Dome Doghouse - Ltsky311

[TaffGoch]

On Saturday, January 14, 2017 at 12:10:36, Ltsky311 wrote:

....who would be interested in helping me figure this out.

http://absurd.onlookers.net/indexb9fc.html?page_id=77

I have a Siberian Husky, he likes to sunbathe on top of his house but I want something different and unique. I do however have all the necessary tools to do this, math beyond simple cabinetry is above my capability. Psht.... I'm a dumb cop by trade....

Thanks in advance.

_________________________

Ltsky311 didn't want to hijack another thread, but posted there anyway - huh....

Starting a new thread,
by pasting his post,
-Taff

 

[Gerry in Quebec]

Ltsky311,

 

The construction method shown in the pix you posted is a variation of the Pease panel dome method, named after the Pease Woodwork Co., of Ohio, USA. Individual triangular frames are constructed, covered in plywood or other sheathing, then bolted together. The ends of each strut of dimensional lumber (e.g., 2x3, 2x4, 2x6) making up a frame are cut at the correct compound angles to form butted joints. You glue, nail or screw the ends of the struts together to form each frame. You can also bevel-rip the struts on a table saw so that the plywood pieces sit flush on the frames. This refinement, however, isn't really necessary, especially for a dog house.

 

If the dog house is rehearsal for building a larger dome, then I guess it's a good way to learn the Pease method. But be forewarned: building a dome, even a small, 2-frequency hemisphere, with that construction technique is a heck of a lot of work.

 

An easier way to build a small dome is to cut the ends of the wooden struts at the correct axial angles. These are simple mitre cuts, not compound cuts. You then cut short sections of PVC pipe (nominal 3" pipe has an OD of 3.5") and use these as hubs to connect up all the struts. You drive screws through predrilled holes in the PVC pipe, from the inside, into the ends of the struts. Once the dome frame is complete, you can sheathe it like any other dome frame.

 

For a large building, the hub-screw-strut connection by itself is inadequate because tensional forces can easily pull out the screws (which are more or less aligned with the grain of the wood). But for a very small building like a dog house, this arrangement will work just fine.

 

Apart from not having to deal with compound angles, an advantage of the hub-&-strut method is that there are far fewer struts to deal with. In a 40-triangle panel dome, there are 120 struts (i.e., frame edges); in the hub-&-strut version, there are only 65.

 

Another method worth considering is that used by the Oregon Dome Inc., in the USA, for its panelized dome homes. This is similar to the Pease method, but simpler to execute, especially if you have a good table saw that can rip 2x3s through their wide face on an angle. You can also use 2x2s. Here's a link to a video by Paul Robinson in the UK. His firm, Geodome, uses this method for small, backyard greenhouse domes.

 

http://geo-dome.co.uk/article.asp?uname=dome_plans

 

For now, I'm appending some info and attaching 3 illustrations on how to build a hub-&-strut, 2-frequency hemispheric dome, 5 ft in diameter, using 2x3 lumber for the frame.

 

- Gerry in Québec

 

2v icosa hemispheric dome, class I, hub-&-strut construction

 

The info here is for a full dome. If you remove 5 small triangles to make a pentagonal opening, then you reduce the short-strut count by 5.

 

Materials/components of basic dome (excluding waterproofing)

30 short struts (A)

35 long struts (B)

6 five-way hubs with 10 holes per hub

10 six-way hubs with 12 holes per hub

5 four-way hubs (left-handed) with 8 holes per hub

5 four-way hubs (right-handed) with 8 holes per hub

10 large triangular panels (BBB)

30 small triangular panels (AAB)

260 particle board screws, 2.5" long (for connecting hubs to struts)

480 galvanized spiral nails, 2" long (for installing triangular panels over dome frame)

 

Struts can be cut from 2x3 lumber (1.5" x 2.5").

Triangular panels can be cut from 5/16" plywood or Oriented Strand Board (OSB)

Hubs can be cut from 3" pvc pipe (shedule 40) which has an outside diameter of 3.5".

Hubs should be predrilled, with 2 holes to accommodate each end of each strut. Total of 260 holes to drill.

