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Virtual Designs in Sketchup #18: How to design a Gazebo Bird House

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Blog entry by rance posted 12-27-2012 06:04 AM 7895 reads 0 times favorited 9 comments Add to Favorites Watch
« Part 17: Illusionist's Heart Pendant Part 18 of Virtual Designs in Sketchup series no next part

A fellow LJ member(Belg1960) was asking about designing an Octagon Birdhouse a while back. He recently contacted me and asked if I would show him how I would do it in SketchUp. I thought I would make this public for all to see. The method that Jim Jakosh provided was certainly a good one. Every woodworker would benefit from understanding math as much as Jim does. Me, I tend to lean more on SU to do my math.

The SU method I am presenting here is but one SU approach. There are other ways to do this in SU, but this is the first one and the easiest one that came to mind for me.

Let me say that my purpose with this scenario is to use SU to tell ME the dimensions and angles rather than me having to tell SU those values. This is most often the case with me when using SU during the design.

The constraints given to me to dimension the Gazebo Bird House(GBH) were as follows:
8” diameter base
7” base height
10” diameter roof line
6.7” roof height(derrived from Jim’s scale)
1” hole at the top(for finial placement)
(arbitrarilly chosen on my part)

And YES, he requested a Hexagon, not an Octagon. :)

I begin by drawing a side view profile-triangle of the roof using the given constraints(I rounded the 6.7” to 6.75”):

Note the 1/2” line on the bottom left corner. This represents the radius from the center point to the inner edge on the top where the finial will go. I also make all of this a ’Component’ so it doesn’t STICK to the other parts I’ll be drawing.

I then lay up the profile of a 3/4” board profile where it would lie against the roof profile-triangle:

Next, I rotate the bottom end out to the bottom edge of the roof profile-triangle:
SU tells ME that this is 28.4 degrees. Incidently, this is the cut angle for the top & bottom of the roof panels.

Note how it intersects with the triangle, thus keeping space for the hole in the center and not exceeding the roof diameter. It is not just a parallel fit to the triangle.

Now I convert this roof-panel profile into an actual 3D board by flattening the top & bottom, and pushing/pulling the front and rear faces to give it depth. The goal here is to extend it in both directions further than it needs to be. 5” ought to do it. These will be trimmed off in a later step.

I’ve shown it transparent so you can see how it intersects the profile-triangle. The panel itself is also made into a ’Component’.

Next, I rotate to an arial view to do the real magic. I will be copying(in a circular fashion) that panel 5 more times at 60 degrees(360/6 sides[a hexagon] = 60 degrees). Note the point of rotation around the tip of that line sticking out to the left of the profile-triangle.

And here’s what you end up with:

It actually looks to be a jumbled mess doesn’t it.

Lets come down a bit from the arial view and hide 4 of the panels. I also added a wooden color to the panel we will be working on:

By the way, since these panels are ’Components’, then any changes I do to one, gets replicated on ALL the other panels.

Now comes the math part, but with no math at all. I draw an intersecting line where the two panels cross, from the inside intersection to the outer intersection. This is done on the top AND bottom beveled edges of the panel.

I now edit the wooden panel itself to connect the upper intersecting line to the lower. And then remove the excess just as if I had cut it off with a saw. I have no idea at this point what that bevel angle is that I just created. Later I’ll just measure it using SU. And here’s what I’m left with:

Note that I also hid that one remaining blue panel to help eliminate some confusion to the non-SU users.

I now repeat the beveling for the other edge using the adjacent panel on the opposite edge:

But what am I looking at? Because these panels are ’Components’, any change I do to one, happens to them ALL. Even if I have them hidden.

I can simply copy that one beveled face(now shown in wood veneer for easy identification):

Then paste it onto my all-wood panel:

BTW, I do this using one of the most unused, but most useful features of SU, ’Paste In Place’.

I finish up the panel by simply removing the excess on that other edge of the panel. And what I’m left with is a perfectly formed panel. In fact, if I unhide all the panels, they are all perfectly formed, and with precisely correct beveled edges:

So now, how do we cut these panels? More accurately, how do we measure the bevels? I simply make a copy of one of the panels, lay it down on a flat surface and measure the angles using the Protractor Tool in SU. We already know that the top and bottom bevels are 28.4 degrees:

The side angles for the panels are 15.3 degrees:

And the bevels themselves are 26.1 degrees:

And all the other pertinent dimensions:

OK, now for the base. We are looking for a 8” diameter base at a height of 7”. So we do a similar procedure, but it is easier because we don’t have to tilt the panels. I won’t bore you with the details of this, other than the differences. For the base, I build it extra long, then raise it up into the roof until the top of the inner edge touches the roof panel. I then draw lines that can be used to bevel off the side panels. It is easier to do when having just one roof panel, and one side panel visible:

And with most panels in place:

I drew a 7” vertical line from the base of the roof, downward. This gave me a general idea of how tall to make the actual sides. They need to stick down below the lower roof line 7”, but they are actually taller since they go up into the roof where they attach.

