Using roundover bit with bearing in router table

[Marc Rochkind]

My roundover bits have bearings. When I'm using one of them in a router table (I'm new to this), I assume the work will bear against the bearing. What then is the purpose of the fence? Does one perform this operation without the fence? Does one try to make the fence flush with the bearing (sounds tricky)?

[Don Jarvie]

You adjust the fence so it's just a hair in front of the fence. I put a ruler across the fence and have it barely touch the bearing.

You can use the bit without the fence because of tear out. With the fence you can tale a little at a time but without it your taking it all off with one pass. Only time I use it without the fence is when I use a flush cutting bit.

[Mike Cutler]

Mark
The bit can be used in a hand held router also. In which case the bearing is the guided reference.
The bit can also be used by itself to perform edge work on the router table, but you will need a starting pin in the table for safety and control.
The bearing can be easily aligned with the fence face. Use a metal ruler and just align with the fence face.

Pat Warner is a member here on the forum and he pretty much "writes the books" on the use of a router. Invaluable resource and he's just a few mouse clicks away. Link to his page through his profile and he has tons of info.

[Dave Zellers]

Round edges would require the bit be used without a fence. Straight edges can benefit from two passes with a fence, the first shy of the bearing and the second as Don describes.

It won't take long for it to all fall into place for you.

[Myk Rian]

I use them both ways in the table. Just depends on if I'm doing some freehand, (with a pin) or some straight stock.
Whatever you feel comfy with.

[Von Bickley]

I use that bit without a fence......

[johnny means]

I position my fence close enough to use the dust collection. Unless I'm doing long straight pieces and want to use hold downs. Then I line the bearing up with the fence using a straight edge.

[Ole Anderson]

Yes, dust collection. And feeding the leading edge of the piece into a spinning bit is much easier with a fence. Much safer too.

[Lee Schierer]

If you are rounding over the edge of a board so that you get a semi circle on the edge, a round over bit will leave an uneven edge on the second pass unless you use a fence. On the first pass, the bearing is riding on a flat surface and will make a true cut. On the second pass the bearing is riding on a curved surface. The point where the bearing is actually riding is slightly behind where you want to cut so the cutting edge cuts a bit deeper on the second pass than it did on the first pass resulting in an imperfect round over. You can get a perfect round over if you use a fence adjusted so there is a few thousandths gap between the bearing and the face of the fence, where the bearing is actually slightly behind the face of the fence.

[glenn bradley]

You I put a ruler across the fence and have it barely touch the bearing.

I do as Don does (and believe he meant "adjust the fence so it's just a hair in front of the bearing". The fence comes into play for me several ways. The first is safety; if the cut is straight, the fence adds an element of safety. If the cut is curved, I use the bearing as a guide and skip the fence replacing it with a starter pin.

For large roundovers that I want to make in multiple passes, I set the bit as full height and step the fence back in increments to take small bites of material each pass until I reach the full depth. If I am making a double roundover (profiling with one face down and then the other) on the second pass the bearing is of no use as the surface of the material that normally rides the bearing has been rounded off. In this case I use the fence to reference off of for both passes to assure a proper fully rounded profile

[Jim Finn]

I also use that bit without a fence. I am routing curved shapes.

[Jim Neeley]

I use a fence to maximize my cut quality.

I do this by setting the *height* of the bit to its end setting and then setting the fence up so the front of the bearing is slightly behind it, and make a roughing cut.

Then I readjust the fence to make the bearing either flush or *slightly* proud of the fence and make a final very light cut. This permits a quicker feed rate, preventing burning and the shallow cut minimizes the risk of tearout.

Just my $0.02... YMMV.

Jim in Alaska

[Yonak Hawkins]

I'm with the group that does not use a fence. I find a fence redundant and, having two separate guides which may or may not be adjusted accruately, or wood which may or may not be perfect, the cut may or may not be suitable. Using the fence for the first pass, if two passes are required, may be easier than re-adjusting your router height, and maybe not.

Glenn's and Lee's advice is spot on in the case where your operation will rout away the bearing surface.

[Marc Rochkind]

Thanks, all, especially Lee, who described my situation exactly. With the fence set as he suggested, I was able to rout the other side with the curves matching just right.

[pat warner]

Add a third bearing (2 on the armature, 1 on the cutter) & double the chatter.
A fence will take nearly all of the x/y load, not the cutter. Moreover, the fence is insensitive to (work) edge defects.
Care about finish, jointer-frequency image transfer, cut character, bearing emboss, (on straight line work)?
Then use a fence.