Hollow grind and TBE questions

[Dominick Maone]

1. Is there a good way to hand sand the bevel of a hollow ground knife? Wondering specifically about switching directions as I switch grits. Or should I be focusing on refining the scratches with the belt sander? See first photo. I’m pretty happy with the finish, but it’s not perfect. I am a little more confident with hand sanding than with using the belt sander.

2. How important is perfectly consistent TBE across the blade? The kitchen knife in the last pic was not consistent, it was probably twice as thick closer to the handle than closer to the tip. Hard to see in pics, but the first inch or so is lower than the remainder of the knife after sharpening. The hollow ground knife is not perfectly consistent either, and I don’t want the same problem with the edge being a little wonky.

Thanks for any input.

 

[Richard338]

Hand sanding hollows can be tricky.
Someone was selling hard plastic backings in various radii, but as you say, you can't really switch directions. I used a pvc tube to sand a wide fuller on a sword.
For me, with a hollow grind it is usually easy to lock into the bevel on the grinder and get the best finish working up the grits there.
You might look at how people do the Loveless style chute knives as you often see a mirror finish on small radius hollows.

 

[Joshua Fisher]

I hollow grind most of my blades, I scribe lines to give myself a reference so my edge is a consistent thickness then with a worn 36 grit I grind to my scribe lines at about a 45 degree angle, from there I go to a 60 grit belt to grind my bevels to the height I want and make sure everything is smooth I like to do belt satin finishes so from 60 grit I either go up to a 180 trizact belt to refine my lines then to a maroon scotchbrite belt or I go from 60 to the scotchbrite belt. Your bevels should be consistent and smooth at a low grit like 60 or 80. If you have multiple facets and your trying to go up in grit you are going to get frustrated. Learn to get a smooth grind at a low grit and then refining it is much easier. One of the gentlemen that makes some very nice folders recently posted his belt progression before hand sanding, basically if you want a 600 grit hand sanded finish take it up to a clean and smooth 800 finish on the grinder then drop back to 600 with a radius backer to hand sand the hollow grind.

 

[Dominick Maone]

Hand sanding hollows can be tricky.
Someone was selling hard plastic backings in various radii, but as you say, you can't really switch directions. I used a pvc tube to sand a wide fuller on a sword.
For me, with a hollow grind it is usually easy to lock into the bevel on the grinder and get the best finish working up the grits there.
You might look at how people do the Loveless style chute knives as you often see a mirror finish on small radius hollows.

Thank you Richard for the input. I think it would be best to get some higher belt finish grits/surface conditioning belts and work on refining the lines through my grits. I will check out the Loveless chute Knives to see if I can find some kind of build video. I like the belt finished look a little better than hand sanded, but am not good enough on the grinder yet to get a perfectly consistent look across the blade (and then have to do the other side of the blade too). I might just make something to sand the bevels, and just spend one hour + per grit to make sure all the lines are that particular grit, instead of switching directions.

I hollow grind most of my blades, I scribe lines to give myself a reference so my edge is a consistent thickness then with a worn 36 grit I grind to my scribe lines at about a 45 degree angle, from there I go to a 60 grit belt to grind my bevels to the height I want and make sure everything is smooth I like to do belt satin finishes so from 60 grit I either go up to a 180 trizact belt to refine my lines then to a maroon scotchbrite belt or I go from 60 to the scotchbrite belt. Your bevels should be consistent and smooth at a low grit like 60 or 80. If you have multiple facets and your trying to go up in grit you are going to get frustrated. Learn to get a smooth grind at a low grit and then refining it is much easier. One of the gentlemen that makes some very nice folders recently posted his belt progression before hand sanding, basically if you want a 600 grit hand sanded finish take it up to a clean and smooth 800 finish on the grinder then drop back to 600 with a radius backer to hand sand the hollow grind.

Thanks Josh. I think I will have to get some conditioning belts and check those out. There is mostly one facet across the primary bevel, most of the lines go from cutting side to spine of the knife. But the main problem is that there is (and I have no idea about these measurement, just to give an idea) .005 thickness in some areas at the edge and maybe .015 in other areas. You can sort of see in the middle picture, closer to the handle is say .015, then as it starts to curve closer to the tip is say .005, then back to about .015 at the tip. That is what I am concerned about. The kitchen knife is not a full flat grind, I tried to blend the plunge lines so it looks full flat. While grinding, I was not paying close enough attention to the edge thickness, and close to the handle was probably .025 when I started to sharpen. And of course that is when I noticed it. I guess the lesson is I need to pay closer attention to all of the areas of the knife before beginning to finish it.