Replies

1. 
   WillGeorge | Jan 04, 2010 07:41pm | #1

   Just what I do.
   My circle jig
   Just what I do.

   My circle jig is nothing more than a long supported board attached to my bandsaw. The center point is a small hunk of drill rod. A finishing nail will do and it does not have to stick out very far. I drill a small hole in the board to be cut. I use a center pin that sticks up about 1/4 inch. If you are careful, I think a short pin is safe to use and the tiny hole you drill into your work is very easy to repair. If repair is a issue, you can use a small carving tool to cut out a sliver of wood to be glued back when finished.

2. 
   KiddervilleAcres | Jan 04, 2010 07:44pm | #2

   Hi Frosty,
   Sorry but I'm a
   Hi Frosty,

   Sorry but I'm a little confused. What tool are you using to cut the circle? I'm envisioning a glued up panel that I want to make a round top with. If it has any significant size to it I'd prolly use the bandsaw, as Will suggested.

   How big of a circle are you trying to cut? If you mark lines on a glued up panel connecting each corner, where they cross would be the center, eh? Why the need to be so accurate as panels are usually made with some extra?

   Regards,

1. 
   Jfrostjr | Jan 05, 2010 09:21am | #3

   Morning Bob - I hope you are enjoying winter.

   Yes, I am referring to a bandsaw. In certain cases I find that I want to precisely locate the center of a circle or arc. I bend and squint at the pin, or nail or whatever from the edge of a large glue-up and can't locate the spot I want to 'press it home' to commence cutting.

1. 
   RalphBarker | Jan 05, 2010 12:29pm | #4

   If you temporarily attach a shiny washer to the underside of the piece being "encirculated" (easy to see on-edge with a flashlight), milling a corresponding depression in the jig would compensate for the offset/wobble issue.

   Note that I haven't made my (pretty, oh so pretty) circle-cutting jig yet. I'm still hung up on designing the micro-adjuster that would reposition the jig's center precisely in relation to the cutting edge of the bandsaw's blade For the center pin, however, I was thinking of using 3/16" or 1/4" brass rod (nice bearing surface), which would necessitate a hole in the work piece large enough to fill with a plug cutter.

1. 
   Jfrostjr | Jan 05, 2010 12:56pm | #5

   Ralph,

   Do you have the Taunton book on Jigs and Fixtures? If so, I copied one design from that book but made a really slick (notice my humility?) improvement on the design.

   Let me know if you have the book and I will send you my modification only, otherwise I'll send the entire design for your consideration.

   Jerry

1. 
   RalphBarker | Jan 05, 2010 01:12pm | #6

   Thanks, Jerry. I thought I had the book, but can't find it. My e-mail is rbarker8x10 at netscape.com.

2. 
   KiddervilleAcres | Jan 05, 2010 07:02pm | #8

   Frosty,
   Here's how I would
   Frosty,

   Here's how I would cut a 2' (24 inch diameter circle). I'd make a square panel that is 24 1/8" square and draw diagonal lines connecting each corner (becomes the center point on the panel), and drill a hole that will accept the pin. Set the panel on the bandsaw jig with one edge aligned with the inside cutting edge of the blade and from there align the hole in the panel with the hole in the jig and push the pin through both holes.

   After cutting on the bandsaw set up a router quided bit to remove 1/8" and run it around the circle.

   Regards,

3. 
   joinerswork | Jan 05, 2010 06:54pm | #7

   Frosty,

   Why are you so intent on finding the exact center of the panel? Easier to make an oversize panel, and just get "close enough for jazz" in locating your jig- letthe jig determine the "exact" center, rather than exactly centering the jig.

   If something like a veneered top in a sunburst pattern, even still, being within 1/8" of "right on" would not be visible on a 12" or larger top-- any borders, bandings, etc around the edge are best worked afterwards- using the edge as a reference, rather than the center.

   Ray

4. 
   hammer1 | Jan 05, 2010 10:13pm | #9

   If you start with a square blank, simply putting a mark on the edge in the center indicates the tip of the blade in relation to the pin. With the saw off, place the workpiece so it's touching the blade. Your center hole will be lined up with the pivot pin in one direction. I don't have much trouble finding the hole with this one reference but a mark on the saw table or jig could indicate the center in the other direction.

   The key to cutting a perfect circle is a sharp blade and having the pivot pin in line with the tip of the blade teeth. If the blank is tight to the blade, it should start cutting in immediately. You should finish right where you started.

   I have a wedding cake baker as a customer. He has me cut up a few sheets of plywood into various size circles to support the heavy cakes. Starting with a square blank makes it easy to find the center hole. I'd post a pic of my circle jig but I haven't figured out how to do it in a reply. In most cases, simple is better

1. 
   Jfrostjr | Jan 06, 2010 10:10am | #10

   Ok you guys. I give up. I guess I was trying to be too precise.

   Add the details AFTER I've got the circle.

   Thanks for the comments.

5. 
   Don01 | Jan 06, 2010 11:30am | #11

   Frosty,

   Is it possible to replace the center point with one that is threaded? You would screw it up, set the work on then screw it down to table height, secure with a lock nut. You would need to modify the jig track to accommodate the extended center point.

   or

   Make a new jig top. Replace the center point track with a series of holes. Fasten something like a flanged post to the work and drop it into the best hole. I have been looking for something like the pivot post that is part of the Lee Valley Veritas Router Circle Cutting Center - Item 05J36.07. A prongless t nut might work but not much area for adhering.

   Not perfect, but its wood.

   Don