Belt sander vs belt grinder and other questions

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postoak

Joined
Dec 23, 2011
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I'm thinking about going the power route and thought I'd get something better than the Worksharp. I've looked at a bunch of threads here and am still confused.

Is there a difference between a belt grinder and a belt sander and if so, what?

Does a belt sander convex the edge?

I saw one device that was moving the belt around a wheel -- is that a belt grinder? It seems to me having a wheel behind the belt would allow you to NOT convex an edge.

Lastly, I see people talking about using a belt first and then moving to the Sharpmaker (which seems like something I'd like to do) but can't see how you could 1) match the angle of the Sharpmaker, and 2) overcome the convexing of the edge.

Thanks in advance for enlightening me.
 
postoak said:
I'm thinking about going the power route and thought I'd get something better than the Worksharp. I've looked at a bunch of threads here and am still confused.

The Ken Onion WorkSharp, especially with the Blade Grinder Attachment, I think is an excellent device. One thing that gets overlooked is that it's variable speed, so you have excellent control.

Is there a difference between a belt grinder and a belt sander and if so, what?

i don't think so... not sure though.

Does a belt sander convex the edge?

Typically, yes

I saw one device that was moving the belt around a wheel -- is that a belt grinder? It seems to me having a wheel behind the belt would allow you to NOT convex an edge.

If you sharpen on a wheel, you can actually make a concave or hollow ground, although if you do it freehand, it'll usually come out convex anyways.

Lastly, I see people talking about using a belt first and then moving to the Sharpmaker (which seems like something I'd like to do) but can't see how you could 1) match the angle of the Sharpmaker, and 2) overcome the convexing of the edge.

If you put a lower angle on with the belt, you can then use the Sharpmaker, because the Sharpmaker is just touching up the very edge.

Thanks in advance for enlightening me.
Click to expand...

Hope this helps.
 
Yeah, after doing some more reading, I'm beginning to think a belt grinder is just more powerful/has a wider belt generally.

I hear lots of complaints the Ken Onion WS (and praise too), and it seems most of the advanced users seem to use it freehand, so why not just go with something like the Kalamazoo?
 
I think most of the complaints with the WorkSharp are using the pull thru attachment, not paying attention, and rounding the tip. The BGA I mentioned doesn't do this,,, it's basically freehand. (You can always remove the guide and use the base machine freehand too).

Nothing wrong with the Kalamazoo... depending on what you want to do. Viel is another one to look at. Size and variable speed are two things to consider... you'll obviously need more room for the bigger machines, but of course can do more too. Plus I like the control variable speed provides... on a bigger machine it can be more expensive to make a variable speed setup. Again some of this just depends on what you want, where you're going to setup, cost... etc.
 
postoak said:
... Ken Onion WS ... most of the advanced users seem to use it freehand, so why not just go with something like the Kalamazoo?
Click to expand...

I use the WSKO freehand, with the Blade Grinding Attachment. The biggest advantage I see is that the WSKO allows you to set a variable angle between the belt and horizontal. This allows you to hold the blade horizontal, regardless of the angle of the belt. This makes it very easy to freehand while keeping a constant angle. I believe most folks can judge if a surface is parallel to the floor -- but how easy would it be for you to distinguish a surface at 15 degrees from horizontal vs. a surface at 20 degrees from horizontal?
 
Cyrano - but with the Ken Onion you are also convexing the blade? I don't understand why they would have degree markers if it is convexing. Is it just that they all CAN convex, but if you don't move the angle of the blade to the belt you are not convexing?
 
Also, I just looked at the Viel and it comes with a "platen" that helps with the V grind, which confirms my thinking that having something behind the belt, whether platen or wheel will make getting an angle easier.
 
@postoak:

Yes, the WSKO creates a convexed edge -- but the overall geometry of that convex shape can vary.

My belief (which I cannot yet defend by measurements or inspection) is that changing the angle of the belt affects the final angle of the edge -- i.e., the angle formed by the portion of the convex geometry which forms the actual cutting surface.

I also believe (again, without data) that the degree to which the edge is convex may also be affected by the amount of pressure applied to the blade against the belt. Pressing the blade harder against the belt seems like it would deform the belt more, and form a more convex edge, than would pressing the blade lightly against the belt.
 
ok, there is a difference between a belt sander and grinder, sanders aren't made really for hardened steel a belt grinder is, it dosent have places for the metal swarf to settle in and cause wear.
next if you use a belt grinder with a glass platen it wont convex or concave as long as you guide it and stay on the platen
no a belt grinder isn't always belt driven. some are some aren't a belt grinder is a belt sander made for metal
now go to lee valley tools and look up the viel s-5 and see the difference compared to harbor freight or sears. viel isn't very high priced if you want a sharperner then go to bader, kmg and see what the pros use
 
Some thoughts:

All sharpening produces some kind of varied surface on the edge bevel. If this is rounded in some way (outwards) we call it convex. A lot of hand sharpened edges will have some kind of convex to them. The degree of this convexing varies. I think, in most cases, convex means NOTHING. Sure, an edge sharpened on a WSKO is convex. But what's the degree of convex? How rounded is it? I think it's immaterial unless your edge bevels are REALLY wide.

A platen reduces the amount of convex due to belt "wrap". Your hand's variance is still there, so there's still some degree of convex going on. Again, IMHO, this doesn't matter a BIT.

Why buy a WSKO? Portability. Low power. Variable speed. Variable speed is the biggie. Variable speed setups for 1x42 grinders are WAY more expensive than the WSKO. A 1x42 can be portable... to some degree. But it's nothing like throwing a 3 pound WSKO and some belts in a bag. It's so low power that you could run it from a small inverter plugged into a car's cigarette lighter. It's also low power in terms of grinding. This is good and bad. It's good because it takes longer to make a bad mistake on a blade. It's bad because it takes longer to sharpen.

