Question how to use belt sander for sharpening.

A

alan0354

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Oct 21, 2022
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I just bought my first belt sander and I don't exactly know how to use it. This is the picture.



My question is when I push the edge of the knife towards the sander belt, how hard I push?

As seen in the picture, there is a bottom plate right underneath the sander belt. There's a littl GAP between the belt and the bottom plate. Question is when I push the knife over ( horizontally ), do I barely let the edge touch the belt without pushing the belt all the way to the bottom plate? Or do I push it hard enough so the belt actually touch and glide on the bottom plate?

Thanks

Alan
 
I could be wrong but it looks like you can adjust this bottom plate to touch the belt.... two screws beneath the plate.

Anyway, start slowly.... don't use too much force and see how it goes. Use a cheap knife for a test.
 
TheOne45 said:
I could be wrong but it looks like you can adjust this bottom plate to touch the belt.... two screws beneath the plate.

Anyway, start slowly.... don't use too much force and see how it goes. Use a cheap knife for a test.
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Thanks, that's my first thoughts to adjust the bottom plate to be closer to the belt. The sander absolutely do not come with any instruction. This is a low price sander used by first time people. They should give a little more instructions.

I have plenty of of junk knives to try, just want to start out with the closest way.

Thanks
 
Put sharpie on your blade, use a very light touch, check your work often, don’t go past center belt with the tip,don’t linger on the belt.

Edit: I didn’t answer your direct question.
 
I have been experimenting free hand, using a guide and all. So far, result is nothing as sharp as I use my diamond plate to sharpen my knives. I'll keep practicing, but I am disappointed at the result.
 
What is the difference of running the belt in one direction or the other?
 
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Go easy ,don't use too much pressure and don't linger in any one spot for very long. Like others have said adjust the flat part under the belt "plate" up so it touches the belt evenly. Running the belt towards the edge might be more likely to catch and cut the belt , so away is preferable. Marking the edge with a marker is a good suggestion also , it will show you more easily what it happening after each pass. Do you have a few different grits of belt? You shouldn't have to use the course ones very often unless there is edge damage or you are changing the angle you want the edge to be. I use a 1 inch by 30 inch belt sander to reprofile new knives and to change edge angles mostly and then either a fine stone or strop or even my Spyderco sharpmaker to finish the edge.
 
thebrain said:
Go easy ,don't use too much pressure and don't linger in any one spot for very long. Like others have said adjust the flat part under the belt "plate" up so it touches the belt evenly. Running the belt towards the edge might be more likely to catch and cut the belt , so away is preferable. Marking the edge with a marker is a good suggestion also , it will show you more easily what it happening after each pass. Do you have a few different grits of belt? You shouldn't have to use the course ones very often unless there is edge damage or you are changing the angle you want the edge to be. I use a 1 inch by 30 inch belt sander to reprofile new knives and to change edge angles mostly and then either a fine stone or strop or even my Spyderco sharpmaker to finish the edge.
Click to expand...
Thanks so much, I am using some junk knives to experiment. OK, so I should not run the belt towards the edge, back to away from the edge( from spine to blade edge).

Yes, I use 240 grid to experiment changing the angle of the edge. Yes I have 240, 400, 600, 1000, 2000 and 5000. So far I experimented 240 for changing the angle, then 1000 to sharpen the edge. I find using honing rod ( don't know the exact name, the ones that is for straightening the micro edge, not taking any metal out) really help.

what is the optimal gap between the belt and the bottom plate?

thanks
 
The platen should be right up tight to the belt unless you want a more convex edge, it will eventually start to wear because the backside of the belts are kind of abrasive, it should take a while. A stropping belt will give you better finishing results than the steeling rod you have if you can find one that fits your sander. It is very good that you have some cheap knives to practice on.
 
thebrain said:
The platen should be right up tight to the belt unless you want a more convex edge, it will eventually start to wear because the backside of the belts are kind of abrasive, it should take a while. A stropping belt will give you better finishing results than the steeling rod you have if you can find one that fits your sander. It is very good that you have some cheap knives to practice on.
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Thanks so much, I adjust it closer already, maybe I should get it a little closer again. I really like the flat edge. I am taking my time, not rushing and experiment. I have enough junk knives.

