Pier for 1100GTO #Guiding
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Len Fulham
"It looks like the sides were rolled to produce the shape."
Don, yes/no. I had a boiler-maker make it but there was no roller. A press was used to progressively make small bends to form the shape. I made a cardboard template with bends every 4" for him to work to. I do like the pier that results. On a different scope I replaced a pipe pier (8" dia, 60" long) with a similar tapered pier with great improvement. That one had a 16" base tapering to 6", 60" high but was asymmetric - the Nth side was flat so the equipment C.O.G. was kept over the pier foot. Made of steel these piers are quite heavy, but not intended for portability! Could be made of aluminium of course. As mentioned a straight sided tall pyramid pier would probably be just as stable but has greater bulk higher up where it might affect a long scope. Len, |
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Donald Gaines
Hi Len,
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That is a very nice pier. What you say makes a lot of sense. It looks like the sides were rolled to produce the shape. Thanks, Don On Saturday, March 20, 2021, Len Fulham <lfulham@...> wrote: Embedded or bolt attached pipe piers are commonly and successfully used, but they have an inherent tendency to resonate vibration. Filling with sand or concrete changes the frequency and maybe amplitude without necessarily improving damping as might be expected. |
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Len Fulham
Embedded or bolt attached pipe piers are commonly and successfully used, but they have an inherent tendency to resonate vibration. Filling with sand or concrete changes the frequency and maybe amplitude without necessarily improving damping as might be expected.
The best piers have a broad base tapering progressively to the top. This form minimises the tenancy to resonance and is self damping. It is not a good shape for embedding, but works extremely well for bolted applications (eg bolted to a concrete base). Look at this example: https://ap-ug.groups.io/g/main/photo/113262/13?p=Created,,,20,2,0,0 The pier has a 600mm square base bolted to a isolated concrete foundation. The pier tapers exponentially to 150mm square at the top. It is made of 6mm thick mild steel. It forms an extremely stable base for the vintage AP 706 mount and 6" AP scope. It takes more to organise a pier like this but it is appreciated in the long term. A simpler "tall pyramid" shape (ie tapered flat sides rather than curved & profiled)) would be much better than a pipe, and could more easily be made embeded. Something to consider, Regards, Len. |
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Should be able to find a suitable piece of pipe at a scrap yard. I would get a piece of 8" Sch40 pipe, weld a 1/4" flat plate on top and an 8" ANSI150# flange on the bottom. I would pour a concrete footing in the ground and cement in a matching 8" flange welded to some rebar. I would set the cemented in flange about 18" below ground. One would then bolt the pier to the flange then attach an AP flat surface adapter such as the 119FSA. The reason for the underground flange is should one move it would be much easier to take down the pier system and reclaim the area. Don Anderson
On Friday, March 19, 2021, 01:46:54 p.m. MDT, Keith Olsen <keitholsen@...> wrote:
If you really want a heavy duty pier get a schedule 80 pipe and have a plate welded on top and bottom. Mine is 5" nominal(5 1/2" OD) 3/8" thikness and about 21 lbs per foot for my OBS with my Mach1. I bolted the Losmandy field tripod adapter to the top plate with the astro-physics LT2APM adapter attached to that. I will be getting an 1100GTO and will install it on the same pier. 5 1/2" OD seems small but this thing is solid and heavy. My wife owns a steel business and made mine, she looked today and it is going for $24 a foot here in Illinois but the price has been varying a lot lately. |
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Luca Marinelli
Something to keep in mind is that deflection of a pipe with an end load is equal to F*L^3/(E * D_o^3 * Delta_D), where F is the applied force, E is the modulus of elasticity, L is the length of the pipe, D_o is the outer diameter, and Delta_D is the thickness of the pipe wall (assuming the pipe wall thickness is much smaller than the diameter of the pipe). This means that in general diameter of the pipe has a bigger impact on stiffness than thickness of the pipe wall.
For example, an 8in schedule 40 pipe of a given length will deflect 3 times less than a 5in schedule 80 pipe of the same length, made of the same material. Other considerations (for example weight) may drive towards narrower pipes.
