Author Topic: Earth and Moon  (Read 2390 times)

Offline BillTodd

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Earth and Moon
« on: May 07, 2019, 06:23:55 AM »
50 years ago... a human stood on the moon.

Now, I'm building a garden ornament to celebrate   :)

The Earth :  here represented as a 300.00mm aluminium oceanographic target ball (scrapped after a minor telephone related cockup )  It'll stand on another piece of 350 x 180mm Diameter bar and one of the many 500mm x 13mm discs of invaluable scrap we seem to generate at work every day.

Work holding proved to be tricky (the set up worked but wasn't the most secure) First task was to bore a 1100 mile diameter bearing pocket into the south pole - the problem here is that I didn't have head-room for a boring bar so had to rely on the cnc interpretation of a circle which ,due to backlash, was rather elliptical , a second pass in the opposite direction got it close enough for a minor planet ;-)

The bearings drop onto a 25mm stainless bar fixed into a convenient hole in the middle of the scrap bar (it was too big for my lathe and too tall to bore in the mill (just managed to pilot a hole circle in the bottom ).

Next...

The Moon :  To be a 81.75mm aluminium ball (just a tad too big to use my ball turner  :scratch:). Not sure how to mount this yet
Bill

Offline BillTodd

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Re: Earth and Moon
« Reply #1 on: May 07, 2019, 06:30:40 AM »
Unfortunately the pics of making the stand didn't develop (damn this digital chemistry).

so here's a pic of the thing so far (I may mill some flats or flutes on to the column - looks a bit plain ATM).
Bill

Offline PekkaNF

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Re: Earth and Moon
« Reply #2 on: May 07, 2019, 08:46:27 AM »
Sooo.... since they are scale - where are you going to place the moon? I mean it is pretty long way to keep everything in scale.

Pekka

Offline BillTodd

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Re: Earth and Moon
« Reply #3 on: May 07, 2019, 10:49:31 AM »
8.7m away  . should fit on my front lawn  and puzzle the locals for a while .
Bill

Offline awemawson

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Re: Earth and Moon
« Reply #4 on: May 07, 2019, 11:26:30 AM »
Think of the traffic accidents if you tether it with string  :lol:
Andrew Mawson
East Sussex

Offline PekkaNF

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Re: Earth and Moon
« Reply #5 on: May 07, 2019, 01:27:33 PM »
8.7m away  . should fit on my front lawn  and puzzle the locals for a while .

Very good! Hope that curious ones will connect the dots.

That is really cool.

https://tomroelandts.com/articles/earth-moon-system-to-scale

Pekka

Offline BillTodd

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Re: Earth and Moon
« Reply #6 on: May 07, 2019, 02:18:18 PM »
I've been wanting to put together a scale solar system for a few years now.  The governors of the local park sounded keen but seemed to find an increasing number of obstacles to put in my way without trying in anyway to help.

I may try again with a different park (nearer the school so I may get a better response) . It'll take the whole length of the park plus most of the length of the school road to fit in all the planets if I use the 300mm ball as the sun.

Bill

Offline BillTodd

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Hard cheese
« Reply #7 on: May 11, 2019, 02:43:46 PM »
I thought of a couple of ways to machine the moon sphere :

First thought was using a boring bar in vertical mill with part at an angle in a dividing head  - but my boring heads are too small to swing the 80 - 100 mm necessary for the trick to work.

In the end I decided to adapt the horizontal mill into a ball turner using a rotary table and a cheap Soba boring head.

Holding the work was a puzzle,  but simply turning  short int30 register on one end and holding the part directly onto the spindle with a 12mm draw bar worked out perfectly.

I'm having fun and games with chatter ATM (it's not the best rotary table ever made) but I've still cot a couple of mm to remove from the diameter so I'll play some more tomorrow.



Bill

Offline BillTodd

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Over the Moon
« Reply #8 on: May 12, 2019, 09:38:54 AM »
Solved the chatter problem with a piece of ground and honed high speed steel . Then lashed-up a 'power feed' for the rotary table 'cos it was difficult to turn slow and consistently.

The result was better than expected, so i couldn't resist applying some grey scotchbrite, elbow grease and T-Cut ...

I'll leave it on the machine for the moment while i work out how to mount it and what to do with the south-pole.

Bill

Offline PekkaNF

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Re: Earth and Moon
« Reply #9 on: May 12, 2019, 09:42:49 AM »
That looks very nice.

OT: Tell me more about that PSU. Barrety pack and some sort of voltage controller?

Offline BillTodd

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Re: Earth and Moon
« Reply #10 on: May 12, 2019, 09:55:38 AM »
That looks very nice.

OT: Tell me more about that PSU. Barrety pack and some sort of voltage controller?

Ta  :)

It's a useful little battery powered supply  made from a 'Ruiden' (? - search ebay for 50v 5A psu) Chinese made power supply module (cheap and very good) in a di-cast box. Inside is a  step-up converter (250 Chinese watts!) so 18v from the battery will give up to 50v out if required. On the back, is a home-made  DeWalt 18v battery adapter  (carved from a piece of nylon)  and a XLR plug for and external psu (old laptop supply).
Bill

Offline WeldingRod

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Re: Earth and Moon
« Reply #11 on: May 12, 2019, 10:06:44 AM »
I saw the display; I thought those were step down supplies!  Is there also a step up brick?

