Bear Claw Observatory: Concrete Pier

[@JoesAstrophoto]

Thanks for watching!! Please consider subscribing and leaving a comment. I try to answer all the comments I can and don't forget to checkout some of the other content on my channel.

[@compubyte2010]

Great job man !!!! I love to see people do things the correct way.. Nothing makes my skin crawl more than some poor sap who thinks, I've built an awesome observatory. and ONLY spent $1500 on it. or whatnot. and it's literally a shed with a Platform, NO hole in the middle, No pier.. just a wooden platform with their telescope and tripod. sitting on it..Bouncing every time they walk or move in a chair? Taking the time to do it correctly is Key to a great observatory!! and your sir, looks like it's going to be a Great Observatory !!!

[@JoesAstrophoto]

Thanks Frank, it definitely takes some planning before you get started. Sometimes I think the 12" diameter and 4ft in the ground with an anchor at the bottom is a little overkill, but it's so nice to know I can put just about any mount on top of this thing and it will work flawlessly.

[@SmeeUncleJoe]

Great job !! They however advise against putting the tube underground for several reasons: They rot and that means it gives your pier a chance to move by about half and inch and the fresh compact, undisturbed earth on the sides of the hole will hold it tight and upright if and only if the cement is contacting that earth. Notice your frostline data probably specifies 'undisturbed earth" or "compact earth".

[@gary7990]

Great job Joe.. I'm going to do the same once the snow is gone and hopefully build an observatory next year... which I will be calling Bearface's Observatory..lol .. so I really like the name Bear Claw.. thanks for the detailed video.. you've got a new subscriber..

[@JoesAstrophoto]

Many thanks Bearface! My observatory has really transformed my hobby, and I know you'll love yours as much as I love mine!

[@tizocsuarez1563]

Greetings from Costa Rica, great video and thanks for sharing. Question, you mention that the pier base plate is made out of some chevy rear break drums, can you provide more details so i can get the same? thanks

[@steveholak7829]

Joe, what concrete mix did you use?

[@michaelm249]

I replaced the altitude adjustment knob on my eq6-r pro with a 3d printed press fit knob (no longer the spring loaded nonsense that came with the mount), it is now significantly easier to adjust. i'm about to start pouring concrete for my own pier and will be using a 2012 chevy malibu rear rotor :)

[@JoesAstrophoto]

Grats on the new pier Michael! I replaced my alt knob as well finally, it makes a huge difference.

[@lawrence5254]

I love your rat cage under your mount. You should have enough room under that for several pet rats since all that wasted space to get mount level is totall not neccessary and degrades from what could of been a better job. The only thing that matters is that your RA is aligned with the NCP that is it!

[@JoesAstrophoto]

Lawrence, I always appreciate feedback, good or bad, but I could do without the ridicule. I'd love to see your pier and mount video. My mount and scope sitting on top of my "degraded" rat cage has produced several award winning images as well as an APOD, so I guess I'm pretty happy with it, degraded or not. Thanks for the feedback.

[@marchoude2303]

I realize this is an old video but can you tell me what the point is of that first 3/16 steel plate? Couldn't you just bolt the brake drum to the J-bolts coming out of the pier?

[@katherinemurphy5739]

The "mount bracket" is a brake disk, not a drum brake. I know it's a nit, but it might confuse people who don't know the difference and go searching.

[@JoesAstrophoto]

Thanks for watching and commenting Katherine! Thanks for pointing that out as well.

[@compubyte2010]

Ya, cuz id be that guy for sure !!! I'd probably have try to mount a drum brake lol

[@alankilgore1132]

did you put a "deadman" conecting to the bottom of the tube underground?

[@JoesAstrophoto]

Hi Alan, I did, but not a very big one, about 2ft x 2ft at 4ft deep, just below frost line.

