Here's one of the parts I have made for my ATV. Made from 7075. Buffing had to be the worst part of it. Those micro scratches from the compound are a real pain to eliminate when your a novice polisher and don't understand what your doing wrong. I think I've finally developed a technique that works good for me, but I still hate doin it. I tried a vibratory tumbler to take out most of the manual labor, but I haven't found that magical formula yet. I've anodized a few 7075 parts with pretty descent results, but don't have any pics of 'em. Next batch I do, I'll snap some.

Those look great Sam, what are they?

Brett

Hi Sam,

The magical formula is to pass the parts onto Ed  -  he says that he loves polishing the stuff.   

Tweakie.


btw. Very nice work.

Nice job, Sam, may I ask what your buffing process is? I'm sure I can learn a bit - 

Thanks,
Dave

That is the master cylinder cover, Brett. There's a rubber boot that sits into the pocket on the bottom side.

I would be glad to pass them on to Ed for polishing. Only down side is that he would most likely want me to pay the shipping both ways, and pay him for the work.

Dave, first off, I wet sand to about 1200-2000 grit. Most people tell you not to worry about sanding to that extreme. "let the polishing compound do the work" they say. That may be true on some parts, but if you want to keep a sharp edge and detail on a part, your gonna need to sand it to a high grit to avoid as much buffing as possible, otherwise the compound and wheel will round everything off. YUCK! So now your wet sanded to a good polish. Go drink a beer. Maybe two. Avoid sitting down at the computer or television, your not done yet. You can definitely see a reflection prior to buffing. I have made a jig for my part to recess into, so I can hold the part firmly and get a good polishing stroke across the entire part surface, without worry of the wheel grabbing it and throwing it across the shop, thereby making it into a half polished paper weight. I made mine from wood, but will eventually make one from the same type aluminum. I would not make one from steel, so as to avoid getting the buffs impregnated with iron, and then the aluminum. That's just my theory, though. Then I heat up the part with a butane torch, getting it really good and hot. Hot enough that if I touch the compound bar to it, it has no trouble in melting. I want it hot enough that the cooling action of the buff wheel does not cool the compound into a solid again. When that happens, the now solid compound damages the part surface, and your back to square one sanding with 220 or 600 or whatever. That's definitely not a good thing. First, I use a sewn cotton wheel with a white rouge compound. Then I finish with a blue rouge compound. All strokes are fairly swift, and only a small amount of pressure is applied with the white rouge, and hardly any at all with the blue. I try to keep the part rotating as much as possable when I polish, to avoid getting grooves into it. After the white polish, there will be micro scratches everywhere. They will be most prominent at a certain angle of light. After the blue compound, there should be no scratches, no matter how you look at it in the light. All the mounting holes and engraving were done after polishing. Keep the buffs raked to a fluff, and never mix compounds on the buffs. Drink plenty of beer, and don't eat the yellow snow. I have no idea if color codes are the same across different manufacturers of compound. I use the buffs and compound from Caswell. I have not used the denim buffs *yet* to have an opinion on them.

What is your preferred optimum buff wheel speed for, say a 10" buff wheel?

Also; there is an electro 'buffing' method that works very nicely on aluminum. Better with higher strength (>T4 treated alloys) and even gets rid of machining tool marks, but it's a mess of apparatus, power supplies, and chemicals to perform. I don't think Caswell has entered that area yet, but probably will....

Bill C.

Well Bill, I'm far from being educated enough on buffing to say anything about wheel speed preference. I have a piece of crap grinder converted into a buffer. I think it turns about 3450 rpm, and I use 8" wheels. A 10" would give you a bit more speed, but I wouldn't consider that a problem. I think the slower speeds come into play with delicate materials such as plastics, wood finishes, and such.
If your talking about electropolishing, and if memory serves correct, I think the acids that are used are some nasty ones. I do believe you still have to get the part to a fine finish before you start the electropolishing process, so you may indeed be referring to something else, if it gets rid of tool marks.

Only mentioned electro polishing in passing Sam. You're correct that it's more trouble and danger than it's worth to do just a few parts now and then.

I usually use the lathe spinning at top speed to polish. The arbor is a long shaft to get the wheel away from the headstock. Works OK but a grinder would be handier. There is always the risk of a knuckle making a divot in a chuck jaw - ouch!

Thanks,
Bill C.

Thanks very much for the long (and entertaining!) process rundown Sam- 

I'm basically doing the same exact thing as you except I do not heat up my parts so that's an interesting tip. It's so true that wetsanding prior to buffing is imperitive to keeping the detailed contours which I had trouble with in the beginning.

I actually do some egraving before buffing but I must admit, using a toothpick and cottom swabs can be time consuming and tedious.

I also use wood blocks to hold my parts, I remember my first aluminum "missile" was a pickup ring for a guitar and the inside cutout caught the wheel and turned that thing into a parallelogram against the wall. Needless to say I won't make that mistake twice 

I would like to get one of these pedestal buffers that you can adjust the speed as I think that would be handy. I'm still a long way from being a pro but I'm getting good enough to be dangerous (as read above).

Thanks,
Dave

Haha..good stuff Dave! I've made quiet a few missiles too! Guitar pickup rings are on my "to do" list also. I will prolly anodize them, when I finally get around to making them next century. It's a shame when you pay $100+ for a pickup, and you get a cheesy plastic ring with it. I too tried the cotton swabs with alcohol or acetone. The cotton always seemed to scratch the part up pretty good. When I didn't heat the part up with a torch, the part would always have what looked like occlusions in it after buffing, but it was really the hardened compound digging in. Heating it up to a toasty temp cured that problem. If you decide to invest into a good buffer at some point in time, Grizzly has a shop fox brand spindle setup for $110. http://www.grizzly.com/products/h3559
Thanks for passing it along, Bill. I too have used the lathe at 2500 rpm to polish round parts. If you use some Eagle One polish (or similar) for a final buff you can get a great "chrome" look. The can is actually filled with a cotton material and saturated with oil or polish of some sort. It works absolutely great. Cloth with WD-40 works pretty good too, if you don't mind wearing it and looking like Alice Cooper on a bad makeup day. I too have had battles with chuck jaws. For some reason, they always win and I always loose. That's where a collet system would come in handy for small stuff.