Replies

1. 
   RalphBarker | Mar 21, 2009 08:25pm | #1

   I'd suggest making something like an octagon with segments wide enough to include the inner and outer radii, rough cut the outer circle on a bandsaw, and then finish with a router in a circle jig.

2. 
   hammer1 | Mar 21, 2009 09:02pm | #2

   Yes, you could cut it with many methods, bandsaw, jig saw, router, coping saw, etc. You can cut the segments individually before attaching them to each other,afterwards or after partial assembly. I would recommend watching the number of segments you use. Although a wide board will allow you to cut more of the circle from a single piece, it also will result in short grain at the ends. These often split and break in the future. Increasing the number of segments will keep longer grain and you will be able to use pieces that are less wide. I wouldn't use 4 segments on a 14" circle, more like 8.

   Circular work can be challenging. When shaping the profile edges of the circle, you have to deal with grain that reverses on each segment. It's frustrating to do all the first phase of the work only to have a big chunk blow out on the next phase. Certain species may be a bit more prone to this happening. A sequence of very light cuts can help but there are times when you may need to climb cut. This requires a special technique for safety and good results.

   Beat it to fit / Paint it to match

1. 
   rshelly | Mar 21, 2009 11:36pm | #4

   The bezel on the antique version of the clock I'm making has 4 segments.....but you have a good point about making it in 8.

   Seems like the bandsaw wouldn't really be an option because I have to cut an inner and outer circle. I haven't used a router jig, but that seems like the easiest. My concern would be how to establish and maintain the center point. Would you double stick tape the piece to MDF, and then establish the pivot point?

    

   Thanks.

1. 
   hammer1 | Mar 22, 2009 05:34am | #5

   I have a vision of an old Seth Thomas regulator in my mind. Wood hoop with a convex glass over the numeral face. The hoop is shaped on the face, basically rounded over. Am I in the ballpark?For a one off, the easiest way to cut the hoop would be with a jig saw or a handsaw such as a coping saw or frame saw. The cuts will need some cleaning up but some of the better jig saw blades leave a fair edge. It just takes a little patience and some added elbow grease.I don't know what you have for tools. Based on work I have done in the past, a router and jig would not be my choice. I prefer the bandsaw and a modified circle cutting jig. Even if you use a circular jig with a router, you will still have to cut the template accurately and you may need a variety of sizes depending on what you want to do to on the profile. I think accurate templates would be easiest done on the bandsaw. If I had an overarm pin router, that would be different.I have a couple of pictures from some arched window casings I did. I would likely do the same process on a 14" clock hoop, same thing, just smaller. I draw out the circle full size on a sheet of something. Divide the circle into segments, factors of 360 degrees. For eight segments, the angles are 22.5. Once my segments are cut I use a circle cutting jig with a carriage attached with a bolt rather than a pin point. This pivot point needs to be perfectly in line with the leading edge of the blades teeth. The carriage allows me to clamp the segments, cut the outside first. Mark all the centers of the segments for alignment on the jig, cut the inside last. This type of jig is very accurate. You can tune in the radius just by measuring from the blade to the center of the pivot point. You need to determine how you will attach the segments to each other. Sometimes a double layer is used, offsetting the joints. Biscuits, splines, T&G or dowels can also be used on a single layer. Some of these might be easier to cut on the segments before going to the bandsaw. I had several of these to do and cut my layout board to act as a clamping form. These were not perfect half circles, the bottom straightened out for a couple of inches before meeting the side casings. That's why the lower segments are a little wider in the pics. For a complete circles, I'd probably do half at a time.One problem with a router and template is holding everything through multiple, incremental cuts. You won't be able to cut through 3/4" hardwood with one pass. I don't think I would trust double sided tape and clamps would be in the way. That leaves screws. Depending on how you want to profile the hoop, a router and circular templates used with a template guide may be the way to go. You will know the center point if you cut the templates with a bandsaw circle cutter, less the carriage. Beat it to fit / Paint it to match

   
1. 
   rshelly | Mar 22, 2009 04:09pm | #7

   You are right....very similar to the Seth Thomas you described. Thanks for the input. Your method would be very effective if I made it in two peices then assembled.

   Thanks.

3. 
   eddiefromaustralia | Mar 21, 2009 10:38pm | #3

   Hi Randy,

   If you've got one, a spokeshave would do it.

   Just take a little while.

   Cheers,

   eddie

4. 
   knuts | Mar 22, 2009 03:33pm | #6

   hammer1 brings out a very good point about screwing the work to the circle cutting platform. I made some pic frames by segmenting stock in an octgon. (22.5 deg ends). Double stick tape didn't hold my work to the MDF, so I located screw holes up thru the bottom and routed away. Router and circle jig make quick work of circles. BTW, do any profiles before cutting the segments.

1. 
   rshelly | Mar 22, 2009 04:11pm | #8

   Thanks for the reply. Not sure what you mean by making the profiles before cutting the segments....could you explain this one further?

   Thanks.

1. 
   knuts | Mar 22, 2009 05:40pm | #9

   Any shape on the face other than flat. My frames had a slight ogee curve made with a panel raising bit. Close examination revealed the octagon outline, but no one else saw it in the round finished frame. Although, it was as obvious to me as tree in a desert.

5. 
   YesMaam27577 | Mar 22, 2009 11:50pm | #10

   A couple of years ago, I made a pair of collection plates for my church. I made them from walnut, but many other woods could be used with this method.

   My design included a flat bottom that was about 3/8" thick; two "rings" that stacked to make the sides; and a fairly large flat ring to be the "grip-edge".

   And I don't own a lathe.

   I did each layer by gluing up boards to build up sufficient width -- no bisquits or splines, just well fit edges and glue. Then, for each layer (except the bottom), I drilled a hole near the center of the panel.

   I screwed through the panel, into the top of my router table, positioning each piece carefully so it would eventually fit with the others. I then turned the router on, and carefully raised the bit till it was cutting about 3/16" deep. I spun the panel on it's screw/axle till the underside had been cut all they way around.

   Then raise the bit and repeat, till the router had cut all they way through the panel.

   Bingo -- a perfect circle.

   Move the screw and start over, this time cutting the inside edge of the ring. Be very careful when making that last cut on this stage. The captive plate (held by the screw) is actually the waste -- its the ring that you want, and if it moves wrong when you finalize the cut, well............

   Also be aware that at two points in each cut, you will be routing end grain, and that at (probably) two points, you will be routing against the grain. Be careful.

   Politics is the antithesis of problem solving.