[@flightdeckstudios1668]

Hi Joe, where did you source the J bolts? Are they Stainless, Or Galvenized? Also, do you think a 12" dia pier is overkill for an EQ6, or would 8" or 10" serve the purpose,

[@JoesAstrophoto]

Hi FDS, the j-bolts are galvanized and think I got them at Lowe's. I went with a 12" wide pier because I knew I'd be upgrading to a larger mount in the future. If you know you are going to stick with the EQ6, I think 8" diameter is more than adequate.

[@lameaxe]

Loved the video. What height off floor level would you say would be the height sweet spot? Have an 8se but want to get into astrophotography. On the cheap as I can. Thanks for this!

[@JoesAstrophoto]

Thanks GS! For me it’s the lowest angle I can image at, which is 20 degrees above the horizon. My pier is 36in above the ground, but it’s dependent upon the height of the walls and how far away the walls are to get that 20 degree angle. Also have to figure in the mount height and if you have risers on the scope, etc. My walls are 6’4” tall and about 4ft away from the scope on all sides. If you wanted taller walls you’d want a higher pier.

[@montygiavelli8125]

This is the first time I've heard about any movement. One degree seems like a lot and makes me cringe. I'm about to build a permanent pier. Could it be that the Sonotube is expanding and shrinking inside the concrete as it dries and then absorbs water? Seems that it would be better not to have paper between the concrete in the ground and the concrete in the tube. Just a thought Monty

[@JoesAstrophoto]

Thanks Monty, you know, I'm not sure what it is to be honest, but it's gotten better the longer I've had it. In the last 3 months it's only off 46 arc seconds. I get this from running "Guiding Assistant" in PHD2. I haven't had a clear night in two weeks to do another PA, but I'll record the date and then in 30/60/90 days see how much it's off. I'm still guiding at a total RMS error of .8, but of course I want that PA within 10 arc seconds.

[@astroazores]

Hello! When mounting the rat cage to the concrete, do you already had the north pole screw and all the rat cage assembled or did you do that later? How to you manage to get it pointing north and have all the screws aligned? Thanks!

[@JoesAstrophoto]

Hi Valter, I built the rat cage prior to pouring the pier. Then I made a wood jig and bolted the j-bolts to it to make sure the j-bolts were aligned correctly. I drilled a hole in the disk brake where the bolt goes for the north bolt after it was all mounted. You can guesstimate this as there is some room to move the azimuth, but I suppose it depends on your mount. The EQ6 has quite a bit of movement.

[@astroazores]

@@JoesAstrophoto, thanks for the quick answer. I currently have a EQ3 and hope to upgrade to a EQ6 in the future. If I do a pier now for the EQ3, it will probably be fit for the EQ6, I guess.

[@JoesAstrophoto]

@@astroazores it should as long as you have a solid pier 8 - 12” in diameter. The only thing you’ll need to change is the mounting plate. Not sure the EQ3 and EQ6 will use the same one, but that shouldn’t be a big deal.

[@denispol79]

Hi! I didn't understand, so the bottom part of a pillar is not permanently set into the ground, or the ground itself is very unstable? Because shifting and tilting up to 1 degree a month sounds really a lot.

[@JoesAstrophoto]

The concrete is permanently set in the ground. My polar alignment seems to be off about 1 degree every 6 - 8 weeks. The concrete isn’t moving that I know of, but from what I’ve read and heard from others is that the pier acts as an inverted pendulum. I think, but not sure, the longer you make it the more effect it has. I made mine a little over a meter deep because of the frost line in my area. Hope that makes sense, and again, not exactly sure myself of the physics, but it’s been very solid and I don’t mind doing a polar alignment once every couple months

[@tjn5845]

What part of Colorado do you live? You mention on your website that you live in the foothills. Are you the western slope? I live in the Denver area and would love to have Bortle 2 skies

[@JoesAstrophoto]

Thanks for watching and commenting. I live in the Beulah Valley, in the Wet Mountains. It’s west of Pueblo on the front range.

