Levelling old sharpening stones

[Pekka Huhta]

The previous owner of our house was a carpenter and fortunately there were quite a bit of his "useless" old tools left in the house when we bought it. A very inexpensive way for obtaining tools, just buy a good set and they throw in a house on the side...

His sharpening stones are something that I've not seen or tried before.
I'm not sure if this is an arkansas or other type, but it sure is hard. In any case it has a bit of a saddle on it after everything I've done to put it straight. I have used a good lot of other stones during the years, but this is the most promising one I've seen. A bit coarse perhaps, but still enough for most of my tools, and the rest need only a touch after this.

To get to the point, how will I get the stone straight? I've tried all available things, but after a few days I still have too much hollow on the stone.

40 grit watersanding on glass was a good try, but the two-pound jug of elbow grease wore out before the stone had more than matchbox sized specks of smooth area on the ends.

40 grit belt sander got me closer to two cigarette-box-sized smooth areas, and I got closer to level surface, but it's difficult to keep the ends parallel. And I burned several belts on this attempt. Of course I had to go through the sanding on glass to get it straight, but I got it about there. Not even close to perfect, but the stone is so good that I use it anyway. And I haven't touched the other side.

Any good suggestions on this one? Diamonds are anybody's best friends, but I really can't afford them. A good glass or steel surface with emery dust (or whatisit these days) would be good for other things as well, including a irrational urge for flat soles

Do you have any good web pages, tricks or should I just stop sorrying my bad tennis elbow (hammer elbow in fact) and just get back to work?

Pekka

 

[engineer one]

pekka
can't you just pretend it was designed for producing curved surfaces?? :twisted: :lol:

maybe a picture would give alf or someone a better idea of what it is.

paul :wink:

 

[Pekka Huhta]

I don't have a picture of the surface just now but here are a few images I have posted previously somewhere else.

Don't make too much fun out of the crude box, I made it just in half an hour so I could use the upper half of the box as a filler between the bench dog and the stone. It's the second one going. And the stone is pretty much straight, OK for knives or plow plane irons. For a plane iron it needs a bit of fiddling.

I have my touch with it and I know what to do, but I did let one of my friends to practice with the stone and it was so miserable that I finally thought that I really should do something about it. It isn't enough that I know what to do to get a good edge. I know that it would be faster for me and especially better for the occasional friends I'm trying to teach how to keep the sharp ends sharp at all times. It isn't helping if they end up with a plane iron which looks like it was intended to sit in a saddle.

Only problem is that the closer I get to a flat stone, the longer it takes to straighten. If the first two specks on the stone ends took a few hours, straightening the stone after grinding took several and the further I'm getting the longer it takes to get to the middle of the stone. I'm just plain lazy and am interested if someone has found a faster way. There is still the other side of the stone to go all the way...

Pekka

 

[David C]

The old stone flattening recipe was silver sand and water on a York paving stone.

Coarse valve grinding paste, loose very coarse silicon carbide or better aluminium oxide grit, used with water or kerosene on scrap glass will work.

Of course the glass will begin to wear hollow after some time and need changing.

I would be a bit worried about using a diamond stone as the stone might be damaged and they are expensive.
best wishes,
David Charlesworth

 

[Evergreen]

Pekka

Following on from Mr C's suggestion, I've used sand, water and a piece of cast concrete slab to flatten an old, very hard natural sharpening stone (don't know what it was). The concrete slab wore away too but it lasted long enough to get the job done. The sharpening stone then needed a little smoothing and I used a medium grit aluminium oxide paper on a piece of mdf for this. All a bit crude but it was cheap and effective.

Regards.

 

[devonwoody]

How about asking our member Niki. He might design a contraption which holds the sharpening stone to a concrete motorway road surface whilst you do a 50 mile drive. :x

 

[Pekka Huhta]

I already had dug up an old jar of valve grinding paste, but yesterday I was sharpening a few plane irons on a Tormek. When pouring water out of of the machine I had one of these "heureka"-moments. The bottom of the container was covered in aluminium oxide slurry removed from the stone. I guess I'll start with that. At least it's free

Thanks for the hints, let's see how it all turns out.

Pekka

 

[David C]

Nice idea!

If truing with the diamond device there will be even more.

This essential tool removes a rather large cut if set as per instructions. I limit cut by placing two layers of 240 grit wet and dry, under the diamond cluster, when setting.

This gives a much finer cut ;-)

David

 

[MikeW]

That is a great idea, Pekka!

There will be swarf in the mix, but I don't think that will be an issue.

Take care, Mike

 

[Philipp]

Hyvää päivää Pekka!

if you wish I could send you some kgs of medium-coarse aluminium oxide for flattening your stone.
I use alumina powders in different gradings for my sharpening on a polished tile and I am content with this cheap solution.
Unfortunately, I will not be able to pack a parcel for you within the next three weeks because right now I am about to start into my holidays - to Finland

Let me know if you still might need some alumina powder in September.

Best regards
Philipp

 

[Pekka Huhta]

Philipp, I just sent you a PM on the aluminium oxide, thanks.

I started with the Tormek slurry, but my glass won't do. It's the first time I'll admit that the old-fashioned blown glass is not OK

I've been restoring my windows on the old house for years, and I have a good (excessive) supply of glass, broken in progress. None of it is thick and almost all of it is the old-old-fashioned blown glass, with bubbles and sags and the best parts of it looking like the glass-blower had a hiccup. I was intending to get a sheet of a bit modern glass on my workbench and chose it only by thcikness. Well now, thickness on the other end was 4 mm which I thought would be OK with a straight 32 mm MDF sheet. Only that the other end was a bit over 2 mm and the part in the middle looked like Hawaii beach after a half-minute sanding

Well tomorrow I'll get something better. I just thought that you might enjoy the idea that a guy from year 1870 would not have chosen a sheet of glass to grind anything straight

Pekka

 

[Anonymous]

I don't really use the old oils stones......but I have some thoughts,

how about using a large stone cuttoff disk.... large enough in diameter to rip a new face to the stones.....uno, those disks regularily bought to cut brick/cement, mounted in some fence like machine, and just push the pipper through and rip yourself up a new face, and then finish off with pastes etc .

