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  #21  
Old 26-04-2011, 11:01 AM
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jjjnettie (Jeanette)
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Steve, I'll have a look in the shed next time I'm at the other house.
There was a bucket full of bits and pieces, and I'm pretty sure there was some spare rollers.
I think that they originally came out of starter motors
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  #22  
Old 27-04-2011, 09:02 AM
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Quote:
Originally Posted by jjjnettie View Post
Steve, I'll have a look in the shed next time I'm at the other house.
There was a bucket full of bits and pieces, and I'm pretty sure there was some spare rollers.
I think that they originally came out of starter motors
Hey, i grabbed that bucket but there was only 1-2 in there.

I think its going to need about 6-8 or something. Next time im at mums I will take a trip out to the local wreckers and see what they say.

They look like larger bearings that have been inserted in a peice of pipe or similar.
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  #23  
Old 27-04-2011, 10:27 AM
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I think I have found my rollers...

http://cgi.ebay.com.au/10pcs-20mm-LM...item4158cd4efb

32mm wide 40mm long Linear Bearing

Attach a 20mm shaft and we good 2 go
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  #24  
Old 20-06-2011, 09:17 AM
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Update

Hi All,

This past weekend was an amazing day under the QLD sun!

I got stuck in and cleared about 1/2 the garden for the observatory.
It was sooo good being out in the sun in the warmth.

Images included :
A 360 Panorama. I used Panorama Factory to do this, FANTASTIC SOFTWARE!
What i cleared saturday
the sun and sky
the KILLER blackbean tree!!!. those nuts are huge and hurt when they fall on your head.
what i cleared sunday, inc my kingcat, gotta love that thing.
what i removed. so many bricks as well.
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  #25  
Old 03-11-2011, 11:54 AM
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Gday all, just a quick update.
I finally got around to getting some plate steel for the top of my pier design. I ended up with 4x 10mm x 200 x 200 which i intend on welding 2 pieces together to make 20mm thickness pieces. i also may bore out the holes in the corners from 14mm to 19mm for 18mm bolts.

Also I picked up some pipe which might make good rollers, 2 cheap bearings jammed into the pipe to make longer rollers.

Progress is slow as money is extremely short at the moment.. but its getting there.

Thanks all for your support, I expect to be up and running late 2013
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  #26  
Old 21-11-2011, 09:02 AM
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Update

Hi All,

Thought I would upload the 1st and possibly final Pier design.

some measurements are not on the PDF, thos measurements are "wildcards" meaning the bolt diameter for example can change.

The plates i mentioned in an earlier post, the center of the hole are actually 25mm in rater than 20mm in the pdf.

The pier consists of 7 pieces.

The base 300x300x20mm

The Pier 165mm pipe 5mm walls

Top and Bottom plates 2x 200x200x10mm welded together to make 20mm thickness. (all i could get)

Bolts either M12 but up to M20 depending on what drill bit I can get, I need to modify my press as it runs a little fast for a 20mm bit.

Adapter plate, 150mm aluminium turned and machined on a lathe by a fellow ISS memeber, the plate is fantastic and fits the EQ6 perfectly.

Similar design to http://www.altairastro.com/product.p...9&cat=0&page=1
Mine is just a little larger and not anodized

I also have comming from ebay some bearings in various sizes to trial making my own rollers for the dome. The plan is 2 bearings inserted in the ends of some pipe.

I have also attached an almost to scale 12" scope to get an idea of what it will look like.. remember its almost to scale, it was a quick "I wonder what it will look like if I do this".

On a side note, I have also started constructing an electric hacksaw. Recent projects have made me relise i hate cutting steel with an angle grider or hacksaw. I dont have the money to spend on a drop saw... yet..
the 1st version will be made using wood, with a 1450rpm 1/2 hp motor. I will use the motor and its pulleys to turn 2 pulleys out of MDF. the end result will be a electric hacksaw that cuts around 60-90 cuts per minute. Meaning slow but perfect cut of metals.
Version 1 will cut the steel to make version 2, a steel version of version 1.

Small things getting done but it is all getting there, completion is just within sight (through a 12' newt with a 5x barlow and a 4mm eyepiece)
Attached Files
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File Type: pdf 200mmpierscope2.pdf (437.2 KB, 42 views)
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  #27  
Old 21-11-2011, 09:21 PM
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Hi Steve,

I like your clear drawings, but the drawing of the scope makes the pier and mount look pretty small - maybe it's just the perspective. Do you know how heavy your scope and mount will be?

