|
Post by Vermin King on Nov 20, 2015 16:23:58 GMT -9
Okay, not so much a request for someone else to do it, as a request for a nudge in the right direction. My original idea was to have this as an entrance to an underground facility. The Shakespeare Birthplace inspired the concept, as strange as that sounds. The inspiration was that it is a model built inside out creating an all white exterior. What better way to yield a snowy mound? So the thought was to use a truncated dodecahedron for the mound. Then remove one of the facets, and have the bunker face fill the void. The truncated dodecahedron was easy enough. I even think I have the geometry of the base figured out, but other than cutting things out, trimming, edging and scanning (seems like the caveman way of doing things), I'm having difficulty wrapping my head around the dimensions of the face. Anyone have ideas?
|
|
|
Post by bluecloud2k2 on Nov 20, 2015 19:04:20 GMT -9
The only thing I can come up with is build the box and measure the gap...
Maybe lay it on paper and trace it. Would also work for getting the base outline.
|
|
|
Post by Vermin King on Nov 20, 2015 19:25:05 GMT -9
For the base, I just copied the central pentagon and expanded it until the side was the same size as the bottom of side piece.
I wish I could find a protractor. I wonder if they'd have one at Dollar General. BTW, if you use brush on Super Glue, the same size that sells for $2.97 at Michael's is only $1 at Dollar General.
|
|
|
Post by lightning on Nov 21, 2015 1:46:46 GMT -9
given:r1 ... radius top r2 ... radius bottom h ... height a(lpha) .... 360/5 looking for:r1 = h1 * cos(a) -> h1 = r1/cos(a) r1 = w1 * sin(a) -> w1 = r1/sin(a) -> wt = 2*w1 r2 = w2 * sin(a) -> w2 = r2/sin(a) -> wb = 2*w2 rd = r2 - r1 (the difference bit of top to bottom radius) d^2 = h^2 + rd^2 -> d = sqr(h^2 + rd^2) but also for the triangle d, x and ht x = (wb - wt)/2 d^2 = ht^2 + x^2 -> ht = sqr(d^2 - x^2) i think this should cover all you need. does it help?
|
|
|
Post by Vermin King on Nov 21, 2015 6:52:54 GMT -9
Bless you and your family to a hundred generations! 'rd' is stupid easy once I saw your diagram. 'h' still seems like the easiest way to find, is to just build and measure. Thank you
I think I just mostly needed to step away and look at this with fresh eyes.
I'm also making this more difficult than it needs to be. The front bunker walls need to cover the gap, but they do not have to perfectly match the edge of the mound. If you have a retaining wall, and it doesn't extend past the edge of the ground a little, you are playing things too close.
Something tells me that a 3d modeling program would make this easier
|
|
|
Post by mproteau (Paper Realms) on Nov 21, 2015 7:56:21 GMT -9
Using SketchUp, you can drop in a 5 sided polygon, push/pull it to the desired height, scale the top or bottom to the desired size, then drop in some lines to carve out the door. Once you've done that, you can pull apart the sides pretty easily and rotate them to make the image flat (or use a plugin to help - I don't typically bother). Now that it's flat, it's pretty easy to measure everything. I redraw it in GIMP by laying down guides at the right position and just connecting the dots. Getting used to SketchUp can be a chore, but then again, getting used to GIMP was a chore, too. Once you have the hang of quickly selecting what you want and rotating things how you want, it becomes pretty straight-forward. I use these models with textures applied to and make instructions and promo pics. Just another option to consider.
|
|
|
Post by lightning on Nov 21, 2015 8:43:13 GMT -9
and you and your family :-)
yep, in blender with the unfold script (or any other working flow) this would be done in warp 5 ;-) but for simple shapes it's a good training to construct it either old school with pencil, ruler and compass or calculate it like here.
i agree, that often it helps to step back, take a deep breath and the solution will come. also i have often experienced that just explaining the problem to someone helped get my brain working again.
if you need help with blender let me know. maybe i can give tips there too.
|
|
|
Post by Vermin King on Nov 21, 2015 16:06:54 GMT -9
Well, I decided to manually determine the necessary piece to fill the opening. Marked the width of the face of the bunker along the edge of a scrap piece of card and folded at the width markings. Used a pencil to mark the scrap card. One of those times when a third hand would have come in handy. I scanned the piece in, but haven't done anything with it, yet. To get a reasonably close trace on the card, I had to glue the dome together first for rigidity, making it useless for being part of the next iteration. So I cut out the filler piece and drew some ideas on it, gluing it in place. The hole is smaller than I anticipated, so instead of building a 3D insert, I'm thinking of doing very faint fold lines on the snow to build normally, but have a thickness of concrete retaining wall along the opening edge.
|
|
|
Post by Vermin King on Nov 21, 2015 20:27:54 GMT -9
|
|
|
Post by Vermin King on Nov 21, 2015 20:57:40 GMT -9
Done! I think I'll throw this in the Hoard
|
|