TheSkySearchers

JayTee wrote: ↑Wed May 25, 2022 7:50 am
Since the obsy is on my main property there is no need for a great deal of storage and a pitched roof does add additional cost. Also, the location of the pedestal within the obsy room is not cast in stone yet. (pun intended). I'm still experimenting with the floor plan layout in my garage to come up with the ideal location for it.

Okey dokey, storage not an issue. Me though, I'm 6 foot tall and would be hitting my head almost as soon as I walked in the warm room. It reminds me of Harry Potter's bedroom under the stairs.

Based on what @SkyHiker said about no wind protection, if you raised the walls of the entire structure and widened the warm room by even a couple of feet, no more Harry Potter room. Your backyard though might already have sufficient protection through...

Food for thought!

Nice looking location!

I sounds like you have done your homework!

Only other suggestion would be to design in a 'plan B' if needed. That way you can modify it to fix anything that might come up.

Please post photos so we can watch the progress!

Gordon wrote: ↑Wed May 25, 2022 5:32 pm I sounds like you have done your homework!

Only other suggestion would be to design in a 'plan B' if needed. That way you can modify it to fix anything that might come up.

Please post photos so we can watch the progress!

I have done some homework. I keep thinking of new ways to test my design on my simulated floor plan laid out in my garage.

I'm afraid that this design (low wall/high wall), once built, will leave me very few, if any, follow on options. I knew from the beginning that this was going to be an "all-in" path for my obsy.

BTW, I'm a little bit vertically challenged as I have shrunk down to 5' 6", plus I'm dealing with upper-body paralysis which makes it very difficult for me to work anywhere above shoulder height.

PIctures of the progress will definitely be provided, although, I believe you may be a bit disappointed.

Cheers,

Now my first construction question:

As I understand it, for the pedestal, I need to pour a footing, an 18" cube of concrete 24" down (this puts it below the frost line).

Should I vertically set 3 or 4 rebars in this block, spaced properly, so that they will fit inside the Sono tube to provide additional strength for the pedestal?

On top of this pedestal will be a 900mm iOtron steel pier so it doesn't need to be a very tall pedestal. Approximately 6 - 9" of pedestal.

JayTee wrote: ↑Wed May 25, 2022 8:21 pm Now my first construction question:

As I understand it, for the pedestal, I need to pour a footing, an 18" cube of concrete 24" down (this puts it below the frost line).

Should I vertically set 3 or 4 rebars in this block, spaced properly, so that they will fit inside the Sono tube to provide additional strength for the pedestal?

On top of this pedestal will be a 900mm iOtron steel pier so it doesn't need to be a very tall pedestal. Approximately 6 - 9" of pedestal.

I used 4 rebars when I built my old one. It was rock solid.

There are two ways to do the footing. The most popular is to drill the hole, and to pour concrete directly into the hole, in contact with the ground, transitioning to sonotube just a few inches below ground level. The other way is if you have to dig the hole. Then you go with a block that is bigger than the column will be, and transition to sonotube immediately above the block, well below ground level. The idea is that the weight of the backfill on top of the anchor block will contribute to its stability.

Both ways have their merits. It sounds like your plan is to do it the second way.

I am surprised that your frost line is only 24" deep. That's great if it is: less digging. But if you only have 6" or so of backfill on top of the block, you won't gain much stability from it. On the other hand, I tend to over-engineer everything, so you will likely be fine. For reference, my anchor block is about 3'x3'x2' high, and its base is about 54" down, re: frost line at 48".

OK, a 150' walk back to the house, sort of marginal if you would stay out in a warm room for an hour exposure or go back inside for a hot coffee. I'm about 60' from the kitchen and there is no question, back into the warm house, hence no warm room. Might save a few bucks deleting the warm room, I would setup out there with a scope and see if it would be reasonable to delete the warm room.

Just more food for thought, but there comes a time when you have to shoot the engineers and go into production,
Steve

sdbodin wrote: ↑Wed May 25, 2022 10:30 pm OK, a 150' walk back to the house, sort of marginal if you would stay out in a warm room for an hour exposure or go back inside for a hot coffee. I'm about 60' from the kitchen and there is no question, back into the warm house, hence no warm room. Might save a few bucks deleting the warm room, I would set up out there with a scope and see if it would be reasonable to delete the warm room.