Could set it up on your table saw. Hellava mess though :lol:

maybe, if all faces are out of true, stick the disk in an over head radial saw,,,,lock the stone, and drop it down,,,,,,

or, maybe get a concreting mate with a specialized tile cutter ??? I don't know.

Bit of a shot in the dark I suppose,,,,,but at work at the moment I'm cutting up a lot of bricks and tiles with these disks in those small 4" hand grinders.....no mucking about....I'm guessing the oil stones will lap much slower than the waterstones I'm used to, so a powered tool may be the go. I imagine some would be found heavily dished, yes ?

 

[David C]

Jake,

This sounds very dangerous indeed,
take care.....

David Charlesworth

 

[scooby]

Jake,

This sounds very dangerous indeed,
take care.....

David Charlesworth

Definately agree :shock:

Possible Darwin award situation..Not good

 

[Pekka Huhta]

If one had a big diamond cutting wheel big enough to slice the whole stone in one cut it might work. A hand-held machine is just murder and even a table saw with a small diamond wheel is not that good as you can easily get a kink on the cutting line if you have to move the stone while cutting.

In any case the hollow in the stone isn't that big, I guess that I would probably get more hollow in the stone if I tried to butcher it with a diamond wheel with a home-made setup

Anyway, even considering the dangers diamond wheels are expensive. For the price of one diamond cutting wheel I would probably get a wheelbarrow full of old oil stones. Only that they would most probably be hollow, the lot of them

Pekka

 

[Jake]

I have a big Duhrer tiler's wetsaw with a spare cheapo 350mm blade - happy to give it a go, if someone has one they don't mind being trashed if it goes wrong.

 

[devonwoody]

I have got a double sided carborundum stone with hollows, you can try if you want to.

PM me if OK

 

[Anonymous]

Hi Pekka,

If one had a big diamond cutting wheel big enough to slice the whole stone in one cut it might work. A hand-held machine is just murder and even a table saw with a small diamond wheel is not that good as you can easily get a kink on the cutting line if you have to move the stone while cutting.

It was just an early days idea. Never know. I agree on not doing it freehand. . All those little wobbles, even when sobber,,,,uno....

But, if the whole process is jigged, I think one might be surprised. I don't see any reason why one couldn't get accurate results with a machine bladed to cut stone.....neat crisp lines like one could get when cutting wood with a machine.

When I do it freehand, even with a steady two-handed grip I feel quite confident cutting to a line with a small angle grinder. The diamond disk on tiles is just brilliant. And tiles generally are brittle.....Just steady light passes to keep the heat down.....

In any case the hollow in the stone isn't that big, I guess that I would probably get more hollow in the stone if I tried to butcher it with a diamond wheel with a home-made setup

Sounds like your right. Probably not worth doing if you have to go out of your way setting up a machine. Just seems like a lot of effort to flattern an oil stone. Toss em and settup buffing wheels instead :wink:

Anyway, even considering the dangers diamond wheels are expensive. For the price of one diamond cutting wheel I would probably get a wheelbarrow full of old oil stones. Only that they would most probably be hollow, the lot of them

Pekka

Honestly, whats the truth behind that ? .....how dangerous would they be ? I mean, their used everyday in masonary arn't they..... I'm using them at work currently to cut bricks ruffly, freehand ......The continueous wheel I'm using seems to cut crisply through stone and brick

I feel that a stone or tile cutter drop saw style would make a clean cut. ....as long as the blade drops square and the stone is held fixed and its kept reasonably cool.....might have a mate who'd do it for you. Never know,,,,might take him just a few seconds to do. ?????

But don't listen too me. I'm no mason and I'm definetly NOT safety conscious by nature. I took 1/2" off the tip of my right middle finger on the jointer about a year ago ...... Now where near as offensive as I once was on the road :shock: (joking)

 

[Alf]

I spent this lunchtime flattening oilstones (various) and can provide the following insights fw they're w.

Norton India stones are hard. Oh boy. Went through two sheets of 80g HCAB (aluminium oxide) and while it still isn't quite as good as I'd like it did do the job. The coarse diamond didn't appear to touch it, but I stopped fairly quickly when nothing seemed to be happening in case it was all happening to the diamond instead... I think a loose grit would be much more effective than the paper, but I only had 400 which is far too fine. Drywall mesh, so beloved of the waterstone fraternity, did a cracking job on the Norton Washita (hot knife and butter spring to mind) and my other unidentified natural fine stone, but was eaten alive by the India. End of observations.

Cheers, Alf

 

[bugbear]

I spent this lunchtime flattening oilstones (various) and can provide the following insights fw they're w.

... Drywall mesh, so beloved of the waterstone fraternity, did a cracking job on the Norton Washita (hot knife and butter spring to mind) and my other unidentified natural fine stone, but was eaten alive by the India. End of observations.

I've never flattened an india; I've flattened various slate stones (wheee!). That goes nice and quick.

I also flattened a translucent arkansas. That wrecked a large amount of Alox abrasive before I finally got the stone flat.

I had issues with convexity of the stone during the prcocess BTW

BugBear