Sanding, when and how.

M

MoSmith

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May 28, 2017
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I'm a newbie on this so I'm probably asking some dumb questions but here goes. *S*
I'm making some small skinning knives out of O-1 and I have the blades beveled and tapered etc. My problem is finishing the blades. They look really rough and I want to put a nice finish on them, if not a mirror finish then something close. So two questions:

1) Do I finish them before heat treating, or after, or some of each? I'm using charcoal in a forge and this has worked well in the past for me.

2) Is there a better way of doing this? Right now I'm using wet or dry sandpaper and it looks like it's going to take a week or so to get a reasonable finish on these. I've already used quite a bit of 240 grit paper and it just doesn't seem to be cutting.
I'm hoping there's a smarter way of doing this.

Thanks and regards

Jack Smith
 
Good sandpaper is key.
Order some Rhynowet red sheets.
I start at 60-120 grit, then move to 240, 400, 800 etc. If you start too high it will take forever.
 
The less scratches that have to be removed post-HT the better.
If hand finishing blades, go to at least 400 grit pre-HT. Many go higher. My buddy polishes his blades to almost a mirror finish pre-HT. That is overkill, but he does not have to worry about sanding out deep scratches.

As said, good paper helps a lot.
 
All good advice already, but for me I found the biggest thing to minimize my hand sanding time has been to get the bevels as flat as possible before hand sanding. This eliminates those pesky deep scratches that make up the bulk of hand sanding. What tools are you using? Do you have a belt grinder or disc sander or are they made with files? If it's just hand tools, I would recommend draw filing before heat treating to get it nice and flat, then go up to 400 grit before HT like Stacey recommended. If you have a decent disc grinder you can also use that to true up the bevels at any point in the process. Otherwise holding your blade diagonally on the platen can help even it out too. That depends on the type of grind you're using though.

All in all though, when you're starting out it just takes a large amount of time to get your blades with a nice clean finish. Good tools help a lot, but mostly it just takes practice. If you haven't already seen Nick Wheeler's videos on hand sanding on YT then you should really check those out. He's the G.O.A.T. of hand sanding. Take you're time with lower grits and make sure you get all the scratches out from each grit before moving to the next finer one.
 
tell us about your sandpaper, the brand. i ask because my first 20 knives were made with home depot sandpaper made for wood and no wonder nothing was happening :rolleyes: . also with a charcoal forge like i used to use, its easier to get really deep decarb which is a pain to sand out. if your using charcoal i would suggest going down to 120 or lower grit until the metal is clean. that way, with the next higher grit all you need to do is remove the previous grits scratch depth of metal.
 
weo said:
to what grit?

I'm down to 120 on the grinder right now. The hand sanding wasn't working so I backed-up one step. I'll get some of the Rhynowet paper and see how that goes for me.
Click to expand...
Thank you for this.
 
john april said:
tell us about your sandpaper, the brand. i ask because my first 20 knives were made with home depot sandpaper made for wood and no wonder nothing was happening :rolleyes: . also with a charcoal forge like i used to use, its easier to get really deep decarb which is a pain to sand out. if your using charcoal i would suggest going down to 120 or lower grit until the metal is clean. that way, with the next higher grit all you need to do is remove the previous grits scratch depth of metal.
Click to expand...
Right now I'm just using some wet or dry paper I got from Ace hardware. It sounds like I need to get something more appropriate. Several folks have recommended the Rhynowet paper and I'm going to get some and go after this thing again. I know what you mean about the decarb. I love my charcoal but it can be a pain.

Thank you
Jack Smith
 
A good sanding block/backing is key also. Even good sandpaper loses its bite pretty quick, I change it out frequently. There's advice on the forums to use belts like they are free. That goes double when hand sanding I'd say.
 
You might also try some EDM stones as well. They don't replace sand paper, but they do the bulk of the work and keep crisp lines. You want either N stones from Falcon Tool or Die Star stones from Congress Tool. The harder stones tend to create gouges, so lasting longer than the soft stones really doesn't help.
 
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