I am thinking that you might want (or need) to beef-up the pipe diameter a little. I used a very similar design with 250 mm bolt spacing on the square plates and found that I needed to use 19 mm bolts (actually threaded rod) rather than 12 mm which resulted in too much flex with my set up. Each threaded rod was 250 mm long, and I had a 8" SCT on a wedge. This arrangement provides a steady platform. http://www.iceinspace.com.au/forum/a...se.php?a=76330

Chris

Last edited by ChrisM; 21-11-2011 at 09:27 PM. Reason: added link to pic
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  #28  
Old 22-11-2011, 08:59 AM
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Quote:
Originally Posted by ChrisM View Post
Hi Steve,

I like your clear drawings, but the drawing of the scope makes the pier and mount look pretty small - maybe it's just the perspective. Do you know how heavy your scope and mount will be?

I am thinking that you might want (or need) to beef-up the pipe diameter a little. I used a very similar design with 250 mm bolt spacing on the square plates and found that I needed to use 19 mm bolts (actually threaded rod) rather than 12 mm which resulted in too much flex with my set up. Each threaded rod was 250 mm long, and I had a 8" SCT on a wedge. This arrangement provides a steady platform. http://www.iceinspace.com.au/forum/a...se.php?a=76330

Chris

Hi Chris, thanks for the reply. Unfortunatly the pipe diameter is all I have, I'm limited on time so I cant easily go looking in scrap yards for larger diameter so I grabbed the largest I could from Direct Steel. I hope it will do however I have always had a plan to build a larger pier If I did come accross a larger diameter pipe. I would use this one for my 6" scope. I agree about the 19mm thread.
I only have a basic drill press which in my opinion runs too fast for that size. I will try some oil when drilling, hope fully that will work. If not im sure i can make a new pulley system and slow things down.
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  #29  
Old 22-11-2011, 12:28 PM
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Just thought ide drop a little bit of knowledge in on this.

A little while ago i ran basic analysis on the best sections to use for perm piers, and contrary to popular beleif a circular section isn't the best at all. Great in torsion but in bending not so.

If you can get your hands on 200 x 5 SHS which should be readily avalible from your local steel merchant, it will proform better. As for bolts and threads, i woudln't have gone anything less than M16 as M12 like has already been said will move a bit.

here is the link to my blog talking about it
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  #30  
Old 22-11-2011, 03:27 PM
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Interesting..


Perhaps you could do a dedicated post on ISS, there is little information regarding scientific tests of the deflection of steel piers.

Im presuming the program you used is a simulator, you didnt actually go out and get some massive pieces of steel and weld a 50kg weight on the end and get a deflector meter (i know wrong name) and measure it.

If that is correct and if its reasonably easy, could you do a simulation for me? my tube size is 500x165x4.9mm. 50kg is accurate.

In the meantime I will send direct an email bout the SHS cause they do have that in stock.

Thanks heaps
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  #31  
Old 22-11-2011, 07:23 PM
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ZeroID (Brent)
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Quote:
Originally Posted by steve000 View Post
....I only have a basic drill press which in my opinion runs too fast for that size. I will try some oil when drilling, hope fully that will work. If not im sure i can make a new pulley system and slow things down.
If you haven't got any cutting oil try WD40 or CRC 5-56. And start your hole drilling with a small drill size first then take it up in easy steps so you don't overload the cutting edge. You can also take small bites at it by lifting the drill up and down quickly and just letting it cut a few turns each time it goes down. Keeps the heat down and clears the swarf. ( Old engineering trick when you didn't want to be bothered changing the drill speed )
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  #32  
Old 22-11-2011, 11:31 PM
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... There was a very heated debate about it hence the general tone of the blog... see ARM CHAIR EXPERTS.... S

The program I used in that analysis is Multiframe which is a structrual analysis program I use programs like that on a daily basis but understand how to actually do all the calcs manually, that would put the fear into most mortal men some of the calcs.

As for 50 KG if you are in a obs youll never get that kind of loading on it not in a blue fit as your scope is balanced and the weight is dragging though the center of gravity or the centroid of you equipment. Thats what makes me laugh most of the time when people talk about the whole pier deflecting or the vibration when you hit it or filling it with sand. Sand will only dampen the high frequency vibration (the ringing sound) itll do squat for anything else, unless somebody can bring to the table scientifically peer reviewed testing ill stand by what I have said.

