Sharpening for luthiers
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Tagged: instrument making, sharpening
- This topic has 18 replies, 7 voices, and was last updated 6 years, 5 months ago by Larry Geib.
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Hi,
hobbyist luthier here. Actually nothing special, about two dozen restorations of plucked instruments and four lutes made from scratch (all of that in a time span of 7 years), just free time home activity. It started as an exploration of various musical areas, but led me to have great admiration for woodworking crafts and artisanry. I am working at my own, looking for pieces of information over the Internet. Mr Sellers’ videos are my main source of knowledge about traditional tools and techniques. Thank you, Mr Sellers!Mr Sellers mentioned once, that his violin-making son has been using stones up to 25,000 grit. I would love to get some facts what he uses and what are options for amateur instrument maker, just to have perspectives for future. Maybe from Mr Sellers himself, or maybe from other forum members? Any help is greatly appreciated.
17 October 2017 at 4:02 am #335570There are Shapton water stones that get to very fine grits. I’ve never tried them and they’re expensive. I use DMT diamond stones and the extra extra fine stone gets you to about 3 micron size particles, about 6-8,000 grit I’m guessing. I believe 3M sells adhesive abrasive paper that gets finer than that. You stick them to a flat surface, glass or stone, and use water as a lubricant. Hope this helps!
Question from the uneducated…why would you need something sharper than what we get with our strops to make musical instruments? i.e. if I’m effectively stropping at 12,000-15,000, is there any perceivable difference between that and say 25,000? What would the finer grit accomplish for the violin/guitar/etc. maker?
For the OP, do you have a reference for exactly where that was said? I ask because I have never heard of such stones, and I strongly doubt they exist. I suspect you may have mis-heard or perhaps Paul mis-spoke.
From what I’ve seen, in order to get past the “teens” (in thousands of grit, American Standard, e.g. 15000), you have to move into lapping films, aka micro-polishing films or synthetic diamond powders.
@etmo https://paulsellers.com/2013/11/sharpness-mean-real-terms/
@dbockel2 That’s the thing I wish I get to know 🙂Don’t natural oilstones go to such levels by chance?
Diamond paste – that might be something. Maybe it can be used to hone cutting edge on a marble slab with one face polished? Would it work? But continuous usage of fine diamond pastes will be way more expensive that finest diamond plates, probably?
And I forgot oen thing – greetings from Poland 🙂
- This reply was modified 6 years, 5 months ago by Antoni B..
18 October 2017 at 12:14 am #336023I have diamond stones to 8K ( years ago everybody sharpened to 400 grit)
Frankly, I don’t see much difference between 1200 stropped and 8K, so maybe I’m not the expert. I only use temperate climate hardwood, softwoods and some mahogany. I think that encompasses most soundwood.
I did get a used Black Arkansas cheap, but I really haven’t put it to use yet. It’s what is touted as what people use for scalpels and razors.
Interestingly, the vendors of black Arkansas don’t really put a grit on it. I suspect that’s because it is variable and a natural product.
@antekboodzik — ok, as I suspected, the link you posted says, “he sharpens his planes to about 25,000-grit”
Note that nowhere does it state that a stone has such a grit, only that 25000 is the grit used. So micro-finishing films or powders on a surface plate seem to be the likely suspects.
As for why, hopefully someone can chime in.
It’s really hard to have these discussions without certain details. Specifying a grit without specifying a grit system makes it close to impossible to cary on. As Larry pointed out, some abrasive surfaces aren’t sieved and are mixed in nature, and don’t have a grit number.
I’m afraid the honest answer here is that, if the OP is interested in learning how to sharpen for lutherie, Paul’s informal comments aren’t going to be very helpful and the best bet would be to find a lutherie forum or a luther to ask directly. Why waste time guessing if you want to go further with instrument making? Of course, one should ask what is the dominant effect on sound. The species of wood? The climate of the specific tree and its specific grain structure? The carved profile and overall mass? The grit of the sharpening stone?
19 October 2017 at 6:01 am #336941After I wrote, I did find a site that compared grits across sharpening media.
https://www.sharpeningsupplies.com/Sharpening-Stone-Grit-Chart-W21.aspx
That black Arkansas I talked about is rated by them at 4-8 micron range.
That’s the same range they put my 4K grit DMT stone in. I will say, the Little I’ve used the black stone, it doesn’t cut as fast.
maybe that’s why I couldn’t really say much about it.They rate my 8K eefine DMT Diamond stone at 2-4 micron. Not what I expected when I picked up the black stone…live and learn.
And they rate most diamond and other powders and the Green Chromium oxide honing compound at 0-2 micron, Which jibes with my comment that I didn’t see much difference between 4K with honing and 8K.
Chris Schwarz has a several part segment on sharpening he did recently. His views seem to have evolved with the rest of us.
