Flat part on round router base

[Joe Scharle]

Anyone know why router bases are no longer a full circle? Personally, I prefer round. This came to me while making another round replacement base.
I know from use that there's more friction with the flat against a fence. And if the flat moves just slightly away from flush, the bit will swing greatly off track. But if a point on the round base is used as a reference, then less friction and the reference is more forgiving.

This jig is the main reason I like a round base. The 2 fences are squeezed against a sample of the piece that will fit into the resultant dado regardless of it's thickness. I like to run the router down & back without having to rotate the router, cord & vac hose. BTW, this pic shows the setup for a rabbet, but dado or sliding DT the is same.


http://www.ncwoodworker.net/pp/data/194/Rabbet1.JPG

[Roger Warford]

I believe one issue is that it's difficult to get the bit centered precisely in the base plate. Thus if you are keeping the plate against a straight edge, rotating the router will vary the distance of the bit to the edge, and keeping one point on a round base against the edge is hard. Personally, I don't think any of my work is that precise, so I probably wouldn't notice! :eek::rolleyes::) Maybe more knowledgeable Creekers will have a better explanation?

[Anthony Whitesell]

At first I thought the same thing, but I found out (first hand) that if you twist the base in the slightest with the flat against a guide, the bit moves almost exponentially away. Much worse than I could ever get my round base off center.

Centering a round base is a usually a matter of installing a guide busing and centering cone. This given that the center opening and open edge are concentric from the manufacturer.

[Myk Rian]

The flat is so you can run the router against a straight edge and get a true cut. Many times a router base may not be exactly centered. If the router is turned during the operation, the cut may not be straight.

[Chris Padilla]

As Anthony said, there are ways to exactly center a bit in a router. The Jasper circle cutting jigs come with a 1/4" drill rod stock that will perfectly center their jigs on a router. I also have the cone type that are like 1/2" on one side and 1/4" on the other side.

[Clifford Mescher]

At first I thought the same thing, but I found out (first hand) that if you twist the base in the slightest with the flat against a guide, the bit moves almost exponentially away. Much worse than I could ever get my round base off center.

Centering a round base is a usually a matter of installing a guide busing and centering cone. This given that the center opening and open edge are concentric from the manufacturer.
Exactly. It is easier to use the cone then to keep flat edge against work piece.Clifford.

[Chip Lindley]

If the truth be known, makers of newer routers probably realize a few cents savings in cast aluminum by trimming the edges off router bases. Its all about the bottom line to them. The flats may or may not be useful to guide a bit along a straightedge.

All my "old" Porter-Cables have round bases. I don't plan on any other iteration since they will probably outlast "me"!

[Danny Thompson]

Agreed, the flat side only causes problems when used as a guide.

My Hitachi came with two base plates: one round, the other with a flat side. I concluded the flat side is meant to keep the base from rotating when embedded in a router table. So, I use the round one for all my hand routing and the flat one is embedded in an mdf/formica table top. Works great!

[Larry Edgerton]

All my "old" Porter-Cables have round bases. I don't plan on any other iteration since they will probably outlast "me"!

Ditto. I tryed one once and screwed up a couple of things because of the flat, and gave it away.

I have over twenty Porter Cables, and am buying a few more, so I too am set for the rest of my life.

[Anthony Whitesell]

The plunge base on the Bosch 1617 has a flat on one side, whereas the fixed base does not. I once made the mistake of trying to make a mortise with the plunge base against a straight edge. It is very surprising how far the router bit moves with very little twist of the base.

I love my bosch and won't be giving it away any time soon. I just use a different jig for mortises now.

[Mike Henderson]

I don't know the answer, but you can always make a round base for your router. You could even trim it on your lathe to make sure it was exactly round. There's a plastics place close to me that sells scrap and that's what I use for special router bases.

Mike

[When cutting plastic on a lathe, use scrapers and keep the scraper pointing downward. You'll get a catch with a gouge or if your raise the scraper too much.]

[Chris Padilla]

You could even trim it on your lathe to make sure it was exactly round.

Lathe? What is that of which you speak? Lathe? :confused:

Is that there one of dem spinny contraption thingies???

;)

[Douglas Brummett]

Good anti-flat debate. I actually used that flat to my advantage when I was edge trimming a couple of weeks back. I rotated the base and held it for a light pass, then went back over with it flat for the next pass. It was kid of handy.

If you are set on round bases Pat Warner makes them
http://www.patwarner.com/round_subbase.html

[Joe Scharle]

And Pat makes some nice bases. However, I make my own and while doiing so I got to thinking, "What's that flat spot for?". Hence the original Q.

[Jim Becker]

Just use an alternate sub-base that is round. The flat area is likely for clearance so you can get closer to an obstruction or for clearance when using an edge guide if it's oriented in the "right" place.

[Jeffrey Makiel]

Interesting post.

During my last router purchase, a round base was a requirement for me.

I often wondered unto myself why some have flat spots, but dared to ask.:)

-Jeff :)