ARTISTIC GEODESIC SPHERES

Geodesic domes were once popular. They still have the outstanding quality of enclosing the largest area with the least amount of material. But to build a large structure as a house, standard building materials have about 50% waste when incorporated in the build. Standard windows, doors, counters, and furniture don't fit. The many angles and joints make them complicated and hard to keep from leaking. So unless you like a challenge a large size dome (sphere) is out. But a decorative small sphere is sorta easy.

Here are some of my many spheres. One with tent poles and K+S metal #1115. This cost around $60 in metal! The others are scrap copper and aluminum wire.

This INSTRUCTABLES will give you details of the build. Help you select a sphere (dome) size and material.

A 3d printer is needed for the 92 hubs. (check your library for use of a 3d printer).

Plastic spray paints. And a choice of wire or strut material.

My post is detailed but if you want the best website see 'desertdomes.com' The information there may be overwhelming so I made my post easy and simplified the math for the diameter and struts. If you read my full post you will avoid the 30 years of mistakes I have made. I tried to make this as clear as I can....good luck + enjoy.

My yard size sphere doubles as a bird feeder that keeps the hawks away as the song birds eat. The song birds get very comfortable inside this protected zone. Sometimes they just sit inside and enjoy the day. To fill a bird feeder (inside the sphere) I need an opening big enough for my hand. This makes the big strut 'C' 100mm. With the ball about 22 inches in diameter. (560mm) I made bigger and smaller. As the size increases the tension on the struts does as well. This is where a soft wire (strut) will bend or deform. And too small and you can't get your hand inside just to assemble it.

Now is the time to get a rough size in mind for your project.

FORMULAS for sphere diameter and struts.

The sphere I make is called a 3V. The website 'desertdomes.com' is the BEST site if you want more info. The 3V is the most common with an appealing look and not too complicated. This has 3 size struts (wire here) A,B,C. I have two formulas for this type of sphere. Use the largest strut 'C' and make it any size you want. (Working with mm is easier than inches.) Then to find the dome diameter divide by 0.19 this is close. So if strut 'C' is... 88mm / 0.19 = 463mm dia. (about 18.22 inches)

The other formula is ... again use strut 'C' and multiply to get B and A strut length.

'C' * 0.9785 = 'B' strut length.

88 * .9785 = 86.10mm for strut B length

'C' * 0.8453 = 'A' strut length.

88 * .8453 = 74.38mm for strut A length

The three formulas gives you sphere diameter and strut sizes based on strut 'C'. DO NOT cut the struts ... some adjustments may be needed later.

I will talk about the wire first because you need to know the exact gauge of the wire BEFORE you print the 92 hubs. Many wires I have used 'advertise' gauge size and you get a smaller size. So wait till you have the exact wire on hand before printing any hubs. The BEST size is 12 gauge or 2.5 mm.

Some wires I have used are:

The soft 'aluminum hobby wire for jewelry'. Way to soft and WAY over priced and any color soon fades to gray. Good for smaller domes or spheres. Bends way too easily but easy to straighten and work with.

Another wire is #12 romex. Much stiffer but needs to be striped and straightened. The wires straighten well between 2 thick tiles. I stand on the tiles and roll the wire. Way too much work but the results are great.

Coat hangers are good but you can only get about 6 good straight pieces. That is about 50 hangers. Tough to cut and they RUST.

#2 awg aluminum electric wire. This is the typical wire to the main breaker box in a house. Very cheep or even free as leftovers. This is way TOO MUCH work just to strip, untwist the 7 strands, and straighten. Just cutting to size is a good workout....but it's free!

K+S precision metals #1115 aluminum tubing is great but one sphere cost me over $60. Brass tubing is good too. But I can't find it cheep either.

CPVC is good but it sags and looks like junk even painted. It is way too thick for a sleek artistic look.

My final choice is aluminum fence wire. I like that it is shiny, stiff, no striping, and long. It comes in 1/4,1/2,1 mile spools! So I got a 1000 feet spool for about 12 spheres. Tractor Supply sells smaller amounts. For making many spheres this is the quickest and easiest....BUT. Always something. Despooling gives nice round coils not straight rod like wire. This is too stiff to straighten with rolling between 2 tiles. So I had to make a wire straightener using 8 ball bearings, 2 oak slats, and 3d print wire guides. I can despool 8 feet almost straight. Then cut to 4 feet and run them once again through the straightener and they are almost dead straight.

