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#1 scopefreak

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Posted 01 July 2013 - 08:38 AM

A few weeks ago I was reading Rod Mollise’s book “Choosing and Using a New CAT” and came across an interesting area where he was talking about his friend and astro buddy Pat Rochford and how he had made a wedge for his LX200 8” telescope. The really interesting thing about this was that he had made it out of WOOD!! Now I’m a firm believer in the strengths of plywood where it applies to most things, as back in the mid 80’s I built a GEM out of plywood and 2X4’s. I built this in anticipation of the delivery of my first Newtonian reflector from Coulter Optical. It was the 8” Odyssey and it was a Dob. So far in my astronomical journey I had only been using GEMs and so I was kind of spoiled when it came to this. I had never used an Altaz mount and didn’t want to start so I built a GEM due mainly for the fact that I could not afford a store bought GEM big enough to hold an 8” scope.

But back to the wooden wedge that Rod’s friend built. In the book Mr. Mollise also said his friend had built a permanent pier for his observatory out of wood as well. There was a picture of the completed work but its quality was not very good. Being a member of the Yahoo group for the EQASCOM project I sent Mr. Mollise a message asking him if he had any better pictures of the construction of the wooden pier/wedge in Pats observatory. He informed he did not but sent me a link to the newsletter Skywatch in which there was an article written by Mr. Rochford detailing his plan and construction details of the wooden pier/wedge. This was indeed just what I needed as I was also planning to build a new pier for my Atlas mount/C11 combo in my observatory, Black Hole Observatory. The Atlas mount has been part of my astro adventures since back in the early 90’s and I am now on my second Atlas, the Atlas EQ G with the GOTO system. On my Atlas mounts had ridden a C8 very happily for quite a few years while I saved my coins to purchase a larger CAT. Well that day finally arrived in early May of this year (2013) as I ordered my C11 and waited anxiously for it to arrive. Of course, as with any new astronomy purchase it seems to bring cloudy weather and my case was no exception. I waited for about 6 days for the sky to clear so I could give the C11 first light, but that is another story. What I did find out on the night of first light was the pier that I had in my observatory was not quite “beefy” enough to handle the increased size and weight of the C11/Atlas combo. So I began to research options for a larger pier to replace the one I had.

That brings us to the main topic of the post. The building and testing of a wooden pier for a permanent installation in an astronomical observatory.

After making a few calls to plumbing suppliers here in the eastern KY area I was amazed at how much a steel pipe cost. For an 8 inch diameter steel pipe the cost was $29.00 per FOOT!!! I needed a section of pipe at least 40”s long as well as for someone to weld it up to plans I had drawn up. Total cost estimate was around $300.00 dollars and a significant wait time to get it all done. While waiting, my observatory would be hard down with no place to mount the scope/mount combo, as the person who was going to be fabricating the pier would need my existing pier for a template in order to get the hole spacing correct where it connected to the bolts embedded in the concrete filled sono tube under the floor. I also looked into pre-made piers from some of the venders on the internet and was amazed at how much these things cost. The least expensive I found was $800.00 and this did not include an adapter for the top plate to hold the mount!! So this was not an option for my poor pocket book. Plan “B” then was in effect. I went to a large home improvement store and purchased a single 4X8X3/4 sheet of oak plywood. I had worked out my dimensions and determined that the entire pier could be made from a single sheet. Along with the plywood I purchased all the hardware I figured I would need to put it together and make it as strong and stiff as possible. This list included 12 5/8” bolts, nuts, flat washers, and lock washers. I also got a pound each of 2 ½” and 1 ½” fine threaded drywall screws and a 1 pint bottle of Titebond III water proof glue. The stain and poly coating I already had so didn’t need to purchase these items. The total cost for this trip to the hardware store?? $116.00!! I now had all I would need to begin construction of my “wooden pier” ala Pat Rochford’s design idea.

The first phase was to cut all the pieces I would need out of the single sheet of plywood. This was made easier by the simple fact that the store would cut the sheet to my dimensions and only charge me .50 cents a cut. I had them rip the sheet into 4 pieces as my ripping skills are very much nonexistent. I am fine cross cutting on my table saw but ripping an entire sheet of ¾” ply was not in my best interest. I play guitar and really like my fingers.

Plywood ripped and hardware in hand I began cutting the ripped sheet into smaller pieces. The main pier column was to be 10” by 10” with a base of 20” square and 40” tall. My plan allowed for the base plates to be double thickness for a total thickness of 3”. The very bottom plate was painted black with a primer coat as this piece would be in contact with the top of the concrete. The other bottom plate was attached directly to the pier column and stained/polyied to match the rest of the pier parts. I also added double thick gussets to the sides of the pier column that were 20” tall and 4 ½” deep to provide extra support for the pier. (See pictures attached). All pieces were then glued and screwed together and then stained or painted.

