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> Pilot's Cross Observatory
dbeckstrom
post Nov 12 2006, 06:45 PM
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Hi Everyone,

Well, I thought it was about time I shared some photos of my observatory project.

I live in Minnesota about 35 miles north of Minneapolis. As you might imagine, its cold here in November and we are at risk of snow at any time. My goal is to have all of the cement work done before it snows and before the ground freezes. As long as the cement is done, I can continue construction regardless of the weather.

You guys will get a chuckle out of this, but I have never looked through a telescope at the sky or stars. I got interested in astronomy a couple of months ago and I've decided to purchase a telescope between 10 - 14 inches. I quickly realized with the weather and mosquitos here that I would need an observatory to make my experience enjoyable and a year-round activity.

Because of the intense time pressure with our pending weather, I've started building the observatory before I have purchased a telescope. The big drawback with that approach is the questions it leaves open with regard to the pier height. Therefore, I have decided to make a pier out of cement with a steel top that can be changed out to accomdate whatever telescope(s) I may have in the future.

I'm very interested in computer controlling the dome and the telescope and astrophotography. I'm a computer software engineer (among other thngs) and I will enjoy the building of the obeservatory as much as automating it.

On Friday, November 3, I drove to Litchfield and I picked up my Explora-Dome.
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dbeckstrom
post Nov 12 2006, 06:58 PM
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Sunday, November 5, 2006. Gorgeous 50F degree day.

I'm modeling my Observatory after Mark Cisclo's. I liked his design and since I don't have months to plan my obesrvatory and I needed to get building I decide to build something similar to what Mark did.

I dug a 3 foot by 3 foot hole 60 inches (5 feet) deep. Code here requires we go at least 42 inches to get below the frost line. However, in Northern Minnesota they go down 60 inches and I decided to be safe rather than sorry. At the bottom of the hole, I took a bucket and I dug the base out to about 4 feet wide to give a little more support. We have sand here and there was no need for putting down gravel.

(IMG:http://img296.imageshack.us/img296/1874/hole1sm2.th.jpg)

It took me about 2 hours to dig the hole.

This next photo shows a bit more perspective on the hole. You can also see the 2x6 form I have ready to place into the top of the hole.

The dog is our new Sheltie Puppy. His name is Buster. He helped me dig (so he thought) the hole. He watched me digging and then he went into the garden and started digging too. He would stop, look at me, then go back to digging!

(IMG:http://img387.imageshack.us/img387/9461/hole2tk4.th.jpg)
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dbeckstrom
post Nov 12 2006, 07:05 PM
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Sunday, November 5, 2006.


I still had some time left in the day after digging the hole so I welded up 1/2 inch rebar to form the center column for the pier. Since I didn't know how high my pier would need to be, I made this thing 15 feet long. 5 feet would go in the hole which would leave 10 feet above ground. I will cut the excess off with my 4" grinder once I decide on the final height of the pier.

(IMG:http://img137.imageshack.us/img137/9111/pierrebarhl7.th.jpg)

I used some 3/4 inch square tubing to make a square spacer to hold the rebar at the proper separation.
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dbeckstrom
post Nov 12 2006, 07:08 PM
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Monday, November 6.

I built a rebar cage out of 1/2 inch rebar and I lowered down into the hole. I set it on some brick to hold it off the bottom about 3 inches.

I built an opening in the center of the cage to accept the rebar for the pier. I then hung a plumb bob to make sure that the pier was perfectly vertical.

(IMG:http://img137.imageshack.us/img137/2585/rebar2rq4.th.jpg)
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dbeckstrom
post Nov 12 2006, 07:36 PM
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Here is the hole ready for the pour. Once I had saw the size of the hole I realized I did not want to mix the concrete myself. I ordered 2 yards for delivery but expected only to use 1 3/4 yards. Best to have some extra rather than run short.

In this photo you can see that I have a 2x4 run horizontal across the hole and its elevated about a foot off the ground. Another 2x4 runs perpendicular to it. These maintain the spread on the rebar and they keep it from shifting. I did not want the concrete coming out of the chute of the cement truck and hitting the rebar causing it to shift. Its important the pier be perfectly vertical.

You can also see another 2x4 across the hole but its screwed right down to the form. This is for added support of the pier rebar during the pour. Once the concrete is in the hole, this 2x4 will be removed.

The criss-crossed 2x4s that are a foot of the ground will remain in place until the concrete dries. The advantage of the way I set this up is that there won't be any obstructions to cause problems when I use a 2x4 to skreet off the top of the concrete. I have full access to the top of the form when I skreet.

I left the plumb bob in place to keep an eye on the vertical pier rebar for plumb.

