# Need some advice on polishing



## kvom (Jan 8, 2010)

So after 3.5 engine builds, it's time to learn a bit of bling. Actually I blame George B. for shaming me into it.   ;D The past couple of days I have made some baby steps. I have a 6" buffing wheel setup and have been using the coarser (black) compound on some trial pieces. I followed the advice posted by 'divided he ad" on madmodder as well as the Caswell website. While my results are not terrible, I am sure they can be improved.

To start I had the set of aluminum oxide tapes from Enco in 160, 240, and 320 grit, as well as the purple Scotchbrite. I also have a set of small diamond files, also in 160, 240, and 320. So before starting the buffing, I used the progressive grits to try to remove tool marks.

First, I think that the 160 grit is too fine for the first pass, as it took a lot of elbow grease before the round endmill marks weren't visible. So a recommendation for a starting grit would be useful. Also, would it make sense to use a tool like a Dremel for the first step?

Once I had used the buffing wheel, I still see more marks on the surface than I think I should. So I'm guessing I need some finer grit paper than the Scotchbrite. Would 1000 be appropriate, and if so what type? Should I be sanding wet or dry? FWIW, the brass parts seem to come out better than Aluminum when using the grits that I have.


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## cobra428 (Jan 8, 2010)

kvom,
All I can say is watch how you buff. If you catch an edge into the descending part of the wheel.....be prepared to rebuild that part! The wheel will rip it right out of your hands. This is the only time I will recommend wearing gloves (heavy leather types) This way if it does happen you won't get cut up.
This comes from experience.

Last finishing... a cream sort of polish is good. It will protect the metal (for a while) from corrosion.
I like Sim Chrome, Flitz or Mothers. Applied by hand. All available at an auto parts store or a motor cycle dealer (those guys like bling too). Brasso available at the super market will work to but not as good as the above.

Hope this helps
Happy Blinging!

Tony


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## jonesie (Jan 8, 2010)

you can buy stones fron travers that are made for removing machine marks. in moldmaking we would start with a 220 grit stone and dip it into savosal or kerosene to keep it from loading up. make sure you move the stone in different directions or you will dip the stell when the cutter marks are gone then move up to a 320 then 400, you can then use 320 or 400 wet paper then if you want you can go to a brass and the nyon whell with diamond paste. you could with a little practice or a lot you could end up with a mirror finish.you might do a google search for mold polishing. good luck


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## black85vette (Jan 8, 2010)

I treat my metal much like I do paint on hotrods. I use 400, 600, 800 and 1000 grit paper and like to work under running water with a wood or rubber block. Then I have 3 buffing wheels and 3 compounds. I never use more than one compound on a wheel. Final buffer is very loose and "fluffy". Just to get buffing marks even. Depending on how good it needs to be, I may go through 4 to 6 steps of wet sanding and buffing. Kind of time consuming if you want to get all the tool marks out AND you want it mirror flat.  The key to buffing is to not use much pressure and let the compound do the work not the pressure against the wheel. You also have to go easy on corners so that you do not round them off. I always buff off or along an edge and never into it.

I am not sure about why you have trouble with the end mill marks. If everything is trammed and I have a good end mill I can get a good flat surface with 400 grit in a very short time. I make very light (.002) finish cuts at fairly high speed and use climbing cuts on the side of the mill for a final pass. I very seldom use less than a 400 for finish work. Less than that I am actually trying to remove or shape the metal and it just leaves too many deep scratches to remove.

Not saying the above is the BEST or the RIGHT way to do it. It is just MY way. Your mileage may vary.


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## Cedge (Jan 8, 2010)

Kvom
As a registered bling addict, I've got sandpapers up to 2500 grit, buffing materials into the microns, so you might call me a little obsessive....(grin).

Depending on the material, I've begun the process with 100 grit and progressed to 2500 grit before ever going to the buffing wheels and polish sticks. I then finish things off with a very fine metal polish called MAAS. Granted.... I do tend to keep at it until I can pick my teeth in the reflection.

For a satin or brushed aluminum finish I usually stop somewhere around 600 - 1000 grit. 

Steve


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## Blogwitch (Jan 8, 2010)

Just a few tips about polishing.

A lot of people think that a buffing wheel is the be all and end all to getting a nice finish. Nothing could be further from the truth.

The buffing wheel shouldn't be for removing machine marks or any other surface defects. For small item polishing that we aspire to, the buffing wheel should only be used for imparting the final lustre. The workpiece, before offering it up to the wheel, should be as smooth as the final required result, except for the final gleam.

Do NOT use your fingers or any other soft backing to your hand finishing materials if at all possible. You really do need to have the emery or W&D either resting on a flat hard surface or backed up around polishing sticks. If you use your fingers as a backing pad, you will be imparting curved surfaces onto what should most probably be flat, and it will show up in final polishing as an undulating surface, the same result as you will obtain if you try to polish out machining marks, and it will look even worse than if you leave the marks on there.

There are no shortcuts to polishing, in fact using a mop can sometimes be a bad thing. It can take hours of handwork to get the part ready for polishing, only to have it all destroyed by polishing on the wheel for too long, and it ends up as a round cornered blob of material, rather than a highly polished version of the sharp edged item it should really be. A couple of minutes polish time should be the most it takes, and that is on a rather large and complicated item, small items should only take seconds.

I have seen artisan polishers taking a rough stainless casting and turn it into a work of art within minutes, removing 1/8" of surface material in seconds, but they have had 30 or 40 years of continuous working at it, all we can hope for is to emulate their finished article, and the only way to do that is with handworking of the part to the best finish you can obtain. Only then give it the final touch up with the buffing wheel.

