Thanks. By luck that's what I have.
Lapping stones for flatness
- Thread starter trailhunter
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Thanks. By luck that's what I have.
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I have a relatively inexpensive black granite reference plate I bought at a Woodcraft store some years ago. They sell these as a work surface for sharpening chisels & plane irons, levelling plane beds or flattening waterstones, using sandpaper. Measures about 9" x 12" x 2" thick. Sourced overseas, they're 'certified' to be flat within pretty tight tolerances, and came with a mapped spec sheet with those details. Just the upper surface is graded to be perfectly flat and finished smooth; but the bottom side of it still seems to be plenty flat itself and a little more coarse in finish. Occurs to me, I could probably use that bottom side for a lapping surface if I wanted to. Wouldn't want to dish out the top of it, but the bottom side isn't so critical.
Yeah you ideally don't want a polished surface for optimal lapping, forgot to mention that. Lapping on it will pretty quickly take care of that though.
Re: using the surface plate bottom - I'd probably prefer to just get a cheap granite tile rather than risk contamination of the precision surface with loose grit particles...
Re: using the surface plate bottom - I'd probably prefer to just get a cheap granite tile rather than risk contamination of the precision surface with loose grit particles...
Just wanted to share .. whoever enjoys reading about my lil activities 
First a repost of a photo showing the bottom face of my 302UF:
Thanks Spider Co. for this "ultra fine" finish
. I am gonna leave the bottom face as is, it still cuts okay. Either face isn't mean flat. I heard about lapping with SiC powder on a granite tile, stuff which i don't have and don't wanna try anytime soon.
But i finally started lapping the 302UF top face with sandpaper. @NORTHWEST_KNIFE_GUY It's my first ambitious project with sandpaper ever go figure! The top face started glazing in the center section, while the outer sections weren't:
Others used 3M Wetordry SiC sandpaper, i used MATADOR 991A Wetordry SiC sandpaper (by STARCKE, made in gemani), of which i bought grit rating ranging only from P360 to ST5000, that's 12 stages! I mounted a small glass plate with double-sided adhesive tape (carpet tape) on the green cutting mat and then placed a dry sandpaper sheet on the dry glass plate, wetted the sheet with a splash of soapy water, and started the sanding (lapping). There is no need to fix/secure the sandpaper on the glass plate; the sandpaper stays in place, once its back side is wet, too.
I started the lapping with P800. Worked well to sand down the raised lines of the machining marks. As expected the glazed center section was the dished section regarding mean flatness. And the more i had to sand down, the slower got the progress. So i switched to P600, then to P500, then to P400, and finally to P360. I spent hours with P360 and am still not done: the dished section has become smaller (progress!) but it is still there with its pseudo-glazed finish.
I am hopeful though that with 2 more days i should reach the bottom of the dish, at which point i will have created a mean flat 302UF top face. Practical tip: Don't use a marker (Sharpie, Edding, etc) for drawing a grid on the face but use a pencil. The pencil lines don't dissolve with the soapy water and they don't penetrate the stone surface. And they're easier to clean later (with an eraser), if needed.
Now here comes the surprise
The P360-sanded sections are by now even more glazed (and "mean smoother") than the dished pseudo-glazed section! And i am loving it, mwuah!!
Because the purpose of my lapping efforts is the creation of a uniformly superfine stone finish with mean flatness, and possibly with no more evidence of machining marks. The latter isn't really important: if i get a mean flat 302UF surface which is uniformly superfine (i.e. much finer than the original 302UF finish) as in "glazingly fine", then it's mission accomplished ("302UUF") and i'll move on.
I did a few quick tests. The even more glazed surface still cuts, can create a burr (with sufficient pressure during sharpening), and mirror-polishes nicely, not perfectly but finer than the Degussit DD57UF. I'll have to test the performance and usefulness of 302UUF more, once i have completed the lapping.
Looks like i don't need a higher/finer grit than P360, that also comes as a surprise, lesson learned (experience gained). Well, once i have reached mean flatness, i'll go up the ladder (P400, 500, 600, etc) anyway to see/learn what difference that makes. Maybe i'll end up with a mirror polished finish on the 302UUF haha.
