Theres something special about a small table with a round top-it invites intimacy. When I sit at one, I stop and savor warm memories of lingering with my wife in a quiet caf or bistro years ago.
It can be difficult to make a round top, but it is possible. Well, it could be easy if you just made the whole thing from solid wood sawed into a circle, but I dont think a top like that has a pleasing look. A linear grain pattern usually fights with its shape.
A round top can also be made by ironing thin bands around a piece plywood. However, sooner or later, the banding will crack or delaminate and ruin everything.
The round top I am referring to has a plywood core and a wide segmented rim made of solid wood around it. An edge like this can be rounded over to be elbow-friendly and is durable enough to take years of use and abuse.
A router jig is perfect for making the rim fit snugly. Ive designed one that makes both the plywood center and the rim with a high degree of precision. Let’s take a quick glance at the functions of the jig before we get into the details about how it is built and used.
This article will show you how to make a top of this size. The center of the top is birch plywood, while the rim is solid cherry. Youll make both parts using just one router table jig.
Guide For Quick Start
Step 1. Cut the wood for the rim segments so the pieces make a perfect octagon.
Step 2. (Fig. 05.) Rout circular arcs on the inside edge of each segment. The jig has two major parts; this step uses both of them.
Step 3. Clamp all of the pieces end to end, forming a straight-sided doughnut with a big hole in the center.
Step 4. (Fig. 06.) Make a plywood center that fits perfectly inside the doughnut. Here, you only use the lower section of the jig.
Step 5. Glue the rim segments around the plywood, using spline to keep them aligned.
Step 6. Make a cut at the top’s outside edge, and then level it. Rout a profile around it.
Fig. 01. Exploded View
Fig. 02. Plan View of Pivoting Jig
Fig. 03. Pivot Block
Fig. 04. Cross Section of Stationary Jig
The Cut List
Build The Jigs
These jigs can be used to make tabletops ranging in size from 71 cm up to 122 cm. These jigs are easy to construct and can be modified to make tables with smaller or larger diameters. The fixed jig fits a router table with a top thats less than 210 cm deep.
Build the fixed jig first, starting by shaping tongues on both inside edges of the platforms (A). You will need to make the three cleats B, C, and D. However, you won’t be drilling holes for the adjusting rod F yet. Make the pivot block (E) as shown in Fig. 03) from a piece thats at least 15 cm long, for safety. The grooves should be cut along the length of the piece. Next, make one end into an L shape. Finally, cut the pivot block to the final length. For the adjustment nut (G), drill a hole in the pivot block. Next drill holes for the washers (H), and the adjusting rod (G). Make sure the holes are aligned with the pivot block’s center (Fig. 04).
Fix the cleats to platforms so that the pivot block moves freely. Mount an adjusting bolt onto the front end the adjusting rod with epoxy or Loctite. Install the adjusting rod by tightening the locking nut (J), so that the pivot block has no play from the front to the back.
The arc-shaped window in the pivoting jigs base (K, Fig. 02) need not be precise-you can cut it with a jigsaw and leave the edges rough. Fasten the pivoting jigs fence (L) so its even with the base. Youll add the stop (M) later; its location will depend on the exact size of the rim pieces you make. Position the pivot plate (N) so that the distance from its hole to the fence equals the radius of the top youre making (including the rim pieces.) Draw a line from the fence to where the pivot plate is located using a framing piece. Then, extend that line up and across the fence.
Start With The Rim
Let me show you how I used the jigs to make a top with an 8-sided rim thats 91 cm in diameter. I first drew the top on a piece plywood. I then realized that the rim would need to be 5cm wide. I needed blanks 2-7-20cm wide and 43cm long from the outside point. (Although the center of the top will be made from 3/10 cm plywood, I made the rim pieces 1-1/10 cm thick to make the whole top appear thicker.) Here’s how you start: a target diameter, drawing and the exact size of the rim blanks.
Photo 1. Make the rim segments first. This table will have 8, forming an octagon, so their ends must be cut at precisely 67-1/2.
The next step is to cut the blanks accurately enough to form an octagon whose miters are perfectly tight (Photo 1 and How to Make a Perfect Octagon, at end). Make a few extra blanks in order to test your setups later on. Make a stopblock (M) with one side cut at the same angle to the blanks. Mark a center line across one of your blanks and clamp the piece to the pivoting jig Photo 2. Attach the stop to your jig.
