DMT Duofold worn out prematurely

[Bill1170]

Hi Guys,

I just came back from a summer road trip and faced a sharpening conundrum. When I take a car trip, I often sharpen the kitchen knives at the homes I visit. Because sharp knives are a dark art known only to a few, the blades I encounter are often badly abused, requiring significant metal removal to reestablish an edge. For this I take a set of DMT Duofolds, which have different grits on opposite sides, along with a 204 Sharpmaker. The Duofold with the x-coarse/coarse grits gets the main use. I thought I was being careful not to press too hard, letting the tool do the work, but the x-coarse side has worn itself smooth after reprofiling about 15 kitchen knives. Is this to be expected?

I was surprised because I own a coarse DMT 8" by 3" plate that I have used for years and it still cuts well after hundreds of sharpening jobs, including reprofiling chipped chisels. I also own a double sided DMT benchstone that is the kind with holes on a plastic billet, and this seems to have worn much faster than the continuous plate on the thick steel backing has. Are the heavy diamond plates that superior to the ones with holes over plastic, or is my technique with the Duofold somehow wrong? Typically I use the Duofold by swinging it along the blade freehand, much like how a stone on a jigged system is used. This seems to give a good result rapidly, and requires not a lot of force to remove the steel from the bevels.

This failure occurred before I had finished all the knives in the last house, so I bought a gray Coghlan's pocket stone at a local hardware store (only one in that town!) and glued it to a wooden paddle. This setup worked nicely to reprofile the remaining knives. I used it dry and when it glazed over I opened the surface back up by rinsing it under running water with a Scotch-Brite pad. The wet stone then worked a nice slurry on the hatchet I was improving, just like a water stone.

I love the lightweight, compact nature of the Duofolds, and am disappointed in the lack of durability. I want a rapid removal abrasive that is portable for the road, and am open to suggestions. My homemade paddle stone was inexpensive and pretty good. I wish I knew what the abrasive on it is. The website says it is "electric furnace abrasive grain." link:http://www.coghlanscampinggear.com/coknshst.html

I look forward to your suggestions.

Bill

 

[THG]

I think the same thing has happened to my coarse diafold sharpener for serrated blades.

And also, I think the same has happened to my XXC, XC, and F stones. They all still cut, but it's very obvious that some sections of the sharpeners are "sharper" than others. I can even "see" the spots that are dull in the reflection of light.

For this reason, I'm a little bit less fond of diamond sharpeners. For my coarse work, I got some Norton Crystolon stones. I still like my fine stuff by DMT, though; as the hone gets worn, it seems to do better for polishing.

 

[Bill1170]

The Crystolon stones, are they silicon carbide? Do they cut fast? Do they work dry or require a lubricant? I seem to recall Ankerson recommending Crystolon stones at some time in the past.

 

[Jason B.]

I have noticed the same but think it has more to due with the use of too much pressure. Also for whatever reason the XC DMT stone seems more prone to loosing diamonds with the misuse of pressure more so than the others. You are also doing a lot of work with a small stone.

I'd recommend a XXC plate, fine Norton Sic stone, leather strop with fine Sic slurry applied. Bring along a UF SM rod and you would be set. You could also skip the XXC plate and just get the combo Norton Sic, strop, ceramic and have a cheap but very capable sharpening setup.

 

[Bill1170]

I have noticed the same but think it has more to due with the use of too much pressure. Also for whatever reason the XC DMT stone seems more prone to loosing diamonds with the misuse of pressure more so than the others. You are also doing a lot of work with a small stone.

I'd recommend a XXC plate, fine Norton Sic stone, leather strop with fine Sic slurry applied. Bring along a UF SM rod and you would be set. You could also skip the XXC plate and just get the combo Norton Sic, strop, ceramic and have a cheap but very capable sharpening setup.

I am considering the SiC 8" stone for a cheap material remover, may get the XXC plate later on. I read online that the Norton stones are pre-oiled, but I'd prefer to use them dry or with water on the road, for less of a mess in others' homes. Do you think that'll work okay? Also, are you suggesting using the slurry from the fine SiC stone to charge the strop, or to purchase a SiC compound for this purpose? I have found that the UF rods are overkill for the knives I sharpen for kitchen use. People are thrilled when I get the bevels to meet, overjoyed after the medium Sharpmaker rods, and a bit scared after the fine rods when the blade shaves effortlessly. I could stop after the medium rods and nobody would complain.

