Monthly Archive for June, 2010

Doorbell: arch moulding

Published on June 26, 2010 in Jigs and Fixtures and Joinery. Closed Tags: .

Making the moulding for the arched top of the case is the most challenging part of the project.

The arch moulding is made of six 2-1/2"-wide segments, each about four inches long, with their ends cut at 75º.

I know three ways to make an arch: bandsaw it from a large solid board; laminate it from long, thin strips; or glue it up from segments. I chose the latter approach, using six 2-1/2″ wide segments, with their ends cut at 75º, as in the diagram at left.

I cut the segments long  with a sliding miter saw, then cut the angled ends to the right length with a Dubby sled on the tablesaw. Then joined pairs of segments together with biscuits.

Here are two segments glued and clamped, while a second pair await gluing.

The finished segments will be only 2″ wide and 1/2″ thick, I used a little Craftsman joiner and R1 mini-biscuits—just perfect for such small work.

Clamping these oddly-shaped pieces can be a challenge. In my Jigs and Fixtures class, students make one of these clamping boards, along with various wedges and accessories. As the picture shows, the board makes this job simple, with no costly, special-purpose clamps.

Here's the completed arch, all three pairs of segments biscuited and clamped together, face side down.

Here’s the final assembly. Again the clamping board simplifies an otherwise very complicated holding problem. The moulding is face-side down, ensuring that the faces will all be in the same plane after gluing. At that point, a couple passes with a handplane will level minor height differences and remove mill marks.

Next step—cutting a dado on the back, then shaping the segments into a smooth semicircle.

Doorbell project: bleaching

Published on June 22, 2010 in Finishing. Closed Tags: .

Sometimes, wood’s almost the right color.

The highlight of this project is a panel that echoes the floor of the entry hall, where the doorbell lives. That floor is 20″ squares of sand-colored limestone with 1/4″ grout lines. So I planned to scale it down 90%, making a cross-hatch of 2″ squares separated by .025″ inlay stringing. With that in mind, I perused my on-line veneer sources.

I found the perfect stuff, a long sheet of quilted maple with billowy cloud figure. But when it arrived, it was much redder than it appeared in the vendor’s pictures. It didn’t go with the floor at all. It looked beautiful, though.

I thought about  returning it, but there’d be a couple weeks of delay, and no guarantee its replacement wouldn’t have the same problem. So I decided to bleach it, once I’d pressed it on an MDF panel. (I’ll talk about the vacuum veneering process in another post.)

I used Wood Kote's Lite-N-Up to bleach the red tone from this maple veneer, leaving it sand-colored.

Chlorine bleaches will remove dye colors, but don’t affect wood’s natural color. To get rid of the red tint I needed a two-part bleach, available at woodworking stores and on line. I used Wood Kote’s Lite-N-Up.

This product consists of two chemicals, hydrogen peroxide and sodium hydroxide. By themselves, neither does much to wood. But mixed together and brushed on, they form a powerful oxidizer that will remove the natural color from bare wood. An advantage of Lite-N-Up is that it is self neutralizing, so it doesn’t require a separate step later.

I brushed on a coat and let it dry, but decided it hadn’t removed quite enough color. So I gave it a second coat. In the picture you can see a piece of the original veneer on the left, and the bleached veneer (with a few coats of blond shellac on it) on the right. The red is gone, and it’s now a good match for the floor color.

Doorbell: moving again

Published on June 21, 2010 in Joinery. Closed Tags: .

Biscuit joints
You can see the biscuit slots—in the sides of the sides, and in the face of the back and bottom. #20 (large) biscuits will tie it all together.

I recut the sides and arch to fit the new scheme: making the cabinet in the shop and popping it into the wall recess (instead of building it in place). This afternoon I cut the biscuit slots for the easy stuff—the straight sides and the bottom. I’m using #20 (large) biscuits to get the most gluing surface.

Guide to locate slots in the back face

A plywood plank, clamped at each end, guides the biscuit joiner as it cuts slots in the face of the back.

Biscuit joinery is straightforward and fast. The sides are the easiest part. I laid them against the back and used chalk to mark biscuit positions approximately every 6″. Then I clamped the sides face-down on the workbench and cut the biscuit slots on my marks. (I use chalk because I can just wipe it away later, unlike pencil marks.)

The straight elements of the carcass.

Here you see the straight elements of the carcass together (but not glued).

Getting the slots in the right places on the face of the back is trickier. I cut a piece of scrap plywood to the width I wanted for the inside of the case, centered it side-to-side on the back, and clamped it into place. Then it was a simple matter to butt the biscuit joiner up against the plywood’s edge and plunge it down into the face of the back on each mark, cutting the slots you see here (with biscuits sitting in them).

Here you see the straight elements held together by the biscuits (no glue yet).

I know! It looks just like it did days ago when it was a bunch of separate pieces fitted into the wall recess. But this is better. Really. Everything is straight and square, and I didn’t have to make two dozen trips between the house and the shop to get things to fit.

The hardest parts are ahead. I had to recut the arched top shorter. Next I’ll kerf it and bend it, then figure out how to attach it to the back. Biscuits won’t work unless I fill in some of the kerfs. I’ll have to noodle on it a bit. Ideas are welcome. Also, I have to assemble and shape the curved moulding for the top.

Some setbacks

Published on June 14, 2010 in Uncategorized. Closed Tags: .

Well, progress has slowed for a couple reasons.

