I think chairs are the most challenging projects for me in the shop. Similarly difficult is the design of chairs with all their complex angles and shapes. I think Windsors are particularly hard to design because of the sculpting of the seats. There is no sculpting, carving, planing, or other shaping tools in SketchUp, so I have to improvise and compromise. In the shop I will use spokeshaves, files, travisher, carving tools, and drawknives. I look for the day that SketchUp provides an analog for these handy shaping tools in the shop. Meanwhile we are limited to creating Follow me shapes and Intersect to sculpt and shave off material. It's tedious and rough, and I don't try being too accurate with the slices, since it just takes too much time. Nevertheless, here is my procedure for making a Windsor.

I chose a design found in Fine Woodworking No. 109, November/December 1994. In an article by Harriet Hodges, a Bowback Windsor is described and detailed. Two rough "drawings" or sketches are provided (Figures 2 and 3), which I scanned and imported to SketchUp.

Step 1: After importing the drawing as "an image", traceover the Leg and Spindle shapes with the Line and Arc Tools. I create a half turning shape that is spun into a turning using Follow me.
Before the traceover, the drawing is scaled so that the grid is set to 1 x 1 inches. Also, I straightened the photo so that is was perfectly aligned with the SketchUp axes.
I noted that many of the called out diameters on this drawing were not equal to the drawn size. I used the "drawn" sizes which was equal to the traceover.

Step 2: Do the Seat traceover. I also traced over all the sight lines, depth holes, and locations of Spindle holes, and Leg protrusions.  I traced the front and side profiles as well.

Step 3: Create the "half" Seat component using Push/Pull Tool to a thickness of 2 1/8". The component includes all the sight lines and hole locations.

Step 4: According the article text, the seat is gouged out at a  7/8" depth. The author recommends that a hole be drilled at that location 7/8" deep. So I routed out a scoop using Follow me and Intersect to a depth of 7/8".

Step 5: Do another "scoop" but shallower and wider.

Step 6: Make V-groove at rear of seat using Follow me. Also round the lower back edge of the seat. Sometimes, I improvise with various shapes to sculpt various parts of the Seat.

Step 7: Turn the Back Leg using Follow me and based on the shaping that was done in Step 1. I placed the Leg at the angle shown in the Figure 2 of the article - 22 degrees. I assumed that the hole location shown in Figure 2 was actually the protrusion location in the top of the Seat. Therefore the location of the hole in the bottom of the Seat is closer to the back edge because of the angle.

Step 8: Turn and place the Front Leg.

Step 9: Copy the half Seat and Leg components, flip along red axis, and connect to alternate half. Then turn and place the Stretchers. When I do turnings in SketchUp, I always include a centerline in the component to help with placement. Note that I found my Stretchers to be significantly shorter in length from the dimensions shown in the article Figure 3. So I had to Scale the Stretchers to fit properly.

Step 10: Create the Back Bow. There is scant information about the sizing and shaping of this component in the article. The only information is the total length and angle from the seat - nothing about the diameter of the arc or overall height. So I had to iterate and guess. I tried several upper arc sizes until I felt that I had a reasonable match for the overall length and height.

Step 11: Create guidelines for the Spindle angles. I made temporary plates along the Spindle sight lines to help me with positioning the Protractor Tool to create the proper angles. I found that many of the angles shown in Figure 2 did not work for my Back Bow. The guidelines need to protrude through the Back Bow at the centerline. So I adjusted the angles to suit. Figure 2 shows 15, 12, 10, 9, and 8 degrees. I used 15, 11, 8.7, 7.7, and 7 degrees.

Step 12: Turn and place the Spindles which taper from 9/16" to 7/16". The taper starts 12" above the Seat. I didn't bother creating the end tenons which are 3/8"D. I used one Spindle component to place into the back. Following that, I used the Scale Tool to cut each Spindle to appropriate length.

Here is the final design. This model will help me immensely in the shop. I will be making full-size templates for the Seat and all turnings. Also, I will be able to create an accurate bending pattern for the Back Bow.

