Which grade of Diamond plate for final honing

[Bluekingfisher]

Can anyone recommend a diamond plate for final honing of plane & chisel blades please.

I have a 400 & 1000 grit stone but consider the 1000 grit still too course for final blade honing. If you can recommend a brand or particular type that would be appreciated too.

I am not interested in oil, water or ceramic stones.

Many thanks

David

 

[Paul Chapman]

Diamond stones are not available in a fine enough grit for final honing. Best to finish with a block of wood and diamond paste or Autosol and oil



Cheers :wink:

Paul

 

[Cheshirechappie]

I think there may be a slight difference in the way diamond stones work when compared to - say - waterstones. The diamonds are held in a matrix such that they are immovable, and act like a large number of small cutting tools, shaving bits off the workpiece. Waterstones act more by having moving particles rolling around on their surfaces in a slurry of water, acting with rather more a burnishing, polishing action - as much deforming the peaks of the irregularities on the workpiece surface into the troughs on it as cutting bits of it off. Hence the 'finish' from a waterstone (or some fine natural stones) is smoother and more polished than from a fixed-matrix diamond stone. Fixing very small diamonds in a matrix is difficult, hence there are no diamond 'polishing' stones.

Paul's right, I think - release the smaller diamonds so that they act more like rolling polishers on a strop, and they'll give a much better finish.

 

[Bluekingfisher]

Ah, thanks fellahs, that makes perfect sense.

You've both been very helpful.

Btw - Nice tip with the Autosol Paul.

David

 

[gasman]

Autosol on MDF works very well too

 

[woodbrains]

I think there may be a slight difference in the way diamond stones work when compared to - say - waterstones. The diamonds are held in a matrix such that they are immovable, and act like a large number of small cutting tools, shaving bits off the workpiece. Waterstones act more by having moving particles rolling around on their surfaces in a slurry of water, acting with rather more a burnishing, polishing action - as much deforming the peaks of the irregularities on the workpiece surface into the troughs on it as cutting bits of it off. Hence the 'finish' from a waterstone (or some fine natural stones) is smoother and more polished than from a fixed-matrix diamond stone. Fixing very small diamonds in a matrix is difficult, hence there are no diamond polishing stones.

Hello,

I don't think the reason diamonds stones are different than waterstones is quite like this. Waterstones do actually cut in the main. Fraible nature exposes new, sharp, cutting particles and the slurry contains lots of finer broken abrasive, which all cut. The difference is due to 'point count'. There are a lot less diamonds per surface area than the abrasive found in waterstones, so the scratch pattern is much further apart, even if the particle size is the same. DMT actually make a 10000 diamond plate, which is very fine, but he particles are less tightly packed than those in the equivalent water or oil stone, so do not appear to give as fine an edge. I have been dipping in and out of researching polishing metals and I am getting the impression that the lower point count in diamond stones actually cause sub surface damage to the steel, resulting in earlier edge failure of the tool. When I get more time and if I ever get some spare cash to splash out on a 10000 diamond plate, I will do a comparison between it, Japanese waterstone and Arkansas oilstone.

I have used chromium oxide on leather or mdf, which works very well. Japanese stones taken to a fine enough degree, do away with that stropping stage altogether, though.

Mike.

 

[JustBen]

Didn't Paul Sellers do a video showing that honing/sharpening above 1000g or so makes very little difference to how a blade cuts?

Will see if I can find the link.

Here it is. Sorry it's 250 grit not 1000 grit.

http://youtu.be/UbAo4RpM7oM

 

[woodbrains]

Hello,

Abrasives are measures in lots of different conventions, so are not directly comparable. The European, Japanese and American systems are not the same, be we get things from all over the world now, so you have to be careful which abrasive is being used.

250 grit in any convention is blooming coarse though. The best thing to do is try sharpening(?) at 250 and then at the finest stone you have available and see if there is a difference. I guarantee there is a significant difference and Paul Sellers is talking some tripe there.

Mike.