While building the new pier, I realized that the existing pier was filled with play sand from top to bottom. Inside the new pier column I was going to add a stiffener plate half way up the column. If I wanted to put sand in the pier, it would need a hole in this piece, so I cut a 3” hole in the middle plate and then installed it.

In order to ensure a proper fit I would need to take the existing pier apart and mark the location of the bolts in the concrete. I waited for the very last to do this as I was positive the skies were going to clear up and allow me to test the new pier the very same day I installed it. Well folks, the pier was completely installed and the mount/scope was put in place on Friday the 28th of June and here it is July 1 and still no clear skies are in sight!! :bawling:

So, for right now, enjoy the pictures and wish me luck with this endeavor as I await clearing conditions to perform my PA and put the new pier/mount/C11 through its paces.

Sorry this post is so long, but I thought it might interest those of us who do not possess the resources needed to purchase a “store bought pier”. My total cost including labor (my labor rate when I was employed was $20.00 per hour)? Right at $300.00 for all the pieces parts that went into the construction phase. I already had the power tools as I have always liked working with wood. I did need to purchase a forstner bit to drill the hole for the bottom of the Atlas to fit properly on the double thickness top plate. This cost me $41.00 and was not included in the above total as I will find other uses for it down the road. If you want to add it to the total that’s fine by me. I still was able to construct a pier for less than half what a commercial pier would have cost. :cool:

Oh, by the way, after getting it all put together, I thumped the side of the pier near the top and counted the settling seconds using a glass of water setting on the top plate next to the mount. It damped out in less than 3 seconds!! That’s without the sand as I am hoping I will not need to put any in the column. It’s very messy and makes it harder to take the pier apart should I have to move one day.

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#2 shawnhar

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Posted 01 July 2013 - 09:07 AM

Sweet pier!
Great write up too, I built mine by bolting 4 8 foot 4x4's together and buried 4 feet of it with concrete in the bottom. I need to redo the wooden pier plate though, it was made from a scrap piece of 2x6 and supposed to be temporary, that was over a year ago... Total cost for me was less than 100 bucks.
Mine has a little vibration when you rap on it as well, I just don't do that. :p

#3 Raginar

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Posted 01 July 2013 - 09:52 AM

Yours was way more expensive than mine. I spent 40 bucks on an 8' 6x6.. If I could do it again, I think I'd put 4 6x6s together to make it really good and bolt/glue it together for good stability.

Oh, and that PT 6x6? straight as an arrow after 18 months.

They do have a 'little' vibration, but if you're imaging it calms down after a few seconds and visually I use an electric focuser.

If I was building my 'forever' domed observatory, I'd go concrete. But, if you're looking for something for the moment, wood is a good option.

#4 Chuck Hards

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Posted 01 July 2013 - 10:03 AM

If the pier is hollow, fill it with gravel to dampen vibration. This works for wood or metal piers. You can use lightweight slag rock, it doesn't have to be dense natural pebbles.

#5 scopefreak

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Posted 01 July 2013 - 12:39 PM

Thanks loads for the good words and the ideas about filling the pier. I think if I do fill it I will use the loose rock idea. Might be a bit easier to remove if I decide to move the pier or if I win the lottery and can afford a "REAL" commercial pier. Lol. :lol:

#6 Raginar

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Posted 01 July 2013 - 04:51 PM

Oh it's hollow!!

#7 scopefreak

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Posted 01 July 2013 - 06:49 PM

Yes Chris, its hollow. But it is very strong!!

#8 Pat Rochford

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Posted 01 July 2013 - 08:25 PM

Hello Kevin,

For what it's worth, I have been using a 14" LX200 on that same wooden pier for almost eight years now. I removed the wooden wedge (still have it somewhere, I think) and modified the pier to accept an APT wedge.

At this particular time I am not using a CCD camera, but the pier had nothing to do with ditching the camera (using a photoelectric photometer now - see an article I wrote here on CN recently). When I was imaging, the pier was never an issue. Wind was almost always the culprit, when elongated started showing up. Autoguiding took care of most of the other issues associated with long focal length imaging - which is just plain hard no matter what kind of equipment you're using.

The pier is still hollow, I haven't seen the need to fill it with sand yet. As far as dampening time goes, well I try to avoid hitting the darn thing in the first place. It has always kind of bothered me that people go around thumping their scopes all the time. "Doctor ... it hurts when I do this!"

