Sketchup Tutorials #1: Through Dovetails

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Blog entry by David Kirtley posted 06-13-2010 08:51 AM 3982 reads 0 times favorited 7 comments Add to Favorites Watch
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Just a quick tutorial on how to draw through dovetails in Sketchup.

In this one, I would not even want to try pins first. Tails first all the way in Sketchup. This is the first time I used Photobucket and the images are a bit odd sized to match the forum. I will fix them as I get stuff figured out.

Ok, you want to make a piece the length and width of your stock:

Take the end where you want to make the dovetails and right click to get the menu and select divide. You will want to make one more piece than you want tails. This extra segment will be for the two half pins on the ends.

Now, draw another line for the other piece’s thickness across the face. In this example, I chose 3/4 inch.

We will use several tricks here. The segments represent the center for each dovetail except for the ends. We want the points between the tails instead. Select the draw tool. When you move the cursor along the line, a little green dot will show up for the endpoints of the line and a little blue dot will show for the midpoint of the line. We want the midpoints. Draw a line from the midpoints straight back to the thickness line from each midpoint. Now you need to decide how wide the exposed portion of the pin will be. I chose 1/8 in this example to give me some room for the kerf of the saw. From each midpoint line we drew, draw another segment 1/2 that distance away from the point. When I drew the first one, I entered 1/16 manually from the keyboard for the length once I started from the first point. After you enter the first segment, Sketchup will suggest the 1/16 in each segment you make each time you get close to that distance away from a point on the line. It will usually show a small red dot when it is suggesting. Watch for the little messages that come up while you are moving around.

Now select the protractor tool and we will make some guides for the actual dovetails. Select the offset points on the side of the midpoint line and move the cursor along the axis matching the direction you want and then click to start measuring. The line will change to the color of the axis you are on when you are going the right direction. Once you click the direction, move to the left or right depending on which way the dovetail is sloped and manually type in the angle of the dovetail. I chose 7 degrees for this example. This shows where the actual dovetails will be on the piece.

Now delete the midpoint lines. They will just be in the way and you don’t need them any more.

Select the draw tool and draw a line from the edge to the thickness line along each angle guide from the protractor tool.

Now we are done with the angle guide lines so delete them too.

Now delete the lines to make the dovetails continuous with the rest of the piece.

You can also delete the half tails now. They will just be in the way.

Use the push tool and extrude the thickness of the stock. Be sure and hit the control key first to tell Sketchup to make a new surface instead of just moving the one you had already.

Now select all (Control-A or from the menu ) and create a component. This will be how we are going to make the pins from the tail piece.

Draw the second matching piece for the pins board. You can do it from the end like I did or you can also do it from the inside.

Use the push tool to extrude the stock thickness. (Again, I used 3/4 in.)

Now select the tails board we made into a component and hide it to get it out of the way.

Select the entire pins board and make a component from it as well.

Unhide the tails board and select both components. The pins board and the tails board. Now take the intersection of the two pieces. Either from the menu or right click and select intersect selected. This will create a set of lines where the two pieces connect and will create the pins. The will not be on the pins component though. Hide the tails board again to get it out of the way. Select everything and explode it (break up the component) and then select everything again and recreate the pins component.

Select the pins component and select edit component. Now we can begin deleting the extra pieces that would be filled in by the pins. This will leave some of the faces missing on the sides of the pins.

Select the draw tool and connect the corners on the inside of the pins to fill in the missing faces. Tidy up and delete any unnecessary lines. Exit the component and get back to the whole drawing.

Unhide the tails board and move things around to see how they fit together.

Put the pieces together and start working on the next pieces. Once these two pieces are made, you can use them by intersecting them with the other components to create the remaining corners of the piece.

-- Woodworking shouldn't cost a fortune:

7 comments so far

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David Kirtley

1286 posts in 2991 days

#1 posted 06-13-2010 04:11 PM

Hi Dave,

Really, it is a lot harder to explain than it is to do. I can’t really say that it takes any longer to draw them than to enter all the fields of a dialog and it gives you the flexibility move and size them how ever you want so you can avoid other joinery.

I know I could have done the tails but I want to further fuel the pins or tails first controversy.

Actually, I was just using a trick side effect for the exploding and reconstituting. It takes a few extra seconds but it keeps the pieces more manageable than trying to make the pieces and move them into components later. I am not drawing the pins board at all. I am using the tails board as a cookie cutter to draw them. When I intersect them, Sketch-up puts the lines in the default layer and I am just adding them to the component by exploding and rebuilding. You could also just cut them and enter the component and past them but it would be about the same.

