Dear all
I am in the process of making a large globe of the planet Mars and thought it might be interesting to some people to see how it goes. Since it is a globe of a planet it seemed that PASA was the best place to put the thread (apologies if this is wrong)
Here is a little background to this project.
I have previously made a largish globe of the moon (see below)
It is an enlarge version of Ken West's Moon model. I enlarged by 150% which gave it a diameter of about 50cm. Just to not the model was available for download on ecardmodels before the rebuild, however it is not been uploaded since the rebuild. Hopefully it will reappear there in the not too distant future.
My current project of a 1/24 Saturn V rocket is coming to a close but there was quite some time whilst I could not work on it. So this got me to wanting to start something else, but, I felt like trying something with a lot less parts and more manageable.
I like the finished moon globe and globes in general seem interesting and pleasing to lots of people. So I wondered "just how big could I make a paper globe?"
I settled on 75cm diameter as I thought this was probable the maximum size possible (given the experience of the moon globe) and also the major reason that is the biggest it can be and still fit though the door to remove from my home (an essential criteria my wife told me!)
I considered doing the moon globe even larger than before but 150% is really as much magnification the images can take. So after some hunting around I found something that really grabbed my imagination, namely a globe of Mars and was in very high resolution. This was a really good to me as I am very interested in Mars and think the surface is very visually intersting so makes a really nice globe.
It is on the USGS website
https://astrogeology.usgs.gov/search...s_viking_globe
Here is the template
A quick calculation meant I wanted to enlarge 230% a a little test showed that the resolution is still fantastic after this enlargement. I would have to print is off in sections (using the "take a snapshot" option in adobe). In total there would be 123 pieces.
The first piece is the north pole.
As you can see "a piece" is printed on to a sheet of A4 and then cut out. I used 250 gsm paper. Other than the two poles, "a piece" was two "segments" as drawn on the globe (going around the latitude rings, if you get what I mean)
Here is the first piece of the ring joining onto the north pole (which show what I mean)
I started joining the segments using "joiners" as shown
And here is that ring finished
With the previous moon globe it was strong enough to support itself, however if you were to press on it it would "dent" and stay dented. So to get round this problem for the moon globe I inserted and inflatable beech ball inside the globe and pumped it up to a pressure to repel any denting. Of course the beech ball puts some pressure on the joints of the globe (and not necessarily evenly distributed. To strengthen the inside of the moon globe I first covered all the inside with sellotape and then on top of that covered all the inside with duck tape. I decided to use the same system for the Mars globe.
So here is the tapes I use
When adding the sellotape you have to leave some gap for the next ring to join and you also need to leave a gap from the edge of the sellotape to the duct tape (so you can add the next ring of sellotape). So there is a lag between the ring, the sellotape and the duct tape (pictures will make it clear I hope). So here is the sellotape covering the north pole and join of first ring
Next up is the second ring. However by now I have realised that the globe looks just as good without using separate joining tabs and is easier doing it this way. So here is second ring done, then sellotape and then the first of the duck tape can be added
A useful thing I found was to draw a pencil line around the "top" of the current sellotape boundary. This made it easy to see where to overlap the next layer of sellotape too.
Here is the globe up to this point
As you can see it is already getting quite big.
Regards
Kevin