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I think 300mm may be a little to big. But don't get rid of it but instead if possible get hold of some smaller 150mm pipe and put this inside the 300mm and cut the 300m down 300mm or more. Then just fill both with concrete. You will have the stability of the 300mm base and the extra clearance at the top of the pier.

 

If this makes sense..

 

Cheers,

 

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+1 for going <300mm at the top.

I would suggest you try and get as close to the size of the 'top plate' as you can to maximise the flexibility of the pier. Even if just for the last 150-200mm or so.

You will hit the 300mm base when near vertical with any scope larger the your ED80, especially if you add a filter wheel etc.

Edited by AstroNowt

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15 hours ago, Anthonyexmouth said:

when i put my 300mm template disc below my mount when its on the tripod at a distance i predict the top of the pier to be it looks to be ok but at the moment only have the heq5 and my ed80 to test it on. what kind of equipment in the future would be most prone to having a problem with such a wide pier? would these issues be reduced or increased if upgrading to a larger mount? 

Interesting thread this.

It seems to me that the most critical positions are the normal park position, with the counter weight bar and back of the scope pointing down, and pointing at zenith, with the scope vertical. In a future upgrade, you may have larger counter weights and a reflector which is wider at the bottom/back than a refractor. In the zenith position, a filter wheel and cable connectors at the back of a refractor may be the most critical parts. But if you have strong enough threaded bars coming out of the concrete, you can probably raise the pier plate a few more inches to get the clearance you need. At least for the park position.

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this is the lowest the mount would ever be to the top of the pier, the disc is 300mm . its about the same as the tripod tray and i expect that to be about the place/height the pier will be when allowing for adapter plates and mounts

20181113_085932.jpg

Edited by Anthonyexmouth

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Have a look when RA is 0 and Dec is at 90. It might be very close to your camera when in that position.

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this give a better idea of width. at this point the pier will be the same width as the tripod its replacing. mount could potentially be higher and thus have more room. 20181113_121238.thumb.jpg.2281cb8dbf5c4e81c81b403f1fddf808.jpg

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Swing the counterweight bar to horizontal, then point the scope straight up. If it clears, your good, with this scope and config

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I think from your last image, which is the closest it might get shows the following.

The scope will foul the pier if the mount base to pier distance is smaller than in your image, may i repeat others suggestions, reduce the pier width at the top for 300 mm -400 mm, it will do away with a potential problem, especially if and when a scope change comes along.

 

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what kind of scope/setup increases the chance of hitting the pier? 

here is a better angle with weight horizontal and scope straight up, shows clearance better at the approx height the pier top will be.  20181113_124843.thumb.jpg.1124a2f91f35273814105ff13cfaffae.jpg

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A longer one.
A wider one.  Sounding like a rugby song her!
How are you sitting the mount onto the pier, that distance looks huge for just long bolts.

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mounted on this adapter . im making a 15mm thick steel plate to bolt to the top of the pier on 6x 20mm stainless rods about 50mm from the concrete to allow for leveling and from there 3x 18mm bolts @170mm long to fix the adapter mount to it. 20180916_195958.thumb.jpg.2667345f55875a790a9dbcd50eb1d174.jpg

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It might sound a bit daft but you need to make sure this is right first time round. If you rotate your camera as per you last photo of the mount then I think the camera will foul the pier. You are better off have plenty of space in case of any future changes. If at some point you also add a filter wheel then it would be even worse.

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47 minutes ago, Anthonyexmouth said:

mounted on this adapter . im making a 15mm thick steel plate to bolt to the top of the pier on 6x 20mm stainless rods about 50mm from the concrete to allow for leveling and from there 3x 18mm bolts @170mm long to fix the adapter mount to it. 20180916_195958.thumb.jpg.2667345f55875a790a9dbcd50eb1d174.jpg

So if I am correct it will be 60 mm above the concrete?
Your images place the pillar far lower, this is my concern for you.

20181113_124843.thumb.jpg.1124a2f91f35273814105ff13cfaffae.jpg.6ee3758c43b940c5a032fc3fba69f0b8.jpg

Edited by Alan White

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no, the steel plate to level will be about 50-60mm above the concrete, then that adapter will be 170mm above that on 18mm steel treaded bar. 

in this pic, imagine the mdf template is the 15mm steel plate with 6x 20mm holes that fix to the 20mm threaded rod in the concrete, this will allow levelling. then 3x 18mm bolts in place of that plastic cup. if rigidity becomes an issue i can always insert a 6" steel tube in the center between the plate and the black adapter to tighten the bolts on. 

20181113_135017.thumb.jpg.e8d13fd8ee3a1ca9a5f3d21e411e9fce.jpg

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3 hours ago, Anthonyexmouth said:

what kind of scope/setup increases the chance of hitting the pier? 

here is a better angle with weight horizontal and scope straight up, shows clearance better at the approx height the pier top will be.  20181113_124843.thumb.jpg.1124a2f91f35273814105ff13cfaffae.jpg

I think that with your dslr you're good. You could even have the concrete pier go higher up. But if you ever get an oag or filter wheel, you'd need to start planning where to have things.

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You could drop some WBC bee hive sections over the top - that would look pretty!

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For what it's worth I'd build in some future proofing. What if you decide that you want to go visual and use a long frac lower down in the rings. You might then have an issue which for the sake of a little design modification now, might save a lot of heartache later. I'd certainly listen to experienced guys advising you to narrow a little at the top end.

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