How to Polish Raw Magnesium and Aluminum

[posplayr]

This video shows a step by step process for polishing a large Dodge valve cover in magnesium, but the same principle would apply to any aluminum covers.

How to get a chrome-like finish from raw magnesium. This video will also work for polishing aluminum. I'm using a set of valve covers from a 99-03 Dodge 4.7 In 04 Chrysler went to a Composite Plastic valve cover.

 

[Cipher]

awesome
id have fastened the workpiece to table
he should have weighed em before and after

 

[Kiwi Canuck]

Or use one of these, this is my new Baldor 1.5HP unit I bought last year, which is a beast, but I got along fine with a 1/3HP $100 offshore special for 6 years before.

 

[posplayr]

Or use one of these, this is my new Baldor 1.5HP unit I bought last year, which is a beast, but I got along fine with a 1/3HP $100 offshore special for 6 years before.

View attachment 60637

Yea it always amazes me to see people using battery powered devices for such power work. My 1990's dewalt with Nicad batteries would not hold up more than 5 min doing that stuff. I have had a long shaft HF buffer like that for 20 years.

 

[posplayr]

awesome
id have fastened the workpiece to table
he should have weighed em before and after

Did you see the part when he had his lack of grounding hazard LOL?

 

[Cipher]

Did you see the part when he had his lack of grounding hazard LOL?

heck yes funny
scary and funny

 

[Spyder]

I use a 4 1/2" angle grinder with a cloth polishing wheel. Works very well. Wouldn't even consider using a drill, especially cordless...

 

[Agemax]

On the subject of magnesium, has anyone any experience with machining pure magnesium?
Not so much milling but a bit of turning, sawing, filing etc.
I was thinking of making some magnesium toe sliders for my motorcycle boots.
It is cheap enough to buy but googling machining it throws out all sorts of horror stories, like burning the house down!

 

[Sandy]

On the subject of magnesium, has anyone any experience with machining pure magnesium?
Not so much milling but a bit of turning, sawing, filing etc.
I was thinking of making some magnesium toe sliders for my motorcycle boots.
It is cheap enough to buy but googling machining it throws out all sorts of horror stories, like burning the house down!

Hmmmm. Why do I envision your boots on fire. LOL.

 

[1978GS750E]

Anyone ever thrown a piece of magnesium into a campfire? Burns so bright you can't look at it! It will light up a few acres very well, or so I've heard!

 

[oldGSfan]

I need to figure out a plan for restoring my EPM wheels. The seller told me the front is magnesium, the rear aluminum but I can't confirm that.

I read this post, very detailed and sounds expensive. Shows restoration of the same wheels I had on my beloved '72 Fiat Sport Coupe. He is only one town over so I'll see just how much and if he is working these days.

Otherwise it's DIY time. I am thinking of getting a portable media blast setup as I want to walnut shell blast several parts including the engine. Maybe the wheels can be blasted with shells too?

 

[storm 64]

We use to play with Magnesium at work. We had to have a class D fire extinguisher on hand. Never use water to put out a Magnesium fire, it will explode and spread the fire. Magnesium burns very hot, you must take precautions when machining it.

 

[Agemax]

Hmmmm. Why do I envision your boots on fire. LOL.

Haha, well yes there is that but it also produces pretty spectacular sparks should my boot happen to touch the tarmac when cornering. ( actually it does touch, quite often!)

EDIT, forget i asked the question. A quick google search shows that Alpinestars sell magnesium toe sliders for their boots.
In a MCN write up they say the magnesium sliders are good for protecting your boots but UNLIKE titanium, they do not produce sparks.
So it looks like i need some titanium, which is a bit more machine friendly, as far as explosions go anyways

 

[GregT]

I need to figure out a plan for restoring my EPM wheels. The seller told me the front is magnesium, the rear aluminum but I can't confirm that.

I read this post, very detailed and sounds expensive. Shows restoration of the same wheels I had on my beloved '72 Fiat Sport Coupe. He is only one town over so I'll see just how much and if he is working these days.

