Chiefwoodworker's Blog

The Trundle Bed design is complete and with this post so will the Trundle Bed Design series be. The next Trundle Bed post will be Part 1 in the Trundle Bed Crafting series where we will chronicle the build of this bed. But let’s not get ahead of ourselves and complete this post first before strapping on our shop belt. As always I will make plans for this project available to my readers on my Free Plans page.

Since the last post the only design decisions were that of choosing joinery and allowing for material expansion/contraction through seasonal changes. All panels in the bed will ride in a grove 1/2” deep by 1/4” wide. The panels must be sized to allow for seasonal expansion/contraction, and we would like the panels to be centered in the groves. To accomplish this I will use a relatively new product on the market called Space Balls. Space Balls are flexible polymer balls 0.260” in diameter to fit snuggly in a 1/4” grove. By placing a number of these all around a panel which is appropriately sized they assure the panel will always be centered, eliminate panel rattle and allow for smooth expansion/contraction. Space Balls can be purchased from a number of places, including on the internet from McFeely’s.

The trick to using Space Balls and to sizing panels is to know precisely how much a panel will expand/contract over the course of a season. You have seen me make these calculations before using an application called Wood Movement Master from Kite Hill Software Inc. Unfortunately this application is no longer available and supported. So, while I will use it here, you can find similar free calculators via a search of the internet. If you want to do the calculations by hand see Understanding Wood by R. Bruce Hoadley, an excellent reference for almost anything wood.

The first picture left above shows the results of a calculation for the bed’s Headboard Panel. This panel is quite wide, 22 29/32”. The bed will reside on Cape Cod, Massachusetts, so I choose Massachusetts, Coastal as the “Ultimate furniture location” which specifies the seasonal extremes of Equilibrium Moisture Content (EMC). The species is Cherry which defines the shrinkage percentage. The other critical parameter is the type of lumber, flat sawn in this case. Flat sawn lumber expands/contracts about twice as fast as quarter sawn lumber in most hardwoods. In the lower right you can see the results. This panel will undergo a total change in width of 3/8” over the course of a season. If I cut the panel now it will be at its narrowest because this is just past the peak of the dry season in Massachusetts. Space Balls recommends that panels be undersized 3/8” overall. I suspect this is a typical number for the typical cabinet door panel width. I decided to undersize this panel by 1/2” overall, which is how I arrived at the 22 29/32” panel width. This should work quite nicely.

One other subtlety about this panel, it is not the same width across its length; therefore the expansion/contraction will not be the same absolute amount across its length. See the second picture on the right above. Most of the expansion will take place near the center of the top edge where it will place the most force on the Swan Necks. This is a place where the Swan Necks are not physically attached to anything and hence will act as a lever prying the joint at the Headboard Posts apart. This is another reason why it is important to get this calculation right, that is, to minimize that maximum force generated by expansion. It is also why I will use lag bolts and glue on this joint to make it as strong as possible.

While we are on subtleties there is one more to consider. The width of the panel given is good if I cut it right now. If, on the other hand, I get lazy and don’t get around to cutting it until late summer I need to adjust the cutting width for the planned expansion. If I cut it just past the peak summer humidity I may want to cut it 3/8” wider, lest it be too narrow and create an unsightly gap next winter. It is important to keep expansion/contraction in mind throughout the course of a design and crafting of a piece. Wood is still alive even though it is cut and dried.

Finally we can generate a cut list. Thanks to Cut List 4.0.7 Ruby Script (see Cut List 4.0.7 Ruby Script Connects SketchUp & CutList Plus ) we can pass information directly from SketchUp to CutList Plus and generate a Parts List and Material Requirements as shown above left and right. The rough lumber calculations are based 20% waste, which may be optimistic for hardwood calculations. It should be adjusted for the individual work habits. In addition to the rough lumber requirements shown above, two sheets of 3/4” plywood are needed for the platforms.

Now that we have completed the design I will make the SketchUp model file, CutList Plus file and a complete shop drawings package in PDF format available on my Free Plans page. The shop drawings in PDF format are thanks to LayOut, a presentation package that comes with the professional version of SketchUp. Now it is time to go in the shop and build this puppy. I will see you next for Trundle Bed Crafting – Part 1.

