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Jebediah Eckert
06-27-2015, 10:17 PM
I bunch of years ago I purchased 1500 / 5000 / 8000 (tel:1500 / 5000 / 8000) Shapton Pro stones. I also bought the compact lapping plate / stone holder. This is NOT the $300 one the have today, I think it was like $80 back then. I also have the Shapton lapping powders in coarse, mediums, and fine. Well, I bought all this before the days of YouTube, or at least before I used it.

Lately I have been trying to improve my sharpening, handplane, and chisel skills with decent results. During this I have been brushing up on my sharpening. In some instances I get a great handplane surface and not so much on others. Like tonight I got a better surface off my LN 102 block plane (like glass) then my 4 1/2 that I both just sharpened and setup. Maddening. The wood was mahogany. While reviewing sharpening videos apparently it is "important" to keep your stones flat, make sense :eek:

Ok, how do it do this using what I have? Do I wet the stone and put the powder on the stone? I can't find any instructions anywhere. Somebody must have this system. The 5000 stone needs work but the other two are pretty close.

Any other tips on flattening the stones would also be appreciated.

316436

Archie England
06-27-2015, 11:03 PM
Use your lapping plate to keep all three stones flat.
Soak or spritz with water, flatten backs (at least last 1/4") and bevel. Once you've pulled a significant burr (and worked it off), then move up to the next stone.

Use your coarse grit on a flat plate (not lapping plate) to speed up the sharpening process, or acquire a lower grit stone to do that (YMMV).

Strop the final product on leather, test on end grain, then on with the woodworking.

Jebediah Eckert
06-27-2015, 11:05 PM
Thanks Archie, good tips. But I was more wondering how to flatten the stones themselves using the lapping plate and the powder?

Archie England
06-27-2015, 11:09 PM
I should let a Shapton pro user answer that.

For me, the loose grit on the lapping plate would be too much for the 5/8k stones, and maybe even for the 1500. Personally, invest in an i-Wood 300 diamond plate (Tools from Japan). Atomas are better but pricey, too.

bridger berdel
06-27-2015, 11:31 PM
Go to the home center borg store nearest you. Buy a masonry "cap stone". It'll be between $1 and $3. Get it soaking wet and flatten your stones on that. When it develops a dish get a new one.

David Wong
06-27-2015, 11:52 PM
Use the medium powder (中目), for your 1500 grit stone. Use the fine powder (細目), for 5000 grit and above stones. I use the coarse powder for 800 grit and less. Before you begin, make sure the lapping plate is flat. Check before each use. You can flatten the lapping plate with sandpaper on a granite plate, or a diamond plate. To use the lapping plate, wet it and your stones. Sprinkle a coating of the abrasive powder over the plate. It does not have to be a heavy coat. Then with light pressure, rub the stone to distribute and bed the powder on the plate. You can then increase your pressure, but you really don't need much. You can add more powder as necessary. Drow pencil lines on the stones to tell when they are flat. It is a good idea to flatten fine stones first, then medium, then coarse. That way you do not have to clean the old grit off the plate. When finished, rinse off the lapping plate and wipe with a paper towel. If you don't wipe it, it will rust. If that happens, I just wipe it and use a coarse stone to clean the lapping plate off.

It is a pretty messy process, so I mostly use an atoma diamond plate. I will sometimes use the lapping plate on coarse stones. They seem to perform better afterwards, as compared to using a coarse diamond plate.

Jebediah Eckert
06-28-2015, 12:32 AM
Thanks David, big help. What atoma plate do you use for a 5000 or an 8000 stone? Do you still need lapping powder and do you still wet the stone?

I know there are many ways to flatten the stones. A HD masonry cap is a new one on me but a good economical one for sure. I was just trying to use what I already had.

David Wong
06-28-2015, 3:06 AM
I use an atoma 400 on everything 2000 grit and finer. I have a 140 atoma that I use on 1000 and coarser. Because of the mess, and the risk of contamination by loose silicon carbide grit, I now only use the shapton compact lapping plate for badly out of flat stones, and only in the garage sink where I can wash everything off.