 

[JustBen]

Hello,

Abrasives are measures in lots of different conventions, so are not directly comparable. The European, Japanese and American systems are not the same, be we get things from all over the world now, so you have to be careful which abrasive is being used.

250 grit in any convention is blooming coarse though. The best thing to do is try sharpening(?) at 250 and then at the finest stone you have available and see if there is a difference. I guarantee there is a significant difference and Paul Sellers is talking some tripe there.

Mike.

????
He just demonstrated that it works fine.

And even if there was a difference, if an old man can't feel the difference (someone who is more likely feel it with ageing bones and muscles), is the extra time/cost worth worrying about?

 

[Paul Chapman]

Didn't Paul Sellers do a video showing that honing/sharpening above 1000g or so makes very little difference to how a blade cuts?

Will see if I can find the link.

Here it is. Sorry it's 250 grit not 1000 grit.

http://youtu.be/UbAo4RpM7oM

I think that video is very misleading. Almost any level of honing would be OK if you just use mild-grained softwood as shown in the video. A more demanding timber would require a far sharper blade.

Cheers :wink:

Paul

 

[David C]

This video is both self contradictory and misleading.

The fine side of Paul's old Norton stone was 400 grit. Why does he now sharpen with 3 diamond stones and a strop?

A strop was certainly used by many cabinetmakers in the days of oil stones. Why? Because their fine stones were not fine enough.

As Paul Chapman mentions, he chooses to demonstrate with rather superior pine, instead of difficult interlocked hardwood such as quartered Sapele.

I started with the dreaded fine/coarse India stone. Arkansas stones were significantly better and When Japanese waterstones arrived here they were a revalation, being significantly better again.

15, thousand grit is getting to a point that only specialists will appreciate. 8 & 10 thousand grit produce a wonderful edge.

I sharpen with two stones. 8oo King and 10,000 King. No stropping required with stones as fine as these.

There is no way I am going to sharpen my plane blades with 250 grit.

Another point not mentioned is that finer grits produce edges which last longer.

David Charlesworth

 

[Cheshirechappie]

I think there may be a slight difference in the way diamond stones work when compared to - say - waterstones. The diamonds are held in a matrix such that they are immovable, and act like a large number of small cutting tools, shaving bits off the workpiece. Waterstones act more by having moving particles rolling around on their surfaces in a slurry of water, acting with rather more a burnishing, polishing action - as much deforming the peaks of the irregularities on the workpiece surface into the troughs on it as cutting bits of it off. Hence the 'finish' from a waterstone (or some fine natural stones) is smoother and more polished than from a fixed-matrix diamond stone. Fixing very small diamonds in a matrix is difficult, hence there are no diamond polishing stones.

Hello,

I don't think the reason diamonds stones are different than waterstones is quite like this. Waterstones do actually cut in the main. Fraible nature exposes new, sharp, cutting particles and the slurry contains lots of finer broken abrasive, which all cut. The difference is due to 'point count'. There are a lot less diamonds per surface area than the abrasive found in waterstones, so the scratch pattern is much further apart, even if the particle size is the same. DMT actually make a 10000 diamond plate, which is very fine, but he particles are less tightly packed than those in the equivalent water or oil stone, so do not appear to give as fine an edge. I have been dipping in and out of researching polishing metals and I am getting the impression that the lower point count in diamond stones actually cause sub surface damage to the steel, resulting in earlier edge failure of the tool. When I get more time and if I ever get some spare cash to splash out on a 10000 diamond plate, I will do a comparison between it, Japanese waterstone and Arkansas oilstone.

I have used chromium oxide on leather or mdf, which works very well. Japanese stones taken to a fine enough degree, do away with that stropping stage altogether, though.

Mike.

Interesting stuff, Mike! By the sounds of it, your research is more advanced than mine. Certainly, the density of cutting edges - 'point count' - does sound like a significant factor, though I'd stick by my suggestion of a 'rolling' particle having a more burnishing than cutting effect. The overall picture is obviously more complex, with some abrasive systems being a combination of the two, and some being biased more to either cutting or burnishing.