 

Spherical radius = floor radius = 30"

Dome height = 30" + about 1" due to the 10 cylindrical hubs around the base

 

Vertex-to-vertex lengths (i.e., before taking into account the hub thickness)

A-type edges: chord factor 0.54653 x 30" = 16.40"

B-type edges:  chord factor 0.61803 x 30" = 18.54"

 

Strut lengths (long edge of the strut), taking into account hub thickness:

A: 12¾"

B: 14⅞"

Mitre angle for both ends of:

A struts: 15.9º

B struts: 18º

 

Hub clearance:

All A struts: 9/16"

All B struts: 1/2"

Hub clearance is the distance by which a mitered strut end protrudes above the outer end of the hub. These clearances help ensure the plywood panels align properly on the dome framework.

[ltsky311]

Thanks for taking the time to put this together. I appreciate it. I want to do the panelled version, I know it's way overkill for its intended purpose. So will the 2lb foam and radiated concrete floor. But my dog makes me alot of money so he earned it. Plus I have a surplus of 2by wood either I burn it or use it. I will look into the peace and Oregon dome methods further.....

As far as tools I have a full festool workshop I use to make cabinetry and other items. 

So table saw and compound miters as well as planing the angle for exterior surface to sit flush.

That's is the math that had me just dumb.....

Thanks again.

Sent from my T-Mobile 4G LTE Device

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[TaffGoch]

Itsky311,

I'm a woodworker, myself, and require plans for every project. I've gotten to the point that I don't start a project without 3D plans. For that I depend on SketchUp, although other computer 3D programs can serve.

I can replicate the design, although it's an approximation...

...since I don't know the final dimensions, nor the dimensions of the lumber to be employed.

With a SketchUp model, I can measure required angles for ripping and cross-cuts, and transfer the measurements to my tablesaw and mitersaw. For geodesic construction I find SketchUp indispensable.

-Taff

[Sh Mc]

That's awesome, the radius I am using will be 3ft. He sits at about 30 inches so a little room is good. Plan on using  ripped 2x4 materials. I have tried to use sketch up but need to watch more tutorials I get so frustrated with it. I am going to skin the roof with 1/4 osb or ply depending on what I have scrap. Then rhino liner spray on top of that (I may just fiberglass skin the roof since it's just laying around maybe some carbon fiber texil,  (blue silver) . It's a great roof sealant will not be black though gets too hot in the sun. Then 2lb foam insulation interior skin made from bathtub fiberglass 4 inch pad with some left over radiant floor. He'll I may kick the dog out and hang out myself. (Thank God I have second job in construction. And get lots of left over materials free)

Yes I realize this is insanely overkill for a dog house. It's also a test run for a future home. And my dog is my Search and Rescue dog he works hard so he deserves it.

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[TaffGoch]

Am I correct in assuming that you plan on ripping the 2x4s to produce 1x4s?

-Taff

[Sh Mc]

No ill probably do rips that give me .75x1.75 or just a traditional rip down the wide face.

On Jan 18, 2017 10:32 PM, "TaffGoch" <taff...@gmail.com> wrote:

Am I correct in assuming that you plan on ripping the 2x4s to produce 1x4s?

-Taff

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[TaffGoch]

Correction of rip specification: 0.75x3.75 ?

-Taff

[Sh Mc]

Err doh... it would be 1.5x 1.75 may just use 1x2 but right now rips of 2x4 down to 1.5 x whatever dimension needs to be. Keeping the 1.5" factory dimension and ripping it in approximate half or finish dinension.

On Jan 18, 2017 10:37 PM, "TaffGoch" <taff...@gmail.com> wrote:

Correction of rip specification: 0.75x3.75 ?

-Taff

--

[TaffGoch]

Got it....

-Taff

[TaffGoch]

ltsky311,

I've modified the 3D model, to reflect your material specifications, and 36" height:

I have to do some minor cleanup, and will then add angular measurements. If you think that you can take all other linear measurements, using SketchUp, then I won't add those.