A super sneaky idea!

Sent from my SAMSUNG-SM-G891A using Tapatalk


Offline awemawson

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Re: Earth and Moon
« Reply #12 on: May 12, 2019, 10:07:17 AM »
Now Bill, I understand that the Earth is not a true sphere, but is rather 'squashed flat' at the poles, but I don't know about the Moon. Should your models actually BE  spheres, or do they need a session under my 60 ton press ?

Nice work by the way   :bow: :thumbup:
Andrew Mawson
East Sussex

Offline BillTodd

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Re: Earth and Moon
« Reply #13 on: May 12, 2019, 12:09:39 PM »
I saw the display; I thought those were step down supplies!  Is there also a step up brick?

A super sneaky idea!

Sent from my SAMSUNG-SM-G891A using Tapatalk

Yes another cheap chinese module . It can be switched in when necessary  . very handy for testing 24v stuff.
Bill

Offline BillTodd

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Re: Earth and Moon
« Reply #14 on: May 12, 2019, 12:30:23 PM »
Now Bill, I understand that the Earth is not a true sphere, but is rather 'squashed flat' at the poles, but I don't know about the Moon. Should your models actually BE  spheres, or do they need a session under my 60 ton press ?

Nice work by the way   :bow: :thumbup:

 :smart: The earth is only about 20km out of "round"   (radius) at my scale that's not that far off from the machined tolerances and well within the current condition of the ball (the boss decided to re-enact the rolling stone scne from Raiders of the lost ark by bowling it down the loading ramp  :Doh:) .  For comparison, the 100km of our atmosphere would be only 2.3mm thick.

The moon is even 'rounder' and definitely rounder than my ball  :D
Bill

Offline AdeV

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Re: Earth and Moon
« Reply #15 on: May 13, 2019, 12:53:43 PM »
I've been wanting to put together a scale solar system for a few years now.  .... It'll take the whole length of the park plus most of the length of the school road to fit in all the planets if I use the 300mm ball as the sun.

Hmm.. slight issue there: If the Sun is represented as a 300mm ball, then the Earth (if it's to scale...) will be a 3mm ball  :bugeye:

I suppose the advantage is, you can probably buy one off the shelf  :lol:
Cheers!
Ade.
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Or: Zhengzhou, China. An even longer way from anywhere...
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Offline BillTodd

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Re: Earth and Moon
« Reply #16 on: May 13, 2019, 01:37:24 PM »
I've been wanting to put together a scale solar system for a few years now.  .... It'll take the whole length of the park plus most of the length of the school road to fit in all the planets if I use the 300mm ball as the sun.

Hmm.. slight issue there: If the Sun is represented as a 300mm ball, then the Earth (if it's to scale...) will be a 3mm ball  :bugeye:

I suppose the advantage is, you can probably buy one off the shelf  :lol:

Yes (smaller actually) but that's the point one can grasp the relative sizes quite easily but the distances between things is mind boggling!

 Once you've got in your head the scale of the solar system and the fact that the earth is a tiny bit of dust orbiting a tiny star  - there are stars out there that are larger than the whole solar system - the red-ish colour one top left in the orion constellation for example - you can really start to imagine the scale of the universe .

"let's hope there's intelligent life
 somewhere out in space ..

'cos theres bugger all down 'ere on earth"    (monty python)

Bill

Offline AdeV

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Re: Earth and Moon
« Reply #17 on: May 13, 2019, 02:39:05 PM »
Comedy AND intelligence - you have to hand it to the Pythons - they were capable of incredible stupidity, but also breathtaking genius - and all of it whilst making you laugh your arse off...

Cheers!
Ade.
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Offline mattinker

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Re: Over the Moon
« Reply #18 on: May 14, 2019, 05:34:54 AM »
Solved the chatter problem with a piece of ground and honed high speed steel . Then lashed-up a 'power feed' for the rotary table 'cos it was difficult to turn slow and consistently.

The result was better than expected, so i couldn't resist applying some grey scotchbrite, elbow grease and T-Cut ...

I'll leave it on the machine for the moment while i work out how to mount it and what to do with the south-pole.

I really like your ball turner! Will definitely use that idea!!


Regards, Matthew

Offline BillTodd

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Re: Moon
« Reply #19 on: May 16, 2019, 02:44:47 PM »
Knocked up a quick stand - or would have been quick had it not been too long for the lathe

Looks all nice and shiny, much better than the earth , so might have to take a power mop to the globe .

Bill

Offline BillTodd

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Re: Earth and Moon
« Reply #20 on: May 22, 2019, 08:55:58 AM »
I've placed to moon and earth on the front garden (it amused the neighbour :-)) .

I've skewered the moon base into the real earth to make it a bit less 'portable' (we don't get too many light-fingered types around here but...) and set a camera up to catch reactions (if any) .

incidently my , overgrown , tree is about the same size as one of Saturn V's  F1 rocket engine .
Bill