The warm room is definitely needed for the 4.5 months of winter up here. We are a bit colder than you are. So much so that the 150' back to the house feels like 150 miles!!!
There should be enough room for a coffee maker in my "Harry Potter closet"

KathyNS wrote: ↑Wed May 25, 2022 8:51 pm I am surprised that your frost line is only 24" deep. That's great if it is: less digging. But if you only have 6" or so of backfill on top of the block, you won't gain much stability from it. On the other hand, I tend to over-engineer everything, so you will likely be fine. For reference, my anchor block is about 3'x3'x2' high, and its base is about 54" down, re: frost line at 48".

I am now seriously considering method one! My frost line (according to my local handyman) is only 20 inches. My soil up here is very "clay-ee" so the backfill of 9 to 12" should be enough to immobilize the pedestal. Finally, what type of concrete should I use? Posthole quick set or some other type?

As always, thanks again for keeping me on the correct path. So, I'm off to dig a hole...

Lastly, the obsy already has a name based on the local geography -- The Rimrock Observatory.

Great building plan JT. I hope it works for you.

Finally, what type of concrete should I use? Posthole quick set or some other type?

I used this: https://www.homedepot.com/p/Quikrete-50 ... /100318521

It was easy to mix and setup great.

Here's the photos of mine when I was still in Southern California (no frost line). The center post is a regular galvanized fence post. It was sunk 4 feet into the ground. The base was 36" x 36" and the pier was a 10" diameter. Remember to set some bolts into the top of the pier concrete so you have something to attach to.

@Gordon thank you so much for those pictures. They are definitely worth a thousand words.

Mine was an "idea" that became reality. (like yours!) It served it's purpose for about 10 years before we moved. I was lucky and was able to leave it. I feel sorry if the new owner decided to remove it.

Tomorrow starts the job of digging the hole for the footing and then pouring the footing. As I look ahead I see that almost everyone has a metal plate between the cement pedestal and in my case an iOptron Pier that's going to go on top of the cement pedestal. Is this metal plate something that I fabricate? If so, is there a standard template I can follow so I don't reinvent the wheel? Any help would be appreciated, thank you.

A metal plate is required of the mount goes on top of the concrete, just to have somewhere for the bolts to go.. Since you will be bolting on a pier, the plate would be optional. Whatever is bolted onto the concrete, make sure you have it on site before you pour. You will need it (or a discardable template made from it) in order to set the anchor bolts.

JayTee wrote: ↑Tue Jun 21, 2022 4:44 am Tomorrow starts the job of digging the hole for the footing and then pouring the footing. As I look ahead I see that almost everyone has a metal plate between the cement pedestal and in my case an iOptron Pier that's going to go on top of the cement pedestal. Is this metal plate something that I fabricate? If so, is there a standard template I can follow so I don't reinvent the wheel? Any help would be appreciated, thank you.

Let me look. I might have the old plate from my observatory I had in Murrieta.

My understanding is that I can pour the concrete footing and the concrete pedestal at different times. If this is the case, then I will pour the fitting now and wait till the pier arrives so I can see the bolt pattern on the bottom of the pier before I pour the pedestal. Let me know if this is the correct approach.

Additionally, there will be 4 pieces of rebar sticking upward from the footing that will secure the pedestal to the footing. I won't just be pouring concrete on top of concrete.

JayTee wrote: ↑Tue Jun 21, 2022 6:14 pm My understanding is that I can pour the concrete footing and the concrete pedestal at different times. If this is the case, then I will pour the fitting now and wait till the pier arrives so I can see the bolt pattern on the bottom of the pier before I pour the pedestal. Let me know if this is the correct approach.

Additionally, there will be 4 pieces of rebar sticking upward from the footing that will secure the pedestal to the footing. I won't just be pouring concrete on top of concrete.

That sounds like a good approach.

JayTee wrote: ↑Tue Jun 21, 2022 6:14 pm My understanding is that I can pour the concrete footing and the concrete pedestal at different times. If this is the case, then I will pour the fitting now and wait till the pier arrives so I can see the bolt pattern on the bottom of the pier before I pour the pedestal. Let me know if this is the correct approach.

Additionally, there will be 4 pieces of rebar sticking upward from the footing that will secure the pedestal to the footing. I won't just be pouring concrete on top of concrete.

That's pretty much the way I did mine.

Re: the top plate. I found my old one. Photos to follow.

Okay,
@JayTee
Here's the plate I made.

It's 8.5 x 8.5 inches with 4 each 1/2 inch diameter mounting holes for the pier. There are currently 3 holes for mounting. I used both an EQ5 and and EQ6 with this plate. The additional 3rd hole was for the centering block for polar alignment.

The plate is aluminum and is 1/2 inch thick.

Is it something you can use?