Polishing: Why is 800 grit paper better than a wheel loaded with compound?

[Arch]

I have to ask:

In Alex Hamilton's "Pistolsmithing" column in the American Handgunner (Sep/Oct 2005 issue) he talks about retoring pistols, and basically states that you want to do all your polishing work with sand paper, working up to about a 600 or 800-grit finish. He goes on to state that you don't want to send your pistols to someone who does all their polishing on "a 1,500 RPM wheel loaded with 80-grit polishing compound".

So my question to those in the know, is why is hand sanding for a finish better? Does it give finer, more even results? But wouldn't it remove more metal? Educate me on the topic!

Thanks guys.

 

[brickeyee]

The 80 grit is the problem...

 

[dfariswheel]

The reason is, polishing with power wheels is a high-level skill that's more an art, and one momentary slip can ruin a part.

It's always easy to spot a polish job done by someone inexperienced. Holes are dished-out, sharp edges are rounded off, and flat surfaces have waves in them.
It doesn't matter HOW bright and shiny the final finish is, if the metal is distorted and the careful factory flats and edges are altered.

In order to do GOOD power polishing work, it takes YEARS of experience.
As an example, back in the days when all guns were blued, Colt was basically running a "polishing farm team" system.

New polishers went to school and were taught how to polish on Colt's factory-made leather covered wooden wheels.
They started actually working on the line with an experienced polisher literally looking over their shoulder, polishing budget guns like the Official Police.

After years of experience, they would be allowed to work on more premium guns.
After years more experience, only the very best would be moved to the Python line.

Few ordinary polishers get enough experience to develop the skill enough to do a really good job.

For this reason, instead of using power equipment that does require lots of experience to develop the "touch", less skilled people are advised to use abrasive cloth on flat bases.

One method, is to actually glue the cloth to thick pieces of plate glass.
The flat surfaces, like slides, are pushed over the abrasive until all scratches are removed, then you go down to a finer grit, until you reach the level of polish you want.
For curved surfaces, the abrasive cloth is glued or wrapped around round or curved shapes that allow polishing the surface but still keep from changing the contour.

This method allows polishing parts, but reduces the chance of a slip damaging the surface.
In power polishing, an instants slip can ruin a valuable gun part.
By doing it by hand, the chances of one slip doing irreparable damage is reduced.

You CAN still botch the job with the hand polish method, but it takes longer, and allows checking the work to spot problems before they ruin a part.

 

[Old Fuff]

I second what dfariswheel said:

Hand polishing takes time - usually a lot of it, but when you get done you'll see the difference and be glad you did it. Wheels are a good way to get into trouble fast, and if you make a bad slip it's all over with. Also if you work by hand you are far less likely to wipe out important markings and/or numbers.

 

[Arch]

Thanks for the replys guys. That prettymuch answers it all.

Just one more question though. When polishing using abrasive cloth, approximatly how much metal do you wind up removing? Are we talking thousanths of an inch here?

 

[Old Fuff]

It depends ... The idea is to remove surface inperfections, rust, pits, etc. without doing away with markings you want. You also want to keep the curves true and flats, flat.

One other thing that may apply to you. The first thing you must do is remove any plating - nickel, chrome, whatever - from the parts. This may be done either through a chemical or electrolitic process depending on how the plating was applied. For more information contact the technical folks at Brownells. Telephone: 1-800-741-0015 FAX: 1-641-264-3068 Internet: www.brownells.com

 

[Arch]

Old Fluff,

Thanks for the clarification.

Actually my reason for asking is mostly just curiosity and interest. Currently I have no plans to do any work on my Model 15, as the chrome finish is still in very good condition. But the knowledge is transferable to V8 rocker covers...

I guess the next thing I will be looking to do after learning to apply a decent polish, is finding out how hard it is to apply nickel plating (via electrolisis).

Thanks again.

 

[Old Fuff]

The nice people at Brownells sell the equipment, and they'll send you a copy of the instructions for free. I don't know if there would be problems shipping the necessary chemicals to where you are or not, but you could ask.

 

[Arch]

Old Fuff,

I have just realised that I have been spelling your name wrong all over the place.

My sincerest apologies, as this was not intentional.

Cheers.

 

[Old Fuff]

Oh Dear ....

This will probably cause an international incident ...

Our president will have to call your prime minister ...

I will go crawl under the bed and sulk for weeks on end ...

Who knows what the implications may be ...

But of course I have been called worsre ....

 

[Arch]

Our president will have to call your prime minister ...

Bush doesn't have to call our PM. Haven't you seen the ankles of our Prime Minister protruding from your President's rear end?

 

[Old Fuff]

Well that is a happy thought ...

 

[dfaugh]

Not to be contrarian

but I always start with courser paper, or better yet, emery cloth(medium, then fine)...Once I've removed any pitting and such I then move to a buffing wheel, first with red rouge(courser), then white rouge(finer)...I then degrease to remove any traces of rouge, and follow with 0000 steel wool to "even out" everything...This has given very good results on a variety of guns.

If you haven't done much with a buffing wheel and rouge, practice on some scrap first, to learn just the right amount of pressure to apply(not all that much)...It takes a bit of practice but not all that much.

My .02

 

[Arch]

dfaugh,

Thanks for the input. This sounds like you could get good results from that method.