Recommendation? What step am I doing wrong with my grinding. And how to I avoid these lines after buffing.

[TaylorBlade]

Hi, I’ve been looking up questions for a while but finally joined to ask my first question. After using two of the Red Label buffing wheels my knives always seem to be covered in grind lines. My belt process has been 36, 60, 120, 240, 320, 400, non woven belts, buffing wheels. I can’t tell if these are low grit deep lines or if I’m just not going high enough. I don’t include any hand sanding in my process currently fyi. Any help would be greatly appreciated.

https://imgur.com/g78mQpf

 

[Del Raso Knives]

You need to decide what finish you are aiming for. Buffing over a 400 grit belt finish will always give you the same result. Your choices are: (1) leave it at 400 as it comes off the grinder (belt finish). (2) hand sand to remove belt finish (hand satin finish) (3) hand sand to a minimum of 1200 before buffing (mirror finish)

 

[TaylorBlade]

You need to decide what finish you are aiming for. Buffing over a 400 grit belt finish will always give you the same result. Your choices are: (1) leave it at 400 as it comes off the grinder (belt finish). (2) hand sand to remove belt finish (hand satin finish) (3) hand sand to a minimum of 1200 before buffing (mirror finish)

Thanks, that really helps. So buffing after 400 I’m basically just exposing all the belt lines. I’ll try hand sanding to a higher grit for now. Thank you!

 

[Ken H>]

I think most folks will agree for a mirror finish you'll need to sand to at least 1200 grit, being SURE to remove ALL grind lines from previous grits before advancing to next higher grit. Typically a mirror finish is reserved for a display only knife, not a user blade.

When using a mirror finished blade it's easy to get small tiny scratches with use and they really show up in the mirror finish. With a nice matt finish those tiny scratches hardly show.

 

[Stacy E. Apelt - Bladesmith]

IMHO, a mirror finish is a waste of time for a knife that will ever be used. It will be destroyed almost the first use.
I sand to 400 and use a maroon scotch Brite belt to give a smooth satin look. It lasts nearly forever and can easily be touched up if needed.

 

[GRapp]

A friend in here recently helped steer me in the right direction with a lot of help from this video, good luck.
Edit to add: For my knives, I see no need in going higher than 400 grit on the grinder and then again by hand.

 

[daily_grind]

I have watched the Nick Wheeler videos at least three times. They're great. I'm probably going to copy his sanding platform too.

 

[GRapp]

I have watched the Nick Wheeler videos at least three times. They're great. I'm probably going to copy his sanding platform too.

His technique works a lot better than what I was doing prior! It should help TaylorBlade, if only to understand progression through grits.

 

[FredyCro]

All things said, those look like rougher grit scratches. For stainless cooking knifes I really like the finishing with grey and green scotch brite belts. I run them with glass cleaner or WD40 and they leave a semi gloss surface which hides small use scratches perfectly. I finish to a clean 220 before taking it to the scotch brite.

 

[Lorien]

the practical reason for a mirror finish is to optimize corrosion resistance

 

[JV Knives]

TaylorBlade You are just seeing left over lower grit marks partner. Just work through your progressions (belt or by hand) to clear out each previous grit marks before moving on. Don't more than double your grits in progression. Example: 36...60...120....240.....400. Easier said than done. In time, your eyes will be able to basically identify which grit is associated with which marks. Until then, when you think your ready to move to the next grit, give it one more go over

 

[HPD]

IMHO, a mirror finish is a waste of time for a knife that will ever be used. It will be destroyed almost the first use.
I sand to 400 and use a maroon scotch Brite belt to give a smooth satin look. It lasts nearly forever and can easily be touched up if needed.

I have learned that a good 320 grit finish, meaning no lower grit scratches and all the final 320 grit lines in the same direction, looks much better than a bad 600+ grit finish. Less done right is more.

 

[C_Claycomb]

Two things I have found helpful.

EDM stoning length ways to highlight low grit belt scratches. The stoned finish does not need to be pretty, just even. Abrading across scratches removes them quicker than grinding in line with them. Lets say grind to 220, then stone at 220, then grind at 400. Easy to see when all the long 220 stone scratches are gone and you know all that is left are 400.

Better finishing belts. Engineered Norton structured ceramic, and the newer water resistant Gator belts. Much more effective than 120 and 220 resin bonded ceramic or AO Norax (which gives a good finish when new, but glazes and doesn’t mix well with water).