Luca
From: main@ap-gto.groups.io <main@ap-gto.groups.io>
On Behalf Of M Hambrick via groups.io
Sent: Friday, March 19, 2021 5:33 PM To: main@ap-gto.groups.io Subject: Re: [ap-gto] Pier for 1100GTO #Guiding
Hi Don |
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Bruce Donzanti
For my 1100GTO, I built a cement pier that runs over 4 feet under ground and is about 15 feet above street level with Pier-Tech adjustable steel pier on top of that. It has worked great for over 3 years for imaging. It is essentially my observatory on top of my 4-car garage.
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Donald Gaines
This is all really great information. Thanks every body.
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Don On Friday, March 19, 2021, Pete Mumbower <pmumbower@...> wrote: For my incoming 1100GTO I ended up buying a SB pier designed for the MX/MX+. It is 10" OD and have 1/2" plates top and bottom. Like others above, I have it attached to a 18" dia, 6ft concrete poured into the ground with stainless J-bolts. Really solid setup. I just need to drill and tap the top plate for the ADATRI. Nice thing with the SB pier is it is around $720 in wide range of heights(I have a 48") that are usually in stock and ready to ship. |
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Pete Mumbower
For my incoming 1100GTO I ended up buying a SB pier designed for the MX/MX+. It is 10" OD and have 1/2" plates top and bottom. Like others above, I have it attached to a 18" dia, 6ft concrete poured into the ground with stainless J-bolts. Really solid setup. I just need to drill and tap the top plate for the ADATRI. Nice thing with the SB pier is it is around $720 in wide range of heights(I have a 48") that are usually in stock and ready to ship.
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Hi Don
Robert Berta had some really good comments about the benefits of using a bolt down design. I also like the 5-inch schedule 80 pipe idea from Keith Olsen. What would the same length except 6-inch schedule 40 pipe in 304 or 316 SS cost ? Before I took an eight year hiatus from the hobby I was thinking about getting one of the Le Sueur piers to set up in my back yard, but they had gone out of business when I got back into the hobby. Lately I have been checking CN and Astromart regularly to see what's for sale. I have not been looking for Le Seuer piers, but I will; have to pay attention to see if any show up. Mike |
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Luca Marinelli
I have built two steel piers for my roll-off roof observatory last Summer. They are both extremely stable, one carries the Mach2 with an FSQ106 and the other a AP1100 with a 10in f4 Newtonian. I have imaged with both system in pretty windy conditions with gusts up to 50mph and the yield is very high. I have not needed to update polar alignment of the mounts since they were first installed.
The base is a reinforced concrete column of 18in diameter and almost 6ft deep into the ground. It is unformed concrete against undisturbed soil up to six inches below the surface and then I used a 18in sonotube to bring it up to the level of the floor of the observatory. Obviously, this structure is completely separate from the observatory itself and I use soft foam to fill the space between the floor and the concrete columns so critters don’t get in. 3/4in galvanized steel J-bolts were set in the concrete with a wooden template matching the drilling pattern in the base of the steel pier.
The steel piers are made of 8in schedule 40 steel pipe welded to 1/2in thick steel base (18in square cut into an octagon). On top of the steel pipe, I made a cap with 10in steel disc welded to a 5in section of 6in schedule 40 steel pipe. The steel disc was drilled to accept the ADATRI (respectively the flat pier adapter for the AP1100). Six 1/2in bolts lock the steel cap in place. Everything was primed and painted to keep it from rusting and I think it looks pretty good. The only work I outsourced to a local shop was cutting the octagon and welding. Altogether, materials and labor cost roughly $450 for each pier. There is an interesting thread on CN called “Pier engineering” that has a lot of useful ideas.
An advantage of the steel pipe is that it is inexpensive to change the height of the pier if it becomes necessary. I am in the process of shortening the pier with the FSQ106 to use a RASA11 on the Mach 2, for example.
