Polishing and Cleaning Aluminium Castings

[Whiskey98]

I'm sure this topic has been done to death already but I'm not really wanting to shell out a few hundred on getting my various cast aluminium parts vapor blasted and I'm wondering what DIY methods you lot have to clean and polish cast aluminium parts to a decent finish similar to it? I'm talking in terms of a finish suitable for parts such as crankcase halves, cylinder heads, gearbox casing, fork sliders etc. Parts such as the timing cover, primary cover, wheel hubs etc I will use a buffing wheel and compound to achieve a mirror finish.

Many thanks!

[ChrisTheChippy]

My method is wd40 and scotchbright pads starting with coarse and working down to fine. Plenty of elbow grease. Initially you will be disappointed with the result but then dry , apply solvo autosol and watch the magic happen !
The choice is then yours with the finish and depends how long you want to spend on the task .
I just go for a medium bright sort of finish as I get bored with it .
Don't be mean with the wd40 and you should get a good result.

[Andy G]

Similar..

Scotchbrite, applying a 50/50 mix of Autosol and Elbow Grease. Toothbrush in narrow spots and buffed with a dry cloth, though now I'd likely use a polishing wheel in a drill.
To maintain you can adjust ratio nearer 20/80 and a soft applicator.

[Greybeard]

Polising wheels, elbow grease and regular cleaning is the way forward for the outer cases - and fork sliders - for a smooth bright finish. I find that this

leaves a cleaner, less greasy finish than atosol - pricier though and worth shopping around.
For the casings vapour or bead blasting gives a nice peened finsh to the metal that seals the surface pores of the metal so it doesnt hang onto the muck. My G80 crankcases and head were done over 30 years ago and still look as clean as when they were first done. No more than a wipe with a petrol dampened rag is all thats needed. Vapour blasting isnt expensive in the overall scheme of things, just make sure that the parts are thoroughly cleaned before reassembly. Though a good blaster will already have done that, it doesnt hurt to do it again.

Steve

[Pharisee]

Polishing to a mirror finish, I'll leave that to those that want it. Personally, I like a bit of patina. I'll keep it clean, and be happy with that.
Vapour blasting I do like. I recently acquired a basket case Norton 650SS that had been dismantled and then left in a shed for more than 4 decades. It was rough, to say the least. The gearbox case and covers were cleaned by Simon at "Bike Aquablasting". By previous arrangement, he did those for me in a couple of hours. I left them with him in the morning and collected them later the same day after meeting up with a couple of friends for lunch.
The crankcase I dropped off at "T & L Engineering", on my way back to my home in Lincolnshire from a London trip. I expected to have to make the 150 mile round trip again to collect them, but Barry turned them around for me in 40 minutes, literally, while I waited. They were still hot from the parts washer when I picked then up.
It's much nicer reassembling an engine into cleaned cases. In the great scheme of things, it wasn't expensive. A total cost of around £120
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[Whiskey98]

Thanks for the tips! I'll get myself some scotch pads and autosol tomorrow. Sending the larger items to someone with an industrial parts washer is certainly an option too!

[magnusk750]

Scotchbrite, first red - the coarse one, then grey, often use them wet, less aggressive. Finish off with autosol on a tooth brush. Ugly marks may be sanded down with emery cloth, but that not very often.

[Shelby-Right]

You can also get a real nice finish if you just bead blast , it's only the old dust that makes it appear dull , so you can put brand new beads into the cabinet and finish off , it will add a lovely sheen ..you can also use hydrochloric acid for cleaning alloy available at the hardware store , just google it ., then make use a scotch Brite.

[Andy G]

..you can also use hydrochloric acid for cleaning alloy available at the hardware store

I've used this method, it's vital not to leave parts in the dip, and you must be very careful to wash off every trace afterwards. But it does a great job.
Typically sold as patio/masonry cleaner, I dilute and use it for taking rust off stuff.
Wear rubber gloves and eye protection.

[SPRIDDLER]

I'll get myself some scotch pads and autosol tomorrow.

Be sure to ask for the right one

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or you might just as well stick it where the sol doesn't shine.

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