Replies

1. 
   Scrit | Nov 18, 2005 09:32am | #1

   Why not rip your own solid wood lipping? Plane timber one side then rip on either bandsaw or table saw to get the required thickness (say 2 to 3mm = 1/12 to 1/8in which should bend easily enough - although some timbers require steaming to make them flexible enough). Chamfer the ends then bend and glue onto your piece - you'll need edging cramps to do this (which can be simple guitar-makers cramps : two turned blocks of timber, through drilled and held together with a nut and bolt - wedge behind the thread to hold the edging). If you haven't a compass plane to take a smoothing pass then a router/trammel should do the job. Way easier than trying to chamfer/cooper/router before applying. If more thickness is required more layers can be glued on then profiled.

   Scrit

2. 
   ring | Nov 18, 2005 09:54am | #2

   Any number of possibilities:

   1.  Maybe there's a production shop in your area who can do the edgebanding for you.  If so, it would definitely be the cheapest and quickest way.

   2.  Make your own banding.  Oak strip about 1/8" thick will take that 8' diameter bend with no problem.  Use straight-grained material with no defects.  If you don't have enough clamps, a lot of tape will work just fine.

   3.  Your own suggestion of glueing on solid edging and then cutting the curve.  I wouldn't rack my brains over the math of it.  Decide how many sections you want and draw them on the piece itself.  Make each solid edging to match its place.  It doesn't matter if they're not perfectly identical.  You're not doing 1000 of 'em.  This option will change the esthetics of the piece, so think carefully about how many sections if at all.

   good luck,

   DR

1. 
   Scrit | Nov 18, 2005 07:28pm | #3

   1.  Maybe there's a production shop in your area who can do the edgebanding for you.  If so, it would definitely be the cheapest and quickest way.

   But make sure you ask for solid wood banding (not the thin self-adhesive iron-on/hot-air type) and that they have a glue pot profile edgebander. Straight line machines (as beloved of kitchen cab shops) simply can't do the job and a lot more common. A good shop will either have an oak lipping in stock (although commercial lippings are finger-jointed every 8ft or so - ask them to show you what I mean) or they should be able to cope with home-ripped stuff up to about 1/8in thick - abovre that you'll have to ask

    

   Scrit

3. 
   douglas2cats | Nov 19, 2005 07:03pm | #4

   Like others have mentioned, resawing some thin edge banding that you can bend around the table would work well.

   But if you're really after a thicker solid wood rim, you really dont need a calculator to figure out the miter angles. There are formulas available. I have them somewhere and tried using them on laying out a half-moon table, but in the end they weren't that much help. You need to fit the rim to the table, not the math anyway. The critical factor in getting the rim to fit snugly will be setting the trammel arm to the right inner and outer radii after the rim segments are glued up. As long as you use enough segments and wide enough segments to compensate for any slight errors in dividing your arc into exact angle portions you shouldn't have any problem.

   Take a scrap piece of plywood that can double as both your layout board and a jig to screw (from underneath) the glued up segments to when you cut the arc out of it. First decide how wide you want your finished rim to be. Use your trammel arm and a pencil to draw your inner (the same radius as your outer plywood radius) and outer rim radii on the layout board.  The wider the uncut segments are, the fewer segment pieces will be required. Decide on an initial raw segment width and lay a piece of scrap that width (or even paper/cardboard) on your layout board centered on the radii lines. Just by eyeballing, you'll very quickly see whether you need to make adjustments in the width, and roughly how many pieces and how long are required to fit the rim. Allow yourself room for error. 1-1.5" or so on either side of the radii lines should be enough. Once you've got this tuned in, divide the angle sweep your table makes by the number of pieces you came up with and you have your miter angles. If your table is a true semi-circle, you'll have 180 deg. divided by the nbr of pieces. If you've got just a partial arc of the circle, you'll have to figure out your total angle and divide. With a straight edge and protractor draw the angle lines on the layout board from your pivot point through radii lines. You can now transfer all those layout lines onto your stock to get the segment lengths. While you're at it, decide how you're going to join the segments. Biscuits? Hidden splines? Draw those in on the layout board to make sure they wont show when you cut out the rim, and transfer those marks onto your segment stock too.

   After they're glued up, lay the assembly back on the layout board and run some screws up through the bottom into your segments to hold everything in place for cutting. Also make sure your trammel arm pivot is resting on a piece of stock the same thickness as your segments or you'll cut a bevel that you dont want. Also dont forget to account for the router bit diameter when setting the trammel arm to cut the inner rim radius - it's not the same setting as the outer plywood radius.

   I pretty much used this scheme putting the segment frame for this half moon table together.
   http://forums.taunton.com/fw-knots/messages?msg=23074.4

    

   Waddaya mean it wont fit through the door?

4. 
   mudman | Nov 20, 2005 02:36am | #5

   My preference would be a lamination. 4 or 5 plies of oak planed to 1/8" or so. You can use contact adhesive and avoid the clamping issues, but I would use yellow glue and heavy strap clamps.

   Mike

1. 
   Scrit | Nov 29, 2005 08:50pm | #6

   The biggest problem with contact adhesive on a curved edge like this is creep - in due course the edge will probably move - a lot! Leave contact adhesive for bonding Formica onto worktops. If the laminae are thin you don't need zillions of metal cramps at all - masking tape will do the job, although you will need a LOT of it and you'll have to do the laminae one at a time (i.e. glue/tape one, let dry, remove tape, repeat)

   Scrit