Pat

#9 scopefreak

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Posted 02 July 2013 - 06:29 AM

Hi Pat,

That is a very good point about thumping the pier. It really doesn't make good sense to go and thump the pier. :foreheadslap: I try and do like you: stay away from it. I invested in electric focusers just so as to NOT have to touch any part of the scope mount combo.

In building the pier I just used my imagination and common sense about what might make it the most stable of a platform as possible. I hope I did your design justice. :bow:

#10 John Miele

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Posted 02 July 2013 - 12:41 PM

Hello Kevin,

For what it's worth, I have been using a 14" LX200 on that same wooden pier for almost eight years now. I removed the wooden wedge (still have it somewhere, I think) and modified the pier to accept an APT wedge.

At this particular time I am not using a CCD camera, but the pier had nothing to do with ditching the camera (using a photoelectric photometer now - see an article I wrote here on CN recently). When I was imaging, the pier was never an issue. Wind was almost always the culprit, when elongated started showing up. Autoguiding took care of most of the other issues associated with long focal length imaging - which is just plain hard no matter what kind of equipment you're using.

The pier is still hollow, I haven't seen the need to fill it with sand yet. As far as dampening time goes, well I try to avoid hitting the darn thing in the first place. It has always kind of bothered me that people go around thumping their scopes all the time. "Doctor ... it hurts when I do this!"

Pat


I may be wrong, but I think the purpose of the "thump" test is to get a feel for what the scope might do when hit by a brief wind gust. If you are wind protected or always image on calm nights then that is probalby not an issue...John

#11 Raginar

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Posted 04 July 2013 - 09:46 AM

Hey Kevin,

What's it anchored to and how did you attach it to the ground?

#12 dawziecat

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Posted 04 July 2013 - 10:59 AM

What's it anchored to and how did you attach it to the ground?


The sticking point to a pier for me always comes down to the need to get 5 feet below the surface to avoid frost heaves. :(

#13 scopefreak

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Posted 04 July 2013 - 11:41 AM

Hi Chris,

It is attached to the top of a sono tube filled with concrete buried 4.5 feet below ground level. the top of the concrete enters the obs about 1.5 feet above ground and extends a little over a foot inside the obs. In the top of the concrete are 4 5/8" bolts that the first double thickness plywood base is attached to. the pier base is also double thickness and that is in turn bolted to the first plywood base with 12 5/8" bolts that go all the way around the circumference.

The pier tube is glued and screwed to the top of the second plate with the gussets glued and screwed to the sides of the pier tube as well as the second bottom plate.

It is very strong and as far as I can tell immovable. Of course the further up the tube you go you will get some movement but like I said in an earlier post it damps out in less than 3 seconds.

Here is a picture of the first base plate.

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#14 Lorence

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Posted 04 July 2013 - 01:38 PM

The sticking point to a pier for me always comes down to the need to get 5 feet below the surface to avoid frost heaves.


I built my pier out of four PT 6x6's bolted together. I had an excavator drive it into the ground like a pile. It is down over five feet. Hasn't budged in over three years with temps ranging from high 90's to -40 deg.

The ground around here is very hard. It's difficult to dig a hole with a powered post hole auger. By hand you better have a lot of time on your hands.

#15 Raginar

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Posted 05 July 2013 - 11:46 AM

Lorence is spot on.. digging by hand took me 3 hours in rocky soil to get 3 feet. I gave up at that point :). My single 6x6 dampens out in about the same time 3-5 seconds and for AP it's perfect. For visual, having an electric focuser is the heat.

Clear skies,

#16 scopefreak

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Posted 06 July 2013 - 09:09 AM

It was my good fortune to have a very moist and sandy soil composition when I dug the pier footing. It also helped to have some help as digging that deep of a hole would have probably killed me. :p

The only regret I have is that I used a 12" sono tube instead of an 18". This was fine with the smaller diameter pier I started with, but when I went to the bigger scope (C11) I would have liked to have had the bolts spread a little farther apart then they are. :bawling:

All in all, it turned out well and like I said earlier, it is strong and stable. Now if I could get some cloudless nights to try it out and get polar aligned..... ;)

#17 scopefreak

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Posted 08 July 2013 - 10:02 AM

Last night was the first light for my new plywood pier and I must say it was a wonderful experience. :grin: The difference between the new pier and the old was like night and day ( pun intended ). Even though the original pier was fine for the Atlas and the C8, this bigger pier handled the C11 like it was no bodies business. Vibration was practically non existent and when I experimentally "thumped" the side of the pier the image damped out in about 3 seconds. Performing the first PA was a piece of cake compared to the old system as it was next to impossible to get the main bolt tight after azimuth was adjusted. With this new pier I cut a 4" hole in the south side of the top of the pier so I could more easily get a socket on the bolt after the adjustment was complete. All night long I bounced from one side of the meridian to the other and all of my GOTO's were either dead center or just off center.

