Polishing Stainless Steel

[RickH]

I need to polish stainless steel propellers .... these are large heavy (15") props

They are new ... but the stainless has not had a huge effort into polishing during manufacture a lot of it is semi-matt.

I kept them clean on previous boats with Autosol metal polishing paste, it's going to need a bit more than that to get them initially right.

Happy to work my way through wet & dry grades 240, 400, 800, 1200, 2400 ...... but what then ... is Autosol the best for Stainless steel ? The standard Gold packaged Autosol states Chrome, Aluminium & metals.
There is a 'Black' packaged that states Chrome, aluminium, stainless, brass & copper.

Not sure if there is a difference, or is there something better.
Probably going to have to be handwork ... as all the complex curves on props not easy to get at with power tools.
Maybe a die grinder/flexible shaft with a small mop would work - but don't have one - a Dremel and flexible shaft I don't think is up to it.

Need to get it looking good then protection.

 

[Lower]

You need a die grinder and flap wheels to start with. Probably 80, 120 and then 240 grit. Then use a polishing mop head with green polishing soap.

If the props have lots of residual casting or machining marks on them, trying to do it by hand with various different grades of wet and dry will take forever.

 

[JohnD]

.

 

[Burnerman]

Excellent call from Lower there
If there is a lot of work to be done - especially when the props have done some work - consider fine grit flap discs or even scotchbrite ones which fit into small angle grinders.
With stainless props its a sound idea to apply a crack testing spray too.
John

 

[RickH]

Props are new (not even been out in water other than PDI test)
Just not as well finished as I like.

 

[funinacup]

Would love to hear more info on these polishing methods (flap wheels etc) I have a coffee machine that should be mirror finish but years of use have left it very scratched and hazy.

I bought a stainless polishing kit with a mop that fits onto an angle grinder, and has 3 different polishing bars - black, green and white. It has brightened the stainless but not removed the scratches, I suspect I need to go the sandpaper route first. Can I do it with the angle grinder? Is there a suitable product?

Thanks
Michael

 

[Burnerman]

Look into the possibility of using very fine grades of wet and dry paper, Michael......the water used acts as a lubricant to wash particles away.
Practice first if you can, and make sure you rub in only one direction to give that 'brushed' finish.
If you are over zealous you could make things worse, so I'd forget about the angle grinder.
John

 

[opps]

My stepfather used to work for a lift engineer. They used to use GarryFlex blocks.

https://www.axminstertools.com/garryflex-abrasive-cleaning-block-ax20009

Most the stainless steel was brushed so they used the more course variants but the finer ones will work on polished surfaces.

 

[RickH]

You need a die grinder and flap wheels to start with. Probably 80, 120 and then 240 grit. Then use a polishing mop head with green polishing soap.

If the props have lots of residual casting or machining marks on them, trying to do it by hand with various different grades of wet and dry will take forever.

I now have access to a Die Grinder takes 1/4" shaft tools .......do you have a link you could point me at for suitable flap wheels.

 

[Lower]

https://www.axminstertools.com/sit-flap-wheel-60mm-diameter-x-80-grit-950973

 

[RickH]

Thnx ... my misunderstanding was looking for rubber-backed tools with replaceable discs, glad I asked.

 

[Lower]

As you're polishing something with a complex shape, you want something that you can easily manoeuvrer around the blade and hub. Discs would be too flat and tend to cut into the material at the edge of the disc.

You might want to try something like the below too:

https://uk.rs-online.com/web/p/abra...0vcml0elkQR3-8zVrRxoCgvMQAvD_BwE&gclsrc=aw.ds

You can get them in different grades and they sometimes allow you to skip different grit steps.

 

[RickH]

Don't they require an arbour though ...... I do like the idea of using them, in preference to coarse abrasive but die grinder just has straight 1/4" chuck

 

[Lower]

You can get them on shanks, or you can just buy a threaded taper that will fit in your die grinder:

https://www.thepolishingshop.co.uk/spindles-accessories/spindles-adaptors/standard-mop-taper-700005

 

[RickH]

OK .. have them on bench grinder ... didin't know they did baby ones.