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Removing corrosion from old pier

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#1 Hilmi

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Posted 28 March 2013 - 04:11 PM

After a year of struggling somebody to move my old pier from my parents house, I finally got it moved today, but the pier plate and parts of the pier are very badly corroded. I tried using a rotary brass brush attached to a drill with very limited success. How do I remove the corrosion from my pier so that I can repaint it and protect it from further damage?

Sorry for the blurry pic. Mobile phone in low light

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#2 orlyandico

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Posted 28 March 2013 - 04:15 PM

You could slather it with rust converter and then paint over the resulting organic thing...

If you also want to redo the paint job you would need to get all the existing paint off. A sand-blasting rig would probably clean it up and get the paint off fastest. Then you'd need to prime it and repaint it.

The rust converter is the least effort because the converted rust protects the underlying metal. It is kind of ugly though.

#3 Hilmi

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Posted 28 March 2013 - 04:23 PM

Never heard of rust converter before. I will go check what brands are available in Oman. thanks for the tip. I just spent 3 hours with the drill attached brush with very limited success. Sandblasting is not an option because it means I have to again struggle to find people willing to carry this beast of a pier.

#4 orlyandico

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Posted 28 March 2013 - 04:34 PM

If you have an Ace Hardware or equivalent they should have rust converter. Usually its a small bottle so you'll need to buy several. The converted rust turns into a hard black corrosion-resistant surface that doesn't even need to be painted.

#5 frolinmod

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Posted 28 March 2013 - 04:36 PM

I was going to suggest a vigorous cleaning with naval jelly and then a rust conversion primer until I saw the picture. I doubt anything short of soda blasting or more likely sand blasting will be sufficient for that top part.

#6 Hilmi

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Posted 28 March 2013 - 04:44 PM

Its actually not as bad as it looks in the picture, the corrosion is very superficial. I tried to scratch a bit and its not all that deep, it just wont come of off with the brush since it's not loose rust.

#7 Mike E.

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Posted 28 March 2013 - 04:45 PM

Sand blast it.

#8 Hilmi

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Posted 28 March 2013 - 05:22 PM

I just saw a video on Youtube about using citric acid. I have some food grade citric acid at home. Costs $1 per small pack. You soak the metal part in citric acid then simply brush off the rust. I'll experiment and see if it works.

#9 frolinmod

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Posted 28 March 2013 - 05:31 PM

Its actually not as bad as it looks in the picture, the corrosion is very superficial.

In that case, generously slathering it with naval jelly and letting it sit for awhile before cleaning it off might be sufficient. Repeat until satisfied.

#10 Midnight Dan

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Posted 28 March 2013 - 06:08 PM

Hi Hilmi:

"Rust Converter" essentially converts the rust to a polymer to prevent further rusting. It can then be coated with paint.

Just want to point out though, that wire brushing, rust converter, or naval jelly will NOT change the surface texture if the rust has made it rough and pitted. If you're looking for a smooth surface, the only thing you can do is sand or grind the metal down to a fresh surface.

If you're ok with a textured surface, the other techniques will work fine.

-Dan

#11 CharlesW

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Posted 28 March 2013 - 11:57 PM

You can work yourself to death trying one chemical after another. I would suggest you find a sand blaster business. They don't charge a lot and it will be clean.

#12 orlyandico

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Posted 29 March 2013 - 12:45 AM

Charles, his problem is the pier is so heavy that just getting it to his place from his parents' house took a year. So taking it to a sandblaster (and back) would be quite challenging.

#13 Hilmi

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Posted 29 March 2013 - 03:31 AM

OK, I got some citric acid and I have soaked the top part of the pier in tub with water and the acid powder. It is supposed to soak for upto 24 hours with such heavy corrosion, so far it has been half an hour. I took it out and did a quick test with the drill mounted wire brush. The results speak for themselves. I cant wait to see the results after prolonged soaking. The problem remains with the pier. I cant exactly dunk the pier in a tub. So I am considering soaking some old towels in the solution, the wrapping them around the pier.

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#14 Hilmi

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Posted 29 March 2013 - 12:37 PM

Pictures coming soon, I have managed to remove almost all the corrosion using the citric acid bath, including that on the pier. It is only the bolts that I struggled with since the drill goes wild and out of control when I bring the wire brush in contact with the bolts. I'm putting up a picture with my newly repainted pier soon :)

#15 tomcody

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Posted 29 March 2013 - 12:58 PM

Hilmi,
If they are available in your country? sanding wheels, also called flap wheels are good for that kind of work being made of small sheets of sand paper, the do not jump and buck when working around bolts etc. Just do an image google on the above names to see what they look like, be warned you will need a few of them as they do wear down.
Rex

#16 Hilmi

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Posted 29 March 2013 - 01:06 PM

So that's what they are for! I have them in my dremel toolkit, but I had no idea what they where for.

#17 Hilmi

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Posted 29 March 2013 - 01:17 PM

The picture as promissed

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#18 rdandrea

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Posted 29 March 2013 - 01:57 PM

Very well done.

#19 tomcody

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Posted 29 March 2013 - 02:02 PM

Yes but Bigger ones for the drill or grinder motor!
Rex

#20 tomcody

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Posted 29 March 2013 - 02:06 PM

Nice job! Hilmi,
Also, now would be a good time to replace the bolts, nuts and washers with stainless steel versions, if possible.
Rex

#21 frolinmod

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Posted 29 March 2013 - 02:08 PM

Blue? Arrrg I'm melting.
Please replace those old rusted nuts bolts and washers with new stainless steel ones. T316 is very nice. :jump:

Oops, there's an echo in here and I'm it.

#22 Hilmi

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Posted 29 March 2013 - 02:18 PM

The nuts are replaceable, but the bolts are welded onto the plate. I plan to replace this plate with a better one in the future so I don't plan to spend much money modifying it. I gave blueprints to the machine shop and they took my money in advance and they got it all wrong. In the end I had to accept it because all the machine shops I could find where not interested in dealing with individuals. All their work was for big contracts. This one has 4 bolts which makes it difficult to balance The hole placement is also not to my requirements this reduced the different possible configurations. Like when I upgraded from my LX200R to the Losmandy mount, the holes didn't line up properly. For now, this is will have to do.

Now that I have my G11 on a pier, it is as if I have upgraded to a new mount. First of all, polar alignment was dead easy, I have no idea why the pier should make a difference here. After alignment my go too's have definitely improved. My tripod used to shift a little as I moved from one side of the meridian to the other. Finally, my autoguiding is super good, my errors are +/- 0.5 arcsecond. MaximDL is not calculating my RMS for some reason, but I figure it's very good. So, overall I'm very happy with the pier and I am glad I finally managed to get somebody to transport it to my house.

#23 Hilmi

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Posted 29 March 2013 - 02:25 PM

I forgot to mention that citric acid is a degreaser. my hands look like prunes and feel like rubber gloves even after I finished half my wife's cream supply. This stuff strips all the oils from your hands.






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