Well, the last of the design decisions involving the look and functionality of the trundle bed is complete. Two changes were made. The finial has been redesigned and made slimmer and shorter. This gives it a somewhat more delicate look while remaining substantial enough to look at home with the rest of the bed.

The second change was in the trundle itself. It originally had two faux drawer fronts, one on each side. The thinking was that if the trundle bed were placed in the middle of the room both sides of the bed would have the pull out drawer look. The problem is that the faux drawer front rises above the mattress and would make the bed feel like a hospital bed, not allowing the person sleeping in it to dangle their legs over the edge. I lowered one side to the height of the head and footboard. This doesn’t completely solve the problem, but it gives the sleeper one side to favor when dangling a leg.

It is now time to turn our attention to joinery and shaping. I like to have a strategy for shaping before I go into the shop even though it may change significantly once I start. The most complex pieces to shape are the Swan-Necks, Headboard Panel and Finial, in that order. So I will start with the Swan-Neck. The first and most important thing to remember about the Swan-Neck is that there are two of them and they are mirror images of one another. The shop drawings that I have created show one Swan-Neck, the left one. The drawings are annotated in a number of places to remind the craftsman that there are two, and the second is the mirror image. I don’t know about you, but I have made several pairs of things and discovered during glue-up that they were the same and not mirrored. Be forewarned.

The first thing you notice when looking at the Swan-Neck’s overall dimensions in the picture above left is that the stock is 3 1/4” by 3” – very hefty. Immediately you wonder – “What kind of router bit or shaper cutter can handle this profile and how will one actually move the stock through the cut?”. I decided that it is best to make the Swan-Neck out of two layered pieces, and, after some research of router and shaper bits, use two router bits and one shaper cutter to do the shaping of the stock. The Swan-Neck S shape will be formed using the band saw and various sanders. Before moving on to the next picture notice the mortise cut in the bottom of the Swan-Neck to accept the Headboard Panel. This will be cut with a slot cutter. At the end of this blog I will list all of the router bits and shaper cutters required to shape the Swan-Neck.

Looking at the Swan-Neck cross section picture above right you can more readily see how the two pieces will be shaped. The front, and smaller piece, is only 1” by 2 1/4”. This curve can be shaped with Freud Raised Panel Cutter #UP209 and the companion Rub Collar #RC101. This cut will want to be made in a number of passes, probably by lowering the blade with each pass.

The second piece of this two piece sandwich is 2 1/4” by 3”. I will use two router bits to form it. The first is a rabbet cut 1/4” by 1/4” using a rabbet bit. This will remove most of the material. Then, using a 1/4” cove bit, I can shape the remaining curve.

Take a look at the Swan-Neck back piece pictured above left. You will see that it is cut from a piece of stock positioned such that the grain of the stock runs through the center line of the Swan-Neck S. This stock should be 2 1/4” thick and minimally 8 1/2” wide by 28” long. The longer the length, the better. This will provide the opportunity to slide the template up and down the length of the board to choose the best grain pattern.

Note also the mortise slot for receiving the Head Board Panel. The particular slot cutter I have chosen cuts a slot 1/2” deep. The Headboard and Footboard Panels are designed to have a 1/4” tenon. Hence there will be a 1/4” gap. This gap will be filled with Space Balls, a hard rubber like ball that will give as the panels expand/contract with seasonal changes. More on this in a later blog.

Also notice the annotation that suggests that cutting and shaping the ends of the Swan-Neck may be a hand cut and sanding operation rather than using router or shaper bits. This is to avoid tear out ruining the entire piece. Better safe then sorry.

A similar picture of the Swan-Neck front piece is shown above right. This time I will use a piece of stock 1” thick by minimally 8 1/2” wide by 28” long. Again, the longer the better so that I have a choice of best grain direction. Also, as with the back piece, the ends will likely be shaped by hand to avoid tear out ruining the whole piece.

I promised a list of the shapers and cutters I plan to use to shape the Swan-Neck. These can very well change as I begin working the wood, but at this moment here is the list:

If you don’t have a shaper you can use similar or equivalent router bits. But they will have large radii which will require slow cutting RPM and they may not cut as cleanly as a shaper cutter.

