small as you can, without it touching the bit.

[Bob Turkovich]

I have no doubt that not being able to perceive the perceptible is the major issue here.......... This would explain (at least partially) why the bow went away when I extended the gap between the bit and the outfeed table. (Any offset between the bit and the offset table will have less effect when it's over a greater span.)

Just for kicks, I tried to find those longer fences that Brian suggested. I found them stored in the rafters above my workshop......right next to two pieces (one plywood, one MDF), both marked with my own writing "This edge is perfectly straight".....

I'd forgotten that a couple of years ago I had taken the two pieces.....using the long fences and the spiral bit... and created straight edges that I could use with a pattern bit so I didn't have to go through this every time I wanted a straight edge.

When I went on retirement 18 months ago, I didn't realize my brain retired, too........