Derek Cohen
06-28-2015, 4:03 AM
Life in the shop is too short to muck about with inefficient methods of sharpening and flattening stones. I use a 275 grit diamond stone for all my waterstones, Shapton (1000/5000/12000 - the latter no longer used much) and Sigma (6000/13000).

Atoma have a good reputation. I have Eze-lap and a Shapton diamond plate (used for about 10 years now). It will last for many, many years if kept for the stones and not used to lap steel as well.

Further, I do not see a coarse diamond stone being limited to coarser grades of waterstones. I do not believe that a coarse flattening stone affecting the finer waterstone grits. The sharpening media lie with the grit in the stone and not in the texture of the surface. Therefore one coarse diamond stone (250-275 grit) will do it all.

Regards from Perth

Derek

Jebediah Eckert
06-28-2015, 9:14 AM
Thank you, I am not a fan of messy but it will have to do for now. I do not have a sink in my shop. I'm going to give it a shot this morning flattening them as instructed.

If I were ever to switch to a diamond stone how is that done? Do you just spritz the a Shapton stone and then lap it on the diamond stone, or just do it dry?

Derek Cohen
06-28-2015, 9:39 AM
Thank you, I am not a fan of messy but it will have to do for now. I do not have a sink in my shop. I'm going to give it a shot this morning flattening them as instructed.

If I were ever to switch to a diamond stone how is that done? Do you just spritz the a Shapton stone and then lap it on the diamond stone, or just do it dry?

Best done under running water. The alternative is a tub of water.

The good thing about these stones is that you do not need to flatten them as often as with others.

Regards from Perth

Derek

Jebediah Eckert
06-28-2015, 12:43 PM
I just gave it a whirl and had zero success unfortunately. The stones are dead flat across the width but dip off ever so slightly lengthwise. About 1/3 flat in center and the outside 1/3 dip off slightly. I'm using a starrett ruler off the combo square and it is in good condition. I've been at it for an hour and am not making any headway. I drew a cross pattern with a pencil and that is removed within 10 strokes or so but still not getting flat.

I then put the Shapton lapping plate on 80 and 120 grit sandpaper on a granite lapping block. I worked at that a while but it is hard to tell if it's flat using a straight edge because of the voids in the design. I marked the whole surface with a marker and it took it all off.

Back at the stones still same results. Maddening.

Maybe the lapping plate needs more flattening? Maybe it is slightly bowed and that would account for taking more off the ends. I don't know.

I wish i knew somebody local. I would be curious to see how "dead flat" their stones are, maybe I'm being too picky. My wife says my eyes are too good and my rulers too precise. Maybe I should have bought a cheaper straight edge and been none the wiser? I don't usually get crazy on accuracy when it comes to this stuff but from all the reading it seems important to get good sharpening results. Only after good sharpening do you have any prayer of getting good results from a smoothing plane.

I guess as long as they are flat side to side it should be fine for plane and chisels sharpening lengthwise? If not it will have to do for now til I figure this out, although I'm not sure what else I can do.

Maybe I can try flattening the stones on 120 grit sandpaper on the granite plate and see how that goes.

David Wong
06-28-2015, 1:04 PM
When I use the lapping plate, I vary the directions I lap the stone on the plate, on the theory that it will equalize any pressure and wear bias I may be applying. I move the stone lengthwise back and forth, diagonally across the lapping plate, and in circular and figure-eight motions, and counterclockwise. I also flip the stone 180 degrees and go through the same motions. I count the number of strokes in a particular direction to try to equalize wear in the opposite direction. This sounds complicated and a lot of work, but it goes really fast. I mentally count 8-10 strokes in every direction. I do the same thing when I use a diamond plate.

Inking the lapping plate and rubbing on sandpaper is how I flatten it also.

