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Help Attaching/Aligning 12” Aluminum Pier to Masonry Footing

Astrophotography Equipment Observatory Polar Alignment
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#1 GaryShaw

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Posted 23 October 2021 - 12:11 PM

Hi All

 

I’ve ordered a 12” diameter, 48” high aluminum pier from ATS and am now starting to build the masonry footing that the pier will be bolted to.

 

The top of the ATS pier is a blank 12” diameter, 0.50” thick aluminum plate that I need to drill and tap to receive a low profile rat cage to attach my CEM 70 mount adaptor to. This is all new territory to me so I’m hoping that some of you might be able to offer advice on how to design (or purchase?) the rat cage and then how to best attach the iOptron mount adaptor so bolts and holes are all in the right places for polar aligning the mount.

 

I appreciate any guidance or suggestions in how to go about this. I can upload pics of the iOptron mount adaptor and ATS pier if that would be useful.

 

Cheers,

Gary 

 

 

 



#2 macdonjh

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Posted 23 October 2021 - 04:19 PM

GaryShaw,

 

Since the top plate of your pier is not drilled, you can install your pier as soon as your footer is ready.  If you are pouring concrete, you can set your anchor bolts into the wet concrete and the allow the concrete to cure around them.  It's best to have a template made of plywood.  You drill holes, matching those on the bottom plate of your pier, in the plywood.  Then you install your anchor bolts in the template and use that assembly to keep your anchor bolts spaced and aligned properly while you sink them into the concrete and tamp the wet concrete around the bolts to ensure there are no air pockets around your anchors.

 

If you're building your footer out of blocks or bricks, you'll have to wait until after your footer is built and the mortar is cured.  I'd still suggest a wood template.  Use the template as a guide for a hammer drill (you can rent them at Home Depot) to drill holes in your masonry footer.  Then, using anchoring epoxy (also available at Home Depot, but also Grainger, Fastenal, etc.), glue all-thread studs into the holes and let the epoxy cure.

 

Once that's done, you can bolt your pier to your footer.

 

I suggest looking up the solar transit time for your location for a day when you have time in the afternoon to work on your pier.  At the time the Sun transits, you can use a straight edge held plumb to mark a line which will be aligned north-south.  Now you have a reference for north.  If you've already installed your pier, that reference line can be directly on your top plate.

 

If you don't want to make a plate for your mount yourself, contact Dan's Pier Plates, he may already have a template for a CEM-70 and be able to make you a top plate.  If you want to make one yourself, you can get small aluminum plates from Grainger, or Metals Supermarket, or even eBay and Amazon.  iOptron likely has a dimensioned drawing of their mounts' bases so you can make yet another template, this one from paper, to guide you in drilling holes in your top plate and the plate on your pier.  Aluminum is very soft, so regular wood drill bits will do just fine.  Just use some oil for cooling and lubrication, and don't use the drill's highest speed.  Make sure you align your template with your north marker.

 

I wouldn't bother tapping the plate on your pier.  Simply install your rat cage bolts and put a nut on each bolt below the pier plate and one above the pier plate.  That will hold the bolts in place and you'll be ready to install another set of nuts for your pier plate (with you mount bolted to it) to rest on.  A fourth set of nuts over the top of your pier plate will hold your mount down.

 

If you really want to tap your pier top plate, just buy the correct diameter tap and go slowly.  Once you start cutting threads, I wouldn't turn the tap more than 1/4 to 1/3 of a turn before backing the tap out to clear the chips.  That way you won't "tear" any of the threads.

 

Good luck.



#3 macdonjh

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Posted 23 October 2021 - 04:31 PM

I didn't do a good job of marking north when I installed a different mount on the pier in my observatory, but everything else went well.  I built a jig which centered my three anchor bolts on my pier.  Here's a photo of me using the jacking screws I included in the jig to level the jig (which made the guides for the drill plumb):

191025 jack screws.JPG

 

And here is a wider shot of the jig ready for me to drill:

191025 drilling.JPG

 

It's important to get all the concrete dust out of the bolt holes before you squeeze the epoxy in.  I used very sophisticated tools for that:

191025 clearing.JPG

 

Rather than a rat cage, I grouted my pier plate.  Before I mixed the mortar (real machinery grout was too expensive and I could only find it in 50lb sacks), I made sure my plate was level.

191025 check level.JPG

 

 


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#4 macdonjh

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Posted 23 October 2021 - 04:39 PM

Here's the pier formed up for pouring my mortar/ grout with the pier plate installed and level.  After I poured the mortar I set the pier plate down and jiggled it to remove air pockets.  I then removed the excess mortar which squished up around my plate.  Then I let the mortar harden.  It only took a couple of hours, which surprised me.

191025 poured.JPG

 

Those black bolts in the pier plate are jacking screws and I'm glad I included them.  My plate was well adhered to the mortar and I'd never have gotten it off without damage to the mortar without those jacking bolts.  Using them, it popped off suddenly.  Pretty neat.  I needed to get the plate off the pier because I had to bolt it to my mount from the underside of the mount, then set the assembly back on my pier.