[@tjn5845]

Thanks, looks like a beautiful area

[@marvinwhisman3333]

Joe, is there concrete around the outside of the sono tube underground or did you just pour the tube and then backfill with dirt? I am assuming you put in the tube first, then poured the deck after? Getting ready to build mine using the same technique and wondered about some of those details? Did you take pictures of the construction? Sorry for so many questions. Thanks for your assistance.

[@JoesAstrophoto]

Hey Marvin, no worries on the questions at all. I poured some concrete, like a 2ftx2ft square at the bottom, then while still wet put the sono tube in the hole and poured it. 4ft in the ground and 3ft above, yours may vary based on frost line and your needs for pier height. I built my deck after the tube with 4x4s and 3/4 in plywood all pressure treated for ground contact, but did place them on concrete pavers to level. Unfortunately I didn’t take any video or pics of the build, but if you have any more questions I have no problems answering the best I can. I can tell you I went way overkill, but the cost of building materials weren’t that high at the time I built it. Good luck on your build!

[@marvinwhisman3333]

@@JoesAstrophoto I am going to follow your general plan and try to get the metal fabrication (holes drilled) by a machine shop if I can find one. I didn't realize the floor was a wood floor. It looked like concrete in the video. Making a wood deck would certainly be easier and probably cheaper than concrete. Also, how big are the metal plates you are using? Thanks

[@JoesAstrophoto]

@@marvinwhisman3333 The metal plates I used for the rat cage were 8" x 8" and 3/16" thick. Depending on the size of hardware you are going to be using, it may be cheaper to have them drilled out or cheaper to just buy titanium drill bits. The titanium bits get very pricey above 1/2" and hard to find. I used a cobalt bit for the 5/8" holes and it took forever to drill.

[@OlliesSpace]

Great name Bear Claw Observatory.

[@JoesAstrophoto]

Thanks Ollie!

[@Zealor365]

I'm not sure i'm going to keep the house, so I am trying to figure something semi permanent.

[@JoesAstrophoto]

Thanks for watching and commenting Mark. Ya know, I’ve seen a lot of people using four 4x4s butted together. That’s a whole lot easier to remove if you decide to move and you’ll still have the mount base to take with you to your next house.

[@RL112871]

Check out a local metal fab shop. You could probably get a steel pier fabricated for about $300 - $400 dollars. Pour a concrete pad 2x2 or 3x3 about 4 -6 inches thick. Mount said pier to the pad.

[@katherinemurphy5739]

The polar alignment problem may be caused by the section of bolts beneath the mount bracket. This is often referred to as a "rat cage". It's purpose is to level the mount, however it is redundant since the equatorial mounts already have this adjustability built in. Therefore, it just adds another area for movement. Seems like it would be relatively easy to temporarily remove this section and see if it fixes the problem. You would just need to drill some extra holes in the brake disk. If you search some of the forums or Facebook pages for "rat cage" you will find it is a controversial topic with experts on both sides, so you'll need to decide for yourself :-)

[@JoesAstrophoto]

Thanks again Katherine, I originally made it that way so that I could easily lower the entire mount if I needed to, but now I'm not sure I'll ever have to.

[@MasseyLee]

I built a pier pretty much the same as yours and found that the long bolts coming up out of the concrete allowed too much movement. I could see the mount resonating when I stopped a slew. So, I cut them short and it was much better.

[@JoesAstrophoto]

@@MasseyLee Thanks Lee, I have it setup so that I can just screw the plate down closer the concrete, so I can give that a try as well. In effect shortening the bolts to an inch or so.

[@lachezarkrastev7123]

It is all good, but when I see all those levels of threaded rods and plates on a concrete pier, my head is going to explode ...

[@JoesAstrophoto]

Unfortunately for me, the rat cage was the best way to go. I need space below to attach the mount with a sufficient bolt and the ability to change the mount plate in case I want to upgrade later, but I hear what you’re saying lol

[@lachezarkrastev7123]

@@JoesAstrophoto great observatory otherwise :)

[@JoesAstrophoto]

@@lachezarkrastev7123 Many thanks!