In the next blog in the Trundle Bed Design series I will cover the shaping of the Headboard and Footboard panels.

Sneak Preview – Possible LayOut Tutorial

As I mentioned earlier I purchased a SketchUp 7 Pro license and I am using LayOut to generate my shop drawings for this project. When they are completed I will make them available to you from my Free Plans page. I am also thinking of (quite seriously thinking of) creating a tutorial series on how to use LayOut. If there is enough interest I will get to work on it. To see how much interest there is I have a polling question at the top of my blog page. Please vote whether you are interested or not.

The Trundle Bed design is almost complete. The joinery still needs to be added to the SketchUp drawings and I am not happy with the finial design at the top of the headboard. Also, I may dress up the faux drawer fronts a little to make them stand out more. The overall dimensions are 4’ 6 1/8” tall by 6” 11” long by 3’ 10 1/2” wide. The trundle will accommodate a twin platform mattress of 39” wide by 75” long by 8” thick. As it stands now the bed will accommodate  a twin platform mattress or a combination mattress & box spring of 39” wide by 75” long by 12” thick. Because the bed sits over the trundle its platform is necessarily longer, just barely enough to squeeze an X-Long mattress of 39” wide by 80” long by 12” thick, but with no margin for slipping a fitted sheet over it. The design could easily be modified to accommodate a few inches of margin.

The trundle rolls out on non-turning casters aligned to make rolling out and in easy. The faux front drawer pulls also help. I debated using knock-down hardware to assemble the trundle instead of glued dovetail joinery. It certainly would make moving this bed easier. But in the end I couldn’t bring myself to abandon hand cut dovetails on a piece of fine furniture for knock-down hardware. The movers will just have to suffer. The overall trundle dimensions are 3’ 7 3/8” wide by 6’ 6 1/2” long by 12 1/4” tall. The faux drawer front is cock beading 1/4” thick with a 1/8” radius bead. The swan-neck cap on the headboard is rather thick, 3 1/4” in cross section. I may need to dress up the drawer front with more substantial and decorative trim to provide balance of attention garnered by the bed and trundle.

The shaping of the swan-neck will be done on my shaper using shaper cutters. The profile shown is an estimate of what I desire. In reality I will have to research my inventory, and on-line, to see which cutters I need to approach my desired profile. I have already done this for the shaping of the panels. They will require a Freud UP207 Raised Panel Cutter. Since I don’t have one I will purchase it on-line for about $140 plus tax. Shaper bits are not cheap, but in order to get a larger cut on the raised panel, I need to use shaper cutters rather than router bits. The Freud UP207 is designed for 5/8” panels which is what I have used in this design.

I am not real happy with the finial design. Though the bed has a substantial look, the finial seems to be too large and not delicate enough. I have changed it numerous times and still have more work to do. it is possible I might eliminate it all together and replace it with a reading light. One of those old style desktop lamps with the thick shade, dark green on the outside and white on the inside, might look good mounted on the pedestal. Alternatively a bedside table style lamp with a decorative shade might also look good. I have to check with the boss.

In the next installment of this series I will show the joinery and explain why I chose the joinery I did. One of the reasons for leaving the joinery to last is so that I can get accurate measurements of various components and then calculate the expected expansion and contraction during the course of a year. This drives the choice of joinery. In addition, leaving the joinery to the end allows for easy changes in design. Once the joinery is added, changes are much more complicated and require more work. Stay tuned.

After reviewing the styles and design criteria with Willow a few decisions were made. First, she fell in love with the Swan Neck headboard style shown in the third picture in Trundle Bed Design – Part 1. The second decision required a quick budget analysis of the component parts that made up a trundle bed’s height. This was aided by a few SketchUp drawings like the one shown at left. The total height of the bed from floor to the top of the top mattress was 30”. That included two 12” thick mattresses. Thirty inches was too tall because it was 4” above the sill of the window it would reside next to. Reasoning that a trundle is seldom used except as guest overflow, and that futons are often 4” or less, we chose to reduce the allowance for the trundle mattress to 8”. It should be rather easy to find a very comfortable platform, single  mattress, that is 8” thick or less.

