Taliesin Desk Build - How's and Why's #10: Arches for Aprons

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Blog entry by EarlS posted 09-04-2016 02:01 PM 344 reads 0 times favorited 2 comments Add to Favorites Watch
« Part 9: Time to Talk Tenons Part 10 of Taliesin Desk Build - How's and Why's series Part 11: Moving Along »

Finally feels like the project is starting to move along.

Alex from Glass Heritage just told me the glass for the inserts have been cut. He sent some pictures so I can approve the colors.

Meanwhile, I’d better pick up the pace if I want the desk to be complete by the time the glass is ready.

Making smooth arches seems to baffle a lot of folks. The problem is that most arches require a combination of a circle with a large radius and just the right amount of flattening the circle into an oval.

You could use an oval cutting jig. I have one and it is not very easy to use to make an arch. It is much better suited for its main purpose, cutting ovals for things like table tops.

Which leaves me back at square one: How Do I Make an Arch?

Plenty of folks make a template and use double sided tape to hold the board on the template. I’ve had mixed results. I’ve had the tape slip causing the piece to be ruined. I’ve also had problems getting the tape residue off of the board causing finishing problems. I stick (like the pun?) with a sled where the template is on the bottom and the piece is held down on the template with clamps.

Let’s start with drawing the arch on the template.

I keep both a 1/8” and ¼” strip of excess wood from when I rip saw the boards into usable dimensional lumber. After the first pass on the table saw to get the rough edge off, set the fence so you can make a thin strip. Generally, ¼” is better for a long strip 4’ or longer, and 1/8” is good for a shorter strip. The strip should be flexible but not flimsy.

Next, cut the template board to size. I use 1/2” mdf. Since I use the template as the base of the jig, I allow extra width and length for the 1-1/2” square supports that will be used for the hold down clamps. Also, don’t forget to include the length of the tenons on the right end where the 1-1/2” support will be.

Mark the ends and the center point of the arch. Mark where the supports will be placed, as well as the tenons. Also mark the height for the center point. In this case it was 1-1/2” for the bottom aprons. The stringers will be 2”.

As a cross check, put all of the pieces on top of the template along the marks where the edges will be to make sure everything is laid out correctly. That should eliminate the need to do it all over again when you realize you were off by an inch on one side and the center line is not in the center of the apron (yep – first hand experience is a great teacher).

Clamp a piece of mdf to the work bench using a ¾” piece of wood that is ~2” tall (needs to be taller than the wood strip), stood on end just above the center line. Make sure the edge with the arch is aligned with the outside edge of the work top.

Place clamps at either end of the mdf panel, a couple of inches off the ends. Make sure the back of the clamps are on the outside. I use small Bessey clamps.

This is the tricky part. Place the ¼” strip along the bottom of the template and the side clamps. Use a clamp to pull the 1/” strip back to the 2” piece of wood that is clamped behind the center line. Notice that the wood strip extends past the backs of the side clamps.

The backs of small clamps on either side of the piece can be rotated slightly, while keeping the clamp tight to fine tune the ¼” strip to the exact corner of the arch.

Check to see if it looks proportional and even on both sides. If so, use a Sharpie to draw the arch.

As you can see here, an inexpensive metal ruler also works. Notice the position and orientation of the small clamps on the outside of the arch. Rotating the side clamps is the key to being able to fine tune the ends.

From there, it is a matter of rough cutting the arch on the band saw, smoothing it out on the spindle sander and screwing the back and side supports to the template. Since the template will be used on the router table, the screws are counter sunk so they won’t scratch the router table. The side support is also on the right side of the template so the board will be pushed into the support as the piece is fed through the router bit.

Mark the board using the template, rough cut the arch on the band saw, clamp the board down on the template jig. I use a a ¾” x 1-1/2 straight bit with a flush guide bushing on the bottom for template routing most arches.

Since the apron arches are 2” thick, I ran the pieces through the ¾” bit with the bottom bushing then flipped the piece end-for-end in the jig and ran it through the router a second time to get the material that was above the bit on the first pass . Inevitable variations in the left and right sides of the arch causes some slight ledges between the two cuts that were sanded out on the spindle sander. This approach guaranteed that the arches were symmetrical.

Alternatively, I could have switched to a ½” x 3 flush bit with a top bushing. The piece would be flipped over so the profile from the initial pass was on top. Since the profile from the first cut is on the top of the board the template is not needed. The top guide bushing rides along the profile ensuring the second cut matched the initial cut.

All that was left was a little sanding on the spindle sander followed by some hand sanding to finish them off.
The stringers quickly followed and then I realized I forgot to cut the bevels in the through tenons…….. Guess what the next post will be???? Yep – how to recover from a missed step.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

2 comments so far

View WhattheChuck's profile


220 posts in 2977 days

#1 posted 09-04-2016 03:24 PM

Nothing wrong with doing it that way. But I make a fair amount of Craftsman furniture, and all I do is cut a spline from some scrap wood, have someone hold it midway and at the ends, and draw a line.

After that, it’s off to the bandsaw, and final smoothing happens with a compass plane. Until you have a compass plane, it’s hard to appreciate what a great job these things do with these kinds of jobs. I think if I had to make multiple tables, the templates would be worth it. But for one? Not so much.

-- Chuck, Pullman, WA

View EarlS's profile


280 posts in 1765 days

#2 posted 09-04-2016 04:08 PM

Chuck – I can’t seem to get a nice smooth curve that is reproducible if I mark the board and cut it out without a template and then use that to mark the next board, and so on. The arches all wind up slightly different.

I don’t have a compass plane so the router and spindle sander have to suffice for smoothing out the arch. I will have to look for a compass plane.

As with everything in woodworking, there are many ways to get the same result. Always interested in hearing how others do it. Thanks for sharing your approach. Always glad to hear from you.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

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