 

[Jason B.]

In that case the combo Norton and a strop would be more than enough to put a smile on their face.

Yes, some slurry from the fine Sic stone on the strop does wonders.

Water runs through these stones fast, I have tried soapy water and it works but its water everywhere. Yes they come preoiled but not much, you could easily get it out if you wanted I used soapy water from day one though. Windex and simple green watered down is said to work well also.

You can use them dry but they will load quickly, easily cleaned though with scotch brite. Using them dry also yields the better edge but using them wet makes them cut faster.

 

[Bill1170]

Thanks, Knifenut. Cutting faster is what I'm after, refining an edge is a lot easier than establishing it in the first place. It is good to have multiple approaches in one's arsenal. Improvisation is king when on the road.

Last summer I was in Colorado and our friends there had a four-sided diamond hone that had four different grits on the sides of a plastic block. Each face was about 4" by 2" wide, thin steel with diamond shaped holes, 200 through 600 grit diamonds were the claimed grits. The thing cost under $10 at Harbor Freight, and it did a fine job on their kitchen knives. For the price, it was a great tool. Maybe they still have them?

 

[Jason B.]

They might, I have the older set of 3 individual plates. They have been mainly used for lapping plates but I have sharpened with them a few times. They work but nowhere near a DMT or ezlap stone. You will also find better results from the Norton stone.

The coarse side of the Sic stone will be a near match for cutting power to the XXC plate, setting bevels will be easy

 

[sykes3170]

The Crystolon stones, are they silicon carbide? Do they cut fast? Do they work dry or require a lubricant? I seem to recall Ankerson recommending Crystolon stones at some time in the past.

I bought some Norton silicone carbide crystolon stones off of ebay for pretty cheap. I didn't like the oil so I boiled them in a pan with grate type spacer (something the wife had in the cupboard with the pans) in the bottom to keep them off the bottom. Worked great. It really cleaned them out and removed all the oil. I also did this with all the other old stones I had. I then grabbed an old floor tile and used the back side to true them up. I guess you can use a sidewalk also but it was about ten degrees out so the tile looked better.

 

[THG]

The Crystolon stones, are they silicon carbide? Do they cut fast? Do they work dry or require a lubricant? I seem to recall Ankerson recommending Crystolon stones at some time in the past.

Yes, they are SiC. I use mine dry, but it does load up quickly. I just use water to rinse it off.

I bought some Norton silicone carbide crystolon stones off of ebay for pretty cheap. I didn't like the oil so I boiled them in a pan with grate type spacer (something the wife had in the cupboard with the pans) in the bottom to keep them off the bottom. Worked great. It really cleaned them out and removed all the oil. I also did this with all the other old stones I had. I then grabbed an old floor tile and used the back side to true them up. I guess you can use a sidewalk also but it was about ten degrees out so the tile looked better.

What do you mean by "grate type spacer?" I'd like to get all of the oil out of mine, if possible.

 

[THG]

The Crystolon stones, are they silicon carbide? Do they cut fast? Do they work dry or require a lubricant? I seem to recall Ankerson recommending Crystolon stones at some time in the past.

Yes, they are SiC. I use mine dry, but it does load up quickly. I just use water to rinse it off.

I bought some Norton silicone carbide crystolon stones off of ebay for pretty cheap. I didn't like the oil so I boiled them in a pan with grate type spacer (something the wife had in the cupboard with the pans) in the bottom to keep them off the bottom. Worked great. It really cleaned them out and removed all the oil. I also did this with all the other old stones I had. I then grabbed an old floor tile and used the back side to true them up. I guess you can use a sidewalk also but it was about ten degrees out so the tile looked better.

You can just boil the stones to get oil out of them?

 

[sykes3170]

Yes, they are SiC. I use mine dry, but it does load up quickly. I just use water to rinse it off.



What do you mean by "grate type spacer?" I'd like to get all of the oil out of mine, if possible.

Sorry, I guess the proper term is a round cooling grate. It's about the diameter of the pan. It sits about 3/4" off the bottom of the pan. Yes you can just boil the oil out of the stones. I think I put a few drops of dishsoap in the pan with the water.