Any wire you choose you will need 270 times the length of strut 'C'. In my sphere 'C' is 100mm * 270 = 27,000mm ... about 90 feet (100 for sure).

So pick your wire size and type, DO NOT cut yet...next

Any wire needs to be straight or I call flat. No bends or curves or kinks. To straighten some wires I use 2 THICK floor tiles. I tried to find 2 steel plates but no luck. This works best ONE wire at a time and shuffle your feet. Hold on to a bench too.

See other photos for the homemade wire straightener.

My other straightener is made from 2 scrap oak 3/4 x 1.5 x 14. It has 2ea 5 x 1/4 bolts and 8ea 1.25 x 5/8 bolts with 1 inch thick washers. I drilled 1/4 holes in the oak and then added some oil and the 5/8 bolts just screw in. The hard part is keeping the bolts in a PERFECT straight line. The ball bearings are standard 608ZZ (8x22x7) and fit the 5/8 bolts well. Need to 3d print the guides with PLA it flexes some. Some may split so print extra.

All my spheres in the past have been hard work because the HUBS all need to be the same.

Without a machine shop or lathe and just a hand drill this was impossible. The answer was 3d printing. This is GREAT fun. Many local libraries have them.

My hubs have large surface contact and holes higher up so they don't get distorted. Other hubs I have seen print unsupported base or the holes are too close to the base. ABS always curls upward when printed and this also distorts the strut angle. The other problem here is PLA is not for outside. If you read further most filaments DO NOT work outside. ASA and PETG say they could work outside. I have used PLA and ABS outside for almost a year without any failures or problems. I do not know how long any of the filaments will last and reading many articles nobody has a outdoor lifetime time frame. I do know that any plastic outside will fail and uv damage WILL happen. So I paint the entire surface of the hubs. I use a good plastic base primer spray paint. Always 2 coats. 24 hour to dry. Then 2 coats high GLOSS finish. AND I add 2 coats of a good uv clear coat just to top it off. That's 6-7 coats and 7 rain free days!

The wires need to be snug inside the hub holes. If you rotate the hub the wire should not fall out. If you need pliers to insert the wires into the hub holes... the holes are too small. Adjust the scale of the printer to get this correct BEFORE printing 90 wrong ones. (sorta did that). The hole depth will change with the scale and this will affect the size of the 'A' strut. Later instructions will correct for this.

The wires will be glued in place so too tight will knock off the glue and split the plastic. The hubs WILL shrink and this makes the holes BIGGER and the glue is all that holds the wire in place. Printing ABS curls the ends and distorts the holes and the strut angle. This will ruin the whole sphere. Be careful with the prints and quality control. I print ONE hub at a time. Check for distortions. Toss or save. Printing a whole bed of hubs requires a better printer and someone who knows how to run it.

I have only 2 hubs and 2 angles. The correct attack angle of the spares are 10, 11.5, 12. The 5 point is 10 degrees. The 6 point is 12 degrees. This is close enough to make a good sphere without distortions. If you make a wooden or metal dome 14-16 feet you NEED to have these 3 angles PERFECT.

You need:

80 each 6 point hexagon hubs

12 each 5 point pentagon hubs

paint paint paint paint and let dry

The best way to assemble is to make the 5 point pentagons first.

But do NOT cut all the wire yet. Just cut FIVE of the 'A' spars to length. Then FIVE 'B' spars to length. This step is critical for a good sphere.

pict 1 Take a 5p hub and NO GLUE and put the 'A' spars in hub.

pict 2 + pict 3 Spars should be even and raise up at a 10 degree angle.

pict 4 Then add 5ea of the 6p hub with 5ea of the 'B' spar. This should fit well. If you had to bend the wires to fit or they pop out or the whole thing is poofed out. Here is where you need to make adjustments in the wire lengths. If the pentagon is poofed out beyond a 10 degree angle, the 'A' spars need to be shortened. Start by trimming ONE mm from each of the five spars. I have found that corrections with only the 'A' strut is needed. When you get the pentagon to lay flat and have about a 10 degree angle in the center. Use these measurements for the whole sphere and cut all 'A' , 'B' , 'C' wires to length.

you need:
A = 60 ea

B = 90 ea

C = 120 ea

The more exact these are cut, makes putting the sphere together easy.

