Technique for this?

[Maicojames]

Hello all . I have six mc hubs to polish. They are porous througout-I have tested and only get more pores with more material removed.
I have a plan to spin them and sand, maybe up to 1000 grit at low speed( metal lathe). I still want ot try to get a shine on them. I was thinking canton loose wheel and whit with very light pressure.

Any opinions appreciated.
Thank you , James

[mpierich]

Try it on one. I doubt that canton will do much of anything...if you go to 1000 grit you'll probably still end up using tripoli or emery to get the initial shine.

[Maicojames]

Been so busy, forgot to follow up. Well, this was strange they were three pairs for Rickman hubs. These are British Mc hubs circa 64-75 or so. Being British parts of this era, very porous-I even wonderd if they were the rarer Magnesium versions at one point. After much failure, I took a new plan.

First, I used scuff pad with acetone to clean. Then on the worse pieces, I buffed with sisal/ sisal bar. Finally I made extensions for the shaft on my buffer and ran it through a reostat. It was really tough to find hdwre these days...but I got all thread and coupling nuts along with the washers supplied with the buffer( which happened to have the perfect contour needed ).

I spun them at a slow speed and after covering the motor, sanded with 180,220,320, and 400 on the machine-using very little water. I tried the cutting oils, WD40, etc-and nothing cut like soapy water. Finally-I heated a
6" spiral wheel by buffing it on a junk part with emery-mounted to my drill.
I then lightly ran against the spinning hub, followed by the same step with spiral/ white. While the porosited were still present, they came out smooth and with a decent shine. I have to find the pics.

It is my opinion now that, these parts had a solid surface only near the top, and polishing removed it. It would be far better to have then plated( where the copper coat and be used as a filler). I am not suggesting you do the steps I did to polish such parts-I suggest you do not try to unless you have acess to a metal working lathe-and even then they really need to be plated.
Some parts are just porous all the way through-the more you cut,the more pores you will see, they are not the same pores, but they are there.

So, be wary of any British MC hubs from the 80s and back. JMO.
MJ

[mpierich]

Originally Posted by Maicojames

Some parts are just porous all the way through-the more you cut,the more pores you will see, they are not the same pores, but they are there.

So, be wary of any British MC hubs from the 80s and back. JMO.
MJ

Yep. And not to mention most other older parts from many makes as well as some newer ones.

[jrow]

Maicojames,

I think the trick here is to not polish through the top layer of the aluminum. If it doesn't have a coating on it (anodized/powder) or a lot of scratches then try using some tripoli on sewn buff. After you cut the top layer off you will get into "pits" thats something you don't want to get into!

John