Tim
http://killenwood.com

One of the advantages of using SketchUp for woodworking projects is that it makes it easier to communicate with others. You can make perspective views and add things like walls, floors and so on to create context for the project. Apply materials to your model and perhaps turn on shadows to enhance the 3D appearance and there'll be little question about the project. This can place you a long way ahead of the simple pencil sketch.

If you want ot take your drawings to the next step there are a number of programs out there that can take the model you've drawn in SketchUp and make it look much more like a photograph. Most of these programs are very involved and have a fairly stepp learning curve. Recently though I 've been playing with the demo version of a new commercial plugin for SketchUp called LightUp . Although it doesn't generate reflections and shiny surfaces, it does create a nearly photographic appearance right in your SketchUp window. It is simple and quick to set up which is also very appealling.

This morning I finally finished up my version of Thos. Moser's Windward Collection and I've been playing with LightUp. Here are some examples. Pardon the unmade bed. The bedding is in the laundry.

First, this is a raw SketchUp image. the shadows are from SketchUp's sun.

Click here  for a larger view.

This is the image from LightUp.

Click here for a larger version of this image.

The LighUp images were made using a bunch of add-in lights but no sun.

Now this isn't quite photographic in quality but it does add a little extra realism to the model. I didn't do it in these images but one could add lights in the model if desired. It's quick and simple. the LightUp image was rendered in less than a minute. It might not be fore everyone but you may find it useful. Give it a look.

Dave

I can't stand to have tree cuttings going to waste as they are noisily crushed in the powerful commercial chippers. So when we recently had some major tree surgery here at home, I quickly recovered branches that I could use for rustic chairs. I needed straight stock (difficult in live oak) between 1 to 2" in diameter. After gathering sufficient material, I began the SketchUp design.

I found that it was very helpful in this type of design, to build a stick model only of connected centerlines - then build the components over the top of these lines. Without these centerlines, I find that it is very difficult to accurately connect and position the various components. So in my process, each turned component carries its own centerline, the ends of which are the "connect" points to adjacent components. So I can use the Move/Copy Tool to attach to the end of these centerlines, then move over to another component's centerline endpoint.

In this case I'm designing a "rustic" chair, but I believe this procedure could be as valuable for a turned ladder back for example.

Step 1: Build the stick model. Here is my version, a design for an arm chair……. Note the only angled piece is the Arm, which slopes slightly from front to rear.

Step 2: Create the Front Upright component. I use the Circle Tool to place a 2" D circle on the floor, and Push/Pull up to the end of the centerline at the arm intersection. Then I use the Select Tool to select the newly created post and make it a component. Note that the component should include the centerline that was part of the stick model. You can check this by using X-ray view.

Step 3: Create the Back Upright and Comb in the same way as in step 2. At this point of the design I am not working the tenon joints….. that comes later.

Step 4: This is the hardest part of the modeling - creating the sloped and tapered Arm component. Since the Arm is at an angle, it is necessary to create the front circle at the proper angle. I built a small temporary plane to help with establishing this circle properly. Then I Push/Pull to the Back Upright intersection (you will need to be in X-ray mode to see the intersecting lines inside the components). The Arm tapers from a diameter of 1 3/4" at the front to 1" at the back. After making a component of the Arm, I moved a copy over to the right clear of the chair to make it easier to work. Then I selected the back end (face and circle boundary) and used the Scale Tool to bring the back end down to 1" D. Now we have an Arm that is both tapered and sloping to the back.

Step 5: Continue making the Rails which are 1 1/2" D in this design. Here I'm showing X-ray mode so you can see how the components connect at their centerlines.

Step 6: To create the tenons on the ends of the components, I created Tenon Cutters. In the shop I use Veritas tenon cutters in my portable drill to produce the joints. In the shop I use one tenon cutter to make all the 1" D tenons, no matter what diameter of stock I am cutting. However in SketchUp, I made two cutters for 1" D tenons, one for each different stock diameter. These cutters were made with the Follow me Tool. (Reviewing this design just now while compiling the blog,  I believe the cutters could have been made without the outer circular shield).