I spent about 45 minutes sharpening 3 kitchen knives for my aunt over Thanksgiving. I used the WSKO, which I brought with me because my relatives always have super dull kitchen knives. Could I have done that with a 1x42? Sure, but it wouldn't be nearly as easy as my small bag with the WSKO and all my belts and accessories.

It's all about the right tool for your intended use.

Brian.
 
I love the Ken onion work sharp and the blade grinding attachment. While technically a convex edge doesn't have an angle per say, the variable angle setting simply adjusts the angle the knife approaches the belt. Giving the user the ability to make a thin or thick convex depending on what your sharpening.., obviously you don't want your knife convexed as thick as your ax.

Also as mentioned pressure on the belt will also effect the amount on convexing, more pressure greater rounding.

The ko with blade grinder is honestly the best set up you can get for portability and ease of use.
 
All slack belt sharpening produces a convex edge. Put a platen behind the belt and the edge becomes mostly flat. If you control the angle while your sharpening on a platen, the edge becomes extremely flat. Add a misting system and you can produce extremely fine edges consistently. If you have the money, get yourself a 2x72 belt machine. The reasons are: the belts last much longer, there is a wider range of belts available than with the less common machines. Lastly, if for some reason you decide to make knives, you have a machine to do it with. Below is our wet machine that we sharpen blades on.
20150707_011729.jpg



[video]https://youtu.be/lCBUa4CAE4c[/video]
 
That appears to be your average Harbor Freight high speed belt grinder.
The regular price is nowhere near $221. You really have to look carefully
and listen to the folks here who will give you good guidance.

It will be difficult to use that grinder for sharpening as it goes so darn fast
you will have trouble keeping the edges from burning. Work slowly, use very little pressure
and dunk the blade in water often, like after each pass.
 
Bill Hoffman said:
That appears to be your average Harbor Freight high speed belt grinder.
The regular price is nowhere near $221. You really have to look carefully
and listen to the folks here who will give you good guidance.

It will be difficult to use that grinder for sharpening as it goes so darn fast
you will have trouble keeping the edges from burning. Work slowly, use very little pressure
and dunk the blade in water often, like after each pass.
Click to expand...
I think that depends heavily on the grit used and the quality of the belt.

My 1x42 Kalamazoo is a handy tool I used to thin out a few blades including a gyuto, which is already thin to start out with. So long as you don't keep it on one spot excessively, heat doesn't become a problem. Never had an issue with regular sharpening using my Trizact belts.
 
bgentry said:
Some thoughts:

All sharpening produces some kind of varied surface on the edge bevel. If this is rounded in some way (outwards) we call it convex. A lot of hand sharpened edges will have some kind of convex to them. The degree of this convexing varies. I think, in most cases, convex means NOTHING. Sure, an edge sharpened on a WSKO is convex. But what's the degree of convex? How rounded is it? I think it's immaterial unless your edge bevels are REALLY wide.

A platen reduces the amount of convex due to belt "wrap". Your hand's variance is still there, so there's still some degree of convex going on. Again, IMHO, this doesn't matter a BIT.

Why buy a WSKO? Portability. Low power. Variable speed. Variable speed is the biggie. Variable speed setups for 1x42 grinders are WAY more expensive than the WSKO. A 1x42 can be portable... to some degree. But it's nothing like throwing a 3 pound WSKO and some belts in a bag. It's so low power that you could run it from a small inverter plugged into a car's cigarette lighter. It's also low power in terms of grinding. This is good and bad. It's good because it takes longer to make a bad mistake on a blade. It's bad because it takes longer to sharpen.

I spent about 45 minutes sharpening 3 kitchen knives for my aunt over Thanksgiving. I used the WSKO, which I brought with me because my relatives always have super dull kitchen knives. Could I have done that with a 1x42? Sure, but it wouldn't be nearly as easy as my small bag with the WSKO and all my belts and accessories.

It's all about the right tool for your intended use.

Brian.
Click to expand...

I hope this isn't too much of a thread drift; if so, my apologies.

Brian, I'll be buying a Ken Onion with the blade grinder attachment. Does it come with instructions on what speed to use under what circumstances?
 
Rey HRH said:
I hope this isn't too much of a thread drift; if so, my apologies.

Brian, I'll be buying a Ken Onion with the blade grinder attachment. Does it come with instructions on what speed to use under what circumstances?
Click to expand...

As owner of same, I'd caution you: selection of belts this size are meager and they are expensive IMO. Once they are somewhat worn they really convex an edge.
 
Nomo4me said:
As owner of same, I'd caution you: selection of belts this size are meager and they are expensive IMO. Once they are somewhat worn they really convex an edge.
Click to expand...

There are several places you can get belts... search for: Klingspor, Econoway, MicroMesh, SuperGrit, TruGrit (some you have to call or email, but have no problem making 1x18 belts).

The belts that come with the BGA last a long time though. You might look into getting a belt cleaning stick (it's like a giant rubber eraser)... it still amazes me how well it works... and I avoided getting one for a long time thinking I didn't need it.
 
Rey HRH said:
Brian, I'll be buying a Ken Onion with the blade grinder attachment. Does it come with instructions on what speed to use under what circumstances?
Click to expand...

I don't have the BGA, just the regular WSKO. It came with instructions on which belts to use for which kinds of knives and I think which speeds to use. I mostly just experimented on my own with speeds and belts. I started with literally the slowest speed and very quickly moved up to a middle speed. I think you could use fairly high speed for most blades as long as you didn't mind the noise, and were careful about how long you keep the blade in contact with the belt.

Brian.
 
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