It’s worth a read and called “sharpen this” done in his usual style.
https://blog.lostartpress.com/category/sharpen-this/
You may find it rot or worthwhile, but it will get you thinking about what sharp is beyond a few hundred grit.I wonder what size diamond powder they sharpened to in the Antonio Stradivari attellier? One luthier has his tools from a Cremona Museum on his site:
http://www.kevinleeluthier.com/stradivari_tools/StradivariusTools.htmFour finger planes and a pile of scrapers, which are burnished, for the most part
Myself, my son & his father-in-law are also hobbyist luthiers & we have built a number of solid body electric guitars (easy) & a couple of acoustic instruments (a steel string guitar, a mandolin & soon a classical nylon string guitar) which are more difficult than solid body instruments.
Particle size in microns is the only reliable way to compare abrasives from different sources. Note that the “DMT® Diamond Grit Size – Color Coding” chart from the DMT website gives measurements in terms of “mesh” NOT “grit” whereas the Eze-Lap website gives measurements in terms of “grit” NOT “mesh”.
It is immediately obvious from a side by side comparison that DMT’s 1200 mesh diamond stone is NOT equivalent to Eze-Lap’s 1200 grit diamond stone. Helpfully, DMT publishes their mesh sizes in microns whereas unfortunately, Eze-Lap does not.
However, as noted in my post https://woodworkingmasterclasses.com/discussions/topic/ezy-lap-vs-dmt-diamond-plate-particle-sizes/ one of the Eds on this site contacted Eze-Lap & obtained the micron sizes of their grits. If the info he obtained is correct (& my experience with both DMT & Eze-Lap diamond stones would indicate that it is) then the following would seem to be the order of increasing fineness:-
Micron order
DMT XXC…..120 mesh..120 microns
EZL XC……….150 grit…….60 to 65 microns
DMT XC…..…220 mesh…60 microns
EZL C…………250 grit…….50 to 55 microns
DMT C……….325 mesh…45 microns
EZL M………..400 grit…….40 to 45 microns
EZL F…………600 grit…….30 to 35 microns
DMT F……….600 mesh…25 microns
EZL SF…..…1200 grit…….15 to 20 microns
DMT XF…..1200 mesh……9 microns
DMT MXF..4000 mesh……6 microns
DMT XXF…8000 mesh……3 micronsThe “sharpeningsupplies” site that Larry refers to above recommends that to get to less than 2 microns, Diamond Paste, Green Honing Compound or Abrasive Powder should be used.
So, my current freehand sharpening regime for well maintained chisels & blades for both lutherie & general woodwork consists of:-
EZL F to EZL SF to DMT XF to Green Honing CompoundIf a second hand tool requires the re-establishment of its bevel then I may have to resort to a grind wheel followed by DMT XXC to EZL C to EZL M or starting anywhere along this sequence depending on how out of shape it is.
I don’t have any preference for either DMT or Eze-Lap, they all seem to work adequately, it’s just that these are my current 8 inch long stones. I also have DMT XC, DMT C, DMT F & DMT XF in 6 inch long stones but have found that they’re limited in their ability to comfortably sharpen wide blades & there is a restriction on the length of stroke.
Well, thank You a lot for all your comments and bouncing ideas off 🙂 Many, many things for me to consider.
But I must admit I was hoping to get to know a little more about oilstones. I have never used any. And I think one or two traditional, natural oilstones would be perfect combination for a small, early instrument making workshop, because they are natural and traditional 🙂
Let me ask one more thing. Years ago an English lutemaker David van Edwards presented on his website a kind of sharpening “system” (unfortunately, links are dead now). That system had consisted of a bench grinder with an abrasive wheel and a stitched calico wheel mounted, but it had been arranged to rotate backwards (!). So you could polish (with stitched calico wheel loaded with green compound, which had been added also, presumably) a plane iron, or chisel offering it to that polishing wheel in an usual manner. Mr Edwards claimed, that it had done miraculous effect to edge tools, and with macro-pictures included he stated, that it was not only polishing the edge, but “re-arranging” it at molecular level or so. He also stated, that felt wheels hadn’t worked as good as stitched calico ones.
Has anybody seen something like that?
I have experimented a little with stitched calico wheel on a shaft, and loaded with green polishing compound set in an ordinary electric drill. I mean, that it seemed to work just by very gentle but thorough polishing, but it hadn’t enough speed probably, so it was inconclusive to me.
Anyway I am stropping with aluminium oxide white buffing compound (have bad feeling about the green one), but sometimes I use just a leather strop glued to a piece of wood/MDF without any buffing compound. I heard somewhere, that chromium is used in tanning leather (and it might become toxic – beware of East Asia leather!), so the leather may come “loaded” actually. I am not 100% sure which is witch, but some pieces of leather I found here and there really do polish steel when not loaded pretty well. Does anyone agree with me?
21 October 2017 at 6:11 am #338064Mr van Edwards still has a site and comments on what he currently prefers, which is the couple of stones you talk about.
