Quick question to those with more knowledge than I, but I picked up a Carborundum 118S in very good shape for dirt cheap. Looking online through various forums and here on B&B, there is very little information on the as to where these synthetic hones fall grit-wise (I've seen anywhere from 4K to 8K to unknown, and others have used them as bevel setters) and their hardness level. It came in the box, was labeled as a razor hone and was made/sold in 1965 but it appears to have seen little use. Laying it on a piece of polished granite, you can see a slight glimmer of light in the center of both sides, so it has been used and will need to be flattened before using it to hone, be they razors, knives or chisels. I saw one comment that carborundum hones can be difficult to lap/flatten due to their hardness, but I'd appreciate any feedback on what to use to flatten it, as well as any guesses as to where the grit level of a 118S might fall. It's only 4x2x3/4 in size so not optimal size-wise, but I got it dirt cheap.
Carborundum 118S Question: Grit Number and How to Flatten It?
- Thread starter Lord NSIC
- Start date
Here’s some info from @Gamma ‘s site.
www.tomonagura.com
Carborundum 118s | TomoNagura.Com | Keith V. Johnson
They are not equivalent to waterstones, gritwise. These are vitrified stones, the particles are fused/fixed.
They are pressure dependent, honing medium dependent, skill dependent, prep dependent, etc.
I think the highest grit rating for a Carborundum by the manufacturer was around 1200x, but you can cheat the grit with skill and surface prep. Dry, out of the box, that 118s is usually sorta rough.
The 118s - was sold 'empty'. It was to be filled with hot petroleum jelly by the user. Or something similar. The 102 and 102/103 Carborundum hones were filled at the factory with some sort of soap. So I guess you could use soap too but the instructions were to fill with heated petroleum jelly.
The 'filling' with a lubricant is not unlike how Norton sells their 'pre-filled' India or Crystolon stones.
Anyway - lapping them is an awful task. They can/will wear a diamond plate out. Not worth the sacrifice IMO. I would not lap another one on w/d paper, takes forever.
They are pressure dependent, honing medium dependent, skill dependent, prep dependent, etc.
I think the highest grit rating for a Carborundum by the manufacturer was around 1200x, but you can cheat the grit with skill and surface prep. Dry, out of the box, that 118s is usually sorta rough.
The 118s - was sold 'empty'. It was to be filled with hot petroleum jelly by the user. Or something similar. The 102 and 102/103 Carborundum hones were filled at the factory with some sort of soap. So I guess you could use soap too but the instructions were to fill with heated petroleum jelly.
The 'filling' with a lubricant is not unlike how Norton sells their 'pre-filled' India or Crystolon stones.
Anyway - lapping them is an awful task. They can/will wear a diamond plate out. Not worth the sacrifice IMO. I would not lap another one on w/d paper, takes forever.