Typically, the frame measurements are the most critical. Once the frames are completed, and tested for fit, the OSB/plywood skin can then be added, oversized a bit. Final skin-edge trimming, angled, on the tablesaw, finishes the panels.

-Taff

[Tracy Larsen]

YOU GUYS ARE SO AWESOME.

[biagiodicarlo]

Dear friends, 

What is the name of this kind of joint?

Please,  there is a sketchup file  of this  2v dome?

Thank you.

Biagio Di Carlo

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[biagiodicarlo]

I am referring to this kind of joint.

Can we call it a turbinating joint?

I would like to construct a 

1m in diameter model.

[Gerry in Quebec]

See the first paragraph of the second post in this conversation, dated Jan. 16, 2017.

[TaffGoch]

Biagio,

SketchUp file attached.

Note that the hub appearance, of being a turbine, is only an optical effect. The way the panel-frame corners are cut-and-joined produce this appearance, after assembled, panel-to-panel. (Strictly speaking, the "hub" not really a "joint" at all.}

-Taff

[biagiodicarlo]

Dear Taff,

Thank you for the file!

It is possible to level the triangular panel 

in all  the internal lower triangles ?

At the same time I need the SketchUp file of  the 

dome  entirely  triangulated and without the pentagonal opening.

Biagio

[biagiodicarlo]

Dear Gerry,

thank you for the information.

I am including an attachment  from the Pease Woodwork Co, 

for all the geodesichelp  friends.

Biagio

[Gerry in Quebec]

Cute promo, Biagio.

The 1958 Pease brochure, in pdf format, was posted by Katrina Fairley a while back in this conversation:

https://groups.google.com/d/topic/geodesichelp/ScksjrAYbIw/discussion

[Gerry in Quebec]

Here's a pic of a 2v icosa dome model based on the Pease method. It's about 3 ft in diameter and is made of spruce kindling (1/4" x 1 1/2"). I used jigs to assemble the 40 triangular frames.

On Thursday, February 9, 2017 at 12:11:25 PM UTC-5, biagiodicarlo wrote:

[biagiodicarlo]

Great!  This is the model I would like to do.

Maybe do you have my ideal  complete SUp file with:

- axial and facial angles

- A (short)  and  B (long) modules  (I am referring to Domerama drawings)

-  …   all in distinct layers

Thank you  Gerry,

Biagio

[Gerry in Quebec]

Biagio,

The two attached diagrams show strut & panel dimensions at a radius of 500 mm, including angles.

To ensure the panels (e.g., plywood or OSB) sit flush on the triangular frames, thus accommodating the dihedral angles, you can bevel-rip the strut edges on a table saw as follows:

A1, A2 & B2 struts: approx. 11º

B1 struts: approx. 7º

I took a look at Taff's SketchUp model, but I'm not up to speed on the angle measurement tools in the latest version of the software I'm now using.

- Gerry

[biagiodicarlo]

Dear Jerry,

thank you  very much,  for the clarifiers drawings.

I have seen that you used the same data from  Domerama,  Prenis, and Domebook 2.

I have also seen the  ‘Acidome'  and Paul Robinson plans,  but  that they use 

an  different approach from our sources.

On you tube there are several new spanish and brasilian authors.

From my point of view, I find very useful the SUp  drawings by Taff Goch.

I hope he will answer to my request.

Best regards,

- Biagio

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[Kenneth Rhodes]

Just for fun, I thought I'd suggest a construction technique used by Key Domes for what they called a Key Shell Dome.  

For a 2v - dog house you could simply cut the respective triangles out of styrofoam sheets, 

Bevel the 10 equilateral BBB triangles @ 18 degrees. 

Bevel the B sides of the 30 ABA triangles @ 18 degrees and the A sides @ 15.9 or 16 degrees.  

B length chord factor =   0.61803399 * sr

A length chord factor =   0.54653306 * sr

BBB triangle height =   0.53523283445 * sr

ABA triangle height =   0.4507844621754 * sr

Drill small holes perhaps 16 mm from the edge of styrofoam triangles, spaced perhaps  8 cm apart.  