As for finishing compounds, one wheel can't do it all, you need the right wheel for the job on hand, and one wheel for each type of compound, hence that is why a pigtail is used. You can swap mops in seconds. Each type of material requires it's own type of compound. Ali will require different ones than steel, brass, again, different to a plastic polishing compound. That is why they give you such an array of choice when you visit professional polishing suppliers. 

You can play around with the same wheel and differing compounds on the same wheel, but don't expect astonishing results, all you will be doing is building up successive layers of different cutting compounds, and rest assured, at some time in the future, just as you come to impart the final lustre, you will break thru into an old 'hard' compound, and that can really ruin your day. If needs be, and you want to go down that route, then buy yourself a cheap mop rake, that will get rid of most of the old compound before putting on the new, but don't expect miracles.

It is all about practice, and then some.

Blogs


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## shred (Jan 9, 2010)

I like to use my surface plate as a sanding surface (sandy-side up on the plate). Also an Enco free-shipping deal.
You can get a pretty good selection of sandpapers up to 1200 grit at auto parts stores or even Harbor Fright. Cheap is ok because then you'll switch sheets more. I keep trying to skip steps, but rarely succeed-- start with 100 or 200, get the machining marks out, move to 400, get the 200 grit marks out then to 600 or 800 to get the 400 marks out, then to 1000, then think about buffing... (or with my typical laziness, reconsider the attraction of "matte" as a finish  )


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## kvom (Jan 9, 2010)

Thanks for all of the advice and comments. Today I went to the auto parts store and got some sheets of 60, 600, and 1000 paper. Along with the stuff I had I did get some better results than previously. I am using the hard butcherblock top of a workbench as the backing for the paper.

I started on the column I did for Brian's beam engine, which if you'll remember was this:







Yesterday I was using a needle file to remove the milling marks, and this resulted in some ugly scratches. So today I took one of the vertical facets and went through every grade from 60 to 1000, then a quick buff on the wheel. Much better than the other facets. I do have separate wheels for the finer compounds, but haven't tried them yet.

So now I have some idea about how to go for the brass and aluminum pieces.

Is it possible to do something similar with steel? The beam is 12L14 and still pretty "rough", while the flywheel is A2 tool steel, also showing a lot of milling marks.

Note to self: the bigger the engine the more surfaces to polish. I think Gail has the right idea with his small engines.


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## shred (Jan 9, 2010)

Steel sands about the same way, just a little slower and you may have to use more grades of paper, depending on the scratches. For flat surfaces that aren't easy to rub on a big flat plate, make up some sanding blocks and sticks-- just bits of flat stock or wood with sandpaper glued or tacked to them (old timers would just wrap it around a file). It's much easier to keep surfaces flat that way than hand-sanding or worse yet, some sort of rotary tool.


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## Blogwitch (Jan 12, 2010)

Kvom,

I forgot to mention this, save when it has downloaded to the web page.

http://www.caswellplating.com/buffs/Buffbook.pdf

It is a good bit of reading from Caswell and gives some very good advice on types of wheels and compounds, plus how to's and why for's.


Blogs


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## BigBore (Jan 12, 2010)

Nice link, Blogs! Thm:

Has any body here used Micro Mesh? It goes up to 12000 grit even though it's not a comparable grit scale as sandpapers. 12000 is about like 2400 or 3000 wet/dry. It's cloth backed and can be used wet/dry and can be washed in soapy water to clean and reuse. Lasts about 4-6 times paper backed wet/dry. Don't know if it works on metals that well or not.

Ed


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## rleete (Jan 12, 2010)

I've used it on wood for making pens. Haven't tried it on metal, as I can't see needing to go that fine. But it gives an almost plastic finish to CA treated pen blanks.


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## putputman (Jan 12, 2010)

kvom, one of our members, rcplanebuilder, referenced this post he made on another web site.
I thought is was s very good article on polishing. It is long but has a lot of info.
http://www.vintagebmx.com/community/index.php?showtopic=4005471


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## kvom (Jan 13, 2010)

I have just finished thd first polishing "cycle" on the beam engine, with the first buff. While the parts are nice and shiny, somehow I feel that having everything with a mirror-like finish isn't as attractive as I had imagined. It's a model of an industrial machine, not a piece of jewelry after all.   I think the fact that the model is fairly large plays a part in this impression.  I think I will paint the beam and the flywheel spokes with some industrial enamel to somewhat tone down the overall effect.

When I get around to the paddleducks marine engine, I think having a mixture of mirror and satin finish will be more to my taste.

Thanks to all for the advice and reference material.


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## pete (Jan 13, 2010)

Kvom,
I'd like to recomend 2 books to you, "Gunsmith Kinks" volume 1 and 2 avalible from www.brownslls.com, Volume 1 has a very good artical written by Bob Brownell himself, While this pertains to guns, Thats immaterial, Polishing small parts is just that, If a gunsmith ruins a polishing job on a very expensive gun then he's going to be replacing it. IMO your not going to find any written information about polishing better than this book.

Volume 2 also gives some plans for a fixture for round work that alows it to slowly rotate the work while polishing. IMO it's impossible to properly polish work in a lathe as your fine sandpaper is following the same very fine rings left in the material from the tool tip. You have to cut these high spots off by polishing at a 45 degree angle to the work while slowly rotateing the work, Spotlessly clean the work after finishing with that grit of polishing compound, Then polish with the next grade of compound in a opposite 45 degree angle. Plus sanding/polishing without protection for the grit or polishing
 compound on a lathe is a really lousy idea. If you buy these two books then I'd bet
 money you will agree with me after reading them.

Pete


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