Stay tuned for updates on my progress with this Spyderco ceramics lapping project
First a repost of a photo showing the bottom face of my 302UF:
Thanks Spider Co. for this "ultra fine" finish
. I am gonna leave the bottom face as is, it still cuts okay. Either face isn't mean flat. I heard about lapping with SiC powder on a granite tile, stuff which i don't have and don't wanna try anytime soon.But i finally started lapping the 302UF top face with sandpaper. @NORTHWEST_KNIFE_GUY It's my first ambitious project with sandpaper ever go figure! The top face started glazing in the center section, while the outer sections weren't:
Others used 3M Wetordry SiC sandpaper, i used MATADOR 991A Wetordry SiC sandpaper (by STARCKE, made in gemani), of which i bought grit rating ranging only from P360 to ST5000, that's 12 stages! I mounted a small glass plate with double-sided adhesive tape (carpet tape) on the green cutting mat and then placed a dry sandpaper sheet on the dry glass plate, wetted the sheet with a splash of soapy water, and started the sanding (lapping). There is no need to fix/secure the sandpaper on the glass plate; the sandpaper stays in place, once its back side is wet, too.
I started the lapping with P800. Worked well to sand down the raised lines of the machining marks. As expected the glazed center section was the dished section regarding mean flatness. And the more i had to sand down, the slower got the progress. So i switched to P600, then to P500, then to P400, and finally to P360. I spent hours with P360
and am still not done: the dished section has become smaller (progress!) but it is still there with its pseudo-glazed finish.
I am hopeful though that with 2 more days i should reach the bottom of the dish, at which point i will have created a mean flat 302UF top face. Practical tip: Don't use a marker (Sharpie, Edding, etc) for drawing a grid on the face but use a pencil. The pencil lines don't dissolve with the soapy water and they don't penetrate the stone surface. And they're easier to clean later (with an eraser), if needed.
Now here comes the surprise
The P360-sanded sections are by now even more glazed (and "mean smoother") than the dished pseudo-glazed section!
And i am loving it, mwuah!! Because the purpose of my lapping efforts is the creation of a uniformly superfine stone finish with mean flatness, and possibly with no more evidence of machining marks. The latter isn't really important: if i get a mean flat 302UF surface which is uniformly superfine (i.e. much finer than the original 302UF finish) as in "glazingly fine", then it's mission accomplished ("302UUF") and i'll move on.I did a few quick tests. The even more glazed surface still cuts, can create a burr (with sufficient pressure during sharpening), and mirror-polishes nicely, not perfectly but finer than the Degussit DD57UF. I'll have to test the performance and usefulness of 302UUF more, once i have completed the lapping.
Looks like i don't need a higher/finer grit than P360, that also comes as a surprise, lesson learned (experience gained).
Well, once i have reached mean flatness, i'll go up the ladder (P400, 500, 600, etc) anyway to see/learn what difference that makes. Maybe i'll end up with a mirror polished finish on the 302UUF haha. Stay tuned for updates on my progress with this Spyderco ceramics lapping project
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- Joined
- Mar 8, 2008
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- 25,507
Just wanted to share .. whoever enjoys reading about my lil activities
First a repost of a photo showing the bottom face of my 302UF:
Thanks Spider Co. for this "ultra fine" finish
But i finally started lapping the 302UF top face with sandpaper. @NORTHWEST_KNIFE_GUY It's my first ambitious project with sandpaper ever go figure! The top face started glazing in the center section, while the outer sections weren't:
Others used 3M Wetordry SiC sandpaper, i used MATADOR 991A Wetordry SiC sandpaper (by STARCKE, made in gemani), of which i bought grit rating ranging only from P360 to ST5000, that's 12 stages! I mounted a small glass plate with double-sided adhesive tape (carpet tape) on the green cutting mat and then placed a dry sandpaper sheet on the dry glass plate, wetted the sheet with a splash of soapy water, and started the sanding (lapping). There is no need to fix/secure the sandpaper on the glass plate; the sandpaper stays in place, once its back side is wet, too.
I started the lapping with P800. Worked well to sand down the raised lines of the machining marks. As expected the glazed center section was the dished section regarding mean flatness. And the more i had to sand down, the slower got the progress. So i switched to P600, then to P500, then to P400, and finally to P360. I spent hours with P360
I am hopeful though that with 2 more days i should reach the bottom of the dish, at which point i will have created a mean flat 302UF top face. Practical tip: Don't use a marker (Sharpie, Edding, etc) for drawing a grid on the face but use a pencil. The pencil lines don't dissolve with the soapy water and they don't penetrate the stone surface. And they're easier to clean later (with an eraser), if needed.
