@ Frenchy:

I have made an irregular geodesic dome with just a few flats. What you see are the rafters of a part of the dome, already cutted from the hull.

May be, I have made a mistake, when I shelled it with TC, because I can remember I´ve read inch in the imported file, but I made a shell of 10 and in MOI I have decimal again. Don´t know. But the proportions look for good. I will make it with wood.

Hi Rudl, there is a mitering mechanism in MoI in Sweep, it's when you do a sweep of a profile around a one-rail path like so:






However, it's meant to be used on a regular path curve where there is at most 2 segments joining together at any single common juncture.

The way that sweep mitering works is by generating a longer extended piece which then has its ends trimmed off by a miter plane created at the juncture area.

For your case you could either do that same kind of approach that sweep takes internally where you would build a larger extende piece and then trim it to a common cutting plane and then join the pieces together, or possibly you could use the mitered sweep on your 3 branched one if you did half of a profile at a time and did 3 different paths.

- Michael

Attached here is an example for doing 1/3 of your shape by a sweep - note I've slightly modified your shape here so don't use it directly.

But here you can see 2 lines joined for the path, and then the profile is 1/2 of your end shapes.

You can select that profile then run Construct > Sweep, select the 2-line path for the rail and that will generate I think 1/3 of the shape that you want, then you need similar things set up for the other 3 zones and then you can boolean union the results together.

Note that the sweep profile should be perpendicular to the line path, not slanted - the ends of your original shape are slanted, you would probably introduce the slant later on by slicing off the ends.

- Michael

https://groups.google.com/forum/?fromgroups#!forum/geodesichelp ;)

Also a quick note that may help you with some of the constructions that you're doing - if you make 2 construction lines cross each other at a single point there will be a "normal" snap for the line that is perpendicular to both of them.

So for example 2 lines like this that are not flat to any world plane:




Start the line command and drag 2 construction lines each of which starts at that end and goes tangent to those lines:




Then you can place the first point onto that same spot, and for the second point there will be a "normal" snap at the shared perpendicular:






That may help you in some situations to get some element drawn where you need it for building a cutting plane or whatever, without needing to set a cplane for that situation.

- Michael

here the clumping of 3 pieces on a flat plane

Clumping at half

Will be the same process with the inclined beams ;) jags of course will be different and little more complex but easy to make like these one :)

Does this resist to the compression...rotating ejection...shearing...Twisting ...???

Easy to trim in reality ? :)



And you can put a little connector (the circular piece) top an bottom for solidify ;)

By Dave

<< It would be very difficult to accurately cut the final joint on the ends of the beams and I don't think there's enough surface area to to make a strong joint. You'd need to add some sort of plates top and bottom, I think, to hold the beams together and then I would guess the joint on the end of the beams is unneeded complexity.

<< I think the joint could be assembled but keeping it assembled would be the challenge.

<< As for sources for joining more than two pieces of wood like that, you might look for Japanese joinery techniques. there's a lot of stuff on the web about it. It's not very common in western woodworking and carpentry to put pieces of wood together that way and when it is done in carpentry applications (geodesic domes for example), it isn't really joinery because the pieces would get bolted through a common plate. The time required to actually create a joint such as what you've drawn* wouldn't be appreciated. In Japanese woodworking, though, that sort of work would be valued very highly.


* my Moi 3D Draw above ;)

Mitre joint, as I´ve found out is not what I want. I just want simple mitering. My solution now is to draw polylines, make them planar and afterwards a Boolean differenz.

The joint will be made with steel.

Sure more easy and prudent! ;)