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Okay for pier adaptor?


Ryan-y
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Recently I found out my brother has been doing a bit of welding, and I've heard he's got pretty good. As you can guess I thought of the first thing any astronomer would think of in this situation........ PIER!!! :D

turns out he's got a decent piece of 5inch tube I can have, so I'd just need to get some plates.

my plan was to buy a pier adapter and with the plates the total cost would be about £100.

I thought I'd ask my dad if he knew anyone that could machine the adapter for me, and he reminded me he had a lathe and milling machine in the garage that he got from a house clearance about a year ago. I don't think he's had them running since testing them and he said he hasn't used any engineering machinery for a good few years but if it would save me £80 we could have a go.

anyway when we went into the garage to see what bits and bobs he had we found this. My question is will it be too small? It's only 25mm thick and about 108mm across but most of the work is done for us and would make life easier, I just don't want sacrifice stability of an easy life.

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I had a friend machine some disks - Just like those(?): Aluminium (hard variety) 25mm thick, ~100mm+ diameter, to fit as a "plug" inside a Skywatcher pillar tube. It's held in place by three M6 lateral (standard issue) stainless steel bolts. It has a central 1/2" clearance hole and uses a bolt (same size) to attach a 20lb "Owl Box"... an HEQ5... 16lb scope... 16lb counterweights etc. etc. It ain't fallen off yet! But It seems quite typical to use a single M10 bolt to attach HEQ5 / EQ6 mounts to pillards / tripods though? I cannot comment as an "Structural Engineer", but normally, there aren't too many unbalanced forces on these things? :p

I did a bit of reading... The latest Aluminium can be upto 2/3 strength of steel at 1/3 weight? Pretty amazing if true... :)

Edited by Macavity
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That's what I was hoping to hear. I was just a bit worried there only being 5mm at the bottom, but I guess as you say, there isn't any particular stress on that part really.

My dad suggested using nylon block, which I guess would make adjustments nice and smooth but I'd be worried about compression over time.

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Oh ok, how do you hold it in? And would it be hard to get right? Tbh i think the aluminium is 20mm short.

Is the 'leveling plate' design really that bad? I know the mount doesn't have to be level, it just seems like the simplest option. I know an owls nest would be better but would be hard to cut out neatly (plus I'd need a supply of bolts for when I drop them down the tube :) ) and your adapter would be better but would be harder to machine. Has anyone ever deemed their pier useless because of the leveling plates?

I'm not totally sold on the leveling plates, I see where everyone is coming from, and I'll happily change my design if necessary.

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Oh ok, how do you hold it in? And would it be hard to get right? Tbh i think the aluminium is 20mm short.

Is the 'leveling plate' design really that bad? I know the mount doesn't have to be level, it just seems like the simplest option. I know an owls nest would be better but would be hard to cut out neatly (plus I'd need a supply of bolts for when I drop them down the tube :) ) and your adapter would be better but would be harder to machine. Has anyone ever deemed their pier useless because of the leveling plates?

I'm not totally sold on the leveling plates, I see where everyone is coming from, and I'll happily change my design if necessary.

There's nothing intrinsically wrong with 'levelling plates' it's just that that they are not really needed, all the adjustment required is available from the EQ mount itself. As such the pier top does not need to be level. The reason that many people choose the two plate design is for an easy means of access to the bolt that holds the EQ mount down. To go to the effort of building a massively strong pier only to have the important bit (the scope) balanced on three M10 studs seems a bit daft? If you are planning to use a hollow steel tube for the pier it makes sense to machine a solid end 'plug'. Oh- you'll need to drill another hand sized at the bottom of the steel tube as well- that way you feed all your cables through the pier too! My pier top is held on by a bolt tapped through the tube Dscf6227.jpg
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It looks like you've done a great job. Is the bolt that holds the pier top on tapped into the pier top itself or just through the tube? And I wouldn't know how to go about cutting a hand sized hole in the tube, how did you do it?

The reason I was swaying towards the 'leveling plate' design is that it is the simplest to achieve with the limited know-how and machinery I have access to. Would 4 m12 stainless steel bolts over 80mm odd really be that much of a weak point? Surely there are weaker points than that elsewhere in the system.

I was thinking something based on Bizibilder's free standing pier design.

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It looks like you've done a great job. Is the bolt that holds the pier top on tapped into the pier top itself or just through the tube? And I wouldn't know how to go about cutting a hand sized hole in the tube, how did you do it?

The reason I was swaying towards the 'leveling plate' design is that it is the simplest to achieve with the limited know-how and machinery I have access to. Would 4 m12 stainless steel bolts over 80mm odd really be that much of a weak point? Surely there are weaker points than that elsewhere in the system.

I was thinking something based on Bizibilder's free standing pier design.

http://stargazerslou...estanding-pier/

The bolt holding the pier top is not tapped into the pier top. When loosened I can rotate the pier top round (good for coarse azimuth adjustment!) I used a Starret hole saw to go through the tube. They are fairly good quality, should take about 5 mins per hole. http://www.ebay.co.uk/itm/STARRETT-HSS-BI-METAL-HOLESAWS-HOLE-SAWS-Various-sizes-44-86mm-/110948372523?pt=UK_Home_Garden_PowerTools_SM&var=&hash=item19d509d02b There a few companies on e-bay selling aluminium bar off-cuts http://www.ebay.co.uk/itm/150mm-Diameter-x-55mm-Aluminium-round-bar-rod-Grade-7075-T6-/400503746681?pt=UK_BOI_Metalworking_Milling_Welding_Metalworking_Supplies_ET&hash=item5d3fe23079 .

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Thanks for all the info laser_jock99. I think I am going to change my design. I don't think I'll go to the effort you have with your pier adapter but if its that easy to cut the hole for the 'owls nest' then I might as well scrap the two plate design and have my brother weld a disk to the top of the tube and bolt the adapter to that. As it will be free standing I don't have to worry too much about extra azimuth adjustment, and that way I can use the aluminium I have already.

I'm moving house in about a month or so and one of the reasons I haven't chosen your design is although the new house is going to be amazing for ap being a semi about half a mile away from the next building never mind village and surrounded by farm fields, it is going to leave me feeling a bit vulnerable to theaft. I've seen somebody with an 'owls nest' pier that had a plate that could be padlocked over the hole, which would give me at least some piece of mind. That and the two German shepherds next door :D

Right, now I can start gathering materials, I'll post my progress.

Thanks again.

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As it happens I'm in the process of planning a 'mini pier'. One that will sit outside in the garden with an EQ6 attached ready to rock-n-roll once the main scope is up and taking subs. Something I can play around with while waiting for the main scope to do it's stuff. Security is an issue- but I have some anti tamper fixings I can use.

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Good luck with it. :cool:

I do like the general idea of cutting a modest access hole (slot?) in the pillar side. Full access to the "infamous nut" is only required once. From then on, if you can get a 30 deg(?) turn on it, with a spanner, you can tighten / loosen it as required. Don't go overboard and buy: http://www.scopesnsk...nest/AC389.html like I did? A FINE thing, but weighs over 20lb! I have adapted it to use as my pier top as noted above. And if ever need somewhere to put m'coffee mug... :D

Edited by Macavity
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