Sandpaper grits and their uses?

[tuffluv]

Is this about right?

Re-profiling edge geometry: 80 to 200 grit

Sharpening: 400 to 1000 grit

Maintenance (daily or weekly): 2000 grit or strop

 

[Obsessed with Edges]

Is this about right?

Re-profiling edge geometry: 80 to 200 grit

Sharpening: 400 to 1000 grit

Maintenance (daily or weekly): 2000 grit or strop

Almost never any need to go below ~150-220 grit, for any re-bevelling tasks. More often than not, I'd start at ~220-320 for that; anything much coarser will leave the edge very rough, requiring much more work to refine it. Whatever speed advantage a very coarse grit gives you in removing metal would be given up in the clean-up of very coarse scratches afterward.

For regular sharpening or touch-up tasks, the grit choice is mainly about preference; great working edges can come straight from ~320 (maybe even 220) and up. Anything in the ~320-600 grit range will leave essentially 'satin' finishes with great toothy bite, and ~800 and higher will start to show a little bit of polish, with 1000-2000+ getting to near-mirror or better.


David

 

[rlucius]

Almost never any need to go below ~150-220 grit, for any re-bevelling tasks. More often than not, I'd start at ~220-320 for that; anything much coarser will leave the edge very rough, requiring much more work to refine it. Whatever speed advantage a very coarse grit gives you in removing metal would be given up in the clean-up of very coarse scratches afterward.

For regular sharpening or touch-up tasks, the grit choice is mainly about preference; great working edges can come straight from ~320 (maybe even 220) and up. Anything in the ~320-600 grit range will leave essentially 'satin' finishes with great toothy bite, and ~800 and higher will start to show a little bit of polish, with 1000-2000+ getting to near-mirror or better.


David

David,

Are you using P, CAMI or something else in ref to grits?

Thanks
Rupert

 

[Russ Prechtl]

I re-profile at 400 or 600, depending on how much work is needed. Start as high as possible, then drop down if necessary. Below 400 has only been necessary for removing big chips.

I usually go up to 1200-1600, then strop at 3.5 and 5 microns for a mirror polish.

 

[tuffluv]

This is very helpful information. Thank you!

 

[Obsessed with Edges]

David,

Are you using P, CAMI or something else in ref to grits?

Thanks
Rupert

FEPA-P is the standard most often applied to the sandpaper I've used, and is what I refer to in my posts about it.


David

 

[rlucius]

FEPA-P is the standard most often applied to the sandpaper I've used, and is what I refer to in my posts about it.


David

Let me say thanks

Rupert

 

[Obsessed with Edges]

Let me say thanks

Rupert

I generally use either 3M 'WetorDry' or Norton 'SandWet' papers. In looking at the sheets I'm using, it may be that the Norton SandWet could be CAMI-graded (or 'ANSI'), as it's not specifically labelled as 'P320' for example. The 3M paper I'm using is labelled with the 'P' prior to the grit number. Between the two standards, most of the differences would be seen at higher grits, as the rated difference between them gets more extreme at higher grits (CAMI '600' apparently compares to FEPA-P '1200', for example; BUT with both using grain size around ~15µ). At lower grits, the two scales seem closer together.

Now having mentioned all that... In actual use, I haven't noticed much cosmetic difference (by naked eye) in finish above ~800 grit or so, as either one seems to yield what looks like a very fine 'satin' finish, maybe with some hints of mirror starting to come through. By ~2000-grit on either paper, both seem to yield very near-mirror finish on most steels.

I'm also reading that the FEPA-P grading scale is held to tighter tolerances than CAMI-graded grit, meaning there may be a wider range of allowable particle sizes for a given single CAMI-graded grit, and a narrower range tolerance for FEPA-P grit.


David