Big Nasty Edges

Re:" Belt Sander

I have a delta that I got at Lowes for under a hundred bucks. I use it to sharpen machetes and yard tools. I have used it to hog some metal off a few pocket knife and fixed blade edges, then I use the Spyderco 204 to get perfect alignment and finish.

It is not very skill intensive, but does require a light touch. An 80 grit AO belt will remove metal so fast you won't believe it.

As for cost, remember that belts in different grits get expensive.

Unless you are going to change the primary grind of a knife, just buy the belts, cut them and half and spray adhesive them to cardboard, then to some scrap wood. The results are great, and it is fast and easy.

It is a method that blademan13 rtold me about a while back, and Cliff has commented on it at length as well.

The slicing edges that you get with a 150 AO belt on kitchen knives is great too.
 
What gets me is how inexpensive such a setup is and that it will quickly enhance the cutting ability of most knives whereas I've spend over $300 on a knife and sharpening equipment to get a blade that's almost as sharp as a $.25 disposeable razor blade.

That's life.
 
When using the sander like Will did, do you hold the edge into the belt, or trailing from the belt?
 
Interesting. I always grind with the edge trailing, including sharpening, which is how Jerry Hossom taught me to do it. I use a 2x48" belt grinder, and do not use a platen behind the belt as I like a slightly convex edge grind. If I have any trace of burr remaining after sharpening this way, I strop to remove it.
 
Ok, I just got one of the leather honing belts recommended for this type of sharpening. I tested it on some kitchen knives tonight and it works like a charm. I used a 320 grit belt and then the leather with white buffing compound. I am afraid to try my AFCK, but it is in need of sharpening. Does anyone have a jig setup they recommend to take the guess work out of angles and minimize steel removal?
 
I believe that Sheffield has a angle guide that goes on the platen for exact angles. I think that if you experiment some you can do it yourself, it's very easy with some practice.
 
Thanks. I find that my hand ground angles are about 14 degrees, by the sharpmaker slots. 20 degrees cuts off the burr and hones great. I just haven't had the nerve to try it with a $100 knife.
 
Cliff Stamp said:
I am beginning to think that the erea of hones has past.
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I think it's just changing. Synthetic waterstones and zirconium oxide sanding belts are easier to come by and more homogenous than Arkansas stones and Washita stones, but they're still hones. Then there's Leonard Lee's idea of homemade wooden strops. They're not slipstones, but the same objective is accomplished.
 
Edge trailing is prone to burr formation and overheating, Lee describes this in detail in his book on sharpening.

You can't of course finish strop on leather, edge into, the blade would just cut the belt in half.

-Cliff
 
Cliff,
I have also found that belts that are "used up" sharpen very well. I sharpen all of my knives on a "used up" 120 grit 3m belt. Once I get a burr I buff on a hard felt wheel loaded with white compound. This produces a very sharp edge.

Tom
 
Cliff Stamp said:
Edge trailing is prone to burr formation and overheating, Lee describes this in detail in his book on sharpening.
Click to expand...

I'm still plodding through his book. Saw a section on how overheating is ruinous to edges (expand > contract > break), but haven't read a section on edge-trailing versus edge-leading yet.

Cliff Stamp said:
You can't of course finish strop on leather, edge into, the blade would just cut the belt in half.
Click to expand...

And yet you can with belts and with mylar sheets. Why is that? Mylar is almost as easy to cut as much thicker leather, yet it glides around very sharp knife edges. :confused:
 
thombrogan said:
overheating is ruinous to edges (expand > contract > break)
Click to expand...

Absolutely. If the temp gets above 400F degrees or so on some steels, it can have a destructive result, even to the point of negating the heat treat.

Next to my belt grinder, I place a water-filled container that is at least as deep as the blade length of the knife I'm working on. I keep the blade moving across the belt, so that it doesn't linger and build up heat from friction, and after each pass I place the blade in water and let it cool back to room temperature or cooler before the next pass. Also, I never wear gloves, so I can feel the temperature of the blade with my hand, although this is no guarantee, because steel dissipates heat as it spreads through the blade, and the very edge can build up a lot more heat than is felt higher near the spine.

I would think heat management is imperative whenever using a mechanical grinder on a finished, heat-treated blade--whether grinding with edge trailing or edge into belt.

Certainly pays to be careful--good point.


EDITED TO ADD: Depending on the type of belt, it's also important to dry the blade before renewed contact with the belt. Trizact belts, for example, deteriorate rapidly if they get wet.
 
I built a jig for sharpening out of some wood. Put simply, it didnt work. I can hold more consistent angles with my hands and how far away from my body I hold them. The jig sorta got in its own way. Also, I came close to shelling out more money to Benchmade to replace the ruined 806 blade. As it stands, I just rubbed some of the coating off and took a little too much off one side of the point. I did thin it down enought that finishing at 17 degrees with some sandpaper only took a few minutes. I do have some repairs to do on a chef's knife that I sorta reshaped and put a recurve in while testing the sharpening guide, but that should only take a couple of minutes.
 
Many milling machines have continous oil showers to cool it off. Can this system be adopted?
 
Anyone tried adding a rheostat to their belt sander to slow the fpm that the belt travels? This would be to manage friction heat when sharpening blades. I've a Sears 2"x42" benchtop belt sander, that probably moves about 3700 fpm - - heats metal up fast. I'd like to slow it down and was thinking of wiring in a rheostat - - but I don't want to burn up the motor. So..., anyone try this already? Got some inside info?
TT2Toes
 
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