Photo 2. Line up the center of one segment with the centerline of the jig. Butt a stop against the segment and attach the stop to the jig.
Photo 3. Draw an arc using a trammel. The arc represents the inner, curved edge of the rim. Place the center of the trammel in a hole drilled through a metal plate attached to the jig.
Mark the rims within the radius of one blank ( Foto 3), and then use a bandsaw to remove any waste ( Photos 4). This piece can be used as a template to mark the blanks and then saw them.
Photo 4. Saw the inner edges of all the segments. This is a rough cut. Keep at least 1/20 cm within the pencil line.
Photo 5. Clamp the lower half of the jig to your router table. Set the distance between a pin in the jigs pivot block and the inside edge of the router bit equal to the trammel setting.
Install a Photo 5). Adjust the position of a jigs pivotblock so that its distance from the pin to the router bit’s outside edge equals the radius of the rim. Place one of the test pieces into the pivoting Jig. Then, rout the inside edge ( Photo 6). To make a clean cut, you will need to do two passes. When clamping a new piece into the jig, turn off the router between passes.
Photo 6. Photo 6. Be careful not to push the jig too far away from you, as the bit rotates.
Photo 7. Measure both ends of each segment; they must be precisely the same width.
Check that the ends of the test pieces are equal in length ( Photo 7). Add a few shims to the jig ( Photo 8) and then try again.
This ensures that all the inner arcs of the rim pieces form an exact circle.
Photo 8. If one end is a bit wider than the other, add a shim or two to one side of the fence and rout the entire arc again.
Ive found that its essential to use spline in order to align the rim pieces with each other and with the plywood center. This particular top was made with a shop-made spline, which was 1/10cm thick and 3cm wide. Photo 9 is a retrospect. Make the spline with the grain running the short direction.
Photo 9. Rout grooves for splines in both ends of all the segments. To steady the pieces, back them up with a block cut at 67-1/2.
Make The Center
Photo 10. Photo 10. Measure the diameter of the circle.
You started with a theoretical diameter for the plywood center of the table-now its time to calculate its actual diameter. Clamp all of the rim pieces together and measure the distance across the circle they form (Photo 10). Draw a circle about 1/20 cm larger than this on your plywood and cut it out (Photo 11).
Photo 11. Photo 11. I use a circle-cutting jig that allows me to spin the plywood on a pivot point.
Photo 12. Rout the plywood into a perfect circle using the lower half of the jig. Remove the plywood from the jig and see if it fits inside the clamped-up rim segments.
Drill a shallow 1/20 cm dia. hole in the center of the circle, on the underside, to engage the pin in the pivot block. The position of the pivot blocks should be adjusted so that the distance between the pin and the edge of the router bit is equal to your radius. Rout the roughsawn circle into a true circle, then use the adjusting nut in the stationary jig to gradually reduce the diameter of the circle until it fits perfectly inside the rim pieces (Photo 12). It is not enough to measure. Remove the plywood from the jig between passes-its easy to do-and try dropping it into the rim. Creep up on the final diameter by turning the jigs adjusting nut in very small increments (Photo 13).
Photo 13. Photo 13. Rotating the nut by one oclock reduces the radius by about .003. Rout the plywood and adjust the nut a few more times until the fit is perfect.
Photo 14. Photo 14.
Photo 15. Photo 15. The two grooves must be offset by about 1/35 cm, so the top surface of the rim will stand proud of the plywood.
Route a groove to spline the entire length of the plywood ( Photo 14). Rout a similar groove along the inside edges of the rim pieces (Photo 15). Adjust the bits height so that the rim pieces are about 1/35 cm above the plywood. Make sections of curved spline (Photo 16) and glue them around the plywood (Photo 17).
Photo 16. Photo 16. Cut the spline on the bandsaw.
Photo 17. Attach the spline pieces to the top.
The Glue-Up
Gluing up the entire rim in one shot would be ideal, but its just about impossible to do without enlisting the help of two or three people. You can glue the entire rim if you only tackle small pieces at a given time. I use a relatively slippery glue, such as Elmers Glue-All, to make it easier for pieces to slide into position. A glue with a fast tack would make the glue-up more difficult.
Photo 18. Photo 18. Let the glue dry before proceeding.