One question, how fast I run the belt? I am putting in slowest speed, but I have to go through a lot of passes, not like in the video that they do one or two pass and start changing to finer belts. I really have to go over and over many times to form the edge.

I push very light to avoid heat building, Just want to know how slow should I go. The edge getting very slightly warm, nothing hot at all. Should I speed it up? What is the guide line on how hot can the edge goes before it will ruin the forging?

Thanks
 
Be careful if you go to smaller grits ... in my experience, they heat up faster than coarser grits. Be extra careful near the tip because there's nowhere for the heat to go, so it builds up. If the steel turns blue, that's a pretty good indicator that you got it too hot. I dip my blades in ice water when grinding on the belt sander. At the very apex or tip, you can overheat the steel in the blink of an eye.
 
Cementite said:
Be careful if you go to smaller grits ... in my experience, they heat up faster than coarser grits. Be extra careful near the tip because there's nowhere for the heat to go, so it builds up. If the steel turns blue, that's a pretty good indicator that you got it too hot. I dip my blades in ice water when grinding on the belt sander. At the very apex or tip, you can overheat the steel in the blink of an eye.
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Thanks

So far, the steel did not turn blue, I run it slow and push light. I'll get some cold water to dip the blade.

I don't know whether the belt can take water, it looks like paper backing, so I don't dare to wet anything.
 
You can also use cheap spraywax for cars on your grinding belts, this will help to keep your edges much cooler than grinding dry.
I also dip the blade in a bucket of cold water after each pass, plus i test each edge afterwards on paper and wood.
Works just fine.

Regrinding/sharpening worn Victorinox carving knives

A set of worn Victorinox carving knives from a local butcher. Edge angles on the really narrow ones were in the 50 to 60 degrees inclusive range, and the request was to see if i could at least make them useful again. Weapon of choice was my cheap variable speed Parkside belt grinder (345-645...
www.bladeforums.com www.bladeforums.com
 
alan0354 said:
So far, the steel did not turn blue, I run it slow and push light.
Click to expand...

I would avoid any temperature higher than straw/yellow, and I suspect even that is pushing it for some steels:

9ZHDUvJ.png
 
Use the sander/grinder to make knives. Sell them, then buy some coarse stones or a cooling system for the grinder. Then use whichever to sharpen. I wouldn’t recommend a belt sander or grinder for sharpening unless it’s cooled, and even then, it’s potentially going to soften the blades.
 
Cementite said:
I would avoid any temperature higher than straw/yellow, and I suspect even that is pushing it for some steels:

9ZHDUvJ.png
Click to expand...
So far, the few I grind it like original color, not even 340deg color. At least I did something right!!! I just run very slow speed. I am going to look into spray wax, not just cooling, hopefully it will have less dust flying as it attract dust.

thanks
 
me2 said:
Use the sander/grinder to make knives. Sell them, then buy some coarse stones or a cooling system for the grinder. Then use whichever to sharpen. I wouldn’t recommend a belt sander or grinder for sharpening unless it’s cooled, and even then, it’s potentially going to soften the blades.
Click to expand...
I agree, I sharpen with diamond plate and stone to sharpen knives. I think with the coarse stone, it's even faster to form edge as I don't have to worry about heat problem. This is like new toy for me, was special sale, only $56 and came with all sort of belts to 5000 and grinding and polishing wheels.
 
Most knife makers and manufacturers use belt grinders to sharpen their knives so I will definitely have to say they are safe if used with care. Just do your best to keep moving the blade and dipping in water will help too. You can use more speed on coarse belts but bee warned they will eat steel quickly, slower on finer grits but watch for heat buildup. Usually the very apex will get a bit too hot but that very edge steel will be sharpened off in time anyway. I use every kind of sharpener there is, from set angle ceramic rods to blade clamping adjustable angle guides and belt grinders, they all have good and bad qualities. There are quite a few members here that will always jump in and say you should just use bench stones and learn to hand sharpen your knives, they are just stubborn and don't like to try new fun toys. Also they probably don't often buy large super steel knives with far too steep edge angles that need to be reprofiled because that isn't fun on a bench stone. Keep at it until you are proficient then decide what you like better.
 
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