Defective or Normal 1200 ATOMA?

[mikedtran]

Hi All, I just got an Atoma #1200 and it is leaving a very interesting pattern when lapping natural stones. What it feels like is there is a couple larger grit diamonds on the plate so it is gouging the stone. The finish when lapping with my Atoma #400 is much more uniform and leaves no "gouging" marks.

Would love the forums thoughts on this.

Natural stone lapped with #1200 Atoma:

Natural stone lapped with #400 Atoma (after the #1200 gouges):

 

[masibu]

if the plate is new they tend to start out much more aggressive, though im surprised the 1200 is acting that much rougher. give it some break in time and you should be sweet... my 1200 is very smooth in comparison.. it tends to stick to the stones a lot though which is annoying for lapping. tend to use the 400 or 140 more frequently

 

[mikedtran]

if the plate is new they tend to start out much more aggressive, though im surprised the 1200 is acting that much rougher. give it some break in time and you should be sweet... my 1200 is very smooth in comparison.. it tends to stick to the stones a lot though which is annoying for lapping. tend to use the 400 or 140 more frequently

It is a little hard to show now that there are some "rough" gouges, but the deeper marks seems to be associated with very particular parts of the plate.

I'm thinking these gouges won't negatively affect sharpening/polishing using this natural stone?

What I'm more concerned about is: has anyone seen this type of markings from a #1200 Atoma or is it likely a defective plate with irregular diamond grits.

I would have to agree lapping with the #400 is much more enjoyable as it doesn't stick as much.

 

[YG420]

When I lap my Jnats, I use a 150/600 diamond flattener and then go over it with another jnat close in grit to take out the scratches. I then rinse both stones very good to make sure no particles from the courser grit stone is left behind.

 

[ynot1985]

So the issue is the stones are uneven sized? Does it leave marks on the stones that reflect the irregular shaped stones/grit?

Sorry can't see from photo

 

[psfred]

Either you have a couple bits of coarser diamond on the 1200 plate, or the coarser plates do and you don't see it until you "shine up" the stone on the 1200.

Easy to find, though -- polish some thin metal to a mirror finish and pass it very lightly over the Atoma from end to end. You will see the deep scratches, so mark where they are across the end of the plate. A magic marker dot, etc will work. Polish the metal again and make a pass across the plate on one end. Mark the side of the plate, repeat until you have made a single pass with something highly polished over the whole length. Draw an imaginary line (or use a pencil point to actually draw one) for each dot to the other end or side of the Atoma. Where those line intersect, use a loupe to see if there is a larger grain of diamond there.

If there is you can pursue returning it or using something very hard to dislodge the offending coarse grain.

I doubt the scratches on the natural stone have much effect on how it works unless you are using differential grits with various naguras, in which case you may have trouble removing the coarser grit since it may stick in the scratches.

Peter

 

[Asteger]

I'm on a mobile so won't write much, but looks like you've got a layered finisher koppa you want to use the 1200 on. 1st, the Atoma will 'mellow out' and even if there's an inconsistency (seems unlikely, I don't know) it could dissipate. 2nd as we're dealing with knives, not razors, I wouldn't worry about being too precious with the stone and it should be fine for knives regardless.

 

[chinacats]

Perhaps you could lap it lightly with the 400 or 140...quick break in...I'm thinking there are a few diamonds sticking out a bit too far and a run or two on a harder surface will take the edge off.

 

[mikedtran]

Perhaps you could lap it lightly with the 400 or 140...quick break in...I'm thinking there are a few diamonds sticking out a bit too far and a run or two on a harder surface will take the edge off.

Good tip. I ran the 1200 on the back of my 400 and also ran it on a very hard very flat stone I have (Chinese natural). After that I did one very quick lap on the 400 and now it seems to no longer have the gouging issue. =)