What would be the best way to cut a solid piece of wood into a perfect circle with a 20 inch diameter?

Question

What would be the easiest, fastest and most accurate way to cut a 1 inch thick piece of wood into a perfect circle with a 20 inch diameter?

Answer 1

If you really want a perfect circle and a clean cut, you'll probably need to use a router with a narrow cutter, and make up (or buy) a trammel.

The trammel can be just a piece of wood, a bit more than 20" long that's bolted to the router baseplate at one end, and has a bolt at the other. A bolt of about 5mm diameter would be about right.

Drill a 5mm hole at the centre of where you want the 20 inch hole to be. Bolt the free end of the trammel through this hole - but not so tightly that it won't swing. Your router will now swing around the centre hole in a perfect circle. You may need to adjst where along the trammel's length the router sites to get the cutter exactly 20" from the centre point.

When it's all set up right, start your router and cut the hole. If your wood's thicker than a few millimetres, you'll probably need to cut a shallow groove first, then deepen it on a second pass, and repeat until you've cut all the way through.

You can buy adjustable trammels to fit your router if you don't want to make your own.

You can see some pics and description of a simple home-made trammel in use here: http://www.woodworkingtips.com/etips/etip030201wb.html

Answer 2

perfect circle? I don't know that it can be done perfectly, can anything?

You have several options, depending on the thickness of the board and the tools available . if it's thin, a Roto-zip with a string or board fixes so that it rotates from the center of the board with a ten inch diameter will work.

For thicker wood, you will probably need a bandsaw. Make a jig so that the wood rotates on center exactly ten inches from the blade, go slow, eventually you'll have the circle. It may help to rough cut it in so only a little around the edges remains to be trimmed. Also you might leave a smidgen extra, say a quarter of an inch or so, so when you take it to a belt or disc sander you can leave it in the jig, but sand the edges smooth.

A board attached to a jig saw may work, but will be very difficult to get the perfection you seek. At any rate, some tool revolving around the center by some means will be the way to go.

Answer 3

Some good suggestions here, but I will add just one more for your own value. Take a piece of string, tie it to a small nail. Drive the nail (lightly) into the center of where you want your wheel hub. Ten inches out from that center, tie it or wrap it around a carpenter's pencil (or regular pencil) and draw your circle, holding the pencil perpendicular to the wood. Use your sabre saw to cut the wood and a belt and/or finish sander to finish the outside edges. I make yard furniture and have used this method for some time now. No system is right or wrong, but I find this one to be very simple. If you need a larger or small wheel, simply adjust the string to half the size of the circle you want. Good luck and have fun.

Answer 4

I would attach a small block of wood to the middle of the piece you are cutting on the back side so there are no marks when you are done.

Find a point that you can rotate on and set your radius for 10" and fix your saw. You can use a number of saws but I would use a router with a cutting bit.

Once your center is established and your saw is secure, simply rotate your wood around the axis until you have a perfect 20" round board. Remove your center block and you are done.

Answer 5

1 inch might be a bit much for a Roto Zip?

I assume you've figured out even a primitive method to create the cut line; either with a nail; string; and pencil; OR even a wooden yard stick that you've tacked to a center point; then spun with the pencil; creating the cut line.

I'd use a scroll saw and make the cut; then a belt sander to refine the cut. As one answer stated "Perfect" might be relative.

Steven Wolf

There are templates for circle cutting with a table saw, but I don't advise that for a DIY.

Answer 6

the simplest way would be a jigsaw (good clean blade and steady hand) backed up with sanding block or sander. put a little time and effort and you may be very pleased with the result. Router and trammel as above is good (more technical) but you'll still probably want to sand the edges anyway. An industrial laser is probably the 'best' way. . jigsaw

Answer 7

d. 21 There is 20 pieces of wood 3 3/4" long and one additional piece of watse of about 1/2" long, if using a blade 1/8" wide, 2.5" are lost in kerf.

Answer 8

With out a doubt, a router is your best bet. I made my own circle jig, but they are available at most wood working stores.

Answer 9

You can use a table saw. It's probably the fastest method. See this example: http://www.toolsnob.com/archives/2007/06/howto_cut_a_circle_on_a_table.php

Answer 10

use a tool called a roto zip. It is like a compass with a saw on it.