New Spyderco bench stones, far from flat ?

[Lasse Hilbrandt]

I just recieved a medium and fine benchstone from Spyderco.

Holding the white one (the fine) up against a lightbulp I could see just with my eyes that it was bend. Holding it against my veritas straight edge I was able to freely push a 0,25mm feeler gauage between the straight edge and the stone.

The Medium was not so bad, it was bend about 0.09 mm which is still too much to my liking.

Are these stones so much out of flat that they should be returned, or is it just a matter of working them against my DMT flattening plate ?

[Allan Speers]

This is a well known thing. Spydercos are made for sharpening knives, so the factory doesn't seem very concerned about flatness.

Use a diamond lapping plate if possible. Otherwise use a diamond sharpening stone, but make very light passes, as the diamonds in lesser stones can get loosened, or something like that.

[Reinis Kanders]

I use xxcoarse plastic honeycomb dmt to initially flatten them, followed by the 600 grit red one. It can take a while if there is a lot to remove.
I still have 3x8 spyderco that had a concavity , once in a while I lap it, one day it will be flat:) It is better than having a bump though.

[Andrew Pitonyak]

I have not yet tested my fine spyderco, and I am not looking forward to flattening it; hopefully it will not need it... but I expect that it will based on experiences form others here.

[Derek Cohen]

My Medium and Ultra Fine Spydercos each took 15 minutes on 250- and 600 grit Eze-lap diamond stones.

Regards from Perth

Derek

[Mike Holbrook]

I just checked both my medium and SF Spyderco stones with my small square. Either I was just lucky or I am less concerned with "dead" flat. I figure if I do not see a gap under my square I am good to go. Maybe my aging eyes are not as good as some peoples. I don't own feeler gauges and have never felt the need for them at least for hand tools. Maybe I wore mine flat with PM-V11 plane blades?

Admittedly I am not generally concerned with extreme accuracy. I wonder if that level of accuracy is necessary for making furniture, cabinets...? Most of my plane blades have at least some camber. I seldom check chisel blades for dead flat, unless one looks "off". My question becomes what are we "sharpening" that needs to be that perfectly flat or straight? I think there have been a number of posts over the years that have suggested that there is no need for a chisel or plane blade to be dead 90 and perfectly straight.

[Mike Allen1010]

I too just got a Spyderco 3 x 8 finest grit stone.right out of the box I wasn't able to get a sharp edge until I checked the flatness. My stone also needed about 30 minutes with an Atoma plate. it's still not completely flat, but I am able to get a good edge. I'll keep working on and eventually hope to get it 100% flat.


Previously I had the three stone set from Stu, I think Sigma power stones? I really like these stones, except the finest grit (I think 13,000) was softer than I prefer (during free hand honing I was prone to gauge the stone), and I finally used it up. I'm very happy to say the Spyderco seems to be much harder and I no longer have this problem.I also have a two Shapton Pro stones comming (1000 and 5000 grit). Any suggestions about how often I should flatten the Shapton's?

With the Sigma power stones I flatten them pretty much before every use, I think that is what Stu recommended. The Shapton's seem a bit harder and I would like them to last as long as possible, so should I flatten before every use, once a day, etc.?

Thanks in advance for any advice and suggestions.

All the best,

Mike

[Mike Cherry]

Mike, I always gave the shapton a a touch up with a flattening stone before using them. You mentioned you had a 1k and a 5k coming, I have an 8k shapton I don't use anymore. Maybe we can plan another get together and I'll bring it down to let you try it out.

[Derek Cohen]

I just checked both my medium and SF Spyderco stones with my small square. Either I was just lucky or I am less concerned with "dead" flat. I figure if I do not see a gap under my square I am good to go. Maybe my aging eyes are not as good as some peoples. I don't own feeler gauges and have never felt the need for them at least for hand tools. Maybe I wore mine flat with PM-V11 plane blades? ....

I do not check for flat with feeler gauges. Instead, I squiggle pencil lines over the stone, and then lap this using a known diamond stone. This will tell me what I need to know.

Most, if not all, Spyderco stones have a hollow on one side. Turn the stone to this. It is easier to flatten than a side with a high point in the centre.

Regards from Perth

Derek

[Lasse Hilbrandt]

But how much out of flat will you guys consider too much and return it?

[Allan Speers]

But how much out of flat will you guys consider too much and return it?


Ask the retailer you bought it from. Theirs is the only answer that matters.

Maybe they can check their stock for a better one?

[Ron Brese]

Even if the stones were flat out of the box they will change pretty quickly in use. Keeping your sharpening stones flat is a fact of life if you use edge tools. Get what you need to do it, flatten the stones and get on with your work.

