How To Polish Aluminum To A Mirror Finish by Hand

How To Polish Aluminum To A Mirror Finish by Hand

Hi, I’m Jenny. I’m a machinist at Tormach,
and today we’re gonna polish up a piece of aluminum to a mirror finish. In a
previous video, I was prepping the lightsaber with stone and paper. If you’d
like to check it out, click on the link above. Since the
previous video, I’ve been asked by many people, “since hand polishing is so
time-consuming, why don’t you just use a dremel or a rotary,” and my answer is
you’re not gonna get the exact same results. First I’m just gonna demonstrate
standard hand polishing technique using this modeling compound, and my knife. So typically when you start out polishing, you use a coarse stone first, because you want to go as deep as your deepest mark. In the case of the part that I was
working on I actually wanted to go as deep as the most superficial scratch. As
you can see, we’re going small overlapping strokes, and we’re only going
as deep as the scratch that you want to eliminate. Actually, you want to go 70
to 80 percent, because we’re gonna go a little more when we get into the finer
stones. And then here’s the cross-hatching, and you’re gonna get
progressively finer as you go. You can see with smaller…smaller scratches, and
typically you’re gonna be going back and forth, but you’re gonna go lightly as to
not disturb it. Metal itself actually has a yield point and so you don’t want to
go past the yield point. Now I’ll show you why in the next piece. Right now
we’re going nice and light, so as you go the material is gonna move forward a
little bit, but it’s gonna go back to its original position. And eventually, you’re
gonna go finer and finer until you’re left with this really nice smooth mirror
surface. There’s nowhere for the light to get trapped down inside those scratches,
and so basically that’s all you’re doing you’re stoning out anything that can trap
light and eventually you’re bringing that polish up so that there’s nowhere
for it to go, and you’re getting finer and finer. Obviously, I’m using modeling
compound here so I’m not going to get a mirror finish on
modeling compound, but it kind of gives you an idea of the technique behind what
we’re actually doing when you’re polishing materials actually,
especially aluminum is really soft and you can actually feel the give
on the aluminum as you’re polishing. You can feel…you’re actually pushing the
material around, but the point with when you’re polishing you want it to be able
to spring back, because you don’t actually want to change the structure of
the material, and you don’t want to introduce heat. As you can see, you’re
creating a real nice uniform finish and you’re gonna be doing that with your
stones and your paper and finally your diamond. I really don’t like rotaries
because anything that’s floating around in the environment is gonna get sucked
down into your work, but the real enemy here is actually gonna be heat and
pressure. So when you’re using a more aggressive cutting, you’re kind of
pushing forward. You’re also heating up the material and this is kind of an
exaggerated motion here, but you can see that materials’ not snapping back. So then
when we go the other way, you’re actually creating small ripples in there and the
small ripples don’t really become a big problem until they start compounding
upon each other and then once you start getting ripples into the material, as
you’re moving to the other direction, you start actually ripping off the
crests of those ripples and they create an orange peel effect, which is actually
small pits. It actually looks like the surface has small pits like an orange
peel would. So you can actually go in there with a power tool and get a nice
shiny finish. Although you do have to be mindful of the heat and the pressure
that you’re exerting on the material, because it’s very very easy to
eventually damage the material, then there’s really no going back if you want
to keep that surface. If you can recall from the last video we got our
lightsaber nice and shiny but it was still kind of a cloudy shiny. It wasn’t a
mirror shiny. I have this set of diamond polish. They’re not industrial grade. I
was just doing this is aesthetic polishing, it’s not industrial polishing
or mold polishing, so I’m not worried about how materials are flowing or
anything like that. I’m just trying to give it a nice pristine
mirror finish. So I actually went on Amazon and I bought a
set of twelve diamond polish for I think it was $14.99. And it starts at the highest
grit, being 40 microns, and going down to the lowest grit being 0.5 microns. Now
because these are diamond polish and it’s a real fine polish you do need
something to apply it with and you want to remember that anything that you’re
applying it with needs to be softer than the material that you’re working with so
you don’t scratch it, because you’ve gotten this far. What I actually like to
use is…I went and just got some bamboo skewers, just over at the grocery store.
And then what I do is, I usually score it, snap it, and then do some old fashioned
whittling, depending on like what undercut I need to go in. But you can
whittle it to whatever shape you need it to. The advantage of this is…
these bamboo skewers are porous so they actually soak up the grit that you’re
using. So after a while it actually kind of becomes a fine stone itself. The one
thing you want to avoid doing is actually mixing mixing grits on your
bamboo skewer or your polishing piece of wood.
Some people use felt. I just happen to use wood because it’s cheap and easily
attainable. So just the other day I was out in the shop, and we got some footage
of me tackling the one-and-a-half micron grit. Take a look. There we go. And now you can kind of see
those lines over there. Can you? I know, so much of it is by feel. And that’s just the bamboo stick? Right? Yeah. And you can show them how the tip is black. I don’t know how much you can
see in there, but you can see that the this stuff gets embedded into the
stick, and it basically turns it into a really fine stone. I go here and then I do
kind of…can I rotate? Go ahead. I give it a rotate. And I want to go right up to the wall,
otherwise you’re gonna leave an area.. What about the wall? I didn’t do
the wall on this. I could have done the wall but… That’s not seen. No. Like you see here, I can’t get all the
way up to the wall with that radius. So then I rotate it. And then.. And then, the holes…the holes suck.
What do you do with the holes? I go up here, get to the wall and the hole. Get next to the hole. Cause it want to suck…suck it in. So you listened to audio books
while you were doing this? Yeah. I went through two really long ones this
weekend. What were they? Um one was Sometimes I Lie, and the other one was
The Last Time I Lied. Okay you’re gonna wipe it? Yeah. This nice clean rag.
Now comes the magic part. Ready? I’m just going to spin it. And yes we’re going a different
direction now. Is that the final buff? No, I got two more. It’s gonna be
even prettier tomorrow. Last night I took the saber home and after about six hours of
using the one micron and the 0.5 micron, I ended up with this. Hey, thanks for watching, and I hope this
video gave you some ideas on how you can make your projects really shine. For more
tips, tricks and stories check out our YouTube channel here, and you can
subscribe over here. Did I do it wrong? No.
I was watching Diesel. Was he running around in the background?
A little bit. Are you gonna get a video shot of him?


