i'm heavily into my third dome but am a little hung up on workable ideas for wooden hubs. i'd like the hubs to be made out of wood for the look & feel once you're inside. plus i have access to lots of ash struts & with this idea could use ash for the hubs as well. if you imagine you take a cross section of the tree, perhaps 5cm deep like this:
& then they've gotta be? 30cm wide?
if i was then the drill holes for the struts at the correct angles(?) is this sounding like a good idea?
has anyone else heard of such disc hubs.. & if anyone could give me some tips on the angles & spacings of the holes that would be a godsend. i''m working on a 2v at the present time. Regards. Adam.
[ Comments 18 ]
It could work.You would have to take the diameter of hub into account for calculating the strut lengths. Depending on the diameter of the ash struts 5cm thick hubs may not be enough to accomodate the strut angles.The angles for a 2v are 16 and 18 degrees which need to be drilled into the edge of the flat hub.
sounds like there might be a better approach? :)
Here`s a graphic of the hub angles for Adam and anyone interested building a 2v hub and strut dome.
Hi Wind, Rather than use an ash disk for the hubs have you considered turning an ash ball then drilling the holes. I think a ball would be less likely to split (as you have more wood) and would look pretty cool.
wow thanks for the idea. i would love to do that it sounds amazing.. i'll have to look into it - i've never done something similar before but i am loving the sound of it!!
& also, thank you colin. the diagram is just what i needed to know.
hi, admin, do you have any info or resources to share on how to go about turning these ash balls? i wonder how many you could get out of a tree.. any idea of what kind of radius we'd be looking at? i'm eager to make this happen & i think this could be the breakthrough i've been searching for
The radius would have to be sufficient to accomodate the strut diameter at the smallest radial spacing, 58 degrees in the case of a 2v. If the ash struts are an inch in diameter the spherical hub needs to be 6.25 - 6.5 inch in diameter to be safe. The struts would be embedded by about 2 inches.
I came across this step by step for turning wooden spheres which may be of interest(replace the x with h)
Sorry for the late reply wind, had a touch of man flue. Anyway had time to ponder this problem and this is my best effort.
Spin up half spheres on the lathe and cut a grove and angle like the diagram below. You would need to turn all the spars ends with a small ball to lock into the hub though.
No angles to worry about and all the turning are the same so you could have them copy turned.
*i cant share my linked image because of the changes to the forum regarding attaching images to replies!!*
~> can you help admin??
I've got a design knocked up from another forum..
You can see that they are cut out of 250mm dia circles (10"), 100mm deep (4"), with faces sloped back to allow for the angle between adjacent pentagons/ hexagons.
this would be laminated out of 25mm thick pieces, with the grain direction turned 22.5 degrees each layer (ie half of half a turn).
good waterproof glue would be used, and clamped up well. Bolts may even be used through the corners after that.
as experienced dome builders ~ is this a sound design? if i make several of these & get well formed hexagons / pentagons, are there any possible complications when it comes to assembling the entire dome?
Many Thanks again for your time!
Sorry about that Adam, I'm working on a fix for uploading pictures. You can still upload, if you paste the code into the contact form I'll add it manually... seeing a picture would make it easier to grasp.
Photo? I'm curious if anyone has the contact information of the person who took that cross-section photo? I'm interested in paying to use it in a printed piece. Please email email@example.com if you know!
Does anyone have the hub angles for 3v and possibly 4v just like the 2v example in this thread?