Start with just one rim piece-lets call it #1 (Photo 18). Glue spline into both of its ends, then place another rim piece, without glue, on the opposite side of the tabletop. Apply glue to the #1 piece and clamp it to the plywood. Check with a straightedge to make sure that #1 isnt cocked up or down. Clean off the squeeze-out and let the glue dry.
Photo 19. Photo 19. To force the pieces to fit together, add the remaining segments without glue. Allow the glue to dry. Then add two more.
As you can see, glue pieces #2 & #3 to the opposite sides of #1. You can then pull them together to #1 by gluing the pieces #2 and #3 around the table. Keep adding pieces to the table in pairs, building up the glue-covered rim.
Complete The Top
Photo 20. The outer edge of this table was cut. I use a circle-cutting jig for this operation, too. The jig leaves the edge smooth and easy to clean by sanding.
When all of the rim pieces are glued, draw the outside diameter of the top and cut off the waste (Photo 20). Then clamp the top to a stable bench and plane the edges until they are paper-thin, proud of the plywood ( Photo 21). Scrape or sand them flush.
Photo 21. Plane the rim almost flush to the plywood, then scrape or sand it even.
Rout a profile around the top (Photo 22). I used a 3/20 cm roundover bit. Use sandpaper to smoothen the outer edge of the rim. Next, rout the profile again to remove any bumps. Finally, rout a 1/20 cm roundover on the underside of the rim, to soften its edge.
Photo 22. Route a roundover around the top of your table. Make sure the routing does not cut into the splines. After all the hard work it took, that wouldn’t look right!
How To Make A Perfect Octagon
Cabinetmakers have a reputation for being meticulous and hardworking. While it is okay to make mistakes when remodeling the house or doing outdoor projects, tight tolerances are required when crafting furniture that you can be proud of.
Using a tablesaw to make an octagon without any gaps is definitely fussy work. The angles must be so precise that you really cant measure them. The practical way to test for accuracy, Ive found, is to actually cut 8 pieces and see how they fit together.
Youll need a miter gauge that doesnt wiggle in your saws miter slot. Some miter gauges have adjustable bars. These are great, but you can modify the bar or shim it to remove any slop.
You should start by getting your miter gauge to the right angle. This can be either 22-1/2 or 67-1/4 depending on which model you have. While I often use a square or a drafting triangle to set my miter gauge, I dont rely on a commercially-made tool for this job-I make a template. You will need a piece of stiff paper measuring 15cm x 15cm with a square corner (I use posters board), a compass and a utility knife to make it.
Photo 1. Begin by using simple geometry to draw a 67-1/2 triangle on a stout piece of paper.
Start by drawing a right angle about Photo 1, step I). Draw two arcs from both points B (step II). Draw a line from A to C, then draw arcs from B and D (step III). You will need a straightedge to guide you knife. Draw a line from A through E.
Photo 2. Set your saws miter gauge using the triangle.
Saw a test set of 8 pieces.
While not perfectly accurate, use this template to set your miter gauge for a trial run (Photo 2). Cut 8 pieces of the exact same length using square and angle stop blocks. (Of course, these pieces must be flat and have parallel sides. You can either use scrap wood or the pieces youll use for your final octagon, providing youre willing to cut them a bit shorter as you refine the miter gauges angle.)
Photo 3. Photo 3. Chances are that one or more miters wont come tight, which means that the miter gauge must be readjusted.
Make an octagon by assembling the pieces. (I use a band clamp to keep the corners aligned.) Check to see how tight the miters are. One or more miters will usually be open. This indicates that the miter gauge angle may not be right ( photo 3).
Photo 4. To slightly alter the angle of the miter gauges fence, you can re-position it. Cut all eight pieces, and then form the octagon again. Continue this process until you get the perfect miter angle.
To tighten the joints, you could adjust the angles of a few pieces, but I prefer the angles for all eight pieces to match, so they can be interchangeable. Shims are the best way to adjust your miter gauge ( Foto 4 ). You can use shim stock made of brass or pieces of paper, or tape. The shims need only be a few thousandths of an inch thick.
Re-cut all of the pieces, on both ends, so theyre slightly shorter. Re-assemble them into an octagon and check the miters once again. You may have to add or subtract more shims, but it wont be long until the miter gauge will be right on the money.
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