Cheers,
Luca
From: main@ap-gto.groups.io <main@ap-gto.groups.io>
On Behalf Of Stone, Jack G via groups.io
Sent: Friday, March 19, 2021 4:05 PM To: main@ap-gto.groups.io Subject: Re: [ap-gto] Pier for 1100GTO #Guiding
What do you guys think about the Le Sueur pier? It’s designed to accommodate many of the adapters for various mounts. Not sure, but I’ve seen many for sale on CN and AM
Jack ~
From: main@ap-gto.groups.io <main@ap-gto.groups.io>
On Behalf Of Robert Berta
If you bury the tube in the concrete you are locked in to the orientation and any shift over time. This can be a big issue if you have climate that is in the snow belt like me. It is far better to pour a concrete base and have bolts imbedded
that will allow connection to the pier base. That way you can adjust for orientation (using slotted holes) and getting the pier top level by adjusting the nuts on the bolts on each side of the pier bottom plate. One person in this topic mentioned burying
his tube 24" deep. That won't work if you are in the snow belt....it needs to be burred deeper. If in the snow belt I would check with city or contractors about how deep it should go to ensure it won't move around as the soil shifts. |
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Stone, Jack G
What do you guys think about the Le Sueur pier? It’s designed to accommodate many of the adapters for various mounts. Not sure, but I’ve seen many for sale on CN and AM
Jack ~
From: main@ap-gto.groups.io <main@ap-gto.groups.io>
On Behalf Of Robert Berta
Sent: Friday, March 19, 2021 12:50 PM To: main@ap-gto.groups.io Subject: Re: [ap-gto] Pier for 1100GTO #Guiding
If you bury the tube in the concrete you are locked in to the orientation and any shift over time. This can be a big issue if you have climate that is in the snow belt like me. It is far better to pour a concrete base and have bolts imbedded
that will allow connection to the pier base. That way you can adjust for orientation (using slotted holes) and getting the pier top level by adjusting the nuts on the bolts on each side of the pier bottom plate. One person in this topic mentioned burying
his tube 24" deep. That won't work if you are in the snow belt....it needs to be burred deeper. If in the snow belt I would check with city or contractors about how deep it should go to ensure it won't move around as the soil shifts. |
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If you bury the tube in the concrete you are locked in to the orientation and any shift over time. This can be a big issue if you have climate that is in the snow belt like me. It is far better to pour a concrete base and have bolts imbedded that will allow connection to the pier base. That way you can adjust for orientation (using slotted holes) and getting the pier top level by adjusting the nuts on the bolts on each side of the pier bottom plate. One person in this topic mentioned burying his tube 24" deep. That won't work if you are in the snow belt....it needs to be burred deeper. If in the snow belt I would check with city or contractors about how deep it should go to ensure it won't move around as the soil shifts.
By the way, another advantage of the bolt down method above is that you can remove the pier for maintenance, replace in the future, etc. Make sure you have it sufficiently high enough. If you change out your mount in the future you may need to get a different height pier. I went from a AP900 mount to a AP1100 mount....on the same pier the 1100 puts the telescope higher up from the floor. I use both a 11" SCT as well as a 152mm APO refractor so my design had to be at a height that could accommodate both telescope types |
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If you really want a heavy duty pier get a schedule 80 pipe and have a plate welded on top and bottom. Mine is 5" nominal(5 1/2" OD) 3/8" thickness and about 21 lbs per foot for my OBS with my Mach1. I bolted the Losmandy field tripod adapter to the top plate with the astro-physics LT2APM adapter attached to that. I will be getting an 1100GTO and will install it on the same pier.
