Today I received confirmation that in a woodworking class, it isn’t only the student that’s handed useful, inspiring information. We spent time this afternoon at IWF with Lonnie Bird. Most everyone knows about Mr. Bird. After nearly 30 years as a woodworker and many years as a woodworking educator and teacher, he has turned to tool design as his latest challenge. And his most recent router-bit design was spurred by a conversation with a student at his school in Dandridge, Tenn.
After building a number of projects with tambour doors and gluing the individual pieces to a canvas backing, Bird had tired of the same issues with each assembly. A student, also building a tambour door, asked if there wasn’t a better method available, maybe a way to join the pieces using no glue or backing. The proverbial light bulb went off in Bird’s mind.
The result of Bird’s design can be seen in both the completed pieces of the tambour and the finished door in the above photo (and on display at the Amana booth at IWF). Two router bits are used to create a joint that slips together to form a ball-and-socket-type joint. The use of these router bits, as explained by Bird, is to begin with stock that’s milled to 1/2″ in thickness and about 2-1/2″ in width. Next, cut the small ball shape into the stock. He suggests you make a single pass at the table saw to waste away some of the material before running the cut at a router table to save additional stress on the bit.
The other part of the equation is to form the twin tambours (two pieces are cut into each piece of stock) using the second router bit. Cut on both faces of the stock to form the ball portion of the joint. This setup is where you need to make sure the ball end fits smoothly into the slot, then rip the stock down the middle into two pieces.
Admittedly, the joint could be broken when pieces are simply slid in position. But, once the assembled door is installed as a unit, the possibility of breakage is nearly nil. This is an ingenious answer to an age-old problem of canvas and glue. I’ll bet Bird’s tambour doors are not going to have to be reworked after a hundred or so years of use, unlike many tambour doors.
For more on the bits, which cost about $175 for the set, visit Amana’s site.
Also in the Amana booth we found another new idea in router bits. This idea is not from the design side per se, but is adapted from the industrial area. Amana has unveiled the In-Tech series of router bits with replaceable carbide insert knives. There are nine bit profiles available and each has a cutting edge that’s a piece of profiled carbide held to the body of the bit with small bolts. When the knives dull, merely install new inserts and you’ve got a bit that’s as sharp as day one.
The company says this is a significant savings for the typical woodworker and think the bits should last up to four times as long as standard brazed carbide tips. The In-Tech bits begin at $16.88 with a matching replacement knife selling at $3.08. The In-tech 1/4″-roundover bit is priced at $31.09 and the matching carbide inserts are priced at $14.92 per pair. You’ll have to make the comparison to your favorite router bits. I have a couple of these coming into the Popular Woodworking shop. I want to get a closer look and see how the bits stack up.