 

[ScarFoot]

A trick I use a lot on flat ground blades is to put a sheet of sandpaper on my granite surface plate when I get to finer grits and sand across (perpendicular or 45 deg) the grain of my last grit pass. Using a perfectly flat surface makes any high or low spots and any left over scratches stick out like a sore thumb. It’s made my sanding at 400 grit and above much more consistent and easier even though it’s an extra step.

Also good lighting and in my opinion magnification is a must. I use an opti-visor for hand sanding and magnifying safety glasses when I grind.

 

[fitzo]

A trick I use a lot on flat ground blades is to put a sheet of sandpaper on my granite surface plate when I get to finer grits and sand across (perpendicular or 45 deg) the grain of my last grit pass. Using a perfectly flat surface makes any high or low spots and any left over scratches stick out like a sore thumb. It’s made my sanding at 400 grit and above much more consistent and easier even though it’s an extra step.

Also good lighting and in my opinion magnification is a must. I use an opti-visor for hand sanding and magnifying safety glasses when I grind.

Excellent point! It is even further beneficial to have multiple types of lighting available to look at your blade before declaring "finished." Many the maker has finished his knife under the incandescents at home only to get to a show under fluorescents and a, "Holy Crap where did all those come from?" Helps to have a positionable lamp shining at an angle in addition to the overheads while you work, too. I see poorly nowadays. I have 2 temps of LED bar lights overhead, an incandescent bulb in one of those old positionable clamping desk lamps, and a Full Spectrum bulb in one of those cheapo clamping spun aluminum fixtures. Each one contributes substantially to the clarity and my ability to perceive scratches. Optivisor and readers are a must.

I come from an earlier approach where everything I made from SS was mirror polished even if it was going to end up satin, so I've had a little experience. The "switch grits at 45° (or whatever) to the current scratches and remove all of the previous grit scratches" is the most important thing one can do when finishing if you want that beautiful finish. Check out Alex Daniel's 400 grit satins on his Bowies. Superb.

Not being a wiseass, but it would step up a lot of game on many knives I see here if a little more devotion was spent to good finishes. You can't see sharpness, toughness, balance, etc, looking at a knife sitting on a show table. But you can sure as hell see a poor finish. My 2¢

 

[ScarFoot]

Not being a wiseass, but it would step up a lot of game on many knives I see here if a little more devotion was spent to good finishes. You can't see sharpness, toughness, balance, etc, looking at a knife sitting on a show table. But you can sure as hell see a poor finish. My 2¢

I agree. Fit and finish get overlooked too often in favor of either higher output or overly complex designs. I prefer to try to make simple knives as nice as I can possibly make them with the tools I have. I’m not great but I’m constantly trying to find ways to get better.

 

[godogs57]

IMHO, a mirror finish is a waste of time for a knife that will ever be used. It will be destroyed almost the first use.
I sand to 400 and use a maroon scotch Brite belt to give a smooth satin look. It lasts nearly forever and can easily be touched up if needed.

Which grit is the maroon belt. I use blue and gray belts….99% of the time I stick with blue.

 

[Stacy E. Apelt - Bladesmith]

The color code is:
Brown - Coarse 80 grit
Maroon - Medium 150 grit
Blue - Fine 360 grit
Gray - Ultra-Fine 400 grit

As you can see, blue and gray are pretty much the same belt. Blue and gray require a 400 grit belt finish to avoid scratches showing.
Maroon gives an even brushed effect and works perfect over a 220-grit belt finish.
The brown belt is good for cleaning up rough forged tools and things that don't need a fine finish. It works well on non-knife tools and things that will be fire blued or black etched

 

[Taz]

I found the Cubitron 726A work really well for a finer grit belt before going to the ScotchBrite. I have used the same 320+ grit belt on a couple blades so far and it's still removing metal well on 62 HRC Nitro V and Magnacut at 64 HRC; I see the grey dust falling off the blade when I use it. It seems to cut the steel and not burnish it as much as other finer grit belts. I use Gators (ceramic and regular) and Norax (ceramics) in finer grits (A 65-A 16), but they tend to polish the steel more and not remove material as much. The Cubitron 726A leaves a different finish, but it's great for ScotchBrite finish prep! I was shocked at how well it removed steel on Magnacut after being used on Nitro V. Leaves a very consistent scratch pattern and the belt is thicker, so it worked very well on a glass platen.