5 1/2" OD seems small but this thing is solid and heavy. My wife owns a steel business and made mine, she looked today and it is going for $24 a foot here in Illinois but the price has been varying a lot lately. |
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Donald Gaines
Hi Mike,
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I was thinking sand at first, but concrete may be a better idea. What are your thoughts on it? Don On Friday, March 19, 2021, M Hambrick <mhambrick563@...> wrote: Hi Don |
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Hi Don
That sounds like a good design. Are you also planning to fill the pier with concrete or sand when you bury it in the ground ? The advantage to a plain pier is that it will allow you a little more range of movement without having to worry about pier crashes. The one downside to the A-P portable pier is that the trusses interfere with pointing to the meridian at some declinations. Mike |
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Donald Gaines
Hi, I’m new to the group but it looks like I’m going to be getting an 1100GTO as well. I am familiar with Astro-Physics piers and I think they are extremely well made, very solid, and work extremely well. I want to put my 1100 in a ROR observatory and really would like something that functions like the AP pier, without the legs. My solution is to by an 8 in OD 7.75 ID aluminum tube 6 ft long cost $220 from a local supplier. This has the same diameter and wall thickness, 1/8 inch, as the tubing AP uses for their piers. I had an old AP Flat Pier Plate to which I took a reciprocating saw and removed the ring on the bottom of the plate, which fits inside the pier tube. This ring is 1/2 inch thick and it took about an hour to cut it off. It is a snug fit inside the pipe, but I will attach it with 6 screws for which it is already drilled and tapped, and place it 3/4 in below the top of the pier. I will drill another 6 holes to attach the 1100 which will sit on the ring. This will give fit and function similar to the AP pier. Since it is 6 ft long it will allow 24 in to be buried, with 48 in above ground. Good luck, I can't wait to get the mount, AP really builds extremely high quality equipment. Don Gaines On Friday, March 19, 2021, Steve C. Mitchell, Sr., O.D. <smitchell@...> wrote:
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Steve C. Mitchell, Sr., O.D.
You’ve been given some good points to consider already. But don’t forget about your wall/pier heights ratio. You don’t want your pier to be to short or you’ll lose those sometimes low objects you might want to capture cause you can’t see over the wall. I actually made an adapter to make the mount higher for my existing 12” pier, I had made for my previous “other brand” mount that was of no comparison to my AP1100, so that when parked my new setup clears the rolling roof with about 5” to spare. A little scary the first few times you open or close the roof when the rafters go passing by, but actually a good distance for safety once you get used to it and “know” it’s not going to hit your camera or telrad or whatever sticks up. I can see all the sky I can see at my location with this height.
Steve
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io]
On Behalf Of dbrannan0523@...
Sent: Wednesday, March 17, 2021 7:05 PM To: main@ap-gto.groups.io Subject: [ap-gto] Pier for 1100GTO #Guiding
I have an 1100GTO mount on order and plan to house it in an observatory on permanent pier with imaging in mind. I own an old AP 8" diameter portable pier. Would anchoring this in concrete and filling the tube with sand be sufficiently stable or is there clear benefit in purchasing a heavier thicker permanent pier for best performance. Any thoughts? |
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Donald Brannan
Thanks for your advice.
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I use my 1992 vintage A-P portable 8-inch pier with my 1100GTO mount. It is rock solid, even with a 180 EDT scope, 16 megapixel camera, and piggybacked guide scope attached. I set up and take down my gear including the pier every time I get it out.
I didn't anchor my pier in concrete, but I did pour 8-inch diameter concrete pads about 2 ft deep into the ground to give the pier legs a solid base to sit on. if I had a permanent observatory I would try to figure out a way to lock the legs into position so as not to disturb the polar alignment. The biggest challenge I had with my old A-P pier was getting the 1100 mount base firmly attached to it. The top of the original pier was not perfectly flat, so I had to hand scrape the high spots so that the mount base made even contact with the top of the pier. The old piers only have three holes for attaching the mount base. I drilled three additional holes in it so that I could attach the mount to the pier using all six screws. Finally, I use NORD-LOCK lock washers on the screws that attach the mount base to the pier to prevent the base from shifting in the pier when everything is attached. I hope this information is useful. Mike |
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Probably could be made to work but is it worth the effort? Don Anderson
On Wednesday, March 17, 2021, 09:56:17 p.m. MDT, <dbrannan0523@...> wrote:
I have an 1100GTO mount on order and plan to house it in an observatory on permanent pier with imaging in mind. I own an old AP 8" diameter portable pier. Would anchoring this in concrete and filling the tube with sand be sufficiently stable or is there clear benefit in purchasing a heavier thicker permanent pier for best performance. Any thoughts?
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