Otherwise it's DIY time. I am thinking of getting a portable media blast setup as I want to walnut shell blast several parts including the engine. Maybe the wheels can be blasted with shells too?

Ideally, you'd strip whatever coating is on the mag and dry blast - then chromate coating quick as you can.
The problems are, firstly, stripping. Some stripping solutions will eat the magnesium....Spot test first.
Then, again ideally, you'd crack test between blasting and chromate coating.

You need your ducks in a row before starting. Don't leave the rims without a coating for more than a couple of hours.

I know of a case here where a set of Italian race mags were the wrong colour....24hrs in the stripping bath and they were toast.

 

[oldGSfan]

Thanks Rick. The link mentions using a chomate primer. I see some for $10 a can. I have lots of stuff to work on, am getting some walnut shell media and a kit that works with my compressor, it's cheap Harbor Freight so we'll see. Mainly I want to clean up various parts and the engine. I am not sure it'll take the gold paint off, but I'll give it a try.

 

[oldGSfan]

Greg (where did I get Rick from?) - as you can see the finish is corroded off in spots already, and has likely been that way for many years. I am not sure if the reason to not leave it bare is due to cosmetics, or the magnesium's structural integrity is the issue. Since it turns black and some like to polish old real 'mags' I hope it's the cosmetic aspect that is the reason, and since they will be painted not polished, maybe it's OK?

I have read to absolutely do not use chromate, use self etching primer. Others say use zinc chromate. Witchcraft I tells ya!

Don't leave the rims without a coating for more than a couple of hours.

 

[GregT]

Greg (where did I get Rick from?) - as you can see the finish is corroded off in spots already, and has likely been that way for many years. I am not sure if the reason to not leave it bare is due to cosmetics, or the magnesium's structural integrity is the issue. Since it turns black and some like to polish old real 'mags' I hope it's the cosmetic aspect that is the reason, and since they will be painted not polished, maybe it's OK?

I have read to absolutely do not use chromate, use self etching primer. Others say use zinc chromate. Witchcraft I tells ya!

It's mainly the mag's structural integrity. Unfortunately my best reference book is out on long term loan but aircraft practise is the best policy to follow. Car mags are not stressed as close to their material linits as bike rims - at least not nowadays. I do remember well a set of early Brabham mags breaking up in street use. Bike rims of the period you have are noted for their propensity to crack. These cracks start from surface blemishes like corroded spots. Which is why I strongly suggest media blasting followed by crack testing.
If they're cracked then any discussion about finish is moot. They become ornaments.

And i strongly suspect I'm the polar opposite of Rick. In any way you choose.

 

[oldGSfan]

OK thanks for the info. I will get them blasted clean, then primed soon after. I have a neighbor that runs a powder coating shop so they should be able to bead blast them for a nice price. I'd hate to invest then find out they are junk, so I"m lucky to have that resource. Then I'll have them tested, I'm sure there are places near me in SoCal.

I have a brand new set of stock wheels taken off in '82 and stored, but these will be much more interesting. They are 18". 3.5 rear and 2.5 front, and rubber is scarce. Shinko seems to be the only choice in the size I want.

I removed the bearings in the front, rear is more, umm, interesting. One side came out fairly easily, but the chain side has two bearings back to back, and I suspect a circlip between them. There isn't much purchase to be had. I'll get there, fngers crossed.

I'll lay off the corn squeezins when posting and get names right in the future... hopefully.

It's mainly the mag's structural integrity. Unfortunately my best reference book is out on long term loan but aircraft practise is the best policy to follow. Car mags are not stressed as close to their material linits as bike rims - at least not nowadays. I do remember well a set of early Brabham mags breaking up in street use. Bike rims of the period you have are noted for their propensity to crack. These cracks start from surface blemishes like corroded spots. Which is why I strongly suggest media blasting followed by crack testing.
If they're cracked then any discussion about finish is moot. They become ornaments.

And i strongly suspect I'm the polar opposite of Rick. In any way you choose.

 

[GregT]

I like the term "corn squeezin's" LOL. probably good paint remover.

If you have to, the outer bearing can have a piece of strip steel welded across it to give you something to bang on.