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MG Midget and Sprite Technical - Alloy polishing

I have quite a lot of alloy trim that is in a poor state with scuffs, stains and wear. Cockpit rails, door capping rails windscreen pillars and frame, all needs polishing.

I have done some testing on a screen pillar, rubbing out the deeper scratches with wet & dry paper 400 down to 1200 grade and then polishing with Autosol. It comes up well but takes a lot of time and effort!

Obvious next step is to go electric and use a buffing wheel. The mops themselves are readily available its just what to mount them on
Electric drill? - but constant side loading on the drill chuck wont do it a lot of good.
Angle grinder ?- probably too fast, I doubt if the calico type mop heads will last long.
Car polishing machine - the ones that look like a larger angle grinder but run at around 400RPM Not sure if one can get mop heads for them
My existing 6" bench grinder?
Or I might buy another specfically for this so I don't have to swap wheels around. But what sort of power is needed for say, a 6" 1/2" buffing wheel?

Thoughts?
GuyW

I use a drill 0-3000 rpm No problems with the bearings (so far). It is a cheap Bosch.Wear safety glasses...

Flip
Flip Brühl

I do polishing from time to time and have a Creusen polisher which works well and I have never had an issue with it, a decent bit of kit. I know another guy that polishes quite a bit of stuff regularly and has a Creusen and complained about it cutting out but it is a smaller version and it was just the thermal protection cutting in as he was pushing it hard, when allowed to cool all good again, he also uses drills and said they don't like it and don't last well.

An angle grinder is far too fast, your bench grinder would be far more suitable. Look to get some mop tapers such as these https://www.ebay.co.uk/itm/6-BENCH-GRINDER-CONVERSION-SET-MOP-TAPERED-SPINDLES-ADAPTERS-FOR-POLISHING-KIT/254245117797 just make sure you get the right size. I think polishing motors have higher capacity bearings than bench grinders as you can lean on them harder but for limited use they should be fine.

Maybe see if you have a local anodiser as my trim rails are anodised and the usual process before anodising is to do a reverse etch to remove any existing oxide coat so I have been told, then polish and get re-anodised. Anodising can be a pain to polish off, consult with the experts. Last time I had anodising done it was far more area than the trim rails and was told they had a minimum order price which came into effect so I could have had about 5 - 6 times the anodising area done for the same price. Anodising is a fairly cheap process.
David Billington

Interesting Guy. Some of the trim you talk of is anodised, so have you removed it and are polishing what is underneath? Some of mine is badly scratched so wondering what to do with it.

The two screen pillars were already bare so I've polished them (by hand!) and they came up well. I think they were painted silver originally though.

By the way I've just replaced the windscreen rubber this weekend which was a job I was dreading. It wasn't as bad as I thought, in fact a lot easier than the later type screen. The worst bit was having to modify the way the 6 screws are held on the sides. I can't believe Healey thought it was a good idea to thread into soft aluminium only 1/8 thick! Anyway I fitted some anchor nuts instead.

Polishing wise I have a wheel on my bench grinder which works ok. But it's very messy so I hardly use it and use elbow grease instead!
John Payne

I bought a 115mm beveled felt polishing wheel specifically designed for the angle grinder. Silverline part number 105864, and blue polishing compound Silverline part number 107879. Both are on Amazon.
I've only used it on stainless (for some yacht fittings I made) and not on alloy, but it's proven very effective and they reckon it's supposed to be good for all metals.
I have a polishing mop on a bench grinder too and the blue compound works well with that on a couple of stainless watch bracelets. It's not a powerful grinder and doesn't need to be, just a little Clarke cheapie.
Can get messy though and as David and John have said the anodising is an issue.
Greybeard

The parts I have are so badly scratched that I will have to sand or file the surfaces in places at least to get rid of the damaged areas. Once this is done any remaining anodising becomes irrelevant as you cannot have components that are half anodized and half just polished.

I doubt very much that I can find any firms in this area that will reanodise the parts. Its going to be either Manchester or Glasgow for that if at all. The alternative will be to polish to a bright finish then either wax or spray with a clear lacquer.

I have been reading up.Polishing seems to be as much dependant on the choice of buffing wheel as the compound used, depending on the metal and the condition. Www.metalpolishingsupplies.co.uk has some helpful tips and a good range of products
GuyW

I'll have the same job to do Guy. Maybe lacquer is ok? Surely all of us restoring have to do this with the ally trim. There are diy anodising kits but the parts are too large and sulphuric acid is dangerous stuff.
Bill Bretherton

I have found that a phosphoric acid product such as Jenolite produces a similar effect to anodising on alloy items, I have used it on my alloy wheels a number of times. Not as Durable as anodising but easy to re-apply at least to the wheels and is much the same as the contents of many alloy wheel cleaners.
David Billington

This thread was discussed on 16/06/2019

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