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Old 10-06-2020, 01:22 PM
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Swagman105 (Geoff)
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Corrosion at base of pier

I purchased a second hand pier some time back for an observatory. It will need a good repaint but when I looked under the base I saw a lot of rust with severe encrustations that prevented it sitting level on a flat surface. I have ground off most of the crusting and also noted a lot of pitting as well. I think with a bit more grinding it should be flat and useable again.
I intend it to be mounted on a concrete pier so looking for suggestions as to What things I could do to avoid this happening again.
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Old 10-06-2020, 01:35 PM
glend (Glen)
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You could try Rust Converter on the bottom, once you have cleaned it up, as this will chemically seal it. Another option is epoxy sealing, good stuff, like boat builders epoxy. Most of the epoxy sold at Bunnings is usually hydroscopic ( will break down exposed to water over time), whereas boat builders epoxy can be submerged for years without breaking down. Try International HT9000 at any Whitworths boating store, or BCF has it too I think.
Do not use normal fibreglass resins, they also are microscopic and do not bond well to metal.
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Old 10-06-2020, 03:07 PM
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The_bluester (Paul)
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I am in the middle of setting up a pier, once I am happy with it I plan to take it down and have it galvanised. You can get some pretty smooth gal coatings. That way it will be protected from corrosion inside and out. Th eonly thing I need to look in to is to ensure I won't cause any galvanic corrosion between the pier and any aluminium parts. But there should not be any current flowing to do that.
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Old 10-06-2020, 03:50 PM
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Just to add to my own post after talking with a friend he suggested that the problem probably happened due to long time exposure to moisture in the steel / concrete joint. This he said tends to form an ironstone like cement between the two materials.
He suggested two things
1 Raise the pier foundation just a little above the level of the concrete floor of the rest of the observatory so that any accidental moisture intrusion due to weather or condensation will not gravitate to the central pier area.
2 Lay a waterproof barrier like tar paper or oromond between the pier base and floor.
Seemed like reasonable suggestions so passing them on.
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Old 10-06-2020, 04:03 PM
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Sounds like a couple of good ideas.
I just wire brushed mine and re-painted ...a couple of good coats of white enamel. I'm pretty sure in the observatory it will outlast me.
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Old 10-06-2020, 04:53 PM
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Thanks, Maybe I'm a bit overworried about it all. Up at Daisy Hill the other day it was -3.5 degrees when I woke up and when the sun came up the melting frost was dripping like rain off the underside of our verandah.
I have not yet fully decided on the design or even whether to buy a ready made dome for my observatory, but moisture will be a key issue all along the journey.
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Old 10-06-2020, 09:38 PM
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Hot dip galvanised then powder coating.
Also mount onto sealed, painted concrete, not bare concrete.
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Old 11-06-2020, 07:46 AM
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That is what I should do once the weather warms again, let the concrete dry for a few months then put an epoxy seal on it.
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Old 11-06-2020, 06:31 PM
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Sounds like a good idea. Galvanising is good for 15 years in regular contact with water or occasional salty spray . That is halved in constant contact with concrete or salty water.

So if it gets wet or salty constantly, galvanised , two part primed, painted and/ or damp proof the concrete. Acrylic paint will not adhere to galvanising but on a two part primer it is still best to use a solvent based top coat.

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That is what I should do once the weather warms again, let the concrete dry for a few months then put an epoxy seal on it.
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Old 13-06-2020, 02:54 PM
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mswhin63 (Malcolm)
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I had the same pier, which is a converted conveyor belt roller from an industrial application.

For mine, I sent it to be sandblasted and immediately powder coated and worked out well until I forgot to make the cutout for the inside of the pipe. The outside worked well, although I sold it a while back, not sure how it faired since my reign.
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Old 14-06-2020, 11:11 AM
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Shouldn't be too much issue with salty moisture so I imagine that galvanising may be a bit more expense than I would be prepared to pay, but I like MSWhin63's idea of sandblasting and powder coating which would probably result in a far better looking job than I could manage myself.
I'll take it down to some local operators for a quote tomorrow.
If it is not a rude question to pose for those who have had such jobs done, what sort of cost should I expect for it to be blasted and coated just to make sure I don't get ripped off.
The pier is 110Hx 17D and Base 40D.
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Old 14-06-2020, 11:26 PM
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To long ago to give a price, but I think it cost about $80 to $100, but I cant really remember.

Here is an image of my pier
before - https://photos.app.goo.gl/5G92kWuomi6a9ndz9
After - https://photos.app.goo.gl/4hEiB4hwjq6UduVR7

Can't find any full images of the after only enclosed one.
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Old 15-06-2020, 05:48 PM
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Best quote I could get to sandblast and powder coat was $180. They said that because it was so heavy the pier would need to occupy a lot of oven time to get it up to coating temperature.
To do it myself would've cost me at least slightly more than $100 for all the preparation and painting supplies let alone the effort involved so I decided to go with the quote. I'd actually already bought all the stuff from Bunnings to do it myself but was able to return most of it unused and get a refund from them.
I decided on "Space Blue" as the colour and will post a pic when it comes back in about three weeks.
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Old 15-06-2020, 09:12 PM
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$180 sounds reasonable for powder coating. Steel with polyester powder coating can be good if it is prepared properly. Powder coating like most things is all about the preparation specification.

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Originally Posted by Swagman105 View Post
Best quote I could get to sandblast and powder coat was $180. They said that because it was so heavy the pier would need to occupy a lot of oven time to get it up to coating temperature.
To do it myself would've cost me at least slightly more than $100 for all the preparation and painting supplies let alone the effort involved so I decided to go with the quote. I'd actually already bought all the stuff from Bunnings to do it myself but was able to return most of it unused and get a refund from them.
I decided on "Space Blue" as the colour and will post a pic when it comes back in about three weeks.
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Old 16-06-2020, 09:31 PM
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A bit of a tip, placing this on concrete, I would place a very thin hard rubber in between to absorb some vibration but it will prevent scratching of the powder coat base that can leave the metal exposed. Galve may provide better protection but at an enormous cost. Hard thin rubber just enough would not induce vibration on the pole as it should be thin enough to almost be nothing between the base and the concrete.

I used a water-resistant 5mm foam myself that crushed to about 1mm or less with the final tension.

Edit found an image of the full pier before I had to cut the extra hole.
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Old 28-06-2020, 10:34 AM
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Have put a halt on the pier job and have taken a step back to review where I seem to be going with all my ideas about having a nice observatory and gear.
Rather than head too far down a path to end up with something less than what I would need, I imagined starting from scratch and I think the most common advice I see amongst the experts is to spend your money on the best mount you can afford as the centrepiece item of your set up. I decided that that centrepiece would be an Ioptron CEM70, so I bit the bullet and have just ordered one from Matthew at Telescopes & Astronomy.
I also realised that the pier I was doing up was originally designed for an NEQ6 so would need an adaptor for a CEM70. I have also ordered a new tripod head to convert my existing 2” tripod to give me functionality for the CEM70 whilst all my fancy observatory ideas get sorted and hopefully the new tripod head should also give me a pattern for making a pier adaptor.
So the powder coating job will just have to wait for now.
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