Unless you are putting a massive telescope up on top. eg Paramount ME + 14"+ the deflection willl never move more than your guiding can handle and even then it will still handle it.

At the end of the day ide be more concerned about the soil that your putting your pier footing in. No bigger isn't best as soil will lift a building! if you have reactive clay be prepared to either stabilize alot of soil or just tweak your polar alignment every now and then.

One of the piers that i constructed for a friend of mine who runs a RC has it standing clear of the ground on 4x M24 threaded rod and bolts with 250 SHS. the footing measures 400 x 400 x 500 and is rock solid, the images he produces are amazing!

Ill flip the analysis though in the morning before i start work and tell you what you can expect in any case with your current section

Brendan
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  #33  
Old 28-04-2012, 11:10 PM
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Plans

Hi Everyone,

Its been a while since I last posted. I havent given up the idea of the observatory

I whipped up on google sketchup some rough plans for what I intend on doing. Its pretty much the right size.

Total foot print 4.8m by around 6.2m.
Observatory is 3.7m dia.
Room on the side houses PC and a bed and electronics etc. This also allows double door access to the dome for better security.

The original sketchup file can be found here http://steve000.dyndns.org/files/observatory.zip . take a look. Any suggestions are welcome.


I need to redo the dome door to a sliding sideways type instead of a sliding upwards type.

Steve
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  #34  
Old 29-04-2012, 05:58 PM
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If you haven't already fabricated the permanent pier, consider eliminating the rat cage at the top.
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  #35  
Old 29-04-2012, 08:01 PM
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Quote:
Originally Posted by frolinmod View Post
If you haven't already fabricated the permanent pier, consider eliminating the rat cage at the top.
haha, I have not made it yet and yes I have considered getting rid of it. From what I read it does not need to be perfectly level to achieve good alignment. Id prefer proper level...

If i do use the rat cage design I will limit the bolt space between the plates to the thickness of a nut and whatever washers I need to get level. See I also have to access the bolt to attach the head to the plate. I would need space to get in a spanner. I cant imagine 15mm of threaded rod would have much movement considering how much force is clamping the plates together.
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  #36  
Old 17-02-2015, 11:34 AM
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Update

Hi All,

I cant believe how long it has been, thanks to Suzy for reminding me.

For those interested in this project sadly nothing really has been done. I never found the time while living in brisbane to work on this observatory.

Good news is however I am now living at mums so in theory I will have more time to complete the project.
In the coming weeks I will finish constructing my new shed, from there I hope to have my pier setup to pick the final spot for my scope and observatory. If it works where I am planning I should be able to run 240v to it from the shed.

The goal for the next 3 years is to get a welder and the associated equipment and practice.
Begin metal casting so I can make any parts I need out of aluminium. I might need a milling machine and lathe for this... hint hint Suzy
Get a 3d Printer so I can make any parts out of plastic.
Relocate observatory to final location after restoring it
Use observatory and take great pictures and all that kind of stuff!!

3d printer and metal casting may not be required for the observatory but they are on the list of things I want to do so I might as well do them. The list... sigh its so long as mums place needs some work but I'll get there.

I am committed to this project and WILL see it complete, I have plans on a new house with rooftop observatory so I'll give this one away one day to someone else who can continue its legacy
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  #37  
Old 18-02-2015, 01:22 AM
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If you haven't made the pier yet, can I suggest a slight change to the top plate as shown in the design you posted way back when?
If the holes in the top plate are threaded, you can use a bolt underneath to secure it and therby achieve a flat surface on the top of the plate instead of having 4 bolts etc sticking up and getting in your way.
Peter
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  #38  
Old 18-02-2015, 04:59 PM
el_draco (Rom)
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If i do use the rat cage design I will limit the bolt space between the plates to the thickness of a nut and whatever washers I need to get level.
Avoid the rat cage like a plague; completely nullifies the rigidity of the pier.
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  #39  
Old 18-02-2015, 10:26 PM
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If you can finish this as per the drawing it will be awesome.

I agree with Rom, the cage is completely unecessary and weakens the design. If you carefully trowel and level the top of your concrete to which the metal pier bolts down to, then the top of the metal pier will be surprisingly level anyway and then perfectly rigid Just cut an access hole in the side of the metal column so you can access the centre bolt for the mount head.

Mike
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