I don't know how much downward pressure you are applying, but you might try lightening up. Especially when distributing the abrasive powder on the plate, just use the pressure from the weight of the stone. A little more pressure after the powder is distributed. Another thing to consider is whether you are using enough abrasive powder. I usually give 2 or 3 taps from the bottle. Make sure to wet the stones as well. I am not careful about the amount of water on the lapping plate. I just dump some water on it to get the entire surface wet, tilt the plate to get rid of the excess, then apply the powder.

Jebediah Eckert
06-28-2015, 1:11 PM
Thanks David. That is basically what I did. I did go light on pressure and did a similar altering pattern. I guess it would make sense if the ends of the plate are bowed up slightly? Even with altering a pattern the ends would get more time on the ends of the plate?

I'm going to grab some more 120 and 220 wet dry sandpaper and try to flatten them on the granite plate like in the Lie Nielsen video. If that works then I guess the problem is the Shapton plate?

Bruce Mack
06-28-2015, 1:15 PM
Just a thought. When I used sharpening jigs I found that slight surface variations stone to stone led to poor registration/repeatability as I moved grit to grit. Free hand sharpening, side to side or Sellers' method, makes it easier to achieve a fine edge. Just try this once and don't sweat the stone flatness. See if the results please you.

David Wong
06-28-2015, 2:31 PM
On my plate, it is the edges that are usually low.

When lapping, I only allow about 1/4 of the stone to go off the edge of the plate. Three quarters of the stone is always on the plate.

Jebediah Eckert
06-28-2015, 8:16 PM
Thanks for the tips, I will try them all. My freehand was abandoned for the jig awhile ago but I will check out the Sellers method and try again.

Allan Speers
06-28-2015, 10:02 PM
I use an Atoma for flattening my stones, but FWIW, I know an old timer who uses a concrete block & a running water hose, and swears by it. Think about it: One surface of a block is dead-flat, because it's created by gravity. The benefit is that you have a very large surface to work with, so none of your stone is ever hanging off an edge. You thus have a better chance at getting an even surface.

I suppose an EZ sharp system with course sandpaper would do just as well, never tried it, though. - But how cool is using a concrete block?

Jebediah Eckert
06-28-2015, 10:09 PM
Thanks Allan. Do you use the Atoma 400 as well for all your grits of stones?

ian maybury
06-29-2015, 7:12 AM
+1 that a 400 or thereabouts diamond seems to do a very god job on everything Shapton down to 12,000 at least. Separately - wonder if uneven distribution of loose carborundum grit on a lapping plate has the potential to cause an out of flat stone?

As recently discussed at length it's hard to overemphasise the frequency and flatness bit, especially if working with a honing guide. Not all diamond plates are accurately flat, so test carefully before use with a precision straight edge against the light in all directions. Send it back if it's not perfect. They need to be flat within microns if you plan to reliably cut right to the edge and along it's full length on a very fine stone. There's probably a bit more tolerance possible if stropping - i'm not sure how people get by with concrete cap stones and the like but stuff like this seems likely to be in the mix.

Micro bevels and hand sharpening (where it's easier to cut right to the edge/it's possible to steepen the angle a hint if needed to get to it) must make it a bit less sensitive, but even at that a hint of widthwise out of flatness has the potential to mess things up.

Having scribbled all over the surface with a pencil flatten the stone - until all of the pencil marks are removed. Take care to apply even pressure/to not tilt the plate, and don't overdo the pressure. Rinse at intervals if it's taking a lot of cutting - large deposits of slurry have the potential to tilt the plate a hint or lead to uneven cutting and cause a problem.

Then hone for a bit in a movement that spreads the wear evenly over the stone and avoids hollowing (see David Charlesworth's 'A Guide to Hand Tools and Methods, p. 84 onwards for specifics - not more than 30 - 50 strokes in total, less on a narrow chisel where the wear will be faster), then flatten again. Repeat…. A ply handle stuck on with high strength (permanent) flexible double sided bonding tape works well on the Atoma (see previous pic posted), and doesn't risk warping the plate.

