Rust removal

[pvb]

Any recommendations on a reliable but reasonably priced angle grinder? I wouldn't know a good from a poor.
And secondly, can it then be used for polishing?

How much you spend on an angle grinder depends very much on whether you think you will have much future use for it. I bought a very cheap angle grinder about 15 years ago from B&Q and it's still going strong. Screwfix will sell you one for £25.

Angle grinders aren't ideal for polishing, so the answer is no.

As an aside, don't get too paranoid about rust on your keel. Iron keels do rust, but it's an incredibly slow process and it's unlikely ever to cause any significant structural problem. It's essentially a cosmetic issue and, as you can't see it most of the time, don't worry too much about it.

 

[Ink]

Ah chipping hammers. Brings back so many memories of a different life years ago. Just not sure these are right for this job.

We were given hammers like those by the Bosun on the STS Malcolm Miller many years ago to chip off paint when there was nothing better to do. Made plenty of noise and chipped paint off fine. Not sure of their effectiveness on rust.

Ink

 

[rogerthebodger]

The higher the rated power the better.

The major issue with the small 115 mm angle grinders is the they heat up quite quickly and if get too hot will burn out.

I was using a bosch 115 angle grinder to polish stainless steel and I had to stop every 10 minuets of use to let it cool down yet some cheap China angle grinders I could use longer before I had to let it cool down.

The big 9 " angle grinders will last a long time but are very heavy to throw around for some time.

There are to schools of thought 1) buy several cheap and rotate their use. (when the one being used get hot put it down and pick up another) or by very expensive and hope it lasts.

There are some 125 mm angle grinders that are a higher power but are quite expensive to the cheap ones

The small angle grinders tend to be too fast for polishing and don't get a variable speed as they heat up too quick at a slow speed.

A 5 " one could be used for polishing but not ideal

115mm angle grinder 12000 to 15000 rpm
5" angle grinder 7000 rpm
angle polisher 300 - 1200 rpm

 

[rogerthebodger]

We were given hammers like those by the Bosun on the STS Malcolm Miller many years ago to chip off paint when there was nothing better to do. Made plenty of noise and chipped paint off fine. Not sure of their effectiveness on rust.

Ink

Effective on thick rust and black oxide as on the top pic in post # 17in my no good for surface rust where HCI and phosphoric acid comes in. A wire brush can also remove service rust but will just polish any thick rust and black oxide

 

[Sailingsaves]

The hydrochloric acid eats all the rust away and should leave clean steel.

Because the steel is so clean it will flash rust quite quickly so the phosphoric acid will convert any flash rusting.

The biggest is any rust at the edges and under any paint. T tend to use a wire brush to remove the paint at the edges of the rusting to ensure I get back to clean steel.

I have also found that washing off the HCI and phosphoric acid after the drying with a heat gun also helps to stop any rusting developing under the new paint.

When I was involved in designing equipment for car factories the steel body would be washed by dipping in tanks of HCI and phosphoric before washing, drying then dipping in primer.

HCI is also used in galvanizing to de-rust and clean the steel before dipping in the zinc.

Really interesting, thank you.

 

[William_H]

As an aside, don't get too paranoid about rust on your keel. Iron keels do rust, but it's an incredibly slow process and it's unlikely ever to cause any significant structural problem. It's essentially a cosmetic issue and, as you can't see it most of the time, don't worry too much about it.

Rust on a keel is more than cosmetic. it bubbles out taking the antifoul paint with it. A real problem if fouling is a problem. ol'will