One, the top of the wallboard recess was just too pointy—too far from an arc of a circle to make the lining look right the way I was pursuing it. Fortunately, we have some contractors working on our house, and they gave me good advice. They said to build the cabinet in the shop, a half-inch shy of the recess measurements all around, then just plug it into the opening, secure it with acrylic latex caulk (glue) and a few nails, and cover the gaps with moulding. That way the top arch could be a semicircle, and all the sides could be cut true and joined to the back at 90º. So that’s what I’m doing now.

Second, the contractors are here for a reason.

Hole in the floor

These are 20" square limestone tiles we had to break up to get to the leaking pipe and repair it.

We have hydronic heating—hot water circulating through pipes buried in a concrete floor and covered with stone or wood. It’s a wonderful heating system, quiet, reliable, and dust-free; and the floors are warm. But when it leaks, time to break out the jackhammers!

We found and fixed the leaking pipe, but water wicked into the mortar below the tiles, and into a room below. We’re repairing the damage, along with a roof leak in another area. So I’ve been busy with all this. Plus, I taught a router class last Saturday. We had a great bunch of people, and it seemed like everybody enjoyed it. Still, it took project time.

Anyway, I’m back working on things now. I’ve recut the sides of the lining to be longer, recut the top arch to be shorter, and done the lap joints.

Hopefully, more progress tomorrow. Meanwhile,

Doorbell, pt. 3: Moulding

Published on June 7, 2010 in Joinery. Closed Tags: , , , .

Here the bottom of the lining is in place, and the straight mouldings are in their final positions on the sides.

Moulding is happening, and it covers a multitude of sins!

The walls of the recess are uneven in surface and depth. I forced the plywood sides into position against the back, then scribed them to project 1/8″ out into the room from the plane of the wall. That way I could make moulding cover the gaps between plywood and wall, and wrap around the fronts of the plywood sides. Those plywood sides fit into dados in the backs of the mouldings, so no gaps or unfinished edges are visible from the front.

I made the moulding and the bottom of the cabinet from Honduras Mahogany, a wonderful wood to work with. Moulding is easy to make on a router table.

First, I milled my board 4-square (always a good practice). Then I ripped 2″ wide sticks and planed them to 1/2″ thick. Next, I mounted a half-round bit in the router table and set it to cut quarter-rounds out of the two edges. Finally, I moved the router table fence over so I could route shallow half-round flutes on the surface. I chose all this detailing to echo a detail vocabulary established by a nearby built-in library cabinet.

The half-round moulding for the top will be a tougher job, and I’ll probably do it as a segmented glue-up. We’ll see.

An end-view of the moulding looks like this, courtesy of Google’s Sketch-Up.

This moulding is 2" wide and 1/2" high, with flutes on top and a groove on the bottom.

Doorbell, pt. 2

Published on June 5, 2010 in Finishing and Joinery. Closed Tags: .

The original plan was to build a door chime and mount it on a veneered board with a cross-hatch inlay to echo the limestone tile floor in the room. But when my wife saw the design, she asked me to first line the recess with mahogany so it would look similar to a nearby door and cabinet. Easy, right?

Well, nothing about this recess is square. Nor is the top an arc of a circle. So there’s going to be a lot of shimming involved, and I’ll have to make a wide molding to hide all that ugly business.

Kerfing the top piece

I had to cut 1/8" kerf every 1/4", almost all the way through the plywood, so it would bend smoothly around the 14" diameter arc.

Here the kerfed arc bends easily.

You can see the results of kerfing. The plywood now bends easily to the required 14" diameter.

The recess lining temporarily clamped in place.

Here are the four pieces of plywood, temporarily clamped in place.

Lining the sides is straightforward, using a couple pieces of 12mm mahogany plywood. But the top piece has to bend. So I decided to kerf it.

Here you see the kerfed piece on the tablesaw. I made the first cut (almost all the way through), then attached a scrap to the miter gauge and inserted a 1/8″ pin in it, 1/8″ away from the blade.

Once this fixture was in place, I could set each kerf over the pin to cut the next, working my way down the board. This edge view shows that the kerfs go almost all the way through the wood. There’s an unkerfed section at each end, with a rabbet to mate with the straight walls.

With the sides and top taken care of, I cut plywood for the back, jig-sawed the top roughly to size, then hand-fitted the curve with a rasp. I drilled a hole to feed the wires through.

The next step will be to make moldings that echo design elements already in the room—in this case, fluting and reeding.

More to come…

The doorbell project

Published on June 3, 2010 in Finishing and Joinery. 7 Comments Tags: .

This is the 5'-tall recess we intended for a nice door chime.

When we remodeled this house many years ago, we framed in a recess near the door for an elegant doorbell. I figured a quick check of a few catalogs (this was pre-internet) and we’d find the perfect item—long tubular bells, like a wind chime or grandfather clock, with a nice wood cabinet for the mechanism.

Keep wishing! Do you know how hard it is to find a doorbell such as this? Me neither, because I haven’t found one. I thought I did recently, a nice-looking German unit in an on-line catalog. But when it arrived it looked tacky, with electroplated plastic instead of brass covers. So I went the do-it-myself route. The next few blogs will chronicle this adventure.

The German mechanism was fine, with a little motor to whirl a disc supporting tubular bells. So I kept that. Everything else went in the parts bin. The first order of business would be to get a functioning mechanism with bells I liked.

I ordered 15′ of 1/2″ aluminum tubing from
 McMaster-Carr and cut it into eight lengths of 18–24″. Those would be the bells. I drilled 1/8″ mounting holes in one end of each bell, then sanded the bells to #600 to produce a satin finish. Finally I wiped on a few coats of Deft lacquer, cut half-and-half with lacquer thinner. I mounted them to the original mechanism’s disc with 10-lb. monofilament, and tried out the chime. It worked, and sounded good!

More to come…