When you are entering arbitrary lengths on a line, Sketchup will suggest the last length you entered. If you want to break a 1” segment on each end of a pre-existing line, click on the end and trace along the line again. Without clicking the second point, just type 1” and hit enter to finish the line. You have the same line with another point 1” from the end. Now, go to the other end of the line click the first point. As you move the cursor along the line, when you get to the 1” (the last length you chose) A red marker will show up suggesting the same length. It will actually remember several. If you are making marks at 3/4 in and 1/8 on a regular basis in a drawing, they will show up as suggestions being lengths you recently used.

The reversed faces are easy to deal with and I just had not bothered to fix them. All you have to do is right click on the object on one of the faces that is pointing the way you like and then select “orient faces” on the pop up menu. This will put all the faces in the same orientation.

-- Woodworking shouldn't cost a fortune:

View jlsmith5963's profile


297 posts in 3341 days

#2 posted 06-13-2010 05:50 PM

Strangely, I was just listening to Bob Dylan’s Self-Portrait album (1970) which of course has the classic tune
I Forgot More Than You'll Ever Know

-- criticism: the art of analyzing and evaluating the quality of an artistic work...

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David Kirtley

1286 posts in 2991 days

#3 posted 06-13-2010 05:55 PM

Well, actually, I make extra components just to use as the templates for the actual pieces. After reading your example, I guess what I am really doing translates as making extra template component to compensate for not having the script to create the outline. Same net effect.

I got used to doing the intersection method from the other stuff I play with:

When you get away from straight lines, it is much easier to intersect stuff and trim and I fall into old habits.

BTW, thanks for the links to your other tutorials. Great stuff. I keep learning really neat stuff that they have put into Sketchup that either is not documented or just well hidden in the documentation. I have mainly been doing things that have unique parts and the components have been pretty much interchangeable with groups since I only have one of each anyway. This is the first time I have started applying Sketchup to furniture type stuff.

-- Woodworking shouldn't cost a fortune:

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David Kirtley

1286 posts in 2991 days

#4 posted 06-13-2010 06:25 PM

Yes, I have been teaching myself boat design. I started out copying other designs but now I do my own. Unfortunately, I don’t have the space to build more real ones. I can’t even start on building a new one until I get the current one out of the garage and it hasn’t even been in the water yet.

The only use I have had in this area for components to to make a mirrored port and starboard version of a part.

I love the scallop on the chair. That would be tough with the bezier tools I have been using. Which curve tools do you use? I have been using the one by Fredo6 and it is pretty good as long as I don’t try to do anything odd. They can be really nasty to use with the follow-me tools since they get broken into segments and if you don’t get it all in one shot, the extrusion comes out in funky angles on some segments.

-- Woodworking shouldn't cost a fortune:

View David Kirtley's profile

David Kirtley

1286 posts in 2991 days

#5 posted 06-13-2010 07:05 PM

I use Free!Ship to start off a project for the hull shape and plate developments and then move to Sketchup for fitting the interior. Free!Ship is pretty icky to work with for interior fittings.

The only other plugin I regularly use is TBD’s desel. If you are not familiar with it, you can select an area and then deselect either the faces or edges in the selection. Really useful if you want to hide a bunch of edges of a surface net.

I just watched your tutorial for the conversion to dovetails in the chest you posted a pic of above. Interesting to watch someone else’s workflow. I have been paranoid about letting it copy the pieces. On some of the curves, Sketchup can miss some connections from what I assume are rounding errors and I have to go in and reset a face manually that it doesn’t realize is connected. It has left me with a draw wide and trim off after zooming in and picking what segment connections it missed.

I can’t blame the tool at all though when I have been using it for things beyond what it was designed to do. I will have to unlearn some stuff now that I am working in a rectilinear world.

-- Woodworking shouldn't cost a fortune:

View Marc5's profile


304 posts in 3335 days

#6 posted 06-15-2010 03:01 AM

What happened to paper and a pencil? Call me old I guess!

-- Marc

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David Kirtley

1286 posts in 2991 days

#7 posted 06-15-2010 03:48 AM

You got to use paper and pencil??? We had to grind up rocks and berries and blow paint onto the cave walls through reeds! In the dark!!

Seriously though, it makes a big difference when you can easily sketch things out and see them in 3D to see how stuff fits together. In a previous life (my original degree field was geology) we had to do a lot of 3D drawings in pen and ink. Being able to switch things around and see alternative versions withuot hours of redrawing opens up a lot of design possibilities and allows you make changes without starting over from scratch each time. Many things we make are similar and to be able to find out dimensions with a program when you make other changes makes it a lot more interesting from the design side of making things.

-- Woodworking shouldn't cost a fortune:

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