Ron

[Derek Cohen]

Hi Ron

The Spyderco stones move less than oilstones, I believe. Certainly, I have not seen any movement in the Medium and only the most minute amount (not nearly enough to consider out-of-flat) in the Ultra Fine over a period of about 12 months. I would, nevertheless, recommend running a 600 grit diamond stone over them every month just to remove any imbedded gunk and freshen the surface.

Regards from Perth

Derek

[Joe Tilson]

I am really glad to see this posting. A couple of years ago I posted about Spydercos not being flat and was sort of laughed at, and told they were flat from the factory. I'm glad to be proven right,and don't feel so badly, now. Thanks guys!

[Lasse Hilbrandt]

I am really glad to see this posting. A couple of years ago I posted about Spydercos not being flat and was sort of laughed at, and told they were flat from the factory. I'm glad to be proven right,and don't feel so badly, now. Thanks guys!

How did you flatten it then ?

[Lasse Hilbrandt]

I decided to try and flatten them my self. The Medium went ok with about 30 minutes work on my DMT flattening plate.
The fine one is more of a work. This is the result after 30 minutes. I think my flattening plate is close to toast.

336014

This is going to be 2 very expensive sharpening stones :(

[Reinis Kanders]

I also ruined one dmt xxfine diasharp stone on spyderco ultrafine. Afterwards I swithched to much cheaper plastic single sided honeycomb DMTs and they have lasted. They in general work well for initial flattening things because slurry does not lift them up as fast as it happens with more expensive diasharps.
Afterwards I used my DMT on 10x3 hard Arkansas stone to remove about 1/16" twist, and it still works.


I decided to try and flatten them my self. The Medium went ok with about 30 minutes work on my DMT flattening plate.
The fine one is more of a work. This is the result after 30 minutes. I think my flattening plate is close to toast.

336014

This is going to be 2 very expensive sharpening stones :(

[Lasse Hilbrandt]

The problem with anything but the DMT Dia-Flat is that the Spyderco are so long 8" that it is as long or longer than all other lapping or sharpening plates. Except the Dia-Flat which is 10"
That makes it difficult to flatten the Spyderco.

[Patrick Chase]

Has anybody tried lapping these things on SiC grit?

Once a long time ago I stripped a Dia-Flat nearly smooth by using it for initial flattening of a Sigma S-II 240. Ever since then I've lapped very coarse water- and oil-stones with loose SiC grit (ranging from #24 to #120 depending on the stone I'm flattening) on a granite surface plate, with a sacrificial laminating sheet both to protect the granite and to hold the grit in place so that it will preferentially lap the stone. Based on my past experiences with SpyderCo ceramic stones I don't see any reason why that approach wouldn't work, though I expect it would take a while (and maybe a few sheets of film).

I agree with the observation that the much ballyhooed "Diamond Hardcoat Techology" in the DMT DiaFlats (and now some of the DiaSharps) isn't all it's cracked up to be. The S-II 240 isn't *that* coarse of a stone, and my Atoma #140 handles it OK.

w.r.t. the comment about flattening 8x3 stones on 8x3 diamond plates: It's very doable. The trick is to be aware of which parts of the stone tend to be under-lapped (the ends and to a lesser degree the side edges) and focus a bit of extra effort on those as you work. If you do it enough times and keep checking your work with a straightedge you'll quickly evolve a technique that works for you. I still check every stone after flattening, but I seldom have to re-lap any more.

[george wilson]

I don't know about silicon carbide,but I can tell you that ceramic grinding belts will easily grind Arkansas slip stones that have gotten broken,into new shapes. But they will not touch a ceramic stone,being ceramic also:)

[Patrick Chase]

I don't know about silicon carbide,but I can tell you that ceramic grinding belts will easily grind Arkansas slip stones that have gotten broken,into new shapes. But they will not touch a ceramic stone,being ceramic also:)

Zirconia-Alumina ceramic (ZTA) abrasives are actually pretty soft with a Vickers hardness (HV) of 15 GPa or so. Pure zirconia ceramics are softer still at ~12 GPa, but most if not all "Zirconia" belts are actually ZTA. I wouldn't expect them to do well against a synthetic ceramic stone. Their main advantage is toughness rather than hardness.

SiC comes in at about 22 GPa, which *should* be sufficient (if marginally so, which is why I said "it would take a while").

The abrasive in Ark stones is novaculite (SiO2, quartz) which comes in at about 10 GPa. For comparison pure Al-Oxide is about 17 GPa, so it isn't surprising that a Zirconium/ZTA belt would grind an Ark stone but fail miserably against a modern engineered ceramic abrasive like Spyderco.

EDIT: Corrected the HV number for ZTA above. I'd previously used the number for pure Zirconia ceramid (12 GPa per Kyocera) instead of the one for ZTA. Different sources report HV in either Pascals (N/m^2) or kgf/mm^2. To convert kgf/mm^2 to Pascals you multiply by 9.81*10^6 (and then divide by a billion to get GPa).