This trundle bed SketchUp drawing is incomplete. It has no joinery included, the headboard and footboard have no panels to hide the trundle, and the faux drawer fronts have no trim to form the false drawers. In addition, the shape of the Swan Neck profile is simply a quick selection of geometric shapes, but I haven’t done a search of the shaper bits available to create them, so they are subject to change. This drawing took little time to produce, but it is very helpful in viewing the concepts and determining dimensions. From here I can try a number of design options.

One quick piece of joinery, and joinery decision, is shown at right. In almost all my projects there is a good size helping of dovetail joints. My favorite joint, and one I love to produce by hand. All that is missing from the trundle sub-assembly is the trim that will provide the faux drawer front look. The platform is 3/4” plywood. I almost never use plywood in my projects, but this is an application that screams out for it. Plywood is strong, it is almost warp proof, takes a finish well and it is cheap. In this application it will not be seen, but fits all the criteria. So I reluctantly submit to its use.

I am an avid SketchUp fan and use it for all if my drawings. You by now have probably seen my beginner and advanced SketchUp tutorials. One of the really helpful features of SketchUp is the one click X-Ray. The picture at left is the very same drawing shown right above but with the X-Ray Icon selected. In this view the casters are clearly visible as are the platform support pieces. This view is not only helpful to see hidden joinery and hardware, but it also aids in the drawing of components when it is necessary to attach a primitive drawing element to an otherwise invisible point. SketchUp also has a companion sectioning tool that helps to make slices though any plane, for example a cross section down the length of the bed if desired.

Another feature of SketchUp is its ability to define views. A view can be from any angle, distance or several drawing representation (e.g. Isometric or Perspective). This helps when dimensioning a drawing or showing sub-assemblies such as the trundle above. At right is the bed minus the trundle sub-assembly. The number of views that one can create are virtually limitless, even in the free version of SketchUp. Recently I purchased the Professional version which includes SketchUp LayOut, at full featured presentation package. As this project proceeds I will use LayOut to create professional looking shop drawings and describe how this is done in this blog series. So stay tuned.

Willow has been after me to design and build a trundle bed for the Cape House guest bedroom for some time. I am finally ready and I thought it would be a great opportunity to write a series of blog posts chronicling the design and build of this bed. So this is Part 1 in the design phase series. The crafting phase will also bring a number of posts in a series.

I will start with the bed’s requirements. The guest bedroom is a rather small room with a window opposite the entry door. Because of the small room size the bed design is limited to a twin (or single size).

We get a lot of guests on the Cape, especially grand children, and we need all the bed capacity we can get. So this bed needs to be a trundle. Also the window it will go against is rather low so there cannot be a mattress/spring combination, but rather two platform bed mattresses.

Twin or single bed mattresses come in two sizes: twin size 39” wide x 75” long or X-Long 39” wide x 80” long (same as the length of a queen or king mattress). The size of the room again dictates the normal size of 39” x 75”.

While the length and width of a mattress is standardized, thicknesses are not. However, a twelve inch assumption is plenty of thickness to acquire a comfortable platform mattress. So now I know I need to accommodate two mattresses, each 39” wide by 75” long by 12” thick. These box dimensions representing the mattress size will drive many of the trundle bed’s design decisions.

With the design constraints in hand it is time to consider bed styles. If you are the really creative type you might do this by sitting in front of a blank sheet of paper with pencil in hand and begin sketching. I am not that creative; I need a starting point for my designs. So I run to my desktop and begin a search for “trundle or twin bed” pictures to look at. There are thousands, but the trick is to narrow interesting and general styles to a few.

There are four that interest me that are represented by pictures on this page. In the first picture left above is a double bed I crafted with a design adapted from an article in Workbench Magazine, Heirloom Bed, March/April 2001, page 52. I like this design and one benefit to sticking with it is that the bed shown is already in the Cape House. Another benefit is that drawing it would be a matter of simple modifications to my current drawings. On the other hand, I like to choose projects and designs that are different one from another. But there are pieces of this design that might get incorporated in the final design.

