Help for a carpenter.

[sander wille]

Hi dome-friends,

I really need someone to help me out with this.

First. I want to build the gd27 and the gd62 Dome by Paul Robinson.
And I want to build it in Oregon Dome style. Separate triangles so i can break it down easily.
The gd27 is 6m diameter and the gd62 is 9m diameter.

What i need to know is the dihedral Angle for the struts and the bevel and mitre angles for the struts and the butted-end Angle for the struts.

My lumber is 50mm x 70mm
So i can Saw this dihedral Angle on the table Saw. So i don't have alot of lumber waste. Then I need to Saw one end of the struts with a compound Angle and then he other end butting on the other.
After all this I Will use the router to cut out some wood on the outside to fit I n glass or polycarbonate plates.

If somebody can help me out. I would highly appreciate!

Because I have a plans to Bring An art event in nearby Future.
And i'm longing for a Dome for several years now. I'm going crazy.

With high regards.

[sander wille]

What I forgot to mention is. 

Paul uses 1 dihedral angle. I would like to have this aswel.
for saving wood.

[sander wille]

These are some pictures 

[Paul Kranz]

Sander: The dihedral angle is so close to 7 degrees all around that you should be fine with that. Do you need the foundation to lie flat, or would you be willing to work around a nonflat one? A flat foundation requires three different triangles, but a nonflat only two different kinds. We are talking about a three freq isosa, right?

Paul sends...

--
--
You received this message because you are subscribed to the "Geodesic Help" Google Group
 --
To unsubscribe from this group, send email to GeodesicHelp+unsubscribe@googlegroups.com
 --
To post to this group, send email to geodes...@googlegroups.com
 --
For more options, visit http://groups.google.com/group/geodesichelp?hl=en

---
You received this message because you are subscribed to the Google Groups "Geodesic Help Group" group.
To unsubscribe from this group and stop receiving emails from it, send an email to geodesichelp+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[sander wille]

Hi Paul,

Yes, the GD27 is a 3V icosahedron but flipped 90 degrees. so that the bottom is flat.

So the dihedral angle for every strut is 7° ?
Here below I posted a picture I found somewhere on this group.
these are the triangles I want to make.
I don't mind 2 or 3 different kinds. or even 4 :)
but as You see I need a simple bevel cut. I suppose that
this is half of the dihedral angle?
and then I still need to know the compound angles.

Thank you for helping out P! 

[Paul Kranz]

Sander: You will want to set the table saw 7 degrees off perpendicular. If you use a 10-inch saw blade and 2 X 4 stock, you will have to make two passes to cut all the way through. A 12-inch blade will work with one pass.

The beauty of the Oregon Dome/Pease system is that there are no compound angles because the boards that need bevelling are already beveled before triangle construction begins.

What do you mean by "flipped 90 degrees?" A pic would be helpful.

Paul sends...

Paul sends...

--
--
You received this message because you are subscribed to the "Geodesic Help" Google Group
--
To unsubscribe from this group, send email to GeodesicHelp+unsubscribe@googlegroups.com
--
To post to this group, send email to geodes...@googlegroups.com
--
For more options, visit http://groups.google.com/group/geodesichelp?hl=en

---
You received this message because you are subscribed to the Google Groups "Geodesic Help Group" group.
To unsubscribe from this group and stop receiving emails from it, send an email to geodesichelp+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

--

Very high regards,

 

Paul sends...

ReviveTheFlame.com

[Gerry in Quebec]

Hi Sander,

Here are some images showing the angles you were asking about. These are for triangles AAB & CCB in the smaller of the two domes (6 m diameter, 3-frequency).

The triangular frame models (calculated in Excel and displayed using Antiprism) are based on a few assumptions:

 -- The dome is a 3v icosa, class I, method 1 (following Joe Clinton's terminology in Domebook 2).

 -- To simplify construction, the dihedral angle between all pairs of triangular faces is taken to be 166 degrees, giving a bevel angle of 7 degrees (the angle mentioned by Paul Kranz) for ripping 50 x 70 mm lumber on a table saw. I do not know how, in practice, this simplification regarding the dihedral angles will affect the fit between AAB & CCB triangles along the B struts.

 -- The lumber is ripped through the wider face (70 mm) as seen in the attached diagram. This means you get two struts from each piece of lumber.

 -- The dome's spherical radius is 3000 mm.

- Gerry in Québec

[sander wille]

Thanks to both of you!

I'm trying to learn with sketchup and I build a 3v octahedron today
It is a little tricky because i want the inside of triangles flat.
so I need 5 different struts to build the 2 triangles. but everythings fit perfectly on the drawing.

I will try to make the 6m diameter 3v icosahedron in a couple of days and will update how it goes.

have a great day!

[sander wille]

a pictuee of the 3V octahedron

 

[sander wille]

Hi, I'm back

just started to draw the 3V icosahedron.
cut exact in the middle. (so the base is flat)
If you check simply differently it is a 4/9 or a 5/9 so this is i guess a 4,5/9 ?
does this affect the strenght of the structure?