I use a stop block to cut to length. See photos.The fence wire will push the block because the wire is so stiff. Check for correct size frequently.

I have assembled spheres so many ways and half way through I get lost. So I now have a pre assembled sections that make it easy. These need to have the glue DRIED before making the sphere. One small drop of glue on the hub then insert the strut (wire, photo 3).

MAKE then let dry:

ALL 12 ea ... 5 leg hubs with 'A' strut.

60 ea ... 6 leg hubs with ONE 'B' strut.

15 ea ... 6 leg hubs with SIX 'C' struts

5 ea ... 6 leg hubs with FOUR 'C' struts

see you tomorrow!

Now take one of the 12 pentagon stars (dried) ... and add one hexagon (one spar) to it. Then go around the edges of the pentagon with all 5 hexagons (photo 3). Use rubber bands to hold in place while the glue dries. Check that the pentagon lays flat. All 5 points touch the bench. Make ALL 12 pentagons. This will use up ALL the 5 leg hubs and ALL the 'A' spars. Then add 5 'B' spars to TWO of the assemblies (photo 6).

let dry....see you tomorrow.

I have worn out this photo. EVERY dome/sphere I ever made I referred to this constantly. I know it will help.

Photo one is the pieces you need on hand and DRY. The spars will keep coming out of the hubs as you assemble the domes. To minimize this you need a supply of rubber bands and have the assemblies fully DRIED. Or have six to ten people help with the build!

You MUST have enough time to build one full dome. The uncured glue allows movement of the spars to insert them into the hub holes. And to keep the dome symmetrical.

Here is where words and photos don't help much. It is like telling someone how to solve a rubic cube over the phone. But here goes...Think of ALL the pentagons as connected at each spar to another pentagon with a 'B' spar. This is photo 3 + 4. Marking the end of the dome pentagon will help. There will be a marked pentagon connecting 5 other pentagons forming the dome. (photo 7) In photo 4,5,6 this will be the start of the dome connecting the pentagons to pentagons. The void is filled with the hexagons (photo 8).

The above is just an explanation not the actual build in steps. Nothing is glued in the photos just a layout

Start with the MARKED pentagon and add one pentagon and one hexagon. Use glue at each joint that connects.Work your way around all 5 pentagons with 5 hexagons nestled between them. This will give you a nice shaped dome. Check ALL pentagons have connections to another pentagon via a 'B' spar. Use rubber bands to hold the shape and set on a flat surface to check that All points touch the surface. (photo 3).

Before the glue dries.... ONE dome gets 5 hexagon stars (all 6 legs photo 4) It will look like photo 5 but with less spars. and should lay flat to a surface.

The second dome gets the 5 hexagon 1/2 stars (4 legs photo 6) It will look like photo 7 and when on a flat surface the pentagons will touch but the 4 leg hexagons will be slightly up. (photo 8)

Both domes should be flat to the bench and have a nice round shape.

let dry....see ya tomorrow

There should be 2 domes. One with all flat spars photo 3. Dome 2 should have 5 hexagon spars touching the bench with some voids between. This dome gets 'B' and 'C' struts to fill in and make flat photo 2. Any leg of a pentagon will get the 'B' strut photo 1 blue tape. Think of it as extensions of the pentagon struts. All leftover gaps are filled in with 'C' spars. The dome should lay flat when done photo 2.

Let this set a few hours but so close to the end I have just gone ahead and put the two domes together.

The 2 domes will fit by connecting the pentagons to the hexagons. Start at one end and circle around the domes to close them together into a sphere. See photo 4 the yellow pentagon touches the hexagon below.

The finished sphere/dome may need rubber bands till the glue dries. This is your last chance to give it a ROUND shape.

Inside or outside the sphere expands and contracts. This glue is flexible but the sphere still needs support. A wire from top to bottom will support the weight. In larger spheres they need crossing wire supports from each pentagon on opposite sides. This makes a diamond like interior web. My spheres made with tent tubes all shifted and I had to drill very small holes through each hub connection to insert wire ties. Most geodesic domes are assembled with bolts and hing at the hub-strut joint. The tube domes need 'through' bolts (wire) to keep them in place. I have dropped some of my spheres and whacked one that had a squirrel inside. To my surprise the spheres just needed some slight straightening.

last photo shows a double hook for hanging with a pole.

THANKS FOR READING THIS.... oldmaninSC