Now here comes the surprise
The P360-sanded sections are by now even more glazed (and "mean smoother") than the dished pseudo-glazed section!
I did a few quick tests. The even more glazed surface still cuts, can create a burr (with sufficient pressure during sharpening), and mirror-polishes nicely, not perfectly but finer than the Degussit DD57UF. I'll have to test the performance and usefulness of 302UUF more, once i have completed the lapping.
Looks like i don't need a higher/finer grit than P360, that also comes as a surprise, lesson learned (experience gained).
Stay tuned for updates on my progress with this Spyderco ceramics lapping project
Glazing is bad. Glazing means the abrasive grains are blunted, and are burnishing (rubbing) rather than cutting, and the extremely hard surface means that if you aren't getting effective cutting you'll be very prone to putting a rolled over burr on your edges. Without actually seeing it I can't be sure if what you're getting is actually glazing or if you're just using it to refer to the surface finish of the stone, but you don't want a glazed surface on any stone. It's not in any way a positive trait.
Don't confuse sandpaper with loose grit on a flat surface. The two have nothing in common, one works for lapping, the other doesn't, as you are finding out. Yes, I have tried both. I have also found sandpaper will wear the outer edges of what you are trying to flatten more than the center.
- Joined
- Mar 8, 2008
- Messages
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The difference between three-body abrasion and two-body abrasion for lapping is so huge that when I first tried the loose grit method I literally face-palmed thinking of all the time I'd wasted using diamond plates in the past.
The afore pictured 302UF bottom face, there is no way that i would treat it with SiC sandpaper; the Spyderco machining marks are just too much my sandpaper could handle, i totally agree. When i lap that face in distant future, I'll gratefully try the 3-body abrasion, no prob. I'm confident that SiC powder rolling will knock down the peaks and everything else of those marks (including the machining grooves) efficiently.
But with the 302UF top face I'm after a mirror-like shiny finish ("glazed", "302UUF"). Such a slow-cutting surface will be useful for mirror-polishing steel parts, leaving a finer finish than the original 302UF (or 204UF for that matter).
I do believe you all that 3-body abrasion is more efficient and leaves a fast-cutting mean flat matt surface. M Mr.Wizard documented it in detailed photos. I'm just saying that i want a shiny reflective finish (mwuah! :-*) for the top face, and i can get there with my sandpaper sequence ("polishing"). I am concerned about the Spyderco machining grooves, my sandpaper method can't get to them in an acceptable time frame. So, out of curiosity, i might call up local companies who would be able to polish to mirror, getting rid of the machining grooves. In the Yellow Pages book i found three potential categories: "Marmor", "Naturstein", "Steinmetzbetriebe". Wondering about their price for mirror-polishing 1 face of 302UF
Btw does a mirror-polished finish on a Spyderco UF qualify as "glazed"?
, there is no way that i would treat it with SiC sandpaper; the Spyderco machining marks are just too much my sandpaper could handle, i totally agree. When i lap that face in distant future, I'll gratefully try the 3-body abrasion, no prob. I'm confident that SiC powder rolling will knock down the peaks and everything else of those marks (including the machining grooves) efficiently.But with the 302UF top face I'm after a mirror-like shiny finish ("glazed", "302UUF"). Such a slow-cutting surface will be useful for mirror-polishing steel parts, leaving a finer finish than the original 302UF (or 204UF for that matter).
I do believe you all that 3-body abrasion is more efficient and leaves a fast-cutting mean flat matt surface. M Mr.Wizard documented it in detailed photos. I'm just saying that i want a shiny reflective finish (mwuah! :-*) for the top face, and i can get there with my sandpaper sequence ("polishing")
. I am concerned about the Spyderco machining grooves, my sandpaper method can't get to them in an acceptable time frame. So, out of curiosity, i might call up local companies who would be able to polish to mirror, getting rid of the machining grooves. In the Yellow Pages book i found three potential categories: "Marmor", "Naturstein", "Steinmetzbetriebe". Wondering about their price for mirror-polishing 1 face of 302UF Btw does a mirror-polished finish on a Spyderco UF qualify as "glazed"?
