Thread: Flattening stones

Now I went and checked my DMT for flatness and it looks as if there is an even gap running the length of it. Do you think this is because of the arrangement of the diamonds, and when I put a straight edge against it, it appears that way? or simply because it's not flat?!

I put the straight edge to one of my 10mm pieces of float glass and I couldn't see light running through. Am I being super anal or should I start using 220 grit on my what seems to be super flat glass?

The diamond plate is definetly not flat. I had a better look today and I can easily slide sandpaper under the straight edge.

I know DMT plates have a reputation for sometimes not being flat- has anyone experienced this, and how did you return it? - dmt directly, or where you bought it from?

Andy

Can't say that I have ever returned a stone of any kind. In theory, the first port of call would be the retailer you bought it from then probably the manufacturer. However, we all know from experience that unless you just bought this last week, the retailer will most likely deflect the problem back on to the manufacturer.

From the DMT FAQ:

What is the warranty on your sharpeners?

The DMT® Commitment:
For over thirty years, DMT® has been committed to one thing: to innovate and produce the world’s finest diamond knife and tool sharpeners. All DMT® products are made using the highest quality materials and workmanship and are guaranteed to be free of defects. Any product found to be defective, will be replaced free of charge – it’s that simple!

My sharpener doesn’t seem to be flat enough, how flat should the sharpener be?

DMT® sharpeners are very, very flat. The DuoSharp® models are engineered to be precision flat – incomparable to any other sharpening stone on the market today. However, if you are concerned that your sharpener is not flat enough for your application, send it back to us for evaluation. Please send it to

DMT® Customer Service
85 Hayes Memorial Drive
Marlborough, MA 01752

I would never attempt to flatten a stone with a diamond plate that is the same size or smaller than the stone - which is why I bought 10" DMTs.

Think about what is happening as the end of the diamond plate goes up the surface of the stone. If the stone was dished to start with (which is presumably why you want to flatten it....), a smaller diamond plate will simply maintain that dishing or take a long time to gradually reduce it to zero.

When using a 10" DMT I'm careful to ensure that the entire surface of the stone being flattened stays on the surface of the DMT at all times, and the stones come out perfectly flat every time.

I'd draw some pictures to illustrate this, but frankly I can't be badgered.....

Originally Posted by Mr Brush

I would never attempt to flatten a stone with a diamond plate that is the same size or smaller than the stone - which is why I bought 10" DMTs.

Think about what is happening as the end of the diamond plate goes up the surface of the stone. If the stone was dished to start with (which is presumably why you want to flatten it....), a smaller diamond plate will simply maintain that dishing or take a long time to gradually reduce it to zero.

When using a 10" DMT I'm careful to ensure that the entire surface of the stone being flattened stays on the surface of the DMT at all times, and the stones come out perfectly flat every time.

I'd draw some pictures to illustrate this, but frankly I can't be badgered.....

I wanted a 10" but carbatec had none in stock. I have seen Stu flatten his stones with his Atoma plate which is the same size as his stone, which is why I settled for the 8". There is a technique to it and it can be done, just not with a dished plate!

I now use a piece of 10mm thick glass (a bit bigger than the 10" DMT) with sandpaper and it works perfectly. No light shines through now.

Andy

Funny, I've never used anything other than diamond plates equal to or smaller than the stone, and never noticed any undue delays in getting the stones flat, nor the stones being anything other than flat enough where I can't find the error, if that error even exists.

Please, do find the time to explain this more completely. I'm eager to know why what I'm actually doing myself with a 100% success rate can't possibly work, or is somehow inadequate.

The only time I actually verify the stone is dead flat nowadays is when the video camera is running. Each time I actually do this, I'm not worried that the stone is going to make me look like a fool and be unflat, I do the check with absolute confidence.

I'm all for hashing out theories and debating them to death. The problem is this one has too much evidence against it, documented and repeatable evidence no less, that I'm kind of disappointed it's been trotted out for display again.

Sorry.

Stu.

Both methods will get there in the end, but the attached doodle may give pause for thought....

DMT just came out with a coarse plate specifically for flattening stones (Chris Schwartz et al have given it rave reviews....). They only made it in one size....

Dia-Flat™ Lapping Plate | DMT® - Diamond Machining Technology

Originally Posted by Mr Brush

Both methods will get there in the end, but the attached doodle may give pause for thought....

No, it doesn't. No pause at all.

The problem is that your little drawing doesn't reflect what actually happens. There's another variable in the equation your drawing does not acknowledge at all...

I am also fully aware of the DMT flattening plate, and I'm not that impressed with it. I'd dearly love to have one for testing, but since they'll never give me one and I'll never part with the money to buy one, that's never going to happen.