The second picture above right is another simple and elegant design. I like the simple single curve of the headboard top. The double drawers would serve as a nice faux front for the trundle. The footboard could remain the same or raised to the level of the mattress and allow for slats that match the headboard. Alternatively a matching curve could be incorporated into the footboard. There are a lot of possibilities with this design.

The third picture above left incorporates a grandfather-clock-like swan-neck “pediment” with one finial forming the top of the headboard. The swan-neck is rather tall and the curves are a little severe, but the narrowness of the bed may dictate that. I would attempt to alter it. The overall design, especially the footboard, could have simpler lines; I don’t like the footboard design shown at all. An American Colonial flavor might be just right for this style. There is also the possibility of adding a swan-neck to the footboard.

The last two pictures above right and left are variants of a sleigh bed. The last picture is more traditional in that both the head and footboard are sleigh bed shapes. The second to last picture uses a platform bed footboard. The last picture is actually a trundle bed design. There are lots of possibilities for modifying both designs into one. The footboard in the last picture exposes the “trundle” which I find distracting. Also the footboard height is well above the mattress, which is traditional for a sleigh bed, but not a feature that will be accepted by Willow. She believes one should be able to lie in bed and look at nature with nothing blocking one’s view.

The bottom line is that my opinion and taste means little. I am simply attempting to give the customer (Willow) some ideas. She will make the final decision of style selection and modifications. In the end it may be that she has a completely different idea. But this is the beginning of the design phase. Stay tuned for follow-on posts on this topic.

Note: All but the first picture was copied from a JCPenny.com website page and are used simply as an architectural example. Any design that I might extract in part from them will not be used for commercial purposes. If you like one of these beds and wish to purchase it I recommend visiting JCPenny.com.

A number of months back Lonnie Bird sent out a newsletter describing a Pennsylvania German Mirror he crafted as a Valentine’s Day gift for the women in his life, his wife and daughters. I showed it to my wife and she said “What a wonderful gift. We should build some as Christmas gifts for our family.” She didn’t forget. A few weeks back she said “It’s time we begin building those mirrors for Christmas. We’ll need five of them.”

So I set about looking for a design. I searched the net and looked at many a mirror but none caught my eye. Then it dawned on me that we had an American Chippendale mirror hanging in our house. Why it took me so long to make the connection I don’t know. I studied it some and realized it was much more pleasing than any I had researched. Better yet there is a story behind this mirror. In that moment of realization a reproduction effort was born.

The original mirror is an American Chippendale mirror made sometime in the late 1800’s. My wife received it from Marguerite Emily Davis, of Fitzwilliam, New Hampshire, who was her maternal grandmother’s older sister. It had originally been a wedding gift to Marguerite’s parents William Aquilla Davis (1855 – 1911) and Hattie A. Haskell (Feb 6, 1858-1929). William Aquilla Davis (named, we suppose, for the Revolutionary soldier) was a New Hampshire granite quarryman who cut stone for the Library of Congress which, in 1897, was moved to a new building east of the Capitol. His initials are carved into the stone of the Library. Hattie had worked in Concord, Massachusetts as the paid companion to Louisa May Alcott (1832-1888), author of the book Little Women, prior to marrying William.  This must have been in Alcott’s later years (though she was only 56 at her death) when she returned home from her work as a Union Army nurse in the Civil War and following the success of her book, Little Women, which provided her with the financial security to afford a paid companion.

A picture of the original mirror is shown at left, above, with a reflection of me and my camera as I take its picture to form the basis of a Google SketchUp drawing.

The first step in creating reproduction drawings was to import this photo into SketchUp and place it on its own layer. I carefully measured the real mirror’s overall width and height and created a rectangle in SketchUp with these same dimensions. Next I scaled the picture until it fit precisely tangent to the rectangle’s edges. Looking at the picture it became obvious that a vertical line bisecting the rectangle would provide a line of symmetry that would be quite helpful. Lastly, using the Cubic Bezier Curve tool (a Ruby plug in) I traced the scrollwork. See “An Intermediate Google SketchUp Tutorial”  Parts 3 through 5B on my Google SketchUp page if you are not familiar with this tool. The results are shown at right.

