I have plans that call for 8", 9", and 10" dia. circles made from 3/4"
stock. These will also need a routed edge all around each. The plans say use
a plunge-router, but I only have a cheap regular router. I tried cutting the
circles using my scroll saw, then routed the edges, and it was OK, but not
perfect by any means. How can I make perfect circles? Are there router bits
for my regular router that will go through material? And how do I make the
circle perfectly round?
Use a "trammel" made from 1/4" sheet goods. There is a picture of one at:
You may have to drill a hole in your workpiece it you don't have a plunge
router, or start with the router on the edge of the workpiece, but that is
no trick. Use a straight cut bit in your router.
Do you have a bandsaw? If so, you can make a circle cutting fixture and
then do the routing after it is cut. You just push the wood on the fixture
to the outer edge and rotate it on a pin to complete the cut. Rockler has a
kit to make the fixture.
Do a search for circle cutting jigs for the table saw, believe it or
not. For circles the size you want, "perfectly" round ones can be cut
on the tablesaw. If you need a routed edge afterwards use a piloted
Yeah, I thought it sounded kind of nutty too, til I actually tried it.
I've seen 2 versions, one that is fixed on the saw table & the blade
is gradually raised to increase depth of cut, the other that has a
slot runner and is gradually advanced into the blade to achieve the
same effect. I already had a few small sleds with single runners so I
just used one of those.
Before cutting the circle you need to cut a square blank, then
cut the corners off to make an octagon. On a really big circle you
could cut the corners again, I suppose, to make a 16 sided polygon
before starting to cut the circle. The blank pivots on a pin or screw
through the center. With the sliding type of jig, you move the blank
so the blade just touches it, maybe cutting into it about 1/8 - 1/4
inch at the bottom, rotate the blank to cut all the way around,
then push it forward a tiny bit more, repeating the process til the
circle is cut all the way through.
With the fixed type of jig, which is clamped to the saw table,
you start with the blade low and raise it very slightly after each
full rotation, similar to cutting a cove.
This safely makes about as perfect a circle as you can make out
of wood, with a very clean edge. :wq
On Fri, 05 Dec 2003 16:13:34 GMT, "Mike in Mystic"
Why? The actual cut happens at the front of the blade.
All you have to do is have the work rotate around a fixed bolt or
shaft, as it passes the blade, it'll get cut. One full rotation will
provide a circle.
In my haste to post I left out a few steps. <G>
First the 4 corners are cut off, then the 8 corners that are
remaining. The idea is to get to the point where the offcuts are
small and flexible.
The early cuts are made with the work FIXED, and only rotated when
away from the blade. Once the rough circle is formed, the work can be
smoothly rotated against the blade.
This technique is illustrated in several books, one of which is Roger
Cliffe's "Table Saw Techniques". I've used it twice with great
A faster way to do it is to rough cut the circle with a coping saw or
jig saw, and then do the final, perfect circle cut on the table saw.
You just need some imagination. No lathe? No problem!
Mount the wood on the shaft of a grinder motor. At 3450 RPM you get a very
With your thought process, I could make 6' round table tops using my
buddy's Piper PA-28 to turn the stock! All I have to do is talk him
into taking off the prop. It's not like he can fly with all this
snow. 180 HP would be plenty to keep the work moving at a steady
I was thumbing through a book on jigs (sorry, I can't recall the full
title) and there on page 34 is a picture of a jig for making circles on
a TS! a pin on a sled to spin the workpiece...
Mike in Mystic wrote:
I made a circle cutting jig for my router. Simply attach a piece of long thin
stock to the base and drive a small nail at the desired radius (through your
jig and into the workpiece). It took me a couple tries on scrap to get it
calibrated but once I had one measured radius I was good to go. I started
roughing the circles with a straight bit, then switched to a roundover or ogee
to finish it. The only down side is the small hole in the center of your
BTW they sell some real cool tape at ULINE.COM
It is marked off in inches so when you make something like this you can put
tape on it to reindex to another size.
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