Done this way the blade will only work a given area of the stone at most several times at most between flattenings.

This may sound OTT, but believe me - it's necessary if you want to get consistently sharp edges off a waterstone with a honing guide. Especially so if honing single bevel as on Japanese chisels. Even very minor/invisible irregularities will mess it up - i used my first well worn Atoma to try to dress a Tormek stone, and even though it looked fine it started as a result of uneven wear to act up by virtue of slow cutting/an invisibly lowered surface in some areas. Close inspection showed that my Japanese chisels were not quite cleaning up uniformly all over the area of the bevel (sometimes leaving a hint of wire edge behind) as a result of some combination of the diamond plate having caused microscopically out of flat stones, and/or the bevel not being quite flat from the previous stone. A new diamond plate instantly resolved the problem.

It's soooo easy to get into a mode of sharpening where we go though the motions without actually SEEING what's going on at the edge (sharpening by numbers), and this is when inevitably some variation creeps in and causes a problem...

Jebediah Eckert
07-09-2015, 3:50 PM
Well......after getting fed up with the Shapton lapping plate I ordered the Atoma 400. I figured the Shapton plate just wasn't flat enough to get good results. The Atoma came today in the mail, I opened it, and started round 2 of flattening.

They are "flatter" for sure, but I say an ever so slight ray of light from dead flat. I stopped because there was no way they were getting flat, I was at it awhile. I altered patterns, very very light pressure, just enough to get it moving. I went from 8000 to 5000 to 1500 and cleaned the plate spotless between grits with several rinsing during the process. I did two and even 3 rounds on each stone with the pencils marks until they were all gone. The Shapton stone was in the lapping plate holder and I worked the Atoma on top only letting the Atoma come off the edges 10% or so tops. I went slow and very diliberate with very light pressure.

Again, they are "flatter" then before but all 3 stones are scratched prett badly. I'm not sure how well it will show up in the picture. A bunch of people suggested this method so I can't be the only one experience this?

Any ideas?

317056

This was the last stone it did (1500) and took the picture after a few strokes. The other stones have scratches are all over the place from altering the pattern.

Paul McGaha
07-09-2015, 4:38 PM
Well......after getting fed up with the Shapton lapping plate I ordered the Atoma 400. I figured the Shapton plate just wasn't flat enough to get good results. The Atoma came today in the mail, I opened it, and started round 2 of flattening.

They are "flatter" for sure, but I say an ever so slight ray of light from dead flat. I stopped because there was no way they were getting flat, I was at it awhile. I altered patterns, very very light pressure, just enough to get it moving. I went from 8000 to 5000 to 1500 and cleaned the plate spotless between grits with several rinsing during the process. I did two and even 3 rounds on each stone with the pencils marks until they were all gone. The Shapton stone was in the lapping plate holder and I worked the Atoma on top only letting the Atoma come off the edges 10% or so tops. I went slow and very diliberate with very light pressure.

Again, they are "flatter" then before but all 3 stones are scratched prett badly. I'm not sure how well it will show up in the picture. A bunch of people suggested this method so I can't be the only one experience this?

Any ideas?

317056

This was the last stone it did (1500) and took the picture after a few strokes. The other stones have scratches are all over the place from altering the pattern.

I use an Atoma 400 on all my stones 1000 grit and up. It works great, easy, very light pressure, I keep the diamond plate stationary and move the stones just front and back (longways). It flattens them easily. At Stu's advice I've flattened Shapton Pro stones all the way down to 320 grit with an Atoma 400.

That looks to me to be way more course than a 400 grit Atoma. Waaaaaaaaaaaaaaayyyyyyyyyyy more. Maybe it was labeled wrong or maybe it's just defective. The Atoma 400 should do a wonderful job of flatening your shapton pro stones.

I suggest you get that picture to the vendor you bought the Atoma from and get it exchanged.

Good luck with it.

PHM

Jebediah Eckert
07-09-2015, 8:17 PM
I will post a picture of the Atoma, maybe you can tell from that? The sticker on the package is correct but who knows.