The scrollwork in the original mirror is 1/4” thick and seats in a grove (mortise) in the picture frame. Using the Push/Pull tool to give my tracing thickness and the Move/Copy & Flip Along context tools to complete the second half, I achieved a single scrollwork piece as shown at left.

A quick study of this image reveals that all four corner scrolls are identical and that only three pieces are needed to complete the scrollwork. A few measurements taken from the picture above right, and the original mirror, allowed me to create three smaller components as shown at right. Notice that I added 1/4” tabs (tenons) to secure the scroll pieces in the slots (mortises) in the picture frame.

The rest of the reproduction was rather basic. I carefully studied the original mirror’s picture frame and made measurement to reproduce the picture frame profile. I used the Push/Pull tool to create a basic component, and then created two more components with mitered corners; one for the vertical frame pieces and one for the horizontal pieces. The mirror is a simple block with the picture textured on its surface. A completed SketchUp image, complete with a textured mirror, is shown at left. An Isomeric view is shown at right below.

Now here is my gift to you; you can access a completed plan for this mirror, including a CutList Plus cut list, Excel cut list or Comma Separated Value cut list by clicking the below hyperlinks.

• American Chippendale Mirror SketchUp Model
• CutList Plus cut list in .cxp file format
• Excel cut list in Excel 97-2003 .xls file format
• Comma Separated Value cut list in .csv file format

You can change the mirror’s texture to put your own image on it. Some dimensioning still needs to be added to the model, but I assume you as a SketchUp user can do that yourself. Also, the texture on the wood is a simple color patch. If you have a good .jpg image of, say tiger maple, you can use it to texture the wood with grain. The mirror itself is 1/8” thick. The original was thicker, but significantly heavier. Otherwise this is an accurate reproduction. Lastly, the picture frame profile, though an accurate reproduction, my require bits you don’t have. Simply change the profile to your liking.

If you choose to craft this mirror please send me a picture of your finished piece.

Clocks are tricky things and this one has been made trickier than normal because of poor documentation. Let me restate that – no documentation. But I used SketchUp to model the gong wire and gong support, printed out a full scale version of it, and then I was able to experiment with placing it in the model. If I had to do this in the shop using mock-ups it would have taken me some time and frustration I wasn’t willing to spend or experience. Ahhhh! Good old SketchUp comes to the rescue again.

The 3D SketchUp model of the gong and seatboard is shown at right. Unfortunately this placement required me to deepen the clock case more than I wanted to. I thought I could find a position where the gong wire would be in the vertical plane. However, that would require excessive bending of the hammer wire, more that I wanted to gamble on. So the compromise was to deepen the cabinet.

Finally, I was able to complete the case design. I created two alternative designs, shown left and right, with two additional minor variants (not shown). Since my daughter is the recipient of this piece when completed, I presented all four SketchUp sketches to her for her selection. I should have known that she would select the most basic, most Shaker looking design. Her tastes in furniture runs like her father’s.

Note the case is constructed using dovetail joinery. You can see this by looking at the top after clicking one of the isometric views to enlarge it. I always include hand cut dovetails in my designs somewhere. It’s a fetish of mine.

Notice the room left in the case below the pendulum. This is to allow for a full eight days of operation. The weights actually fall below the pendulum in the last couple of days. There are no holes in the clock dial for keys to wind the clock. This is accomplished by opening the lower door and pulling the weight chains so that the weights rise to their topmost position.

The upper door opens to allow for setting of time. The arched door design requires special hinges to make it possible for the door to clear the hood.

The difference between these designs is primarily in the trim, door rails and dial mount. The case work and seatboard are the same. But the looks are quite different. The arch design requires a lot of router patterning work and a few clever jigs. I will write about those later. Now it is time to go to the shop and start crafting this puppy.

I have put the SketchUp model for this design on my Free Plans page. Be aware though, that because of the detail I employed in some of my components this file is rather large (2.73 MB). Also, the dimensioning still needs to be completed. Therefore I will update the file when they have been added.

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I need to assure myself that the internal case width, depth and height in the upper movement compartment could accommodate the required placement of the gong. I could either build a mock up and completely assemble the clock works, or I could create a SketchUp model of the gong wire and gong support. I decided that creating an accurate model has many benefits. Since the entire design is done in 3D, a 3D model of the gong wire and gong support will allow me to place it; then move it around until the desired position is obtained.