Step 7: By placing the tenon cutter on the end of the component, then exploding and cleaning up, we have a clean tenon.

Step 8: Cut the 1" tenons on the ends of the Rails. In this model I did not bother creating the holes for the matching tenons. I used the dimensioned stick model in the shop to locate where to drill the components. That was sufficient without detailing these holes in the model, which would have taken unnecessary extra steps.

Step 9: The only remaining components are the Back Sticks and the Seat Pieces.

Step 10: Create the Tenons on each end of the Back Stick. This requires the 5/8" Tenon Cutter tool.

Step 11: Place the Seat Pieces. I used hot-dipped galvanized 8D finish nails to fasten them to the Rails.

Here are two picture of the finished chairs. I'll hold off about a week before flooding with linseed oil.

Tim
http://killenwood.com

Several readers have asked about the toolbars displayed in my screen shots so I thought I'd give you a list. Refer to the screen shot above. You can click on the image to open a larger version of it. Where possible I have included links to the plugins.

Before I get started on that, though, I would offer this advice. There are a large number of plugins available for SketchUp. You may or may not find all of them useful. The more plugins you have in the Plugins folder, the longer it takes for SketchUp to open.

Now, on with the show.

1. Bezier Spline. These are tools for drawing various sort of non-circular curves.
2. Selection Filters These tools make it easy to select all of one sort of entity in the model.
3. Subdivide and Smooth This collection of tools is designed to subdivide faces into smaller ones and then smooth the results. It is useful for making softer sorts of things such as sofa cushions or sculptural pieces. This one is a commercial script from Smustard.com. The current prices is $22.
4. SU2KT 3.0  These are tools for exporting to Kerkythea, a freeware rendering application. There are also tools for creating light sources that will be rendered in Kerkythea.
5. Scenes Toolbar is one of several toolbars included in Jim Foltz's Cutom Toolbars Beta 1 release. It makes it a snap to add, delete and update scenes.
6. Projection Tools These tools make it easy to project edges or points onto a surface. There's also some Push/Pull sorts of tools included in this bunch.
7. Tools on Surface gives you drawing and editing tools for drawing on non-flat surfaces.
8. Joint Push/Pull These tools allow you to Push/Pull curved surfaces as well as Push/Pull along a vector and the standard Push/Pull in the direction of the surface normal.
9. Time Track This is a nice little plugin from Smustard.com that helps you track how long you have been working on SketchUp. I use it when drawing for a client who is paying me by the hour. this is a commercial script but it's only $5.00.
10. Soap Skin Bubble This group of tools makes it easy to draw compound curved surfaces such as you might see in some tent-like structures. My most recent application for this was drawing the canvas for the bimini I am designing for my sailboat.
11. 3D Shapes Pretty much does what it says. Allows you to quickly draw shapes such as cones, pyramids and spheres.
12. Space Navigator. These are tools for setting the behavior of the 3D Connexion Space Navigator. This is a handy tool for controlling the camera in SketchUp. The Space Navigator also works with Google Earth and some imaging software.
13. Skin This plugin generates a skin between edges. I demonstrated the use of this plugin in my blog entry on complex geometry .
14. Construction Line Tool This one gives you a tool similar to the native Line tool but it draws guidelines instead.

There you have it. that covers all of the plugin related toolbars currently on screen. There are a few more that I have but they aren't ones that I use much. For that matter, some of the ones I've shown don't get used often either. You can try them out and decide for yourself.

 

Dave

The other day I was asked by a SketchUp user how to place slats on the back of an Adirondack Chair he was drawing. The chair is similar to Tom Begnal's chair in FWW192. The fellow had already drawn the parts of the chair and had most of it assembled but the slats were giving him a bit of trouble. Here's what he sent me and following that, what I came up with for him.

The slat components as he had placed them were close but not quite right. I copied the two back supports and the center slat away from his model so I could work on them.