The Atoma is dead flat, on the business side anyhow.

How bad are the scratches going to be for sharpening results?

Paul McGaha
07-09-2015, 8:35 PM
Jebediah,

Maybe feel along the Atoma with your finger. Maybe you can find a burr on the plate. It could be a single burr doing all the damage.

Hopefully the scratches aren't too deep. It would be good to get them out.

Allan Speers
07-09-2015, 10:28 PM
Thanks Allan. Do you use the Atoma 400 as well for all your grits of stones?


Yes.

It really doesn't matter how fine the stone is, because it's still seeing a flat diamond surface.

BTW, I started using the Atoma on the advice of Derek Cohen.

Jebediah Eckert
07-10-2015, 7:53 AM
I doubt you can tell from the picture but here it is. I'm not sure if the different grits are patterned different, or color, or anything like that.

Also I felt the surface and I haven't been able to feel a burr or any kind.

317072



I'm not sure why I am having such poor results with it. I ended up redoing the Shapton stones on sandpaper on a granite plate. I got a good portion of the scratches off but it took a looooong time. I probably should have saved the $75 and flattened them like that to begin with. It just seemed like I was always out of the sandpaper I needed when the time came, plus I was hoping for an easier way. Somebody above said life was too short for poor sharpening system, agreed. However, the pursuit of improving my sharpening (flattening my stones) is slowing driving me mad.

Al Launier
07-10-2015, 8:29 AM
By no means am I skilled at sharpening, but I use a 12" x 18" piece of plate glass with wet/dry paper to sharpen my tools. I think people can get "over zealous" with sharpening.

Paul McGaha
07-10-2015, 8:34 AM
Jebediah,

I'm sorry you're having trouble.

If you're sure the scratches came from the Atoma 400, I really do think it is defective and should be replaced.

I have Shapton Pro Stones in 320, 1K, 2K, 5K, 8K, and 12K grits. I routinely flatten them with an Atoma 400 with the exception of the 320 which I usually use an Atoma 140 (Although the Atoma 400 will flatten the 320 too).

I'm glad the scratches are coming out without too much trouble.

PHM

EDIT - I'd add that I think a diamond plate like an Atoma 400 really is a very effective means to flatten water stones. It's the best method that I've found. Fast (Draw a grid pattern and flatten in less than a minute I would think), Less of a mess than wet sandpaper, Affordable.

Jebediah Eckert
07-10-2015, 8:36 AM
Thanks for the help Paul. I may try it on one of the stones again. Under the theory there may have been a burr and when I got down to the 1500 stone it knocked it off. If it still gouges I thinking sending it back is the call.

Brian Holcombe
07-10-2015, 8:42 AM
It's possible a stray grit was in the stone or the plate. I've had that happen....in my case on a finish stone :(. I'm now very careful about stray grits. Everything stays separate.

i've been advised of 1200 atoma plate for lapping finish stones and so...eventually I will have that myself along with a 400 to replace my DMT. I think my DMT is a 325, and I very much dislike it. I have an old serrated top DMT that I like but it's not accurate in flatness.

Accurately flat stones do make life much easier on the finish stone, because the more accurate your work up until then the less work you will need to do on your finish stones.

Steve Friedman
07-10-2015, 9:31 AM
Jebediah,

I'm a little confused. Were the scratches there before you started with the Atoma or did they happen after you started using the Atoma?

Assuming they only occurred after you started using the Atoma, I agree that there must be something sharp and hard that's causing the scratches.

If there's no burr on the Atoma, I wonder if there's some random piece of loose grit from your earlier attempts that are still embedded in the surface of the stone. Or on your bench.

Here are some suggestions - in the order I would try them:

1. Until you have this figured out, I would do everything away from your bench to eliminate any possible contamination source. Find a sink and do this under running water or get a tub of water and do this underwater. Most importantly, far away from where you were using sandpaper and the Shapton grits.