The above picture show the gong wire, gong support and the movement with the bendable wire and adjustable hammer. Click the picture to get an enlarged view. The gong wire is essentially a spiraled wire. To create this model in SketchUp I created a path using the Cubic Bezier Curve tool (see My Favorite Ruby Scripts if you do not have this tool). But first I had to create some guide points to follow. I did this by starting with a circle of a radius equal to the outer radius of the physical spiral. I wanted to create seven spiral loops. I measured the distance between spirals and used that as a distance the radius had to shrink on each loop. Dividing this by four to get the decrement, I then started at the outer radius and continued to rotate clockwise placing a guide point at each 90 degree point with the radius at each point reduced by the decrement amount until I had seven spirals.

Next, at the outermost end of the wire I created a circle whose plane was normal to the path (curve) at that point. Then using the Follow-Me tool I created the gong wire. One problem with this technique using SketchUp is that SketchUp does not do well when dimensions of surface triangles are small. To overcome this you can scale all dimensions up, create the model, and then scale it back down – or you can opt to manually clean up the results you get without scaling. The picture at right is the finished model. To get a model that appears smooth you may need to use the Eraser tool with Ctrl to hide and smooth edges.

Now I can complete the case design and accurately place the gong wire and gong support. Next installment I will show the complete design and then start construction.

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In Shaker Style Chain Driven Wall Clock I wrote about clockworks I purchased for a clock case I am designing and building. The clockworks came nicely packaged but with no information to help in the design of the clock case except for the picture at right. I called the company I purchased it from and they essentially said, sorry, there is none to be had. An exhaustive search on the Internet for a PDF file failed. Fortunately, with the help of AllExperts.com I was able to reach a clock expert. AllExperts.com put me in touch with Charles Barrett of Die Klockwerken Antique Clock Repair & Restoration. Charles was able to answer all my questions which are listed below:

1. What is meant by 7 ½” swing?
   I assume it means if the case is more than 7 ½” wide (e.g. 8″ or more, it should not interfere with the bob.
2. Do the weights fall below the pendulum for an 8 day period? If so, how room should I allow?
3. How do you attach the gong so that the hammer (one hammer) can strike it appropriately? Can it hang from a board or will that kill the sound?
4. How far back should the movement be from the plane of the dial?
5. What cutouts are needed on the seatboard?

As I suspected, 7 1/2″ swing was the minimum distance of the internal wall required to make sure they did not interfere with the pendulum. Charles recommended at least 8″. Since my dial is 10 1/2″ wide which dictates the inside width of the case, there is plenty of room.

Another important question whose answer dictates the case dimensions is how far the weights must fall to provide full eight day clock operation. The skimpy information provided on the suppliers website says the pendulum will hang 34″ from the center of the dial. But does the weights fall below the pendulum and how much? Charles answered this way:

“The weights can fall below the pendulum and usually do for a 8-day run but it is hard to say just how long the critical length of the case drop should be to match the full 8-days. Reason being, is that it depends on the length of the weight shells. With that said, I would compensate a full length and a half weight shell length for max case length to achieve a full 8-day run.”

The weight shell length I measured to be 6″ which suggests the inside bottom of the case floor should be at least 34″ + 9″ or 43″ below the dial center. I decided to make the case height 51″ to accommodate this requirement.

I still haven’t figured out how I am going to mount the gong. As you can see from the picture it is a coil style gong. Charles answered question three as follows:

“Is the gong a coil gong or a rod type? In either event, be SURE that the gong is attached to the most dense part of the case (best if it is attached to the backboard of the clock case and be sure to use a REALLY solid hard wood for this since the mounting point of the gong is going to act as your sounding board.

The hammer strike point should be 1/4 to 1/6 of the length of the rod where the hammer strikes the portion of the rod CLOSEST to the mounted end of the rod–NOT the free end of the chime rod.

If it is a coiled gong, have the hammer strike the INSIDE portion of the flat portion of the coil closest to the mounting point.”

