Grit Finish of Precision Ground Stock

M

me2

Joined
Oct 11, 2003
Messages
5,110
Does anyone know what the final grit finish is on precicion ground stock? I'd like to be able to grind my current 2 kitchen knife blades (planning on chisel grinds) and HT, but I don't know if I need to finish the rest of the blade finer first.
 
Don't know for sure,but on the stock i have it seems to be between 36-60 grit.
Stan
 
It's going to depend on who ground it on what. Also, wheel finishes are not the same as belt finishes. 36 grit from a surface grinder looks a heck of a lot better than 36 from a belt and the scratches aren't as deep. Make your finishing decision based on what looks good, not what the number says.
 
acridsaint is correct. i can use a coarse grinding wheel on a surface grinder and get a nice finish. the same grit belt will leave a totally different finish.
 
Last edited:
Better to sand it before HT. Scratches that take 5 or 10 minutes to sand out before HT will take 3-4 times as long afterwards, at least. Flat sand on backed paper at a different angle to the grind marks, any deep marks will pop right out at you.
 
me2 said:
My intent was not to sand it at all if it wasn't necessary.
Click to expand...

If you like that PG finish, leave it, but I would never recommend that. PG stock is so you have a nice flat, straight, scale-free surface to start from, not so you can skip finishing the blade.

I go to at least 220 before HT, usually more like 800. Post HT I go up to at least 800 even if I'm going to come back down to a basic 400-grit hand rub. Coarse scratches on a knife are an engraved invitation for moisture and gunk to get in there and cause corrosion. Especially on a kitchen knife that will be routinely exposed to acids.
 
james terrio said:
If you like that PG finish, leave it, but I would never recommend that. PG stock is so you have a nice flat, straight, scale-free surface to start from, not so you can skip finishing the blade.
Click to expand...

That's kinda what I was going after. It looks and feels about like the 120 grit finish I left on my Buck after regrinding the blade.
 
It can be all over the place. Some is fairly fine, some is rough as hell.

I frequently leave the PG finish on a knife, if it is the look I'm going for.
 
I have some precision ground A2, and I'd say the finish is at least 120 grit.

I'd take it a little higher before heat treat.
 
I believe it is typically around 46 grit. That does NOT however, equate to what you get on a belt sander. If I had to guess it would be 220 or finer. A wheel controlled to .0002 is not the same as shoving a piece into a belt.
 
I decided I need to go ahead and polish it up some. There is some coloring left from when I cut the profile and my vision is a short, chisel ground, drop point. It will look much better with an even 120 or 180 grit belt finish I think. 180 is the finest available locally I know of. It will look even better when I actually get some grinding skill.
 
Or order some elbow grease and get to hand-sanding. Sorry to be a snob, but 180 is not a finish I would accept on a cheap factory import, much less a handmade knife.
 
Good think I'm keeping it for myself. At any rate, the profiles for 2 are complete and the edge is ground on one of them. Polishing/grinding started with 24 grit belts and I'll go until they're finished, whatever I finally feel that is.
 
After debating on what to leave the finish, I finally decided to take James' advice and hand rub down to 600 grit or so. What is the best way to go about this? I've seen people lap blades on granite blocks, and hand sand using a wood or Micarta rubbing stick. I have a glass plate I use for flattening my sharpening stone. Would it be better to use a rubbing stick or some spray adhesive and the glass plate?
 
The plate is OK for crisping up a large flat, but you get too much surface area contacting the steel and you don't have good leverage on the knife if you want to do serious stock removal. Better to use a block, in my opinion.
 
I just use old files with the teeth and corners ground off, and wrap my paper around them.
 
Any suggestions for starting grit? The coarsest wet/dry I've found at the automotive store is 220.
 
I start with 3M 220 w/d, after working my up to 400 on the grinder*. It's actually pretty aggressive but doesn't leave terrible deep scratches. If that's not aggressive enough you could try draw-filing with a smooth or 2nd cut file. I've done this to get large flats more flatter, it works pretty well.

Once you things nice and even with 220 up to 400, it goes much quicker. A clean 220 really doesn't look too bad, you may decide that's enough for your purposes.

*I'm finding that a 400-grit belt hides a lot of 50 and 80 grit scratches, they pop right out when you go the opposite way by hand with 220.
 
You must log in or register to reply here.
Back
Top