Lapping a stone : Some Questions

Hi Guys,
so last weekend i was digging through an old shed at my house and came across an item i never noticed before. It appears to be an oil stone but is a very fine grit, it has a depression in the centre from being used to sharpen blades.

i know the guides on here say to use 400grit sandpaper, is there any harm in starting lower i only managed to find 180 grit wet and dry paper tonite and was going to have ago lapping it but figured i would ask first.


Also if i post some pics of it is there a chance someone might know what it is? i sense it being nothing more than a man made oil stone but im living in hope i found a gem :D


Kris

I've never seen anyone NOT want to look at pics of stones or razors :) Post some and see what comes about.

How deep is the depression in your stone?

If it's relatively shallow, then I think the sandpaper may be ok. If it's a deep one, and will take some elbow grease to remove, may I suggest a lapping plate?

SRD's website has a few, but you may be able to find a retailer who is in the UK to help with shipping costs.

I wouldn't buy a lapping plate just to lap one hone. You can start as low as 80 or 120 grit. I always start with a 120 grit sanding mesh. It's quicker and lasts longer. Once it's lapped you can easily lap it smooth with higher grits. Depends on the stone how high you'd like to take it.

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Originally Posted by Maxi

I've never seen anyone NOT want to look at pics of stones or razors :) Post some and see what comes about.

How deep is the depression in your stone?

If it's relatively shallow, then I think the sandpaper may be ok. If it's a deep one, and will take some elbow grease to remove, may I suggest a lapping plate?

SRD's website has a few, but you may be able to find a retailer who is in the UK to help with shipping costs.

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the depression seems to be about 1mm at its deepest so i reckon some elbow grease should sort it out. once i make some headway with it i will post a pic see what you guys can come up with.

At 1mm, I rescind the need for a lapping plate. Wet/dry on a flat surface should do well.

I would suggest do not worry so much about the grit for dishing. I often start on 40-60 to get it flat ish before I go for higher grits.
Do not be shy to show the picture as it can save your elbow grease. if the stone is carborundum or ceramic type (hard to recognise grit and usefulness from touch) sometimes is good to keep it for sentimental value but often is better not to bother and gently place it in the bin:gl:

The worst case scenario of starting too low is you'll remove a little more stone than you wanted to when you go to remove the deeper scratch marks with a finer grit. But even then, you are talking about fractions of a mm of hone, so it's nothing to worry about.

Quote:

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Originally Posted by adrspach

I would suggest do not worry so much about the grit for dishing. I often start on 40-60 to get it flat ish before I go for higher grits.
Do not be shy to show the picture as it can save your elbow grease. if the stone is carborundum or ceramic type (hard to recognise grit and usefulness from touch) sometimes is good to keep it for sentimental value but often is better not to bother and gently place it in the bin:gl:

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i get the feeling you maybe right regarding this, i don't have a good quality camera to hand at the moment but it doesn't seem to have a noticeable grain / pattern etc. dont panic though i will get some pics up by the weekend .

i started to lap it with some 180 grit and its coming along good, the "slurry" off it was a sort of battleship grey and very fine. i figured that even if its a cheap man made stone lapping it would be a good thing for experience and so i can use it to sharpen knives.

If you want to know the grit take a piece of steel, an old knife or something, and rub it against the stone till you can see the scratch pattern really well then take a pic of the scratched steel and one of us can tell you the approximate grit by looking at the scratch pattern.

edit
You can use a cinder block or concrete driveway to grind the stone flat on, sandpaper isn't going to be that useful.