I think I will need to talk to him on the phone to unravel this one.

Question four I answered myself once I took careful measurements of all the important points. Also, I am using a 1/4″ backer board, called Dial Mount in my design drawings, which is different than just using the Clock Dial that came with the clockworks. But for reference here is what Charles said about the placement of the clockworks:

“The face should have come with the movement and is mounted to the movement by way of mounting pins on the back face of the dial that protrude through the front plate of the movement. When you close the door of the clock, be sure that you allow 1/4″ clearance measured from the end point of the hour pipe so that it doesn’t interfere with the glass door.”

The seat board is a critical item in the case design. Get it wrong and the clock will not work or will not align with the center of the clock dial. Either is catastrophic. Charles described the cutout requirements as follows:

“Seatboard will have cut-outs for a. chains/cables, b. short cutout for the leader travel on the rear of the seat board closest to the backboard of the case, c. mounting hold-downs for the movement in relation to the threaded posts that connect the front and rear plates together.”

The Seatboard Design Resulting From Careful Measurements

Since I received no documentation I had to make measurements of the clockworks to precisely place these cutouts. This is tricky because the posts connecting the front and back plates together are not symmetrical relative to the center of the hour pipe (the pin that drives the hour hand), the hour pipe is not centered on the front plate, and the gears that support the chains are not symmetrical relative to the hour pipe. I used the center of the hour pipe and the front side of the front plate as reference points for the clockworks and the intersection of the center line and top front edge of the seatboard as reference points for it. After careful measurements, and allowances for tolerances, I came up with a seatboard design as shown.

Because these design choices are so critical to the operation of the clockworks I am going to build a mock-up that will allow me to actually see how well they serve the design. I’ll get back to you in Shaker Style Chain Driven Wall Clock – Part 3 on the results.

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My youngest daughter recently graduated from law school and passed the bar. Her swearing-in ceremony occurred on Friday December 12, 2008, the day of the Ice Storm 0f 2008. I was without power, and trees and power lines were down in my driveway, preventing me from attending. But the law marched on without me and she is now an attorney with a Boston law firm.

My gift to her for the effort and years she labored to achieve this event will be a Shaker style chain driven wall clock. The mechanical 8-day clockworks will be driven by weights and pendulum. The pendulum is 34” long from the dial center to the bottom of the swing. Hence, the clock case will be rater long, about 48”

The clock case design will be similar to the Tall Shaker Wall Clock shown on my Gallery page. However, the lower door panel will be glass so you can view the weights and pendulum – and of course the shelves will be removed. The clockworks are Hermle 241-080 ordered as a kit (see Hermle – Chain Driven – Gong Strike – Item #KIT10) from Clockworks. I was surprised to discover that Clockworks is located in Huntington, MA, not more than a few miles from Swamp Road Wood Works, home of Chiefwoodworker.

Most clockworks suppliers will tell you not to design or build a case until you have all hardware in hand (clock movement and other pieces). There is a good reason for this sage advise. The only installation instructions you receive is something akin to the picture shown at right above. You may have to click on the picture to enlarge it to see the information provided. The first question I asked myself is what is meant by 7 1/2” swing? There are are lot of other questions, like how big is the bob? How far back should the movement be from the plane of the dial? What cutouts are needed on the seatboard? How do you mount the movement to the seatboard? The chains in this picture appear to be in front of the pendulum; one hopes that is not true. The questions are many, and the only way to find out appears to be reverse engineering.

Fortunately, I draw my plans in 3D using SketchUp. So I made a couple of quick drawings to get answers to the first question – what is meant by 7 1/2” swing? I figured there are two possible extremes, a wide swing shown in the SketchUp drawing at left, and a narrow swing shown at the drawing at right.

The wide swing has the bob extending beyond the clock dial edges, which means the inside width of the case would have to be wider than the clock dial. This seems unlikely to me. On the other hand, the narrow swing seems tool little a swing to drive the clock, but maybe not. Anyway, I sent these drawing to Clockworks and asked for clarification. Hopefully they can help.

If not, I will set the clock up in a makeshift case and take a number of measurements before beginning detailed drawings.

I will add updates to this post as I progress, so stay tuned.