Buffing to no effect

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FunkCoaster

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Nov 2, 2010
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I purchased a buffing kit with 3 airway buffing wheels and polishing compounds marketed towards knife makers. Avoiding links for forum rules, but GentryCustomKnives on YouTube has a "HOW To get a BEAUTIFUL MIRROR finish!?" video about this.
This is my dream; to reduce hand sanding. Mirror finish is optional, but getting above a 400 grit finish is a goal.

Reviews and tutorials make it seem magical, with people starting at a 400 grit finished blade, and polishing up to mirror.

When I try the same, it is almost laughably ineffective. Most people are not mentioning the steel or condition of the steel when they are buffing in their videos, reviews, or tutorials.
I am buffing AEB-L or MagnaCut at ~61 Rc hardness.

Some instructions suggest you "might need to sand up to 2500 grit". If true, that negates all benefit of the buffing for me, since that is practically mirror finish already. I also found MagnaCut to severely resist hand-sanding grits above 400.
Do these buffing solutions only work on certain types of steel or steel conditions? Like, can you only use high carbon steel?

I used a buffing rake substantially to clean the wheels and tried different amounts of compound applied. Virtually no effect.
Any advice appreciated.
 
I don't do mirror finishes on any steel, so take that into account. With that said, AEBL should be relatively easy to get a pretty good high/mirror polish with quality abrasives. I have no idea when you would switch from sanding to buffing, but quality buffing compounds should work with AEBL. With Magnacut and vanadium steels, you might have to try looking into compounds that have diamond or CBN, especially at those higher grit levels. Sorry, that's all I have to offer. Good luck!
 
I've hand polished difficult metal before. Expect to have hours and hours of labor in it.

220,400,600,800,1000,1500,2000,2500,3000, 3M wet and dry using soapy water...and then hit it with a buffing wheel.
 
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FunkCoaster said:
This is my dream; to reduce hand sanding
Click to expand...
Buffing WILL NOT replace hand sanding! Buffing will reduce the surface of the blank more or less evenly. Meaning the scratches may have their edges eased but they won't disappear. There aren't any shortcuts to a great knife finish.
 
I have mirror polished hundreds of knives in 440C, 154CM, and ATS34. Old steels. There weren't any shortcuts then, either. You hand sand with every grit you can find and it'll reflect at that point. Back when was AISI 1200 grit wet-or-dry from the NAPA. Then you take it through a couple buffing grits and you have a mirror polish that'll take an engraver's microscope to see any scratches. The only way I ever saw to change that sequence was Steve Johnson's use of buffing compounds on cork abrasive belts.

Have to say, though I haven't tried it, from everything I've read on here you are going to need diamond to polish magnacut and these other supersteels. There are fellows on here who've used diamond belts and diamond-loaded buffing wheels. Hopefully they'll comment.

But, as it stands, it sounds like you have unrealistic expectations of what buffing can typically produce in the knife shop. Mirror finish is more steps, not fewer.

Try that AEBL with every grit paper you have on one blade and then hit it with green chrome rouge. That'll show you all your remaining scratches in a heartbeat and then it's back to handsanding again, &^$#$%*(&*U.

Try mirror polishing once and then satin finish at 600 or 800 grit. Best satin evah...

Good luck.
 
There are a few ways to get a mirror finish, some are hard and some are easy.

You want to know an easy way? Okay here you go

Go to Trugrit and read how to break in a cork belt THIS IS CRITICAL then get a 400g, 800g, 1200g and plain cork belts.

Break them all in get some green compound.

Grind up to a 400 grit as normal then go to the 400g Cork belt and apply green compound, then do the same to 800g . 1200g and finish with plain cork belt with green compound.

At this point it will be mirror finish and you can go to the buffer and lightly go over the blade if you want if it needs to blend in any areas that need it.
 
Scratches so small. Your eyeball can't see them. Even holding it up to the light.

Optically clear. The mirror you're wanting.

No big deal. But know it's about $$$ in the sandpaper alone. Good sandpaper isn't cheap and they know it.
 
You're not going to get there with airway buffs. You need a hard felt wheel, and lots of black compound to start. After that you can go to green. I've gotten mirror finishes on 154CM this way but it does take a lot of work. I also work on top of the buff, not under it. I get a lot better control that way.

Eric
 
There are no tricks or shortcuts.
One improvement I found is using sanding stones instead of sandpaper and only use sandpaper for the last grit.
That goes faster
 
Buffing will work decently on lower wear resistant steel. I got a good finish on 62-63 HRC AEB-L after belt sanding to 400 grit and following a similar buffing progression. It’s not gonna help you with steels that have more than maybe 2% vanadium is what I would guess maybe even 1%.
 
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