Just when I think I know it all...

Langadune

Langadune

Joined
Apr 19, 2012
Messages
212
Actually, I know I don't know it all, but it seems that when I think I have a pretty good grasp of things, I re-discover I still have a long ways to go.

I have my blades back from HT and am working on final finish. I thought sanding (started back at 120 and working my way up) would bring my edge thickness close to finish. I left them at around .5mm when I sent them off. Now it seems way to thick. The sanding didn't really get me very far, in fact the blade just about has the finish I'm shooting for but the edge is too thick. So, I'm a bit frustrated here.

I've been using 3M sand paper but have some Rhynowet Redline coming. Also have some blaze belts coming. Either way, I need to get my edge thickness closer to the final product, but it seems like I'm missing something here.

Any advice would be appreciated.
 
What steel type and blade size/type are you working on? Also, did you measure the .5mm or guess it?


.5mm is about .020", which is a good size for a carbon steel blade edge pre-HT. Half that works fine for stainless steel. If you have sanded the bevels a lot and the edge is still the same thickness, you are probably leaning on the spine more than the edge. Turn the blade around and sand from the edge toward the spine. That should reduce the edge faster. When cleaning up on the belt grinder after HT, I usually grind the blade edge up on the flat platen.
 
You can go back to 60x and grind bevels to get the edge down then progress up the grits again to finish it off.

Remember lots of guys actually totally grind their blades after heat treatment. Just keep it cool and you will be fine.
 
My blades are 154cm and yes the .5mm is an approximation. I'm not sure why I left it so think when I sent it off. I must have been thinking of thicker stock, because this is only .103/.113".

You guys are basically confirming was I was afraid of: I left it too thick and I have a lot more work ahead of me than I was hoping.
 
Why not put them back on your grinder? A couple of passes and you will have a nice secondary bevel. Just make sure to keep them cool by dipping in water.
 
David Stifle said:
Why not put them back on your grinder? A couple of passes and you will have a nice secondary bevel. Just make sure to keep them cool by dipping in water.
Click to expand...

I actually started doing that, but I only have cheap belts at the moment and they wear down fast on that hardened stainless. I have a full flat bevel, so the only secondary I want to have it the final sharpened edge; and I'm trying to keep that as minimal as possible since these are kitchen knives. I have some Blase and 3m ceramic belts coming, hopefully progress will improve.
 
Langadune said:
I actually started doing that, but I only have cheap belts at the moment and they wear down fast on that hardened stainless. I have a full flat bevel, so the only secondary I want to have it the final sharpened edge; and I'm trying to keep that as minimal as possible since these are kitchen knives. I have some Blase and 3m ceramic belts coming, hopefully progress will improve.
Click to expand...

If you do not have good sharp belts just wait until you do. Worn out belts heat up the metal far to quickly
 
AVigil said:
If you do not have good sharp belts just wait until you do. Worn out belts heat up the metal far to quickly
Click to expand...

I figured that out pretty quickly. Those cheap belt wore down fast and then didn't do much except heat up the metal. I stopped using them because it kind of scared me into thinking I might ruin my plans for Christmas. They didn't get hot enough to ruin the HT but it was an eye-opener just how important a good belt can be. I haven't done much for a couple of days now, waiting on better belts to show up.
 
Just to make sure - is the hand sanding you are doing with the paper backed with a block of hard wood or metal?

Normally a block of dense wood, or bar of steel and 120 grit SC paper will take down a bevel fairly quickly. Hand sanding with the paper folded up will not work nearly as well.
Wet sanding makes it even faster.

The heat build-up in grinding a hardened blade is immensely more than it feels. If the whole blade gets hot to hold, the edge may be several hundred degrees higher. Slower speed and fresh belts are the cure. Better post-HT grinding is the biggest attribute of a VS grinder.

I really like the Blue Zirconium belts in 120 grit for taking down the bevel post-HT. Followed by Blue Zirc in 220, then a 400 grit belt ( type doesn't matter much here), and a medium or fine Scotch Brite belt for the final satin finish.

Some folks like to use a A300 trizac belt followed by an A100 trizac ( roughly about 80-100 grit followed by 180-200 grit). These "gator" belts are really nice.
 
Langadune,
I hope you don't mind me thread jacking a bit, but since Stacy brought it up.
Stacy,
You mentioned Blue Zirc belts in 120 and 220. Are you referring to the Norton Norzon belts (R823X) or some other brand? The reason I ask is, I've been wanting to experiment with something other than what I'm using in those grits. I'm currently using 3M ceramic in 120 (977) followed by Trizact (Gator) in A100. Why do you prefer the Zirc in those grits? Is it cost (I noticed they're pretty affordable at TruGrit)? Cutting capability and finish? Just personal preference?
 
bladsmth said:
Just to make sure - is the hand sanding you are doing with the paper backed with a block of hard wood or metal?

Normally a block of dense wood, or bar of steel and 120 grit SC paper will take down a bevel fairly quickly. Hand sanding with the paper folded up will not work nearly as well.
Wet sanding makes it even faster.

The heat build-up in grinding a hardened blade is immensely more than it feels. If the whole blade gets hot to hold, the edge may be several hundred degrees higher. Slower speed and fresh belts are the cure. Better post-HT grinding is the biggest attribute of a VS grinder.

I really like the Blue Zirconium belts in 120 grit for taking down the bevel post-HT. Followed by Blue Zirc in 220, then a 400 grit belt ( type doesn't matter much here), and a medium or fine Scotch Brite belt for the final satin finish.

Some folks like to use a A300 trizac belt followed by an A100 trizac ( roughly about 80-100 grit followed by 180-200 grit). These "gator" belts are really nice.
Click to expand...

I am using a metal bar to back my paper. I've been using 3m paper with Mobil 1 to sand, but I got it at Home Depot, so it's not intended for steel, and espcecially not for hardened stainless. My Rhynowet came in today so I'll try it this evening.
 
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