OK , been doing some head scratching and checking out what I have stashed in my garage rafters.
I've a couple of lengths of plastic pipe : (2m about 6" in OD and a 1.5m of 8" OD , left overs from other projects).
Now either of these would be OK as molds for making a reinforced concrete peir.
But is a concrete peir the best way to go ?
Is a steel peir better than a concrete one ? (one advantage I see straight away is that it can be moved or relocated if you move and it it bolted to a suitable concrete slab or concrete footing , but it will work out more expensive building - need someone to do the welding of top and bottom flanges and reinforcing gussetting for me.)
Last edited by Ian Robinson; 01-11-2008 at 01:28 PM.
Ian,
I'll kick this off.
I used a section of 6" steel pipe, and to this welded a flat that allows me to bolt/unbolt it from the lump of concrete that is in the ground. I don't do this as a matter of course, but I figured it would future-proof the idea. Mine is only about 600mm tall though, built for a newt.
Catch of this is that I also have another section, same pipe, and on a three legged wheelie thing, so in effect a "rolling pier", and the mount is swappable between the two. Of late I am using only the rolling job, as it is a matter of rolling it out, winding down the "feet" and attaching the 240 volt. It is as close to the pole as it needs to be (although while the moon is about I will fine-tune this a little), and with the refractor/guide-scope attached rolls easily.
I voted steel, but can see no reason why the plastic filled with concrete wouldn't do the job either.
Gary
You will be better off filling the pier with Cement Sand..
The sand will absorb near everything. Concrete will still allow vibrations because it is a solid, and so will pass vibrations across its volume.
Sand, will absorb it, as it moves around and stops it from reaching the other side..
That's a really interesting idea. I'm just doing the footings for a slab for a roll-off and have finished preparing the pier hole etc ready for the next step. Because I am sited on shallow soil over tough rock I can't get my holes down more than about 400mm so I have built a 400 x 400 x 400 cube that will be an above-slab extension of the concrete below giving me all up about 800mm of concrete as a base. The pier itself will be some 1400 mm of 8" steel bore casing (as in artesian water bore) I have left over; I had planned to backfill it with concrete at the same time as doing the rest of the concreting for the pier base etc. But now you have made a perfectly plausible case for sand and I'd be really interested to hear what others think of it.
I filled mine with sand and yes it made a difference, although I feel that it was the sheer weight of it that did the trick, also keeps the thermal characteristics of any pier more stable..slower to move off Polar in large temperature differentials.. When it was cold in the obs the pier was still warm. It can only be good, to stabilize vibration and thermal activity, yeah fill here with sand, but not off the beach salt will rust in time...
I filled mine with sand and yes it made a difference, although I feel that it was the sheer weight of it that did the trick, also keeps the thermal characteristics of any pier more stable..slower to move off Polar in large temperature differentials.. When it was cold in the obs the pier was still warm. It can only be good, to stabilize vibration and thermal activity, yeah fill here with sand, but not off the beach salt will rust in time...
Beach sand would useable and "safe" if you give the sand a couple of good soaks in tap water in a big bucket , tipping out over a heshan screen and allowing it to drain well between each wash. 3 or 4 washes would probably remove nearly all the salt.
Sea salt is extremely soluble in water and any salt left in sand will rapidly leach out with each wash.
Beach sand is free , other sands are not.
Looks like opinion is equally divided .... so ..... I guess I'll make one pier from concrete next to the north side of my garage (have a sliding door there and will eventually put a deck there and enclose it with a slide off roof observing shack attached to side of the garage) , and one from a steel tube that wll be bolted to concrete footings about 10 m west of the other pier.
Wish I was still with Onesteel , I could have had the fabrication work all done inhouse as a "foreign order" for some tinnies.
Now just to source my a 6" OD steel tube (galvanised probably) , and a few blank flanges , some scrap reo (for reinforcing the concrete peir) , and someone to do my welding (never learnt how and not a big enough job to warant learning or hiring a welder) and a little lathework (he may as well make my mirror cell slide clips too).
Last edited by Ian Robinson; 04-11-2008 at 05:38 PM.
If anyone in Sydney Australlia is interested I got my brother to weld up a steel pier for me, he can supply the steel and is looking for the work. I am very pleased with mine at a big saving over a shop one.
If anyone in Sydney Australlia is interested I got my brother to weld up a steel pier for me, he can supply the steel and is looking for the work. I am very pleased with mine at a big saving over a shop one.
