Thread: Chinese 12k stone - Over 2.5 hours to lap ! ! !

Originally Posted by roughkype

Holy big cow, that looked like a lot of work.

For the bottom, is it possible to just park it on a belt sander to flatten it?

I just found out you can! I thought why not give it a go so I lapped the bottom almost flat with a 6" disk sander. I'm now lapping it now with my dia-flat. Will post some pics up soon..

I really hope that dust isn't carcinogenic! ! !

I picked up a 12k from Carbatec a couple of months ago and it was almost perfectly flat.
I'm completely surprised that two products out of China are so different, they normally have such stringent QA procedures .

Glad you got there in the end.

I foolishly bought mine from O.S thinking I had got myself a bargain. A week later my good friend Os (Onimaru55),in response to my telling him I had a C12k, said words to the affect, "I hope you got it from Carb-Tec and not from O.S, it's much cheaper to get them at Carba-Tec!" So of course I started kicking myself in the pants. Anyway I found mine needed some lapping too. I also had to do both sides.
Good to see you got it sharp there too, Brighty. Betcha not feelin' so Brighty now though are ya?!


Mick

Well, it took 1/2 a hr with the 6" sander. i used a 120 grit disk and a 240 grit disks.

Once i got it almost flat i re attacked it with my lapping plate, only for an hour this time.

So to get the bottom flat it was a total of 1.5hr but without the 6" rotatory sander i wouldn't have gotten it where it is now!



Has a nice 'Gannet' like grain on this side

Wow. I've had a few of these stones, and none took that long to lap.
You must have gotten a lucky one.

Originally Posted by HNSB

Wow. I've had a few of these stones, and none took that long to lap.
You must have gotten a lucky one.

Yay I'm lucky! lol mmm anyone want some of my luck? hehe

I really hope that dust isn't carcinogenic

Guys be carefull, this stuff IS dangerous. Even if the substances the C12k consists of are not carcinogenic, you can get cancer from it.
Particles at very small scales act different than in large scales. There is no way an Iron rod is going to inflame, whereas Iron powder does so very much.
The smaller the particle, the more its surface plays a role. This is part of the nanotechnology.

Nontheless it is known what impact dust and powder has on your lungs.
I think we can ignore corrosive stuff like acids or agressive particles.
Yet non agressive, even (at macroscales) non toxic particles will be deposited inside of your lung,
if your nose and throat fails to eliminate (ie filter) them. This happens with particles smaler than 6 to 1µm.
The smallest particles may even reach the deepes regions of your lungs, the pulmunary alveoli.

Inside of your lungs there is a security system consisting of your macrophages. These are like little nano-machines (nature is cool, ain´t it?)
patroling your system and if they approach an intruder (wich is most likely some type of bacteria) they try to eat it.
Inside of the macrophage some very clever reactions take place, that remarkably resemble our own way of digestion.
Enzymes and (toxic) peroxides inside the macrophage decombose organic substances and many intruders.
Macrophaces play a major role in keeping the walls of the lungs clean (you know the surface of the lungs are what do the breathing) and carbon collection,
wich is a byproduct of our respiratory system and needs to be removed.
If macrophages are unable to digest the substance, they eventually "die". The black spots on a smokers lung are mainly macrophages that consumed carbon and died.

There are many, many theories of the toxicity of silica for example if it is inhaled. I cannot repeat that.
However there are some simplified mechanisms to be aware of, that show what can happen and what it may cause.

1.- Too many macrophages containing dust, and uncollected dust gather and accumulate at the surface, or inside the tissue of the lung,
damaging it and diminishing its capability of participating in the respiratory system.

2.- While dying, depending on the chemical nature of the substance, macrophages may release toxic substances that will further damage the lung tissue.
Usually this damage can be repaired but in the event of larger amounts of dust inhaled the damage is too much to be reapaired.
The Lungs can be damaged irreversibly


Here is a good source of information for you.
The most important thing is:

The usuall supermarket filter system will not protect you.
These filter the large particles only, that are not our problem anyway.
You will indeed need a very special high performance particle filter,
if you try to sand a couple of Chinese 12k on a belt sander.


My recommendations:

Do it outside with lots of fresh air.
When possible do it wet.
Damage accumulates, so don´t do it often.
Better yet, don´t do it at all.
Ask a professional stonecutter if he can help you for a couple of bucks

Originally Posted by Lesslemming

The usuall supermarket filter system will not protect you.
These filter the large particles only, that are not our problem anyway.
You will indeed need a very special high performance particle filter,
if you try to sand a couple of Chinese 12k on a belt sander.

Wow i don't know weather to say thanks or what lol.. Well, I have cancer but hey i have a really flat stone!

I did have a mask but im sure some did get through. It only filters to 0.3 microns

P2 Conical Respirator
Protection against mechanically and thermally
generated particles and fumes
AS/NZS 1716:2003 approved
Typical Applications
Fumes and smoke
Refining processes
Welding
Grinding
Oxy cutting

Another popular mask used in infection control is a P2, or N95, particulate respirator. An N95 respirator is able to filter out 95% of oil-free microscopic particles, down to 0.3 micron in size. The “N” stands for “Not oil proof”.

Well that sounds like you were protected, unlike others

Like i said i could tell some got through, not that I'm choking on the stuff but my throat has a dry feeling.

If i had have done it out doors and not in my shed i probably would have been fine.. I don't think what i did inhale would be enough to do damage anyway (i hope)

Next time ill do it outside..