I am building a 48 inch round pedestal extension table. I am trying to figure out the best way to mill the top. My first thought was to use a router on a circle cutting arm to cut the top as one piece and then cut it in half. The problem with that is that I would be taking an 1/8 inch piece out of the middle with the table saw blade. Besides that, I am not sure how to guide a round piece that large through the blade. My next thought was to cut the two halves seperately; perhaps rough cutting them on the bandsaw and then using a template and router to trim the radius to final size and finish (the second half would be done by flipping the template over). This also has the advantage of not having to glue up such a large panel.
Am I missing something? Is there a better way to do this?
Replies
Glue up each half seperately then cut roughly to size and shape. Joint the adjoining edges....butt them together and clamp them to keep them there. You can use bar clamps or clamp them to a sheet of 3/4" inch plywood. Then use the router with a circle guide. You'll have to move the holding clamps around to complete the cut.
I think doing each half separately sounds like a good plan. It will allow you to get a good fit for the center joint and the two halves will be easier to work and move about.
You could make a template using the router and trammel and then scribe each piece, cut out with a bandsaw or jigsaw and then use the template to route the final shape. The only down side is that the router will be cutting against the grain for half of each cut. Therefore it may be wise to purchace a spiral template bit for your router in order to minimize the potential for tearout.
Or you could saw very close to the line and use a spokeshave to finish the shape. No need to make a template and it would probably be faster since you are only building one table. Also no need to worry about tearout or mucking up the piece with the router.
Are you planning any special profile for the edge?
J.P.
J.P.
I'm going to strongly suggest you mock this up full size with something cheap like 1/4" MDF. The reason is that it's very difficult to split a round table and insert leaves that generally have straight edges. I have done round extension tables and it's much easier if there is a flat or straight line where the two halves separate even if that flat is only an inch or two long. You see, a perfect circle split in half has quite sharp corners, not ninety degrees, and this makes the insertion of leaves difficult and corners very sharp.
Mock it up, you'll be glad you did.
edit; Don't worry about the table being perfectly round, getting it close is adequate. Sawing to a line and smoothing with your choice of tools whether it's a belt sander or a plane is just fine.
Lee
Edited 4/12/2006 7:24 pm ET by LeeGrindinger
Bear,
As has been suggested, making the top in two pieces is the easiest way to go. Saw just outside the circle with bandsaw or sabersaw, then clean up to the line with compass plane or spokeshave. You can even use a blockplane or smoothing plane to clean the edge up. No need to try for a perfect circle, in 6 months it will have swollen with summer humidity into an ellipse anyhow. Just get rid of the dips and bumps, till it feels fair when you run your hand around the edge.
Regards,
Ray Pine
Assemble the entire table, extension mechanism and all, leaving the table edge unfinished. Have alignment pins & holes in semicircular halves & leaves engaged for alignment. Lock the halves together. Using carpet tape (double sided, very tacky, woodturners use it), bond thin wood or plywood at center of top. Locate center point of table top. (You don't have to do this, but I would: mark & cut semicircular halves slightly oversize on bandsaw or with sabre saw.) Finish cutting table edge with router & circle guide which is pinned to piece of wood held by carpet tape. Install leaves & figure out some way to cut them to match semicircles.
Cutting the circle without having alignment pins engaged is a very risky thing to do! Also, if your circle guide is too short or the least bit flimsy, make your own. I recently did a similar project. I made my own guide from 1/2" MDF which I attached as if it were a baseplate.
Cadiddlehopper
I agree with the idea of using a router once all the jointery is out of the way. I successfully made a 6' diameter table top in oak, that had 2 rule-jointed edges. Hrere's a picture of me at the router.
As mentioned by others, I afixed the central pivot point to the top surface of the table with 2-sided tape. It worked like a charm.
Marty S.
Edited 4/13/2006 2:37 am ET by Sawdust Eater
Thanks for all the good ideas. The carpet tape idea solves a problem I had not even considered yet. I think fully preping the two rough cut top halves and leaves before the final shaping sounds like a good idea. I am realizing how important it will be to get the alignment pins placed accurately. Both centering in the boards and alignment from pin to pin is important.
Any suggestions on getting good alignment of the pins and sockets? I do not have a doweling jig and never thought I would need one. The good ones seem a little pricey (for a seldom used tool). Drill bushings are inexpensive; maybe I can make a custom jig for this operation.
I see that there seems to be two types of pins/sockets - old fashion wooden pins and steel/brass pins and sockets. Any preferences?
Also one responder suggested using a spiral template bit. I have never seen one. Who sells them? and if anyone has used one, does it really do a better job?
Bearcat,Instead of using pins use small floating tenons about 1.5" wide and .25" thick. You can cut the mortices with a router and insert the tenons then pare or plane down to fit. You will need to chamfer the ends of the tenon and then shape it with a slight slope or angle in order to allow it to fit into the mortice easily. Only about an 1/8" to 3/16" will be the actual size of the corresponding mortice.I have seen this method used on many period tables and it works extremely well. You have the ability to fit the tenon just so, so that everything will come together nicely. Plus if you take too much off you can always glue a little on the cheek and start over.J.P.http://www.jpkfinefurniture.com
The simplest way to drill the pins is on your drill press (assuming you have one).Make a jig of plywood / MDF that attaches to the top of the drill press table with a vertical face, (suitably braced with gussets), that hangs down one side.Swing the drill press table from side to side to set the edge distance of the holes and lock it in place when satisfied.Clamp / screw a board horizontally on the vertical face to hold the table top / leaves while you slide them side to side to the location marks to drill. (Clamp at each location if you feel it necessary.)[With a vertical fence also attached, the jig is also usable for doweling the ends of stretchers, skirts, etc.]You should clamp all the boards for the top together to mark them. Use a long straight edge down the length of the top and mark a pencil line across each joint. If you mark and drill it right the leaves will be interchangeable. It should be obvious that all the pins need to point in the same direction across the table.A final bit of advice is to sand the entire top with all the leaves together to get them all flat.
You might also use a plunge router to make pin holes. A piece of tooling is needed to locate the holes from the edges as well as stop blocks to space the holes the same in opposing faces. Tooling design will depend on your method of making holes/slots. The alignment pins need not be spaced perfectly, but the pairs must align with each other. This suggestion would apply even if you use slots & tenons as another writer suggests. The tabletop halves must ultimately br held in alignment laterally as well as vertically. LOL!Cadiddlehopper
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