(IMG:http://img213.imageshack.us/img213/6347/readytopouram4.th.jpg)
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dbeckstrom
post Nov 12 2006, 07:43 PM
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Tuesday, November 7.

Concrete day!

Here is a photo after the concrete was poured. I used an idea of someone else on this forum and placed a bucket over the rebar (drilled holes in the bottom of the bucket) and slid it down about 5 inches into the concrete. This would form a "key" for the pier column when it was poured.

I had to temporarily remove the 2x4 bracing when I slid the bucket down the rebar.

You can see that the surface of the concrete is rough. I scratched it up with a broom. You can also see I added 4 sections of vertical rebar. The plan is to build a 2 foot by 2 foot square form and pour additional concete on top of this slab to help support the column due to the columns eventual height. The rough concrete will help the new pour to adhere.

(IMG:http://img172.imageshack.us/img172/7307/withbucketwi3.th.jpg)
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dbeckstrom
post Nov 12 2006, 07:46 PM
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Another photo after the pour.

(IMG:http://img150.imageshack.us/img150/6124/pour2tm6.th.jpg)
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dbeckstrom
post Nov 12 2006, 07:52 PM
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I had some time in the evenig after the pour so I started cutting my rings. Here is a photo of the jig I made. I can tell you that a sabre saw on a jig and a rotozip on a jig did not work. Too much blade wander. I highly recommend a good router (plunge router is preferred) with a 1/4 inch bit. Make 2 passes on each cut. One at half depth and the second to finish cutting through the 3/4 inch plywood. I snapped a bit trying to cut all 3/4 inch at one time.

Also, wear a dust mask and ear protection when you do your routing.

(IMG:http://img156.imageshack.us/img156/3002/ring1jj0.th.jpg)
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dbeckstrom
post Nov 12 2006, 07:57 PM
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Wednesday, November 8.

Here are photos of the finished pour with the bucket removed. You can see the nice keyway that will provide additional strength for the column when it is poured.


(IMG:http://img297.imageshack.us/img297/6275/plug1lu5.th.jpg)

(IMG:http://img297.imageshack.us/img297/568/plug2oz7.th.jpg)
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Geeo
post Nov 12 2006, 08:11 PM
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Great job and welcome to the wonderful world of ED construction. Looking forward to seeing the updates. Geeo
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dbeckstrom
post Nov 12 2006, 08:12 PM
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Thursday, November 9th.


Sorry for the bad photo. This photo is apparently the only one I have from the day that I poured the 4 footings for the corners of the building. The footings are under the plastic bags.

I rented a post hole auger from Home Depot. About $70 for a day. The plan was to punch 4 holes. However, we had such difficulty with getting the first 4 holes square with the pier that we only drilled 4 holes. I decided I would drill the remaing 2 holes later after I had gotten the main part of the floor on the dome side framed up. Then I could measure from that frame outwards to locate where I needed to punch the other 2 footing holes.

(IMG:http://img167.imageshack.us/img167/681/footingsvp0.th.jpg)

I had hauled 80 bags of quickrete home on a trailer. The guys at Home Depot thought I was a little nuts when I told them I wanted them to load two pallets (80 bags) of 80 pound bags on my trailer. That was 6400 pounds! Once I told them I had a 3/4 Diesel truck with a 20 foot trailer rated at 10,500 pounds -- they stopped giving me grief!

I also bought 8 gags of portland. THIS IS VERY IMPORTANT -- in my experience I have found these bags of concrete mix to be very lacking in portland. We have had cement flake and crack and break that was poured using quickrete or sakrete. They really skimp on the portland. When I mixed this stuff I added 1 to 2 shovels of portland for every bag of mix that I put into the electric cement mixer. This means I will have some much stronger cement.

BTW, I didn't mention it earlier but when I had the cement truck deliver the concrete for the footer for the pier -- I paid the $18 extra ($9 per yard) for them to add additional portland for a 5000 PSI mix. Well worth it.
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dbeckstrom
post Nov 12 2006, 08:16 PM
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Friday, November 10.

Here is a photo of the first pour for the pier. It was 34 degrees the day I poured this.

(IMG:http://img83.imageshack.us/img83/796/pier1tt1.th.jpg)
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Rick Needham
post Nov 12 2006, 08:21 PM
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Looks great so far (IMG:http://www.observatorycentral.com/style_emoticons/default/biggrin.gif) 34 degrees you say? I'm surprised you have no snow on the ground yet. Keep at her...winter's just around the corner!
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dbeckstrom
post Nov 12 2006, 08:21 PM
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Here you can see how I braced the bottom of the sonoa tube for the pour. Yu can also see that I drilled holes in the tube and ran some rebar horizontally through the tube near the base where I will be forming up and pouring a 2x2 foot support at the base.