  • Chenega Bfree

    January 31, 2019

    Thanks… I’d like to use this video for my machining classes..!
    – cheers

  • John's Marine Solutions

    January 31, 2019

    You are not a machinist, you are an artist. Very nice work.


  • Crivo152

    February 1, 2019


  • Jake Ketchum

    February 1, 2019

    Very interesting topic, I look forward to seeing more of the actual technique involved.

  • Randy Cox

    February 1, 2019

    A lot of what I use my 770 for is small injection molds. These videos have given me some really good techniques for how to polish my molds. Doesn't seem to be a lot of information out there and getting this from a former mold maker is awesome. Love the bamboo skewer method.

  • Tim Mallard

    February 1, 2019

    Love this kind of content keep it comming! A rabbit hole I did even know of to go down now

  • Enda Murphy

    February 2, 2019

    Great content… I want to see more of this…well done Jenny.

  • Driftless Joinery

    February 3, 2019

    More shiny. Learned a lot in this video as well as the first. Thanks!

  • CNC Dude

    February 3, 2019

    That is a shiny light saber! That Jedi will have no problem beating the Sith as they get blinded by reflections, heh heh… But on a more serious note, good job on the topic! I was 110% oblivious as to what goes into polishing. Not only the process, but the science behind it. I would have sworn it was a matter of buffing imperfections away, but by your explanation it almost seems as if you are repositioning the metal groove by groove until it becomes "flattened"? If so, polishing is more of metal forming than cutting? I may have misunderstood the concepts, but either way it looks amazing!

  • Shane Harvey

    February 3, 2019

    That is a lot of work but the results are amazing.

  • wjkssmd

    February 7, 2019

    More… More. I wish I had seen this years ago. Bravo

  • Ro Cuevas

    February 8, 2019

    Have someone polished P20 steel molds?

  • Rocket Number 9

    February 21, 2019

    I ♥️♥️♥️ hearing the whys in addition to the how-tos! Thank you.
    Also, she sounded a little too excited when she said “0.5 microns.”

  • cd rom

    March 7, 2019

    I thought about a tool for this. What if you got a sort of device like white out tape roller that has thin soft very anneled copper on spools that you unroll with a handle to lay down on a slope. Then you dip the tip in the polish you want, embed it, use it until its done and crank a small knob to advance clean copper against the 'anvil' so you can put different abrasive on it.

  • James Mahoney

    April 4, 2019

    Great video! This is like “ The Rest of the Story “ for Machining!

    Do you ever use Cratex?

  • Katu Imu

    April 20, 2019

    cute and nice hair👍

  • Aaron Baca

    May 21, 2019

    I have NEVER thought about polishing in terms of stress/strain and have massacred a Nambe bowl in the process of restoring it. Somewhere along the line I hit it too hard. I think it was with steel wool. I suspect that iron depositing on the surface kept it from forming an oxide layer, and to my understanding it's the oxide that we're trying to polish.

    Thank you so much, this was an extremely informative video.

  • alan mass

    May 22, 2019

    Have u any experience on motorcycle aluminum heads and carters?I have been literally breaking my head over some and , after removing the thick factory paint (with paint stripper.. unfortunately blasting glass beads was not possible) and tried with some rotary tools, wheels and buffing soaps, I have ended up with a fair amount of scratches and a semi polished surface. I cannot get into the small gaps and cracks, fins and tiny holes in and on the irregular surfaces of the cases with any of my tools and I was wondering whether you had done some similar work. Could I send u a couple of photos of those parts? Get a few suggestions and tips perhaps?

  • eberfry

    August 16, 2019

    You wouldn't happen to have that link to those compounds?

  • 5x9 bob

    September 20, 2019

    I am the type of person that believes that quality of material or workmanship is what grabs peoples attention. However, there are also those who notice the actual detail and effort that went into the job. I happen to be one of the latter and I enjoy seeing that extra effort and detail that very few will take the time to endure or make the effort to gain the needed wisdom to get the high quality results some have come to appreciate. When I do something, I want to do it once and just maintain as needed. If I spend 15 hours on a project that will look nice, why wouldn't I put in the extra 5 hours to make it look beautiful and exceptional. I enjoy admiring quality workmanship and even more when it's mine. haha Your video content is just that. Thank you for the information and demonstrating for us on how it's done the right way and why. Best vid I've seen yet on polishing aluminum


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