Grinding tool for rust removal of flat steel

[dobson156]

Is the any sort of grinding tool that is good for grinding off non-flakey rust of a large flat steel surface?

For whatever reason flap discs and wire wheels aren't removing it, they're just "polishing" the rust. (well the flap disc works for about 1 minute of use then stops cutting).

Something like normal grinding disc that which can be used flat to the material rather than at an angle like when used with an angle grinder. I guess I am looking something in between a random orbital and a grinder - does such a thing exist?

 

[123hotchef]

these on a backing pad sir https://www.screwfix.ie/p/essential...bre-discs-4-1-2-x-22-3mm-10-pack/37145?tc=BI5

 

[8ob]

Citric acid just to get the worst off ?

Bob

 

[dobson156]

these on a backing pad sir https://www.screwfix.ie/p/essential...bre-discs-4-1-2-x-22-3mm-10-pack/37145?tc=BI5

Thanks will give that a go!

Do you think that'll work where a course (40G) flap disc failed?

 

[bourbon]

let the pad do the work. If you are leaning on it, then the grits will go blunt and just polish

 

[Dapph2]

Check your PM

 

[123hotchef]

Thanks will give that a go!

Do you think that'll work where a course (40G) flap disc failed?

i find them better on flat steel for derusting

 

[bricol]

Fibre stripping discs work for me - similar to these

https://www.amazon.co.uk/Stripping-4-5inch-Durable-Removal-Oxidation/dp/B0D3G5WZ7L/ref=asc_df_B0D3G5WZ7L?mcid=362165cb9c6c3b6bb34e67ce04d25ba7&tag=googshopuk-21&linkCode=df0&hvadid=696451130807&hvpos=&hvnetw=g&hvrand=1112223078741621379&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007196&hvtargid=pla-2309387289984&hvocijid=1112223078741621379-B0D3G5WZ7L-&hvexpln=0&gad_source=1&th=1

 

[anto44]

Fibre stripping discs work for me - similar to these

I find these work great on flat surfaces aswell. Need to be careful around edges and corners though as it's easy to wreck a disc if you catch a sharp corner.

 

[bricol]

I find these work great on flat surfaces aswell. Need to be careful around edges and corners though as it's easy to wreck a disc if you catch a sharp corner.

I used them last year on my garage concrete floor too - cleaning the paint, crap etc off of it to get a good surface for sealant etc. Lasted much much better than I expected.

 

[6ply]

I find these work great on flat surfaces aswell. Need to be careful around edges and corners though as it's easy to wreck a disc if you catch a sharp corner.

Yep, I shredded one a few days ago, only difference being that I use the nine inch version which I highly recommend.

Alternatively, a wire wheel on a 4.5 inch grinder works nicely.

 

[dobson156]

Fibre stripping discs work for me - similar to these

https://www.amazon.co.uk/Stripping-4-5inch-Durable-Removal-Oxidation/dp/B0D3G5WZ7L/ref=asc_df_B0D3G5WZ7L?mcid=362165cb9c6c3b6bb34e67ce04d25ba7&tag=googshopuk-21&linkCode=df0&hvadid=696451130807&hvpos=&hvnetw=g&hvrand=1112223078741621379&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007196&hvtargid=pla-2309387289984&hvocijid=1112223078741621379-B0D3G5WZ7L-&hvexpln=0&gad_source=1&th=1

I tried a prep disc like this and it didn't really do it, IDK what it is about this steel and this rust but it's dead hard, I think it was allowed to form very slowly with the presence of other materials. So far only grinding has worked but I'm going to try those sanding disced mentioned above and see how I get on with those.

 

[dobson156]

Alternatively, a wire wheel on a 4.5 inch grinder works nicely.

I tried a wire wheel and that is what just polished the rust smooth, After I'd spent hours on it with the wire wheel I hit a section with a grind disk and the then-black polished oxidation was stripped off exposing orange rush and then clean steel.

 

[Kram]

Is it new steel? Often it comes with a thick layer of hard oxide and its easiest to chemically strip it or use zirconium flap discs.

 

[dobson156]

It's a I-beam embedded in a wall, probably with some kind of red oxide primer over that. It was then directly plastered over (not be my) about 45 years ago.

The steel has corroded and causes the plaster to blister. Plaster has been chipped off and the steel has a very hard layer off oxidisation with medium pitting - the oxidisation is not flakey and seems more prone to getting polished (turning black) than removed. But when you attack the polished oxidisation it reveals orange oxidised steel - so I'm pretty sure it is "rust" of sorts.

zirconium flap discs

That is what I used at first. But after a few minutes (if that) they just stopped cutting. I might have been putting too much pressure on - but I don't think I was.

Wire wheels and prep disc have also been completely ineffectual. Grinding disc works.

 

[anto44]

Carbide scrapers work well on that kind of rust but might be hard work depending how big an area you need to do. This type

 

[MattF]

How rusty is it? A photo of it may help.

 

[Pond frog]

The flap discs you were using may have had too fine a grit try a coarser version

 

[dobson156]

The flap discs you were using may have had too fine a grit try a coarser version

They were 40G.

How rusty is it? A photo of it may help.

Yep, let me get some photos, it's really crap lighting in the room its in though so might be hard for me to show what I'm on about.

 

[Turbo]

You need the blue or red zirconia sanding discs or flap discs. The brown alu oxide ones go blunt quickly on steel.
And only use good quality ones from a reputable source. There are fake or cheap zirconia ones out there that are rubbish.