Well that’s about it. Any comments, criticisms, and suggestions are welcome. I hope this gives you some new ideas on how to use SU in your future projects.

Oh, and that bevel angle for the tops of the side panels, well that would be 90-(the bottom angle of the roof panel: 28.4 deg.), ie. 61.6 degrees, right? And the side bevels of any hexagonal box are 60 degrees.

And with the finish applied:

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--



9 comments so far

View djwong's profile

djwong

140 posts in 1964 days


#1 posted 12-27-2012 07:50 AM

Really great tutorial. Thanks for posting. I will have to try this soon to see if I can duplicate your results.

I just discovered your design series. Many thought provoking designs.

-- David W. Cupertino, CA

View Belg1960's profile

Belg1960

831 posts in 1810 days


#2 posted 12-27-2012 11:18 AM

Rance, the overall work looks absolutely fantastic. Now forgive the nieve’ question but could I change the dimensions to this in the future? The only other SU project I was involved with was in the SU library and this was made available to me so I could make the changes needed.
I have one question about the 8 5/64” dimension in the attached drawing, is that from long point to long point?
Would it be possible to add a jig to the blog to cut the angled pieces for the roof panels on the tablesaw?
Lastly how about putting the cherry on top with the cap block and a finial. Easy? LOL

-- ***Pat*** Rookie woodworker looking for an education!!!

View gfadvm's profile

gfadvm

11483 posts in 1435 days


#3 posted 12-28-2012 03:44 AM

Thanks a lot Rance. Now I’ve got a major headache!!! I don’t think my brain is wired for this kind of stuff. It took me a long time to figure out that I needed to cut 2 45s to make a mitered corner. OK with you if I just saw my birdhouse from a log with the bandsaw and forego all the math?

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View rance's profile

rance

4147 posts in 1905 days


#4 posted 12-28-2012 04:41 AM

Thank you David. I really like to see how far I can take SU to keep me away from the math. It is a really neat tool.

Andy, I think the birds would be perfectly happy with a log home.

Pat, Yes, the 8 5/64” is from long point to long point. As for a tablesaw jig. I would cut them on a TS sled. Angle the rear fence 15.3 deg. and tilt the blade 26.1 deg. I’ll try to post a mock up this weekend. I’m assuming the cap block is what would cover the seams on the roof. That angle is 127.8 degrees as follows:

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

View Belg1960's profile

Belg1960

831 posts in 1810 days


#5 posted 01-07-2013 10:49 PM

Rance, I was wondering if you had any more thoughts(mock up) about the sled for the table saw? I bought myself a wixey angle gauge and this will help with cutting the .3 or .4 on the tablesaw but I don’t think that it will help me on the miter saw, any thoughts on how to figure these angles for that saw? I know it will work on the miter saw for setting a bevel as I can reference the blade to the table for this, just not when I’m trying to cut the mitered angles. Thanks Pat

-- ***Pat*** Rookie woodworker looking for an education!!!

View rance's profile

rance

4147 posts in 1905 days


#6 posted 01-15-2013 01:59 AM

This is a view from behind the saw, facing the operator. Screw the white block down to your TS sled at a 15.3 degree angle. Then tilt your TS blade 26.1 degrees.

And for the other side:

Hope this helps.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

View stefang's profile

stefang

13623 posts in 2079 days


#7 posted 01-19-2013 12:03 PM

I bow to your mastery of geometry and I am even happier now to have the Woodturner Pro program which does most of this for me. No matter, Your birdhouse design is very good. Solid and attractive too. Well done. I’m sure many will want to build it. Thanks for posting.

-- Mike, an American living in Norway.

View Joe Lyddon's profile

Joe Lyddon

7928 posts in 2797 days


#8 posted 01-20-2013 06:18 AM

Man… I got lost a long time ago…

I started understanding when it got to post #6 LOL

Looks interesting…

-- Have Fun! Joe Lyddon - Alta Loma, CA USA - Home: http://www.WoodworkStuff.net ... My Small Gallery: http://www.ncwoodworker.net/pp/showgallery.php?ppuser=1389&cat=500"

View waleedwaheed2013's profile

waleedwaheed2013

138 posts in 629 days


#9 posted 04-09-2013 09:09 AM

This is good work , I think you are Engineer and you have many Skell s .

Thanks Dear

-- Waleed Waheed

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