 

Here's a recent photo (lot's more renovation work...).

210612 Plot 6 PIer small.jpg

 

I hope this helps you visualize what I wrote in my earlier post.  It's not hard, but you do have to think it through, and have a plan before you start building.


Edited by macdonjh, 23 October 2021 - 04:41 PM.


#5 kathyastro

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Posted 23 October 2021 - 05:27 PM

Because of the way the iOptron mounts attach to their plates (I assume the CEM70 is like the CEM60), you will need to tap the top plate to attach the mount.  Or, as suggested above, get a plate from Dan's Pier Plates.

 

I used the Dan's kit: a standard bottom plate, and an iOptron-specific top plate.  The rat-cage bolts have metal sleeves around them to minimize vibration.



#6 GaryShaw

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Posted 23 October 2021 - 06:23 PM

Hi, 

 

Ok, so I’d attach this iOptron adaptor plate to the 3 bolts on Dan’s image down below? I just need to tell Dan which way true north is on the pier plate for ATS (AP) so he can work out his locations for the 3 adjustable bolts. Am I getting this right?

Gary

 

iOptron Adaptor:

 

D78E4AF6-F9DF-4B02-AB2C-622B7851DDF1.jpeg

 

 

Dans Pier setup on the pier-top plate I supply to him:

 

DB14D598-5E1C-476C-BF7B-72EC1E4778A8.jpeg

 

 



#7 kathyastro

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Posted 23 October 2021 - 07:13 PM

Unless you already have the iOptron adapter in hand, it would be simpler to get the adapter plate from Dan.  That way, the top and bottom plate holes will line up, and the mounting holes for the iOptron mount will be in the right places.  All you would have to do would be to mount the bottom plate onto the pier.

 

If you want to put your iOptron adapter onto a Dan's bottom plate, one of them is going to have to be drilled to match the other one so you can bolt them together.



#8 GaryShaw

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Posted 23 October 2021 - 07:25 PM

Kathy, I do have the adaptor in hand and assumed I would send it to Dan along with the AP pier top with an indication on it of true north, then let him do the rest.

 

If I returned the iOptron adaptor to them ( they are 20 minutes away), would Dan just purchase one to use or does he fabricate his own that works precisely with the iOptron mount?

 

I’d still need to to provide him with the the AP pier top plate indicating true north based on the completed pier installation. 
 

I guess once I’ve been through this, it will be clear, but right now, it seems tricky to get the mount to mate to the three bolts you see in the image above and for the assembly to be correctly aligned north once it’s all together. Thanks for your help with this.

Gary 



#9 kathyastro

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Posted 23 October 2021 - 07:41 PM

I got my CEM-60 pier plate from Dan.  He makes the top plate to the manufacturer's specs, including which way is north, and mates it to his own standard bottom plate.  There was nothing customized about mine.  I just ordered a top plate for iOptron, and bolted it to the standard bottom plate I already had from my previous Skywatcher mount.  Totally off-the-shelf.

 

Since you already have a top plate, you don't even need a rat cage.  The iOptron mount attaches from the top: no access is required from underneath. 

 

Your plate will be tapped already to receive the mounting screws from the mount.  So all you have to do is drill your masonry pier top to receive bolts matching the mounting holes in the iOptron plate.  Finding north will be up to you.  Using the plate as a template, drill the masonry, epoxy bolt anchors in place, and then bolt the plate to the pier.  Attach the mount on top and Bob's your uncle.

 

[edit]  Oops, I see that your pier top is aluminum.  Okay, so you could just drill and tap the aluminum pier top to match the iOptron plate's mounting holes.  Still no need for a rat cage.


Edited by kathyastro, 23 October 2021 - 07:44 PM.


#10 GaryShaw

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Posted 23 October 2021 - 10:29 PM

I guess I am a bit confused now. In the picture above, I believe Dan is showing the top plate of an AST (AP) pier to which he has added the bolts and leveling nuts and washers that would receive the iOptron adaptor and mount - does that seem correct?
 

Since I’m not equipped for drilling an taping 1/2” thick aluminum, I was assuming I’d send him the top plate and he’d do the rest. After I received it all back, I’d attach it to the top of the pier and attach the pier to the footing - in the correct orientation.

Gary



#11 kathyastro

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Posted 24 October 2021 - 09:15 AM

I guess I am a bit confused now. In the picture above, I believe Dan is showing the top plate of an AST (AP) pier to which he has added the bolts and leveling nuts and washers that would receive the iOptron adaptor and mount - does that seem correct?
 

Since I’m not equipped for drilling an taping 1/2” thick aluminum, I was assuming I’d send him the top plate and he’d do the rest. After I received it all back, I’d attach it to the top of the pier and attach the pier to the footing - in the correct orientation.

Gary

OK, I misunderstood what the photo was showing.  Yes, that will work.

 

This is the standard off-the-shelf iOptron pier plate set from Dan's.

P1180267-1000px.JPG




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