(I also have somewhat less faith in what Chris Schwarz says than you do. I'm seeing that from an entirely different angle though, so don't let my judgement sway your faith at all.)

Now, the serious problem we have here is that in the next couple weeks I'm going to be making a video explaining how to get your stones flat (one of a series of sharpening videos). That big DMT won't be included, nor will the Shapton variants. Too much money, no measurable or quantifiable improvement over less expensive, easier to procure methods.

And that's how it is. I'm really sorry you don't believe it and are clinging to the concept that it is essential to have a larger 'thing' to flatten a smaller 'thing'. If I had no experience in the matter, I'd likely agree with you and back you up 100%. But I have 5 different diamond plates from 4 different makers, all smaller than the stones they flatten and they work just fine without any more effort than a rub-rub-rub-done. No special techniques, no question of the flatness achieved on the stones.

I'm sorry. I know I won't change your opinion on the matter, which is slightly distressing but there's really nothing more to say. The smaller plates work, so long as they're actually flat.

Stu.

(If a significantly larger plate was so much more effective than the smaller ones, don't you think I'd be screaming at the folks I know here who make the dang things for something bigger? As it is, I am working on something new, and that it might end up bigger than normal is an side effect of the design, and absolutely not a prime consideration. Interestingly, the primary concerns I have are something DMT chose to completely ignore and also why your drawing is perfect in theory, but doesn't translate to reality... )

Sorry Schtoo, I was forgetting that you're always right.

You stick with your method, I'll stick with mine, and we'll get along just fine.

Originally Posted by Mr Brush

Sorry Schtoo, I was forgetting that you're always right.

I wish I was always right.

I do freely admit I don't know everything, but if there is something I don't know, I either do testing to discover the truth or I ask folks I can trust who can give the me the answer. If I can't get that answer and be able to trust it 100%, I keep my mouth shut and hands off the keys. I can't afford to put stuff out there that 'might' work, not in my position.

I am quite disappointed that you've had to resort to the above comment though.


And I think this is good bye. I don't think I'll be back any time soon. It's things like the above exchange that I know shouldn't affect me as much as they do, but it's the fear that I've become boorish, obnoxious and "always right" that affects me more than anything else. If I get to that point, or even suspect I've reached that point, then I need to walk away and stay away.

I go to extreme efforts to make sure anything I say is backed up by verifiable evidence that can be replicated by anyone who cares to try it for themselves, but apparently that does mean that when I do mention something, it does tend to be correct and repeatable.

If that comes off as some kind of superiority complex, I'm sorry and will leave you all to it.

Good luck, and most of you know where to find me if I'm needed, but I won't be back here again.

Stu.

I'll be sad to see you go Stu, please don't do that.

Cheers
Michael

Originally Posted by mic-d

I'll be sad to see you go Stu, please don't do that.

Cheers
Michael

I agree and do value your opinion so it would be nice if you stayed with us.

Cheers

It'd be a terrible shame if you were to leave, Stu, your contributions have helped me out immensely over the last six months as I've slowly started this hobby. As, incidentally, have Mr Brush's. I'm sure I'm not alone with either case.

I don't mean to trivialise the hobby or profession (really). And I don't mean to suggest that it's ever illegitimate to hold or express strong views about a particular topic.

But what we're arguing about is how to flatten a rock with another rock. Can't we lighten up a little?

What I've found highly unusual about this forum from the start is the tone of mutual respect and civility that members take with one another. In my experience, most internet forums are completely feral. (Not sure why. The anonymity? The lack of paralinguistic communication? Something about the flickering lights?).

But in the short time I've been here, this forum has absolutely been the strict exception.

Now, I don't know a thing about either of you, and I never will. But I'm guessing that neither of you set out to insult the other, patronise their opinions, or generally p*ss each other off for the sake of it. You've evidently both managed that, of course, but it wasn't your intention. Please correct me if I'm wrong here.

So, PLEASE let's resolve this in an amicable, adult fashion.

Or, just sort it out Mad Max Thunderdome style, I don't care.

Either way, I hope I can speak for the rest of the community when I say that we greatly value the input from both of you, and would be greatly saddened if either of you were to leave.

What do you think, Mr Brush?

(Oh, and Stu, don't just think of the community, think of yourself! Imagine how many more pointless emails I'll have to send you if you don't use the forum! )

Stu,

What Eddie said!

I have a Dia-Flat ordered. It is currently en-route. I know there are lots of ways to flatten stones that are cheaper. I'm just fed up with the hassles. Sharpening is a means to an end for me.

Anyway, Amazon are doing a pretty good price on them. Far cheaper than anybody else at the moment.

I will check in later with a report when I get and test it.