I strared with the back supports and added a guideline between the midpoint of the top arc on the upper rail and the midpoint of the arc on the bottom arc on the bottom rail. This guideline is where the centerline on the back of the center slat will fall. I suppose technically it could be argued that it isn't unless the slat itself is curved to match the curve of the support. It would probably be easier to cut lands on the back supports.

For illustration, I drew a vertical plane on which to work. This is an option when you're doing this but I used it to make it easier to see what's going on during the rotation of the center slat.

I selected the center slat and then the Move tool. I grabbed the slat by the midpoint of the back bottom edge and moved that to the intersection of the guideline and the bottom arc on the lower support.

Next I hid the lower rail and orbited so I could get at midpoint of the bottom edge of the slat and see the guideline. I got the Rotate tool and rotated the slat so the back face is aligned on the guideline.

At this point the center slat is in place. the vertical face is no longer need nor are guidelines. The next step is to figure out how to place the rest of slats. We could manhandle the rest of the slat components into place but that's a lot of work. Instead we'll create a point on which to use the Rotate tool and make a radial array.

I opened each of the back support components for editing. On the upper support I selected the top arc and right clicked. I chose Point at Center from the context menu. This places a guidepoint at the center of the arc. I repeated this for the lower arc on the bottom support rail. Then I closed the components and connected the two guidepoinyts with a guideline. This line looks to be vertical but it isn't.

Thie above image shows a guideline marked "Horizontal" (although it is hard to read in this msall image) and shows a guideline placed at 90° to the nearly vertical one. This was done by orbiting into positoin so I could place the green protractor tool on the upper guidepoint and then place the new guideline perpendicular to that line. The horizontal guideline, the pink sector and the 90° tag are only for show here. You wouldn't need to draw them.

I drew a vertical face with edges on the perpendicular guidelines. The size and actual shape of this face are not important. It'll be deleted later.

Push/Pull on the face gives us the top face with is the important one. I pulled it in both directions to make it easier to see but it really doesn't need to bbe that large. The actuall Push/Pull distance is unimportant as long as you end up with the face.

With the center slat selected, I got the Rotate tool. Ctrl invokes the copy mode. I placed the Center of Rotation on the upper guidepoint so that the protractor was laying on the face I created in the last step. Notice it is black rather than the blue it would be if the rotation axis was parallel to the blue axis.

I grabbed the center slat component at the point where it intersects the arc on the upper support. Niotice that as with the Move tool, it is possible to grab the component anywhere. Since the important thing for the initial rotation is to have the edge of the slat align with the left end of the arc, I grabbed the component there.

So the first copy of the slat component is placed to align with the end of the arc at the top of the support. I hit Enter...

...followed by /3, Enter to make a total of three copies of the original slat.

The fellow who drew this named the slat components "Slat 1" through "Slat 4" working from the center outward. With the Components browser opened to In Model, I selected the component in Slat 2's position and then right clicked on the real Slat 2 in the components browser. I chose Replace Selected from the context menu.

This process was repeated for each of the other slats which left me with the next stage.

That's half way or so. To make the opposite side, I could have gone through the same process but I chose a slightly faster way.

I selected all four of the slat components and copied them over toward the right side. I used the Scale tool to mirror the slats.

Then I moved the mirrored slats back to the chair. The center slat is symmetrical so I grabbed it by the top left corner and pulled the four selected components over so that corner corresponded with the top left corner of the original center slat. Obviously this results in two instances of the center slat component in the same space but it puts the other slats in their proper places.

I got the Select tool and while holding Shift, I deselected the three slats leaving the one center slat selected. A tap on the Delete key eliminated that extra center slat component.

 

It's difficult to see in these small images but the slats as drawn overlapped each other. I fixed that by editing them and increasing their tapers a bit. The outer two slats only got some additional taper on the inside edges. I left the outside edges alone.

All that is left is to finish placing the seat slats (which I've covered in a previous post but didn't do here) fix a tall cool drink and have a seat in the shade.

Dave