(IMG:http://img149.imageshack.us/img149/6825/pier12ta4.th.jpg)


After 4 hours this concrete was just as wet as it was when I poured it. At 34 degrees, it was not setting.

I ended up draping a sheet around the sonoa tube and placing an electric heater under the sheet. I let it run all night long and it kept it at about 70 degrees. By morning, the concrete had set and looked good. They say it takes almost a month for concrete to get its full strength.
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dbeckstrom
post Nov 12 2006, 08:24 PM
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Thanks guys. Just to let you know how much pressure I'm under to get the concrete done...the day I poured the pier it was not only 34 degrees....but about 50 miles south of me they received 7 inches of snow!
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dbeckstrom
post Nov 12 2006, 08:32 PM
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Sunday, November 12.

7 days since I started.

Here is a photo I snapped in the dark this evening after I finished working. You can see that yesterday and today I got the 6x6's notched out for the corners and installed. I also got the 2x8 frame squared up and installed and I hung four of the 2x8 floor joists.

(IMG:http://img87.imageshack.us/img87/9981/floormu8.th.jpg)

I left the center open around the pier because I need to put the 2x2 foot form in place around the pier's base (after I remove the bottom half of the sonoa tube.) I'll fill the form using 5 gallon pales to carry the concrete.

I'm very happy to be at this point. Now that I have the main structure's floor framing in place, I can measure off of it to locate where I need to punch the holes for the other 2 footers. I'll probably pour those on Tuesday.

By Thursday I should be at a point where if it snows it won't matter.

I plan to build the walls and roof in my heated garage and then I'll carry them out and install them.

All in all I think I made good progress in 7 days. Time to rest tonight!
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dbeckstrom
post Nov 12 2006, 08:36 PM
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I also finished cutting my rings a couple of days ago.

(IMG:http://img155.imageshack.us/img155/7027/rings2vu2.th.jpg)
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Rick Needham
post Nov 13 2006, 02:03 AM
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QUOTE(dbeckstrom)
Sunday, November 12.

7 days since I started.

Here is a photo I snapped in the dark this evening after I finished working. You can see that yesterday and today I got the 6x6's notched out for the corners and installed. I also got the 2x8 frame squared up and installed and I hung four of the 2x8 floor joists.

(IMG:http://img87.imageshack.us/img87/9981/floormu8.th.jpg)

I left the center open around the pier because I need to put the 2x2 foot form in place around the pier's base (after I remove the bottom half of the sonoa tube.) I'll fill the form using 5 gallon pales to carry the concrete.

I'm very happy to be at this point. Now that I have the main structure's floor framing in place, I can measure off of it to locate where I need to punch the holes for the other 2 footers. I'll probably pour those on Tuesday.

By Thursday I should be at a point where if it snows it won't matter.

I plan to build the walls and roof in my heated garage and then I'll carry them out and install them.

All in all I think I made good progress in 7 days. Time to rest tonight!


You've made great progress in 7 days time! Puts my first 7 days to shame :oops: (IMG:http://www.observatorycentral.com/style_emoticons/default/laugh.gif)
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dbeckstrom
post Nov 14 2006, 08:29 PM
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Monday, November 13, I awoke to about a half inch of snow on the ground. Bummer! Luckily, by noon the snow was gone and it had warmed up a bit. I installed the 2x8 ledger for the warming room floor.

I also built a form for the base of the pier column. I made the form out of the 3/4 plywood scraps left over from cutting the rings. There was a lot of waste from cutting the rings and it was nice to make use of some it.

Tuesday, November 14, we poured the 2 remaining footings for the warming room.

We also installed the form at the base of the pier column and poured it today too! All told we mixed up about 25 eighty pound bags of cement.

I didn't take many photos, but here are two showing the form.

(IMG:http://img142.imageshack.us/img142/1830/base1pk6.th.jpg)


(IMG:http://img142.imageshack.us/img142/6329/base2qz5.th.jpg)
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dbeckstrom
post Dec 17 2006, 09:01 PM
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Hi Everyone,

I got behind on posting photos so it's time to catch up on them!

This is a photo of my column. There is a 3x3 foot slab going down 5 feet, with a 2x2 foot slab on top for extra support. You can also see I started running the 3 inch PVC pull tube for my wiring.

The dog is my new Sheltie puppy. His name is buster and he was a constant helper during my build.

(IMG:http://img219.imageshack.us/img219/189/c1pe7.jpg)
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