Mirror Finish - Wet or Dry

P

popcornpicker

Joined
Apr 3, 2007
Messages
625
I've probably done thirty or so blades and it doesn't seem to make much difference. The only difference I can tell is that wet sanding is messier. The amount of time and the results are about the same.
 
Wet, sandpaper needs the lubrication to get the true mirror IMO.
 
I usually go dry 150, 220, 400, then go wet 400 again, 600, 1200. Buff with green, white, then hi-luster white. But I really dislike mirror finishes, I go satin unless the customer specifically requests otherwise.
 
I don't know any other way to remove scratches from nitwits with grinders. If I only use scotchbrite wheels on a bench grinder you can still see scratch marks.
 
I always use water to finish, yea it's messier but you don't have the grit form the paper becoming airborne. The grit can also build a slurry in the water and sanding can go faster. Finish your final grit using oil instead of water.
 
Not to mention the fact that you'll get more life out of wet/dry paper when sanding wet.not much,but it does'nt clog! if you plan on a mirror i'd grind up tio 600 grit,then handsand starting at 400.
 
I have never been able to get fine scratches out finer than 320 with the grinder, maybe the light or my technique. I grind to 320 thin wet sand with wd40 with 320 then go to 400 up. I sand oposite the direction of the grind and make sure there are no scratched from the grinding before i go to 400 (same direction as the grind) and then 600 oposite direction of the grind. Until I started this I could spend all week trying for a mirror finish. After the first 320 in done right it goes pretty quick.
 
Any of you guys ever tried the worn out belt method?
Take a used 400 or 500 grit belt and work as much grit off it as you can with the edge of a bar of steel. Once you get it nice and clean, turn the grinder down slow and put some buffing compound on the belt and work the blade just like you do when you're grinding it.
 
L-6,
Inthe early 80's I spent alot of time with a pretty sucessful maker.
He did alot of hollow grinds, to finish them he used a "shaved" belt too. He loaded the belt with compound and tracked the belt about a half inch over the edge of the wheel and only used that part to finish with. you couldn't tell the difference from a buffed blade. I've done it over the years also but not as well as him. You need just the right touch. It's dangerous too.
 
Thanks, guys. I modified my techniques and it seems to be a little faster with better results. It seems as if the more different grits of sandpaper, the better it gets. I wasn't sure about the best time to switch from dry to wet was, but the tip about 400 dry then wet, was worth trying. I used to go 400,800,1500, but now I've found if you also use 600,1000,and 1200, the sand scratches are dramatically reduced. It doesn't take as long to sand out the previous scratches if you use intermediate grits.
 
I cant get good results with a worn belt for the life of me.for a high finish,handrubbed machine or mirror this is how i go.

rough with 50 grit 977 cubitron
fresh 220 jflexx
fresh 400 jflex
sometimes i'll go to fresh 600
broken in 400 cork belt with green compound
broken in 600 cork with green compound.

This puts you at a very fine finish.i can move to 400 grit wet/dry and have all grind marks out in under 5 minutes.
 
I recently purchased a black and green rouge from this board member Tracy at http://www.usaknifemaker.com/store/

I already had a worn 800 grit cork belt and added both of these new compounds to the belt and cleaned up 400 grit belt scratches to a mirror finish with very little efforts on both hollow and convex grind. Thanks Tracy.
 
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