2. Keep using the pencil hash marks. Hold the Atoma in one hand and the stone in the other. After 10 or 20 strokes, flip the stone only end to end. After another 10 or 20 strokes, flip the Atoma end to end. After another 10 or 20 strokes, switch hands and repeat the end to end flipping.

3. If the scratches are still there, but less, keep going. Hopefully you'll eventually get below the embedded grit.

4. If you're not flattening both sides of the stone, try flattening the other side and see if the scratches occur there as well. If you have been doing both sides and have scratches on both sides, try flattening the edges of the stones. If the scratches don't appear there as well, it's not the Atoma - it's grit something embedded in your stone.

5. Find someone with soft fingers (child? non-woodworking spouse?) and ask them to feel around the edges of the Atoma and see if they can fell a burr. If you don't have anyone around with soft fingers, use your lips to feel - don't rely on your calloused fingers to try to find this.

6. Wet the stone and get the soft fingered person (or your lips) to feel the surface of the stones to see if you can detect any loose grit on there.

7. Grab your plane blade or chisel with the shiniest edge and try to sharpen it on the 1500 stone. If there's a piece of grit embedded in the stone, you'll see the scratch on the blade.

That's all I have. Good luck.

Steve

Daniel Rode
07-10-2015, 2:03 PM
I use diamond stones except for the final step where I use a 15k Shapton Pro. As a result, my process may be different but this is what I do.

To flatten the stone, I use my coarse diamond plate. I tend to work 1 stroke center (stones aligned), then 1 stroke each corner to corner. I can tell, if it's flat when the dark marks from the steel are all gone. I've seen some people mark the stone with a pencil, but I don't need to with the 15k stone.

No need to do it every time, I do it every 5-6 sharpenings.

I used to overthink sharpening. I thought I need precise angles, exact flatness, micro-aligned jigs and fixtures, etc. My tools became sharper when I stopped obsessing and let the simple act of sharpening be simple.

Andrew Pitonyak
07-10-2015, 3:43 PM
I never really understood that whole loose grit thing to flatten stones... There was a discussion a while back with respect to using sandpaper to flatten stones. Stu mentioned a discussion with a guy who is President of a company that makes stones, and the gist was that the particles can embed into the stone from the sand paper...

So, why do these loose grit particles embed into the stone? Is it because they are not held in place as they are with the sandpaper? Note that I have indeed flattened stones using sandpaper and have not noticed the issue, but for the last few years I have used diamond stones to flatten.

Steve Friedman
07-10-2015, 4:20 PM
I remember Stu's warnings about sandpaper flattening.

I have only used the SiC grit on two stones. I used it to flatten my Sigma 400 stone before I got an Atoma 140, but that stone is hard as a rock (pun intended) and will not let the grit in. I also used it to unclog my Sigma 120 because I don't think there's any other way to do that.

In both cases, I put the grit on those laminate sheets that Lee Valley sells for lapping so that the grit embedded in the laminate and didn't just roll around.

As messy as it is to flatten water stones with SiC grit, it's nothing compared to using the grit with a lapping plate and oil to try to flatten the bottom of plane sole. Now I know why sandpaper was invented.

Steve

Brian Holcombe
07-10-2015, 4:44 PM
I only use the sandpaper and granite setup for flattening backs and setting bevels. I expect that it would not do well for the stones.

Using Tomo Nagura was the way to build slurry for a very long time, but it was recommended to me not to use that method either for the same reason that embedded grit causes issues with the finish on the blade. Some people burnish the stone with an identical stone for naturals but flattening with diamond plates seems to be the over-arching recommendation.

Having discarded the idea that the stone being super flat was important than revisiting the idea I have come to realize through trial and error that maintaining flatness on your stones is very helpful when you reach the finish stones and makes removing the wire edge much easier.

Mind you, I'm using mostly Japanese chisels at this point and so I make a full width bevel.

