Cutting kerfs to curve wood - Woodworking Talk

dwwright · 01-14-2007, 10:00 PM

Hi,

I'm building an oval shaped table and am planning to put a skirt around the bottom side of the table top. I will be cutting out two matching oval plywood forms that the skirt willl attach to as well as provide support for the four legs. I've never built a curved table before, so I was planning to cut saw kerfs on the back side of the skirt material with about 3/16" between kerf cuts and leaving about 3/32" of the face material. Will the kerfs being this close be enough to leave a smooth curve to the finished skirt?

The table is a 36" X 24" oval with the skirt set in about 2 1/2" from the tops edge.

Big Dave · 01-14-2007, 10:07 PM

I don't think so. I've only done one curved project and what I did was to take the peice that I wanted to curve and rip it with a bandsaw into several thin strips. You then take the thin strips and glue them back together bending them around a jig with plenty of clamps holding it in place. If you only kerf the back it will snap at one of the kerfs. I would practice on a 3 or 4 foot peice of scrap to get the process down before trying it on the real thing.

Edit: Another problem with just kerfing it is the wood where it is not kerfed will remain rigid and put more stress on the kerfed portion. I hope this makes sense.

**TexasTimbers** · 01-14-2007, 11:49 PM

What are the dimensions of the table? The skirt? What is the skirt made of? How are you planning to "attach" the legs to the plywood forms"
Do you mean to layer a couple of plywood oval duplicates except smaller so that the skirt will have more gluing surface to which to clamp (you'll need a million very long clamps and then they will start disecting and getting in each others' way)?

It's doable probably but not feasable. I'd either use Dave's methid or steam bend it.

**joasis** · 01-15-2007, 07:24 AM

I would follow Dave's method....kerf cutting plywood, or anything to achieve a uniform curve is nearly impossible, simply because even in plywood, woof fiber thicknesses vary, and tension will change from one inch to the next.....resaw on a bandsaw or table saw, and laminate...If you draw the table skirt on a worktable top, you can cut out form blocks and screw them down...then build the skirt...carefully done, maybe using titebond 2 which has some time to work, you could build the entire skirt in one piece.

Neat idea....I personally like simple lines in furniture...mission style is my own preference...but now I'm thinking about how much of a challenege an oval table would be, and the wheels are turning.

By the way, WELCOME to the forum, we are glad to have you!

dwwright · 01-15-2007, 03:39 PM

Well thank you all for your input and the welcome. I've never done any resawing either, but willing to give it a try. I do plan on using the two smaller ovals to attach the skirt to as well as notch out for the legs to attach.

joasis, It does happen to be a mission style table. I've got several pieces that I've built on my website (gallery link below). My wife is decorating the basement and wants new tables. Had to do the oval due to the layout of the new chairs.

Thanks again,

troubleseeker · 01-27-2007, 10:51 PM

24" is pretty tight to bend a kerfed piece around. I think your best bet is a laminated skirt.

dwwright · 01-27-2007, 11:51 PM

I did a test piece today. Cut the kerfs about 3/16 apart and left about 5/64 of the surface, it actually conforms to the oval pretty nicely. I am thinking about mortising the ends into the legs slightly to help hold them in place.

I do appreciate the feed back, so thank you for the advice.

dwwright · 03-19-2007, 10:25 PM

I finally got around to trying this, I've got a 80 year old table that was my grandmothers I found was done in the same manor. With the two ovals it seems to have plenty of glue surface and plenty of glue went into the knotches to help it stay put. I decided to leave them a little long and scribe them to the legs rather than mortising them.

conscious · 05-02-2007, 11:38 PM

granted, the wood fibers are not created equal in plywood, but they vary in "real" wood too. took a master class at a woodshow and you basically want to make it wider than you need it to end up at, and if you bend and glue it up in a form you want to make sure you have some really strong and perfectly 90 degree metal (preferably) braces to form your curve. build it tighter than you need by a little because it will spring when you release it. don't forget to put waxed paper down on places where glue might stick to things you don't want it to. (table, clamps, etc)

i've had some decent luck with kerfing, but you have to keep the kerfs consistent. this way you also have the ability to rip it to your width, at least it doesn't seem to get out of hand until you build up three layers. again, that is what happened to me, others have no doubt had other varieties of fun.

as far as i can tell, i prefer the glued up resawn strips, but you do need to rip it - which can be interesting on a table saw and jointer to get the real world to cooperate with the theories, and do so safely. the kerfed wood is quite a bit easier and if it is going hard, think about two layers of 1/4 or 3/8 rather than going with 1/2 or 3/4.