My knives dull right after sharpening!

[Matt S]

48 minutes ago, JeannieH said:

I'm using the stropping block from knives plus. I have watched the video on fixing Japanese skiving knives and Lisa sorrels video a while back. I'm skiving 3.5 ounce chrome tanned leather with a soft hand. When I strip, should there be any pressure applied to blade or just lightly pass it over the strop? 

I find best results with lots of pressure, but remembering to keep the angle consistent. Left right left right 12 times as soon as I notice any drag on the knife. Test it on the arm. If it doesn't pop hairs strop again. Repeat until it's hair popping sharp. Then start again as soon as the knife starts to drag.

[JeannieH]

Matt, would that motion of left to right work with the nobuyoshi knife? It only has one angled side...

[Hunhunt]

I have experienced exactly the same problem with a similar knife, the ones sold by Lisa Sorrel. I use a Tormek sharpener and bring the edge to razor sharpness using the stone wheel followed by a stropping wheel. The edge is mirror polished. The knife I use is sharpened on both sides. The knife cuts extremely well but quickly dulls with the chrome tanned leather I use in shoe-making. I have experienced the same thing with the Super Skiver with injector razor insert and with an Osborne french edger/skiver. I make frequent trips to the Tormek stropping wheel to touch up the edge. I have tried varying the angle of the edge but have found little difference. Seems to be the nature of chrome tanned leather and metal edge tools.

[Matt S]

On 11/18/2017 at 3:46 PM, JeannieH said:

Matt, would that motion of left to right work with the nobuyoshi knife? It only has one angled side...

I would do a dozen on the bevel, then one or two with the back of the blade dead flat against the strop to get rid of the burr. Repeat a few times then test as above.

[Grumpymann]

Just a quick question. Are you cutting on a thick Mat? Is there a slash in the mat under your leather? If so I may have the answer to your dilemma..... 

[JeannieH]

2 hours ago, Grumpymann said:

Just a quick question. Are you cutting on a thick Mat? Is there a slash in the mat under your leather? If so I may have the answer to your dilemma..... 

No I'm using a cutting board on top of a granite slab. I just keep stropping as it fills. I guess this chrome tan I'm using is gonna dull the knife. 

[Grumpymann]

Are you digging in the board a lot. I THOUGHT I was having the same problem. But I moved from dull disposable bladed cutter to a sharp round knife. At first I thought I was doing something wrong. I would hone the blade make a few cuts and suddenly I was bogged down and had to hone it again. Or so I thought I was used to a dull blade and I was applying a lot of downward force and the blade was gouging into my mat material.  I solved it by training myself to use a sharp knife. I still dig in every once in a while but at least I know how to fix it. Pull out the blade and cut again.

[jayker2002]

On 11/16/2017 at 0:46 AM, YinTx said:

And a tutorial on sharpening this type of knife here:

 

+1 vote for this video for sharpening the knife. Do exactly the same way , first is 700 grit, then 1000 and polish the last step with 6000 grit stone). After that is strop. My knives working perfectly now. 

 

On 11/15/2017 at 10:06 AM, JeannieH said:

 

 

 

I love the strop you have. How can you apply the compound smooth like that? Hope you can give me the idea. 

Thanks 

[SheltathaLore]

30 minutes ago, jayker2002 said:

+1 vote for this video for sharpening the knife. Do exactly the same way , first is 700 grit, then 1000 and polish the last step with 6000 grit stone). After that is strop. My knives working perfectly now. 

 

I love the strop you have. How can you apply the compound smooth like that? Hope you can give me the idea. 

Thanks 

It's so smooth that I suspect it came pre-loaded.  IF you're loading it yourself, though, mineral oil does wonders - I think burrfection has a youtube video on loading up a strop.

[Matt S]

On 11/29/2017 at 7:52 PM, JeannieH said:

No I'm using a cutting board on top of a granite slab. I just keep stropping as it fills. I guess this chrome tan I'm using is gonna dull the knife. 

Chrome tannages seem to dull knives faster. I tend to get about 10-12" of skiving until I need to strop when using chrome, and nearly double that on veg.

[JeannieH]

On 1/18/2018 at 5:49 PM, jayker2002 said:

+1 vote for this video for sharpening the knife. Do exactly the same way , first is 700 grit, then 1000 and polish the last step with 6000 grit stone). After that is strop. My knives working perfectly now. 

 

I love the strop you have. How can you apply the compound smooth like that? Hope you can give me the idea. 

Thanks 

Hi. The strop came like that. I bought it from knives plus.

[KittenThrasher]

Not everyone realizes how easy it is to lose the temper in a blade, meaning reduce it's hardness and ability to hold an edge, I have made many knives and part of the process is called tempering which is reducing the level of hardness in a freshly heat treated blade, tempering can be done in a domestic oven! (and I do).

When first hardened the blade is so hard it is very brittle, leaving it in a hot oven for an hour reduces the hardness a great deal. I'm mentioning this so you can see that using anything at all which heats the blade can be quite damaging. particularly because the thin cutting edge will heat a LOT faster than the bit you're holding which may not even warm up noticeably or at all.

If you were to put a blade against a grinder to sharpen it, any heat discoloration at all means almost inevitably the metal has been softened quite a lot. the most noticeable coloring is a sort of 'bluing' but there is a level below that which is a sort of straw/tan color, if you even get this the blade is damaged. 

It's quite possible to overheat a blade even on 'wet n dry' papers (if you're brutal with it).

Water stones such as the Tormek avoid this problem completely. Oil stones, or actually anything wet, also avoids the problem as the liquid simply dissipates the heat.

I know chrome tan leather is harder on an edge than veg tan but other than that there are too many variables as to why any particular blade don't work so good. 

If it's any consolation I've tried them all and my favorite skiver is now an old piece of mystery steel which cost nothing, I only started making knives so I could get one I  liked, after a thousand hours I decided I liked the crappy old piece of mystery steel best. 

What a waste of life that was!! although it was fun.

here are a couple I've made along with the piece of mystery steel I use. I really like the ones I made, I just don't like using them for what I made them for.

You might notice on the  mystery steel that the top corner is missing, that's deliberate as the point has no value in skiving, (anyway I chipped it.) also the bottom corner is rounded and not so sharp so it doesn't damage my marble slab (piece of kitchen counter top found in a skip - or dumpster I think you'd call it.). also although it is a 'single bevel' meaning it's flat on the bottom, it isn't totally flat on the bottom as I've put a very slight bevel to reduce the included angle a little, the top side bevel which you can see has also got a bit rounded, that's probably against what's normally regarded as 'correct' but it is a wicked skiver and it's probably the only one I'll ever need.

 

 

[KittenThrasher]

ps. it's also cranked or bent in the middle so it's easier to lay on the leather at exactly the angle I want,