Also, last night was the first time I had used EQASCOM completely by itself. No HC!!!! Just a cheap $20.00 game pad from good ole Wally World to slew and center my alignment stars. What a complete joy!! :) :jump: Suffice it to say that I am hooked on this fantastic, free telescope control program for the Synta mounts. Look in the software forum for a more detailed description of how that went last night later today if you are interested.

Also if anyone wants my plans for the pier please do not hesitate to PM me. Now to get a little shut eye as I was up all night viewing and drinking coffee and I am finally feeling tired enough to sleep ( I hope :p ).

#18 Pat Rochford

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Posted 08 July 2013 - 08:24 PM

Kevin - Really glad the larger version of the pier worked out. Prior to making my pier, I'd built several large Dobs (up to 24") and just didn't understand why wood hadn't been used more often in the construction of piers. If designed properly, the natural dampening property of wood makes it a perfect supporting material, at least in my opinion.

Just as in the case of steel or aluminum pipe, the larger the diameter in wood, the more stable it becomes. If I hadn't come into a piece of 12" diameter aluminum pipe for a dollar (yes, it cost me $1), I would not hesitate in making a larger scale wooden version (for my 14") of what I presently have. All I need to do now is make a larger observatory.

Hope you have many enjoyable nights from here out with your 11".

Pat

#19 scopefreak

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Posted 09 July 2013 - 08:54 AM

Hi Pat,

If it weren't for you and Uncle Rod I would have not built that wonderful pier. I had just never thought that something as important as a pier could be built from wood. I guess my logic was flawed as I did build a GEM from wood back in the late 80's for my Odyssey 8" to ride on (I've never been a fan of DOB's). I will try and find a picture of that mount and post it but I'm not sure where they are :o.

You mentioned building a larger version for your 14". Any way you could post a picture? I'd love to see it.

#20 Lorence

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Posted 09 July 2013 - 03:31 PM

If it weren't for you and Uncle Rod I would have not built that wonderful pier. I had just never thought that something as important as a pier could be built from wood.


"This is how it has always been done and this is how it shall always be done."

I spend thirty nine years working in a high tech environment and have seen tremendous change during that time. I fought with a lot of people with that attitude while I was working. It is amazing how many people think that way.

I was very surprised to find a lot of people with the same narrow minded attitude in the astronomy forums.

Always keep an open mind and at least take a look at new or different ideas before rejecting them.

#21 Pat Rochford

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Posted 09 July 2013 - 03:36 PM

Hello Kevin,

What I need to do is build a larger observatory ... I'm still using the 6' x 12' roll off roof I made for my original 8" LX 200. (Half of the observatory is a warm room, so the 14" is sitting in a 6' x 6' space. Cramped is putting it mildly!)

A friend of mine made me a pier for the 14" out of a section of a ship's bridge mast. It is 12" diameter aluminum with base and top plates, about 42" tall. I've already drilled and tapped it for my APT wedge. Again, all I need to do now is build a larger structure to put it and the scope in.

If I can ever get the ambition and money together at the same time I'll do it and post a picture or two.

Pat

#22 Kraus

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Posted 11 July 2013 - 01:09 PM


Mine is concrete. No vibration to speak of.

#23 Raginar

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Posted 11 July 2013 - 02:49 PM

Kraus,

Yup. I bet it doesn't.

#24 gnowellsct

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Posted 13 July 2013 - 08:26 AM

It's a beautiful piece of work. I consider a three second damping time to be just so-so, however. My wood tripod does better as does the ATS pier which however cost 5x what you paid for your pier. The damping time of the pier however may not matter very much. If the pier is isolated from the floor, you won't have much cause to worry about damping issues in an observatory set up. You won't be in the wind and there won't be passers-by. Damping time does matter to me in the sense that I don't like to get a three second bounce when I touch the focuser, which happens on a *lot* of commercial set ups. But that is a function of the mount and the pier together; you would have to test them as a set-up.

The damping qualities of wood are generally considered to be excellent, one of the reasons it continues to be used in tripods.

Greg N

#25 scopefreak

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Posted 13 July 2013 - 09:37 AM

Thanks for the compliment on my pier. The damping time was just a rough estimate after "thumping" the top of the unit while observing. The pier is isolated from the floor by 2" all around the concrete sonotube that is in the ground 5'. The only contact I ever have with the scope/mount combo is when I change EP's or adjust the sliding counter weight when adding/subtracting equipment. I also never touch the focus controls on either the scope of the EV focuser. Both are controlled by computer or HC boxes.






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