Pier Construction

[robindurant]

I am going ahead with a 8x6' Roll of Roof Ob and am now considering the construction of a pier to take an ED 80 or a 8i. I have looked through old posts (pun?) but find no advice on a timber pier. I am considering a 6' dia hard wood sunk into concrete or a steel 4" or 6" square also sunk in. Any advice would be appreciated.

Robin

[Kai]

Phil (Gepetto) built a completely wooden pier last year i think Robin

[barkis]

Robin, I think you would have no problems with a wooden pier. A 6" solid high density wooden pier would be Ideal for the job. No vibration will be transmitted, It's a great medium to work with too.

I am just thinking perhaps it might be better to concrete in a metal post holder to take the post. You can get a six inch one. They are long and pointed to facilitate driving into the ground, but it would be wise to dig out a pad to a depth of about a foot at least. Drive in the holder to finish level with the concrete fill when it is poured in to the hole. Place the post in without fixing it , and position it exactly perpendicular. Brace in that position and await curing. The post can be wedged and screwed in when completely set.

Just a suggestion you understand.

Ron.

[robindurant]

Thanks Guys, great help ( you were the only two)

Robin

[beamish]

Not quite Robin,

Here's a more general link : http://www.mapug-astronomy.net/pages/memberprod.html

Subject: Telephone Pole as Permanent Pier? --part 1 of 3 From: Doug Bennett <d_bennettmweb.co.za> Date: Oct 2002 >John Ruthroff wrote

>I'm considering using part of a wooden telephone pole for a 'permanent'

>pier mount for my 12" LX200. This post is to invite comments from those

>that may have suggestions and corrections to make to my ideas and

>assumptions.

Gene Horr wrote :

>This should work quite well, if you are willing to live with a

>couple of limitations. The primary one is that you will get

>movement over time, requiring you to be occasionally adjusting

>PA (assuming that you are wanting to do imaging). The second

>is dealing with wood itself - moisture prevention, some sort. At the time my house was being built, my architect took me on a site tour of one of his other projects where he had used telephone poles to support an external roofing structure. The weather on the Transvaal Highfeld is notoriously rough on exposed timber and I've always thought the method he devised to prevent moisture / weathering damage to the poles was both simple and ingenious.

Seemingly, most timber damage occurs due to water moving between the telephone pole and concrete footing. This leads to water pooling in the base of the footing and results in rot. In order to prevent this, his footings were constructed with a rough aggregate stone with a thin coating of concrete slurry. This results in a porous structure which allows water to drain away from the wood into the sub-soil.

Another (theoretical) advantage to this construction method is that the large spaces between the particles of aggregate would allow the footing to be demolished easily.

---------------------------------- Subject: Telephone Pole as Permanent Pier? --part 2 From: John Hilliard <messier27earthlink.net>

Try the link below. I received this on another group and also a post from the "fabricator". He is very happy with it and uses it with a wedge for CCD imaging. We were looking at the wooden pier for exactly the same reasons as you. The generator has been very satisfied with it, has built a couple of them, and uses it inside an observatory.

<http://pages.cthome.net/astroleo/bequip.html>

---------------------------------- Subject: Telephone Pole as Permanent Pier? --part 3 of 3 From: Clif Ashcraft <WA2GUFnetscape.net>

I have used a wooden pier for my 10" LX50 for about 5 years now with completely satisfactory results. I made mine by joining four 8' long pressure treated 4x4s together with structural adhesive (liquid nails) and 6" long lag screws to make a sturdy composite beam with a 7" square cross section. I set it in concrete poured into a 12" diameter, 3' deep hole in the sandy, well drained soil of my backyard. I sawed the top of the beam off at an angle equal to my latitude and oriented to approximately face the pole, and to this angled surface I attached a plate made from two laminated thicknesses of 3/4" oak plywood. The telescope is attached to this plate with three bolts going into the threaded holes in the base of the mounting and three push screws held in the oak plate with tee nuts. Adjustment of the push-pull screws allows precise adjustment of the orientation of the polar axis, albeit not so convenient as some of the super wedges I have read about in this discussion group. Once adjusted it has been stable.

The pier passes through the floor of my tilt-off roof observatory, not touching it at any point. Vibration isolation is excellent: no image movement is detectable when someone walks or even jumps on the floor while I'm observing. Damping of vibrations resulting from accidentally bumping the pier itself is also rapid. If I were to try to improve the pier, I would probably try to make the polar axis adjustment a bit easier than using push pull screws to do the job, but since I don't schlepp the telescope around much, I don't have to make the polar axis adjustment very often. I have not regretted making the pier out of wood.

[robindurant]

Crikey, thanks Beamish. Really helpful

Robin

[beamish]

After having a chat with KK, I have just changed my mind about using a wooden pier, going for metal instead, BUT find a reclamation yard or something of the sort Robin. Reason being is that I recently visited one nr me and he was selling reclaimed telegraph poles of various dia, BUT where they had been cut you could see very clearly how deep the creosote had penetrated, RIGHT into the heartwood. NEVER EVER going to rot !! or crack ! cheap as chips !!

I shan't bore you with why I've changed my mind, but the pole I bought(pressure treated) from a timber yard has already developed some v nasty cracks, I don't fancy trying to dig it out if it failed completely :shock: . I hope you find the text and the link in particular, useful if not at least interesting

Karlo