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I spent hours with P360
Looks like i don't need a higher/finer grit than P360, that also comes as a surprise, lesson learned (experience gained).
Some 60 mesh SiC would have taken care of the initial flattening in minutes. The grit penetration depth on these hard dense stones is low so as you learned the finish produced is much finer than the grit used. Have you read this by the way? https://www.bladeforums.com/threads/condition-ceramic-stone.1644099/
I had the same experience. Actually twice, as I kept using a DMT XC for flattening my Edge Pro stones F320 and finer because it was more convenient; I was shocked when I realized how much better and more consistently they performed after free grit conditioning.
It is my understanding that hard ceramics are not ground by chip cutting but rather by microfracture through point pressure, and that rolling free grit keeps new sharp points impacting the stone.
I do believe you all that 3-body abrasion is more efficient and leaves a fast-cutting mean flat matt surface. M Mr.Wizard documented it in detailed photos. I'm just saying that i want a shiny reflective finish (mwuah! :-*) for the top face, and i can get there with my sandpaper sequence ("polishing")
Does a mirror-polished finish on a Spyderco UF qualify as "glazed"?
Yes, you can get a polished finish with three-body lapping! You really need to try this.
Take a look at "rock tumbling" for some example results.Regarding glazing, what you want to avoid is a blunted surface, like river cobbles. Instead you want high roughness at an extremely small scale. This is the point of modern seeded gel "ceramic" abrasives; under the right conditions they fracture at the grain boundaries producing micro-roughness rather than wearing into smooth plateaus. Three-body lapping is helpful here as the rolling and fracturing particles keep sharp points impacting the stone.
Chemical etching may be the superior conditioning method, applied after polishing. I suspect this may be the factory finish on my Idahone Rod. I have not tried this because I am uncomfortable using such strong chemicals, but the results should be excellent. For example https://pulpdent.uk/produits/porcelain-etch-gel/
(500X SEM)
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i will i will. for the bottom face of my stone. i still want to finish the top face with sandpaper, because i need it as reference and comparison purposes.
M Mr.Wizard so what went wrong with your SiC grit rolling treatment of your two rubies? you got lower results, something which you hadn't expected in the first place.
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Nothing, actually. I got these to experiment with harder stones after reading about the doubled-angle deburring method. I wondered if the stones I had were a bit soft for that compared to traditional oil stones. I never tried to polish these as I wanted edges with some tooth. What surprised me about these under magnification was the amount of pitting and the relatively large grain. By feel alone I had thought that aside from a few inclusions these were finer/denser than that, but since it didn't matter for my application I never checked. In fairness they only call them "3000" out of a series up to "10000" I think. I ordered one of the "10000 agate" stones at the same time but it arrived broken; the pieces did not appear to be good enough quality for me to reorder.
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Your finish is probably getting very shiny with even the low grit sandpaper because you are glazing the sandpaper! This is one of the great benefits of using loose grit. You can regularly refresh with a smidge more sharp grit and keep the cutting going rather than the rubbing that occurs with dull grit.
And you absolutely can get a very shiny glossy finish with loose grit. Using SiC it will get finer and finer the longer you use the grit without refreshing. Thus shinier and shinier. However this will tend to get you that glazed surface. If this is what you're looking for, that is how to get there.
At the end of the lapping process I prefer to refresh the grit several times within a minute or two, so as to keep the cutting action sharp and rapid. Use a fine grit and you will still get a very fine surface but it will still cut well rather than just rubbing like a glazed surface will. A glazed surface is bad because sharpening with it will be mostly a rubbing action that leads to plastic deformation and major burr formation. This will usually result in a burr that flops back and forth as you sharpen and a weak apex that will easily chip and break.
And you absolutely can get a very shiny glossy finish with loose grit. Using SiC it will get finer and finer the longer you use the grit without refreshing. Thus shinier and shinier. However this will tend to get you that glazed surface. If this is what you're looking for, that is how to get there.
At the end of the lapping process I prefer to refresh the grit several times within a minute or two, so as to keep the cutting action sharp and rapid. Use a fine grit and you will still get a very fine surface but it will still cut well rather than just rubbing like a glazed surface will. A glazed surface is bad because sharpening with it will be mostly a rubbing action that leads to plastic deformation and major burr formation. This will usually result in a burr that flops back and forth as you sharpen and a weak apex that will easily chip and break.