I just measured the angle between 2 panels in a hexagon and it's 193,6.. so if you do this minus 180 = 13,6 divided by 2 = 6,8°   so that's close to 7 :)
So Gerry, is this what you meant by saying it will affect the fit?

have a nice day!

[Gerry in Quebec]

Hi Sander,

Your model is a hemisphere, so the the terms 4/9 and 5/9 don't apply. Such fractions apply to icosahedral domes where you have a pentagon at the apex. Basically it's the number of rows of triangles in the dome versus the total number of triangles in the geosphere, between the "north" and "south" poles.

 

As for the 6.8 degrees versus 7 degrees, that's certainly close enough for construction purposes. What I was referring to is the dihedral angle between a triangle in a pentagon section and one in a hexagon section. The dihedral angle is 168.64 degrees. Subtracting that from 180 and then dividing by 2 you get 5.7 degrees. Maybe that too is close enough to 7 degrees.... I don't know.

 

- Gerry

[Gerry in Quebec]

In my last message, I should have said, "...versus the total number of rows of triangles in the geosphere..."

- Gerry

[Paul Kranz]

Gerry: I built a 39-ft 3v icosa using the Oregon Dome method with 7-degree bevels all around and the triangles fit together perfectly. The rough nature of ripping a board lengthwise can be very forgiving!

Paul sends...

--

[Gerry in Quebec]

Thanks, Paul. That's good to know. Sometimes it's hard to "judge the fudge factor" just by looking at a bunch of chord factors and angles in a spreadsheet.

Sander.... About the compound angles in the Oregon Dome method (the exposed ends of struts). You don't actually have to know these angles if you use a triangular "pattern" (jig or template) as described by Paul Robinson in his panel-building video. Some time ago Paul Kranz also posted a description of his assembly method using a triangular jig. I think it was a pdf file with pix. Paul?

- Gerry in Québec on a dialup connection

To unsubscribe from this group, send email to GeodesicHelp...@googlegroups.com

--
To post to this group, send email to geodes...@googlegroups.com
--
For more options, visit http://groups.google.com/group/geodesichelp?hl=en

---
You received this message because you are subscribed to the Google Groups "Geodesic Help Group" group.

To unsubscribe from this group and stop receiving emails from it, send an email to geodesichelp...@googlegroups.com.

[sander wille]

Paul and Gerry,

Thumbs up for both of you guys!
And actually i'm glad that Paul R. didn't respond on my messages.. now I know how to draw it myself. And hopefully develop my skills in drawing and building.

Thanks for all the information and fast responses.

In the 3V Icosahedron (hemisphere) I used the same thickness of struts. when the pentagons and the hexagons connect. there is 0,27 millimeter slighty off on the inside. which is normal for cutting dihedral angles on 2 struts.
I can live with that. A little sanding and it's flush.

To Paul: Do you have any pictures of your dome? is it 39 ft diameter??

to Gerry:  I don't know which method i'm gonna use. but the triangle jig looks allright to be consistent.
But I know a guy with good equipment. So we'll see about that.

If someone can check out my sketchup model and evaluate it.  (I changed it to 7m diameter.. I had more space than I thought) Be free to use it!

with high regards,

Sander (facebook -> Sander Wille) profile-pic is a dome in Copenhagen the background 

[Paul Kranz]

Sander:

Here is the garage that I designed and supervised the construction of in July 2003. It is a 3/8th sphere, 3-freq, 39-foot icosa, in July 2003 (https://www.google.com/maps/place/5626+Connell+Rd,+Plant+City,+FL+33567/@27.9455902,-82.1797172,230m/data=!3m2!1e3!4b1!4m5!3m4!1s0x88dd330453542a9f:0x81edab2947be7573!8m2!3d27.945589!4d-82.17917)

Paul sends...

--
--
You received this message because you are subscribed to the "Geodesic Help" Google Group
--

To unsubscribe from this group, send email to GeodesicHelp+unsubscribe@googlegroups.com

--
To post to this group, send email to geodes...@googlegroups.com
--
For more options, visit http://groups.google.com/group/geodesichelp?hl=en

---
You received this message because you are subscribed to the Google Groups "Geodesic Help Group" group.

To unsubscribe from this group and stop receiving emails from it, send an email to geodesichelp+unsubscribe@googlegroups.com.

For more options, visit https://groups.google.com/d/optout.

[Paul Kranz]

Sander:

[Paul Kranz]

Sander:

How goes the two-pent up, half sphere, 3v icosa?

Paul sends...

[sander wille]

Well,

I'm saving for some better equipment for the moment.

it will take couple of months i guess.

but all the drawings are pretty good.
just trying to figure out a nice way to put in some doors.
don't want to ruin the looks of the structure ;)

[sander wille]

super!!!!