Lanksy 70 grit stone dull after a few days of usage?

[y53p]

Bought a Lansky deluxe set a week ago, one with the dioxi something stones and the ceramic 1000 grit, reprofiled my Buck 119 to 25 degrees each side and managed to get a very sharp uniform edge on it, it took me about an hour in total give or take. Yesterday I was reprofiling a Gerber strongarm from 25 down to 17 and it took an insane amount of time, about 5 hours to get the grind down to the apex at the new angle on one side and then work a little bit of the other side, which I had to finish the next day (had to give up on the knife's tip for now since it literally won't sharpen after a certain point and still has the old chunky and dull 25 degree factory angle). This is quite strange considering that both knives have 420hc which has never been a problem to sharpen (and it wasn't for the 119, they probably do a better heat treatment than gerber ig). I saw these stones tend do apparently clog up with steel, so I tried rubbing some oil in but had no luck. The other stones are ok, besides from the 600 which literally gets eaten away by the blade and has already shrunk significantly.
Is the stone done after just reprofiling 2 knives or is there some other fix? Anybody had a similar experience with Lansky?

 

[Obsessed with Edges]

(Making an assumption here...)

IF the stone was used dry(?), that would clog it up very fast. It's a very small stone at 1/2" x 4", so it doesn't take long to clog it up. So far as I know, Lansky still includes a bottle of oil with those kits, and it's good to use it while sharpening with these stones. A dry stone needs a lot of scrubbing, at least, to clean up the embedded swarf. It'll be more difficult to clean it up with oil after the fact, because the stainless swarf clings very tenaciously to the dry grit in the stone. If the stone is oiled prior to sharpening, and kept lubricated with oil during, that is what prevents the swarf from clinging so stubbornly to the grit. Stainless steels like 420HC are prone to clogging hones, if much heavy grinding is done, like reprofiling.

If the 600 red/purple ceramic is being worn out on these blades, I'd replace it. That's not normal for that stone.

I used a Lansky Deluxe kit for several years, BTW. So, unless they've changed significantly in recent years, I feel like I'm pretty familiar with them.

 

[sharp_edge]

I used one for several years as well. They should not wear out so quickly, though mine is definitely no longer as effective as before. In fact they have become pretty much useless for steels like K390. I later added the purple, orange, and gold(?) diamond ones and coupled them with the yellow ceramic and blue sapphire, which have been what I mainly use for sharpening pocket knives.

 

[y53p]

(Making an assumption here...)

IF the stone was used dry(?), that would clog it up very fast. It's a very small stone at 1/2" x 4", so it doesn't take long to clog it up. So far as I know, Lansky still includes a bottle of oil with those kits, and it's good to use it while sharpening with these stones. A dry stone needs a lot of scrubbing, at least, to clean up the embedded swarf. It'll be more difficult to clean it up with oil after the fact, because the stainless swarf clings very tenaciously to the dry grit in the stone. If the stone is oiled prior to sharpening, and kept lubricated with oil during, that is what prevents the swarf from clinging so stubbornly to the grit. Stainless steels like 420HC are prone to clogging hones, if much heavy grinding is done, like reprofiling.

If the 600 red/purple ceramic is being worn out on these blades, I'd replace it. That's not normal for that stone.

I used a Lansky Deluxe kit for several years, BTW. So, unless they've changed significantly in recent years, I feel like I'm pretty familiar with them.

yes, I did not lube the stones beforehand, just when i saw they were struggling to work, as I had seen that was what you were supposed to do but I guess that information was wrong then. Guess I'll lube them beforehand from now on, do you think im gonna be able to get that debris out using the oil eventually or should I just buy a new stone?(it's a lot of debris, the 70 literally feels as smooth to the touch as the 1000)

 

[Obsessed with Edges]

yes, I did not lube the stones beforehand, just when i saw they were struggling to work, as I had seen that was what you were supposed to do but I guess that information was wrong then. Guess I'll lube them beforehand from now on, do you think im gonna be able to get that debris out using the oil eventually or should I just buy a new stone?(it's a lot of debris, the 70 literally feels as smooth to the touch as the 1000)

You could also scrub them with some Bar Keepers Friend powder, mixed to a paste with water. For severely clogged stones, that usually works better. BKF utilizes oxalic acid to dissolve the iron swarf, so it doesn't require so much scrubbing to get the job done. Apply the BKF paste mixture to the stone, let it sit for a bit (a minute or so) and then scrub the stone. Rinse it all off under running water.

It's also possible the stones are glazed, meaning the surface grit has essentially been polished or burnished smooth. But with the steels you've tried, that shouldn't happen. It's the sort of thing that usually happens when attempting to grind steels with a lot of hard carbide content - especially high-vanadium steels. 420HC and similar steels don't have any vanadium to form those very hard carbides. The standard coarse stones I used in my Lansky kit years ago did glaze, as well as getting dished. But that was after attempting to reprofile a thick-edged S30V blade.

With Lansky stones, they're inexpensive enough that doing too much work to restore them sometimes may be more hassle than it's worth. Sometimes just replacing them is a more pragmatic option. They can all be ordered individually online.

 

[l1ranger]

I agree with David and will note for heavy profiling, you'd be better off with a diamond stone, even on 420HC.
I only use water as lubricant for the diamond hones and light pressure, let the diamonds to the work. too much pressure will ruin the stone.

also - a toothbrush works great with the bar keepers friend paste to scrub out the clogged stone.