Hmm interesting. (just repeating, a glazed surface leaves a finer mirror polish on the steel face, say an AA-battery bottom; works great as a mirror-polishing stone, more likable than the chinese WHITE10000 or GREEN10000 emerald stones)
Anyway i made a few calls in the Yellow Pages, and i should have a usable granite tile soon from a local mason.
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K
kreisler
done for you: https://www.bladeforums.com/threads/stone-photos-chinese-ruby-and-idahone.1707538/#post-19511754
Is it cutting or burnishing?
Is it cutting or burnishing?
It is burnishing then all right.ldoceonline.com said:
Technically the surface still cuts M Mr.Wizard . One can see the micro scratch marks by the stone on the mirror-like steel finish, so the stone is still cutting into the steel and abrading steel particles. The micro scratches are best viewed if they're all in one orientation, i.e. not created through circular rubbing motions.
I meant burnishing in the more technical sense: "To smooth or polish by a rolling or sliding tool under pressure." The stone could leave marks without cutting by way of plowing or impressioning; think of how rolled knurling is applied. Does the stone turn dark from swarf as you use it, and how quickly?
oic then the verb "burnishing" would not apply to UUF's effect imho. i understand your concept, the stone could slide over the steel surface, making it microscopically smoother, without actually abrading fresh steel particles out of the steel surface aha. nah that's not the case. The UUF turns dark from swarf yes; slowly or fast depends on the fineness of the steel scratch pattern when you start with the UUF stage. If the scratch pattern at the start is very fine (like from DD57UF), then it takes some time until you notice the swarf on the UUF.
DD57UF cuts well. UUF cuts but very slowly.
I think with ideal surface conditioning of the "UUF" it would darken almost as fast as the Degussit. Even if the volume of metal removed is less, if the particles are thinner they would still cover the surface.
I am wondering if a DMT F, a DMT XF, and a DMT XXF could be used to flatten (lapping) and to refine the Spyderco UF ceramics surface. Would one achieve a mirror-like polished finish (actually glazed or not, doesn't matter to me) after the DMT XXF?
With enough time investment it should be possible to use a DMT F (instead of a DMT C) for the flattening step imho? And with even more time investment it should be possible to do the entire lapping with a DMT XF? That should avoid gouge lines produced by the DMT diamonds, i believe.
The Spyderco UF finish (the 302UF that is) consists of machining marks of two types: narrowly spaced raised peak lines (which do the cutting, obviously) AND less narrowly spaced thin grooves (which do nothing but are just ugly leftovers from the machining marks). the thin grooves are actually easier to see in daylight than the raised peak lines. A thorough lapping would get rid of both types and leave an absolutely uniform smooth finish (as seen on a Degussit DD57F exfac).
If the DMT F leaves gouge lines, then it's nothing a subsequent XF could fix. Lapping with such highquality DMT plates sounds more convenient to me than buying several plastic bags à 1.0kg of SiC powder loose grit (15€/1kg) and perform the 3-body abrasion. I don't mind the time investment and i don't mind the cutting performance of the resurfaced 302UF. Maybe nobody tried lapping 302UF with DMT XF before .. Anyone?
relevant DMT product codes: W250EFNB, W250EF-WB, D8EE
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Once you try lapping with loose abrasive you will understand. It is something words alone can not convey. You don't need very many grit sizes since as eKretz said it will break down into smaller grits as you use it. This is how a manufacturer does it, they start with a single grit feed stock, grind it down and separate it into the different grits they sell.
The "3 plate method" is using 3 plates of the same material and size to lap together rotating which 2 plates are used for each lapping to maintain flatness of the three plates. If you use one plate, your stone, and a flat, your granite tile or such, the flat will get dished out and your stone will take on that shape as you lap it. Most of us will just get another flat plate to replace the one that is dished, myself included.
The "3 plate method" is using 3 plates of the same material and size to lap together rotating which 2 plates are used for each lapping to maintain flatness of the three plates. If you use one plate, your stone, and a flat, your granite tile or such, the flat will get dished out and your stone will take on that shape as you lap it. Most of us will just get another flat plate to replace the one that is dished, myself included.
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