Vibratory Tumbling

[clayboyrat]

How close can you get to finished mirror AL with this way. What is your media? How many cycles do you do? TNX

[Tng21]

i was gonna ask about tumblers.SO am i right in thinking you buy the right media, buy one of these tumblers, put in your peices, say small aliminium engine parts, put in your media and other stuff, turn it on and it will come out polished?

[UncleJimmi]

I don’t think you can achieve a mirror finish or even get close in a tumbler.
It’s good for de-burring and will leave a uniform finish suitable for industrial anodizing, paint, or powder coat. I don’t like polishing parts that have been tumbled and I hate it when they have been blasted with sand or any other media.
I find that tumbled parts get micro pits from electrolysis and require more sanding.
I also notice it is harder to clean / degrease the areas that don’t get sanded and polished.
Not that I am an expert on tumbling, but I have operated them and had to polish plenty of tumbled parts from several different sources and the results have always been much the same with the occasional “these parts are ruined” thrown in.

[mpierich]

Originally Posted by UncleJimmi

I find that tumbled parts get micro pits from electrolysis...

Hmmm...could you explain this further?

[UncleJimmi]

Whenever different metals are placed in a conductive liquid you create a battery. If you connect these pieces of metal together, current will flow. The current will be removing metal from one of the metal pieces = "electrolysis".


Keep in mind that electrolysis that takes place in a tumbler is minimal.
I have had the opportunity to polish parts from the same batch before and after tumbling.
The ones that get tumbled long enough for the de-burring to occur always have the micro pits. These pits are not visible until you have obtained a quality finish close to or suitable for optical imagery. So many polishers will never even notice.

[mpierich]

Originally Posted by UncleJimmi

Whenever different metals are placed in a conductive liquid you create a battery. If you connect these pieces of metal together, current will flow. The current will be removing metal from one of the metal pieces = "electrolysis".


Keep in mind that electrolysis that takes place in a tumbler is minimal.
I have had the opportunity to polish parts from the same batch before and after tumbling.
The ones that get tumbled long enough for the de-burring to occur always have the micro pits. These pits are not visible until you have obtained a quality finish close to or suitable for optical imagery. So many polishers will never even notice.

OK, cool.

Next question: What materials are you polishing to suitability for optical imagery?

[UncleJimmi]

I could tell you, but then I would have to kill you!

J/K
SS and aluminum. Mostly SS for the medical industry. Some of the equipment uses metal mirrors, and in some cases it is experimental or classified and I have no clue who is using it for what.

[mpierich]

Interesting. As far as aluminum, there's an article somewhere on here re the aerospace/atronomy people not being able to get aluminum to optical quality and experimenting with india ink as a finishing media. Sounds messy, huh?

[UncleJimmi]

Originally Posted by mpierich

Interesting. As far as aluminum, there's an article somewhere on here re the aerospace/atronomy people not being able to get aluminum to optical quality and experimenting with india ink as a finishing media. Sounds messy, huh?

Yea, I saw that, Aluminum is more sensitive to temperature changes, condensation, and a number of other things that can degrade a reflection. It is basically porosity that makes the metal light weight and gasses are trapped in the pores and will expand and bleed out.
These pores also can be the limiting factor in achieving the quality of finish needed for optics. You some times here me say the limits of the metal, mostly when referring to polished castings. Heavy porosity = dull. As long as I am on the subject of porosity and gasses I will say that I never recommend chroming aluminum for just that reason as well as a few other reasons. However if money is of no concern and ease of maintenance is top concern, then chrome away.

[alabama_lowlife]

uncle jimmy have you got a website with a bunch of pictures of your work on it? that one with the minute maid can is breathtaking.