Roger
Will keep that in mind .
I have been considering getting the local muffler guy to do my welding .
I must have cheated, I went a Pier-tech electric lift from the States and just bolted it down. You need to add extruded aliminium (or illuminum) to your pole!
Side note:
I think I may have been ripped - someone please confirm if there is a similar unit made locally in Australia? I herd rumors at issac08.....
I went to the local re-cycling place and got some slow-combustion heater flue tubing to use as a former. I dug a hole as deep as I could - approx 1 metre square by 900mm deep. Whacked in a number of star pickets at angles into the clay at the bottom. Welded and wire-tied other star-pickets that run up through the former. On the top of each of the 4 (vertical) star pickets, I welded 3/4" threaded rod that protrudes through the top of the former.
Filled the hole and former tube with hand-mixed concrete in one exercise. Works a treat. About $50 for star pickets $5 for the former, and $50 for concrete. Absolutely solid!
Later laid observatory slab around the pier.
Couple of pics pre, and during obs construction (with home-made LX90 wedge)
I went to the local re-cycling place and got some slow-combustion heater flue tubing to use as a former. I dug a hole as deep as I could - approx 1 metre square by 900mm deep. Whacked in a number of star pickets at angles into the clay at the bottom. Welded and wire-tied other star-pickets that run up through the former. On the top of each of the 4 (vertical) star pickets, I welded 3/4" threaded rod that protrudes through the top of the former.
Filled the hole and former tube with hand-mixed concrete in one exercise. Works a treat. About $50 for star pickets $5 for the former, and $50 for concrete. Absolutely solid!
Later laid observatory slab around the pier.
Couple of pics pre, and during obs construction (with home-made LX90 wedge)
I must have cheated, I went a Pier-tech electric lift from the States and just bolted it down. You need to add extruded aliminium (or illuminum) to your pole!
Side note:
I think I may have been ripped - someone please confirm if there is a similar unit made locally in Australia? I herd rumors at issac08.....
lol i bought two from sothern cross piers probably for about half of your one, the rumours are true
Hi all,
I built an in-ground concrete pier for my 10" dob and mount...(as the obersvatory is a roll-away type.)
I dug a hole 500mm deep, square in shape...I then cast 3 x 150mm by 800mm concrete pins (using PVC pipe)..which were set in the hole leaving 300mm above ground...the first concrete pour was to ground level and allowed to set overnight..a equalaterial triangular shaped mould was placed over the square...(this would allow me to cast the 3 recesses into the top using polystyrene for the mount's feet after the pour)...all the concrete used had a water barrier additive mixed in.
The ground surrounding the pier had been levelled and packed with builder's sand and concrete pavers laid on top..a 300mm wide x 100mm deep area surrounding the pier at ground level also had sand packed...all viewing chairs have had rubber leg caps fitted so far no noticable vibration viewing at high magnification..works for me!!
Cheers!
Mine is a cast iron modified birdbath plinth. Much prettier than all you guys ones.
It is very stable with 6 long dyna bolts holding it down. The top is just an EQ6 pier extension.
I must have cheated, I went a Pier-tech electric lift from the States and just bolted it down. You need to add extruded aliminium (or illuminum) to your pole!
Side note:
I think I may have been ripped - someone please confirm if there is a similar unit made locally in Australia? I herd rumors at issac08.....
well that is drop dead gorgeous - and i have two of them to install. hey Doug since you have installed i how is the pointing accuracy and the SCP drift when going up and down?
well that is drop dead gorgeous - and i have two of them to install. hey Doug since you have installed i how is the pointing accuracy and the SCP drift when going up and down?
Hi David, The pier itself is very well made and quite stable accross the wide axis. The unit does suffer from quite a bit of side ways movement if knocked or bumped but I have done a little work by propping the two sides with steel tube and this stabalises it quite a bit. I have found that as long as the telescopes and mount is balanced correctly there appears to be no movement in image frames to 30 minutes.
As for SCP drift when raising or lowering, yes there is a small change but it is negligable and still allows the G11 to be very close to target in all positions.
I use this mount to allow me to lower the telescopes well below the roof of my ROR Obs and also to get above the walls. It works a treat and was the best buy I have made for my Obs.
I purchased it from Linak in Melbourne about 6 months back after finding a German site where the Piertech and this DL2 were examined and dismantled completely as a comparison. Guess what they were both the same.
Purchase price was $420 + GST. Linak had several in stock and wanted to move then so they were to be sold very cheaply.
