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By GrahamRounce
Hi - I have some steel discs about 6mm thick and between 4" and 8" diameter. (Units? I'm flexible!)

They're pretty rough, and have some surface rust. I want to tidy them up, nice and smooth and shiny. I've got the first one mounted on the woodworking lathe.

With aluminium, going up the grades of sandpaper works really well.
I didn't expect steel to be that easy, but... !!! Even heavy duty belt sander paper, #60, hardly touches it!

A wire brush in the electric drill did even less. The only thing I've found that works at all is a woodworking chisel, but even that's very slow, and fires off bits of hot metal, not to mention vandalising the chisel blade.

I don't think it's ever going to work, but I'm posting here in case (not for the first time) there's some bright ideas...?
By TFrench
How good of a finish do you want? If you're just getting it back to clean, knotted wheel in a grinder. Starting to get it shiny - higher grit flap discs in grinder. Perfection - metal lathe. Obviously I wouldn't mix the grinder, steel and the wood lathe, thats a recipe for hurt.
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By adidat
A grinder with 40 grit sanding discs will clean them up quickley, but any deep pitting will take a while to flatten off

By sunnybob
Get an old plank of wood about a foot long. Scribe the disc size onto the wood. Chisel out the disc shape to 3 or 4 mm deep. Use a bit of double sided tape to stick the disc into the hole. Use an angle grinder fitted with a flapper disc.
10 seconds a side should work well.
Then if you want them shiny, use wet or dry paper down to whatever grade you want.
By GrahamRounce
Ok, thanks. Regrettably, I don't have a metal lathe, but I do have a sort of mini-grinder.

Flap discs, ok - do they have to be something extra tough & special? Like I said, belt sander #60 paper (it was actually #40), admittedly held by hand, wouldn't touch it.

Securing it should be no prob, as I've made 4 threaded holes to screw it to a plate for the lathe.
Thanks again,
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By Phil Pascoe
Flapwheels are brilliant. Get a mixed pack of ten on Amazon - there is undoubtedly a difference in quality between the brands (+ prices) but the cheapest ones will be fine for most things apart from heavy industrial uses.
By thenormynuts
Wire brush it ok for clearing off a bit of slag bit for real smoothness you need an angle grinder (saves on the scrubbing too!) +1 for the poly disc
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By MikeG.
GrahamRounce wrote:...... I have some steel discs..... I want to tidy them up, nice and smooth and shiny........... The only thing I've found that works at all is a woodworking chisel..........

(hammer) (hammer) People have died for less! :evil: :lol: :lol: :lol:

Mini angle grinder with a grinding (not cutting) disk, initially. The danger with that is that it will take off too much too quickly and you'll end up with an undulating surface. Then a combination of belt sander and flap-wheel sanding. If a home-spun solution like that doesn't produce the result you are after then you are going to have to find someone with a metalworking lathe, where cutting a new flat face down to a shiny polished surface would be a five minute job.