Time to ask the experts.

[sfeile]

I have a nice little Ozuku that has been my main finisher for the last 2 years or so. A few months ago I received a new stone that is a little bit harder and finishes a little better, so I haven't used the Ozuku until last night.

There is a slight crack in the stone, and at the end of the crack on the side of the stone a little chip had come out, but it was in the chamfer and had never bothered anything.
Before I put the stone up, towards the end of my finishing and the slurry was about gone and just water, I would notice I could just slightly feel the crack in it through the blade. It never affected my edges, but I could feel a bit of resistance in my stroke when I hit a certain spot.
Never felt it much with slurry, only when I was getting to straight water.

Last night didn't go very well at all. I got about three laps into finishing a razor I was working on and it really didn't feel right. I checked the edge and found out I had just bread-knifed the dang thing. Got to looking at the stone and saw it had separated a little and where the chip was had raised just enough to catch and ruin my edge.

So I lapped the crap out of it and completely got rid of the chip, re-chamfered the edges and snapped a couple wet pics. You can see from them it sucks the water right out of the stone where the chip was. I did a few more laps on it, but the feedback from the crack towards the middle of the stone is much more pronounced now, so I didn't want to continue on it.

Is there anything that can be done besides more lapping? I'm afraid if I keep lapping, I could just be chasing the same problem deeper into the stone. It's not a large enough crack to get anything in to stabilize it either.... I am at a loss on this one.

 

[*stefan*]

I would remove material and put on radii, thinking to avoid having a wall the blade can hit into, better it goes into a larger radii.

It is a bit difficult to know if reading the picture correct, but as I read it, suggestion:
the red line: material removal, the arcs is radius.
This radius will be easiest to put on with a rounded little diamond file, smooth with sanding paper.

When later flattening you might need to reapply the radii but smaller ones.

 

[David]

Shawn I would let the stone dry for a day and fill that crack with super thin CA until it quits pulling in the glue. I did a picture tutorial on something similar here in the honing section if you want to search for it. I'm away from home now but I will look for it later if you haven't found it

 

[sfeile]

I would remove material and put on radii, thinking to avoid having a wall the blade can hit into, better it goes into a larger radii.

It is a bit difficult to know if reading the picture correct, but as I read it, suggestion:
the red line: material removal, the arcs is radius.
This radius will be easiest to put on with a rounded little diamond file, smooth with sanding paper.

When later flattening you might need to reapply the radii but smaller ones.

The area there is actually flat except for the chamfer on the edge itself. The radii is from that particular spot sucking the water off of the surface before I could even snap the photo.
Let me try to get a couple better photos up.

 

[sfeile]

Here are some better photos.

 

[sfeile]

Shawn I would let the stone dry for a day and fill that crack with super thin CA until it quits pulling in the glue. I did a picture tutorial on something similar here in the honing section if you want to search for it. I'm away from home now but I will look for it later if you haven't found it

So basically just let it suck in whatever it will take, let it dry, and lap it again?

 

[*stefan*]

Sorry, I misread your post, didn´t get that the crack was still there after lapping, despite you wrote so. I have no experience with cracks, except that I have one myself in a small cheap stone.

 

[Ice-Man]

Yes but make sure it is bone dry, I don't know if using a dremel with a small round bit in and just take it down a little but keep the dust and mix with 2 part and refill.
Could that be done but the CA would help stop it or slow it down.

 

[David]

So basically just let it suck in whatever it will take, let it dry, and lap it again?

Yes. But it needs to be super thin CA, not just super glue. Here's what I'm using at the moment but any brand will work. I use painters tape to tape around the edges just to keep from making a mess. Once you start just keep dropping it in steady until it stops. Let it dry and lap again and hopefully you will be good to go. I think I'd roll the edge on the cracked side just a bit more to be safe.

 

[kelbro]

The thin CA works well. Had to do the same thing to a Yellow Green Thuringian and it completely stabilized it.

 

[David]

Here's my old tutorial. I'm using a different CA here but have since found the thinner the better

 

[eKretz]

Whatever you do, don't try to mix stone powder with CA. Two-part epoxy is okay for stone powder mixing but not CA. Stone powder added to CA will "kick" it almost instantly.

 

[David]

Whatever you do, don't try to mix stone powder with CA. Two-part epoxy is okay for stone powder mixing but not CA. Stone powder added to CA will "kick" it almost instantly.

Yes it will. I never bother doing that on small fissures like this. Doesn't need it IMO.

 

[eKretz]

Same here.

 

[sfeile]

Thanks guys! I will see if I have any CA left and give it a go.