vaderdarth
Master Member
Chris is right. Needs to be offset. If it already is, I apologize, I'm just going by the photo. Peace,
Dave
Dave
Building The Death Star - PRODUCTION
- Thread starter PHArchivist
- Start date
PHArchivist
Master Member
Chris and Dave, its not off-set. The wooden arc is centered on the poles as exact as I could get it.
Your observations are correct. But the challenge I incurred is that my arc/guide is 12mm wide, versus just a thin strip of acrylic on the original. I wanted it centered though (true poles as close to the 6mm width point of the arc) so that it will swing in as close to a true circle as possible.
I think the trick wil be to get the marking tool (pencil, whatnot) centered on the width of the arc, perhaps between the wood and the model.
Your observations are correct. But the challenge I incurred is that my arc/guide is 12mm wide, versus just a thin strip of acrylic on the original. I wanted it centered though (true poles as close to the 6mm width point of the arc) so that it will swing in as close to a true circle as possible.
I think the trick wil be to get the marking tool (pencil, whatnot) centered on the width of the arc, perhaps between the wood and the model.
If you offset your arc (not the mount) so one side of the board is centered on the pivot/mount, you will accomplish what he is talking about and it will still swing true. That is one of the advantages of having a square mounting point.
-Adam
vaderdarth
Master Member
Exactly, it's not the arc that needs to be centered, just the mounts. You want one edge of the arc to be centered so your vertical lines all head directly to the pole. The way it is now, you have no way to draw lines remotely close to being lined up on the poles. if your arc is 6 mm wide, your lines will be off by 3mm. Does that make sense? I'm assuming you want to use the arc as your straight edge when drawing your north to south lines????
Dave
Dave
If he's clever ... and he seems to be... He can mount the pencil/scibe tool/ whatever he's using, such that it mounts to the side of the arc and comes in at an angle such that it makes contact with the surface in the center of the arc. since the arc is centered the center of the arc will head to the poles... just thought I'd throw that out there.
Jedi Dade
Jedi Dade
I thought about this as well, but the hard part would be to keep the pencil and the exact angle everytime. I think the offset of the arc would be best.
If I know Rob, if there is anything worth doing right, then it's worth OVERDOING!
Brad
PHArchivist
Master Member
Too true! I'm already re-thinking this...
Was toying with the thought of a 1"-2" wide strip of heavy-gauge styrene or thin acrylic that is heat-formed to follow the curve of the domes, and slotted down the center to run the marking pencil.
The strip of plastic would lay flat on the surface, and the center slot would align with the poles (I'd worry about clearing the lip of the dish later).
At the south pole, I could widen out the strip such that there could be a hole in the strip for the PVC pipe.
PHArchivist
Master Member
I'm such a dip**** sometimes... ALL ALONG I thought the acrylic in this picture was perpindicular to the surface, like a blade sticking up.
Now I realize they did it just as I described in my last post, minus a slot. The clear band in this pic lays flat against the surface (well, not quite in contact with the surface). Without a slot, I wonder how they solved the problem of the edges of the guide not aligning with the poles...
Now I realize they did it just as I described in my last post, minus a slot. The clear band in this pic lays flat against the surface (well, not quite in contact with the surface). Without a slot, I wonder how they solved the problem of the edges of the guide not aligning with the poles...
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PHArchivist
Master Member
Christian, a combination of techniques and a bunch of trial and error! It was one of the hardest things I had to do so far.
vaderdarth
Master Member
Rob, I used to "etch" the details into aluminum R2D2 domes some time ago. I used a styrene strip, which was thin so also flexible. There was a dead center hole in the top of the dome, I drilled the same size hole in one end of the strip and drilled holes in the center of the strip where I wanted horizontal lines. Then attach the strip to the top of the dome with a nail and use a pencil to simply sketch my lines on the dome. For the vertical lines, I used the same strip to mark the start and stop points, but removed the strip, and then used it as a straight edge and simply drew from point to point. It's a PIA, but it will allow everything to line up on the poles. You have to do the top and bottom domes separately if you did it this way.
Dave
Dave
PHArchivist
Master Member
Given more thought, cutting a slot is unncessary...
Here's my current plan: I'll cut this shape from heavy gauge styrene or thin, flexible acrylic (like in the shot of the original).
The upper green dot in my diagram represents the north pole, and the upper mounting point of the guide.
The circle at the bottom is to accommodate the PVC pipe strut. It will be cut on the red line, then reattached to hold to the PVC. The lower green dot represents the south pole.
Precision of course depends on if the PVC perimeter/circumference sits precisly equidistant from the true south pole. I don't know if it does. :unsure
Here's my current plan: I'll cut this shape from heavy gauge styrene or thin, flexible acrylic (like in the shot of the original).
The upper green dot in my diagram represents the north pole, and the upper mounting point of the guide.
The circle at the bottom is to accommodate the PVC pipe strut. It will be cut on the red line, then reattached to hold to the PVC. The lower green dot represents the south pole.
Precision of course depends on if the PVC perimeter/circumference sits precisly equidistant from the true south pole. I don't know if it does. :unsure
vaderdarth
Master Member
Perfect!
I don't think that will work to your satisfaction.
I tried a similar thing on my first R2 dome. The plastic will flex and bow giving you unstright lines. I wound up repurposing a stainless ruler, not possible in your case.
I think you'd be happier with the plex you have now with a block to off set it a 1/4 inch or so.
BrianM
I tried a similar thing on my first R2 dome. The plastic will flex and bow giving you unstright lines. I wound up repurposing a stainless ruler, not possible in your case.
I think you'd be happier with the plex you have now with a block to off set it a 1/4 inch or so.
BrianM
Given more thought, cutting a slot is unncessary...
Here's my current plan: I'll cut this shape from heavy gauge styrene or thin, flexible acrylic (like in the shot of the original).
The upper green dot in my diagram represents the north pole, and the upper mounting point of the guide.
The circle at the bottom is to accommodate the PVC pipe strut. It will be cut on the red line, then reattached to hold to the PVC. The lower green dot represents the south pole.
Precision of course depends on if the PVC perimeter/circumference sits precisly equidistant from the true south pole. I don't know if it does. :unsure
houdiniguy
Sr Member
The work here on this is brilliant!
I would love to get one so bad.
How large is this sphere shown?
Perhaps some leds that lite and pulse from gun area as well?
Kits when done?
Tom
Who can I commission for a 1:1 life sized one?
I would love to get one so bad.
How large is this sphere shown?
Perhaps some leds that lite and pulse from gun area as well?
Kits when done?
Tom
Who can I commission for a 1:1 life sized one?
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