I look forward to your posting more of your findings, when you feel able and willing. I think several of the other regulars expressed interest in the 'why it works' of honing and sharpening, as well as the 'how to do it'.

 

[awkwood]

I bought a DMT 4000 grit plate
It is good for honing an edge for normal use. The edge would need a strop to produce a mirror polish, but that isn't required for a lot of my work

 

[JustBen]

Didn't Paul Sellers do a video showing that honing/sharpening above 1000g or so makes very little difference to how a blade cuts?

Will see if I can find the link.

Here it is. Sorry it's 250 grit not 1000 grit.

http://youtu.be/UbAo4RpM7oM

I think that video is very misleading. Almost any level of honing would be OK if you just use mild-grained softwood as shown in the video. A more demanding timber would require a far sharper blade.

Cheers :wink:

Paul

I though I would try it.

Just sharpened 2 irons to 300 and 1000 (that's all I've got on my diamond stone)
Planed up some oak, walnut and beech inc end grain and can honestly say I felt very little difference.
Both cut well.

 

[Cheshirechappie]

Didn't Paul Sellers do a video showing that honing/sharpening above 1000g or so makes very little difference to how a blade cuts?

Will see if I can find the link.

Here it is. Sorry it's 250 grit not 1000 grit.

http://youtu.be/UbAo4RpM7oM

I'm afraid I'm going to add to the head-shaking and tooth-sucking.

Sharpening to 'fine India' is OK for jack-plane and try-plane work in dimensioning stock, but for finish smoothing and final fitting, something better is needed. I'd agree with him that going to 25,000 grit is over-egging it, but something like a Welsh slate (about 8000 grit), black Arkansas or at the very least stropping with a fine abrasive such as Chromium oxide is what you need to smooth wood consistently to a decent standard, unless you are prepared to spend a long time with cabinet scrapers and progressively finer abrasive papers.

I may have misheard, but at one point he said that his 15,000 grit planed surface was 'too smooth', and he'd have to roughen it up a bit to get a finish to adhere. He is entitled to his opinion and his way of working, of course, but I'm afraid I just don't agree with this at all. The better the finish from the plane, the better the lustre in the final finish, generally.

 

[Paul Chapman]

I though I would try it.

Just sharpened 2 irons to 300 and 1000 (that's all I've got on my diamond stone)
Planed up some oak, walnut and beech inc end grain and can honestly say I felt very little difference.
Both cut well.

The problem with any debate about how sharp a blade needs to be is that every piece of wood is different. I don't doubt that you were able to plane your oak, walnut and beech with a blade honed to 300 grit. The problem arises when other pieces of the same wood prove more demanding. It pays to be able to hone your blades to 'super sharp' for when you come across the more demanding pieces - although I hone mine to 'super sharp' all the time as it's so little extra effort.

Cheers :wink:

Paul

 

[Phil Pascoe]

If it's blunt, it's blunt. If it's sharp enough, it's sharp enough. You just need the experience and knowledge to know what sharp enough is. There's no point worrying beyond that - life's too short.

 

[G S Haydon]

If it's blunt, it's blunt. If it's sharp enough, it's sharp enough. You just need the experience and knowledge to know what sharp enough is. There's no point worrying beyond that - life's too short.

Fact

"You just need the experience and knowledge to know what sharp enough is" + for the task at hand. 8)

 

[woodbrains]

????
He just demonstrated that it works fine.

And even if there was a difference, if an old man can't feel the difference (someone who is more likely feel it with ageing bones and muscles), is the extra time/cost worth worrying about?

Hello,

Paul Daniels' Bunco Booth springs to mind; he demonstrated that bashing a wristwatch with a hammer had no ill effect on the watch, or the Queen was never where it was last hidden!

Seriously, if the only effect a sharp tool has is one that is marginally easier to push, then you are looking in the wrong place.

Mike.

 

[Trafalgar]

By far your easiest and less costly introduction to the whole .x-micron superfine media love-fest will be high grit sandpapers or lapping films on glass.