Wilbur Pan
07-10-2015, 5:27 PM
The good news is that the scratches won’t effect how the Shaptons will sharpen your tools. Put it this way: if scratches in the surface was a problem, then there would be no way that these DMT diamond stones would work.

http://www.sharpeningsupplies.com/Assets/Images/10DMTDUOKIT.jpg

(I don’t like using DMT diamond stones for sharpening for a number of reasons, but this inverse-polka-dot pattern isn’t one of them. ;) )

Where this would be a problem is if you used your Atoma plate on a tool, and a scratch was left in the tool from whatever was causing the scratch pattern on your Shaptons.

There has to be a particle or burr on the Atoma some place. The trick is how to find it. You could lightly brush over the surface with your fingertips. Another way to look is to take a piece of metal or a beater tool of some sort and use it to test the surface of the Atoma bit by bit until you find the area causing the problem. Or put the Atoma plate on one of your Shaptons and slowly move it in a circular pattern, and you should see a little squiggly circular scratch that will correspond to that area of the diamond plate.

Finally, a brute force solution is to jig up a plane blade that’s a bit beat up in a honing guide and just run over the surface hard and fast. Maybe you’ll find the problem spot, or knock off the burr in the process.

Alternatively, you could contact the store where you bought the Atoma from and get an exchange. In the meantime, your Shaptons are perfectly useable, even with the scratches.

ian maybury
07-10-2015, 8:26 PM
Hi Jebediah: Looking closely at the photo of your diamond 'plate' it looks like (a) there's pieces torn away from the top LH and RH corners, and (b) that it's possibly showing wood underneath in those areas. Or is it some trick of persecutive, and the missing 'corners' are the sides?

The stock Atoma plate has a roughly 1/4in aluminium plate backer - this is what gives it its flatness. The diamond abrasive is a sheet of self adhesive foil stuck down on it. It's possible to buy a replacement foil on its own, it's a bit cheaper than the ready to use plate. (which has the foil stuck down on the aluminium backer plate)

Is it possible that you have somehow ended up buying a foil and not a ready to use plate? It's unlikely that 1/4in aluminium plate could be torn away. Also is it possible that you have stuck the foil down on a piece of ply or something similar? If so it's very unlikely that it could be flat. If so it's also quite possible that the torn edge is resulting in some raised diamond grits which could be causing the scratching you report.

Pardon me if you in fact have the proper aluminium plate. It that's what you have, and it's truly flat (checked really carefully with a reliable straight edge against the light) and free of stray grits, and you introduce nothing between it and the stone like large amounts of slurry, or loose grit, or dirt or something then short of rocking the diamond plate about by applying very uncontrolled and uneven pressure it's pretty tough not to end up with a flat stone. Scribbling pencil marks all over the surface of the stone is essential so that you know what is happening as you work.

It'd be a little more awkward if the stone was starting out badly humped, you would need to take care not to rock the diamond plate on it as you worked - but this should be pretty obvious if the pencil marks are clearing up too early from where they shouldn't i.e. from the low areas before the rest has been cut down to the same plane. You can check the stone with the same reliable straight edge and even mark the low areas - they should be the last to disappear......

As before/as the others - if you want to finish out to very fine grits on a stone/will need a very flat stone to get rid of the wire edge (and are not stropping or whatever) my inclination would be to stay well away from sandpaper on granite plates. it's perhaps not impossible, but it's tough to avoid some sort of rumpling in/a wave caused by pressure/displaced water running ahead of the stone and tending to cause a rounded edge. Also as the others, i'd not panic about a few length wise scratches anyway - not unless they are deep enough/in a direction where the edge may drop into them. A DMT type as Wilbur diamond plate is a good example of a sharpening surface that's like a cobbled street - but the point is that the abrasive mesh is all in the same plane...

Jebediah Eckert
07-12-2015, 5:15 PM
Thanks for the responses. I'm going to give it a try again using some of the suggestions.

The Atoma is a regular plate with the 1/4" aluminum backing. The angle of the picture probably just looks strange. I had to crop or way down otherwise it wouldn't upload.

I'm off to search for the culprit grit or burr....