Glue the adjacent triangle edges and lace/stitch the triangle panels together with zip ties.

Cut another set of styrofoam triangles based on a slightly smaller sr so that these triangles will

fit just inside the line of stitches connecting the bottom panels. These top panels do not have

to be beveled. Glue these triangles to the bottom triangles.  You can fill the open seams with

foam insulation.  Paint the dome with elastomeric paint or wrap the dome with chicken wire,  

and cover the dome with mortar adobe style. 

Ken Rhodes 

[TaffGoch]

Ken,

Good suggestion, particularly when ltsky plans to foam insulate, anyway...

...and, with the now ready-availability of FlexSeal ("as seen on TV!") a small project, like this, is an easily-done deal.

-Taff

[Kenneth Rhodes]

Do you have any idea how FlexSeal compares to 

Rust-Oleum 271791 Stop Rust Leak Seal Flexible Rubber Coating (Amazon)

Moneywise a 2 30 oz pack's of Rust-Oleum costs $32.99. Sixty floz = 0.46875 gal * 89.99 for a gal of FlexSeal = $42.20. So Rustoleam is about 22% cheaper - and you get the advantage of being able to seal off unused portions in a smaller container.  Check me on this: According to Domerama a 500mm sr  2v dome would have linear 20559 mm of seams = 67.5 linear ft * 26mm/0.0853018 ft wide = 5.7578715 sqr ft., say 6 square ft. So if a 30 oz bottle of Rust-oleum covers up to 40 sqr ft as claimed, one 30 oz bottle @ $24.82 should be more than sufficient - although the 2 pack is a much better buy.

Indeed. I wonder if the best approach might be simply to glue 1-3 sheets of styrofoam together then cut the triangles with the relevant 9 or 11.21 degree bevel edges. drill the zip tie holes 13 mm in from the triangle edge, apply glue to the triangle edge lengths and then lash them together with zip ties.  After the glue has "set" then cut and remove the zip ties and paint/spray the seams with FlexSeal or Rustoleam, or roll on some Elastomeric coating like RubberSeal. Maybe 16-17 ft2 total surface area, right?

Regards,

Ken

[Gerry in Quebec]

Yes, I think your idea of gluing the rigid insulation panels together, both layers and edges, then removing the zip ties, would work well. Without any wooden framework, though, the doghouse would be very light and could "take off" in a stiff wind. It would be prudent to anchor it to the ground.

There are errors in the Domerama 2v calculator. It overestimates the cumulative length of the 65 struts by 8 percent. The correct value at a spherical radius of 500 mm is 19,014 mm. Also the floor perimeter length is incorrect. It assumes the dome perimeter is a circle instead of a regular decagon.

- Gerry in Québec

[Kenneth Rhodes]

Another Hub-less 2v Dog House idea:

Use cheap 2x4 stud lumber for the struts. Cut the Dihedral Angle bevels into the width of the struts. A base for the dome could be formed by 10 lengths of 2X6 pressured treated lumber cut at 18 degree angles and joined with fasteners and glued. The 10 pressure treated base length will equal in length to the long triangle edges. However, the respective strut lengths should be reduced several inches relative to the matching triangle edge The 10 long struts forming the base of the dome would be formed by ripping 5 2X4's in half centered, fastened and glued on the matching pressure treated base board.  Cut the triangular sheathing Panels out of plywood or OSB.   Assemble the 5 base Pentagons by fastening plywood or OSB panel edges centered on the 3.5" wide beveled struts using short nails or screws and glue.  Join the Pentagons with the equilateral long sided triangle sheathing.  The lengths of the struts will have to be reduced somewhat leaving several inches at each vertex unsupported - this should not be a problem for a structure as small as a dog house. if .5" or greater sheathing is used then the panels could be beveled and glue applied to the edges.  Else, the vertex tips could be tie wired together and caulked.  Elastomeric webbing could be applied to each vertex for good measure.  Coat with Elastomeric paint.

A table saw is required, but this seems to be a contender in the cheap, down and dirty dog house build category.  
 
Regards,
Ken Rhodes