Here’s what he says:“Finally, some means of sharpening your plane iron, knife and chisel. Your dad’s old oilstone is really not quite good enough! If you are really hard up it will do, but you will never be able to get a sharp edge and most of your work will be much harder as a result. There are two schools of thought here: either a very hard smooth stone such as an Arkansas stone, which scarcely wears away at all and remains beautifully flat; or a softer stone made up of tiny hard particles in a weak matrix, which wears away rapidly exposing new sharp edges all the time. I strongly prefer the latter system which is exemplified in the Japanese water stones and the Belgian stones. Either way get a 1,000 grit for initial sharpening and a very fine grit, say 10,000 grit, for final finishing. The German firm of Apex [The box says Apex-Sal-Abziehsteine] produces a very economical double-sided stone which does both jobs admirably. All these stones, whatever the system chosen should be usred with water, not oil, as a lubricant to wash away the swarf out of the pores of the stone.”
So the stone he talks about must be a synthetic stone I’m not familiar with, because no natural stones I know of claim that high a grit.
Beyond that, some other thoughts.
If you don’t like chrome tanning, use vegetable tanned leather. It’s easy to spot because Light or natural leather is VT. The Chrome tanning method dyes the leather blue, so it must then be stained dark to hide that. Get a hard tanned scrap.
The amount of Chrome Sulfide involved in Hand honing is pretty small. A couple drops of olive oil or it’s like will keep it on the leather. Don’t lick your fingers. Of course, if you use a wheel, you’ll be spraying fine non soluble dust all over the shop, which can’t be good no matter the mineral. Use a mask. 2 micron insolubles are in the lung cancer range.Unless you get fine expensive wheels, you won’t get a fine edge off the grinder, and you will quickly wear down the wheel and heat the metal. There are new boron wheels that seem like spinning diamond plates. I’m not interested in a mortgage at this time.
And the idea of trying to hone with any soft wheel seems to me to risk dulling the edge as sharpening it. Sharpening is different than polishing.
That said, there are systems people tout that consist of an MDF hard wheel and buffing compound.I understand the attractiveness of some sort of system that will sharpen for you, but any system like that ties you to the machinery that spins up the wheels. What happens when you leave your shop? Learning to sharpen by hand frees you from expensive and cumbersome machinery.
Pick a system and stick with it, at least for a reasonable number of years. All the systems work.
I guarantee that if you do this 50 years you will use a different system than when you started. Everybody has, but the changes came slowly and for good reasons, with fads like water stones consuming Woodworking store shelf space for a few years, and then diamond stone becoming the rage because there is no mess or maintenance of the waterstones, and they cut as fast.
The Arkansas sandstones from the antediluvian seas of the great plains have been Popular for 100 years and more.Ceramic is now becoming the rage, but I figure if it ain’t broke don’t fix it.
Good luck with your choices.
And consider that mssrs. Amati and Guarnieri and Stradivari built ok sqwawk boxes with just the natural stones available in the fifteenth century without any electricity. Keep it simple.
- This reply was modified 6 years, 5 months ago by Larry Geib.
- This reply was modified 6 years, 5 months ago by Larry Geib.
- This reply was modified 6 years, 5 months ago by Larry Geib.
My carving teacher told me an interesting bit of history. Carving tools require a high degree of polish. When he was a student in Switzerland, they used a hard Arkansas stone. True hard Arkansas stones were still available then, if you searched, but he said that after the world wars, there was such a high demand for stones in Europe that the supply was depleted. He feels that it is rare to find a new “hard Arkansas” stone that is really on par with the traditional ones and that it is difficult to get a good polish on the new so-called hard Arkansas stones. He thus spent some time looking for alternatives and ultimately ended up working with a manufacturer of “sapphire” stones to obtain something that met his specifications. There are a lot of details and not all sapphire stones are the same in flatness or grit size, according to him. I know it sounds like an advertisement, but I trust him and am inclined to take his word, although I’ve not researched it. I use his stone in my sharpening and my only regret is that it is small, maybe two inches by four inches. It is perfect for knives, especially chip carving, but I use it for chisels and sometimes plane blades (with care), especially to knock the burr off the back. It gives a better polish than I get on the extra extra fine DMT plate.
22 October 2017 at 7:23 am #338536Well, Ed, I’m afraid that doesn’t lead us anywhere unless you tell us What stone manufacturer is making this stone.
Sapphire is just a colored aluminum oxide, the same chemical crystal as the old Corundum stones that mr van Edwards talks about your dad used. Is little rocks held together with a binder. If the Corundum is most colors, it’s called Sapphire. If its red, it’s called Ruby. If its black, it’s usually mixed with hematite or magnetite and called Emery.
But is all pretty much the same hardness.
Some Corundum comes out of the Cherokee Ruby and Sapphire mine in Framklin NC.
I took a tour there once.that white wheel on your grinder is aluminum oxide, and a good salesman would call is white sapphire.
Most Aluminum oxide stones and wheels are designed to break down, because the oxide particles aren’t as hard as say, diamond. And some artificial water stones are designed to break down really quickly. That presents new sharp crystals to the steel. With grinding wheels, the broken particles also carry away heat.It would be nice to know exactly who is making the stone they are calling sapphire.
The Arkansas stones are called novaculite, which is a Silicon dioxide crystal we know mostly as sand. In larger sizes it’s like chert or quarts. The particles are harder than the Aluminum based stones, and with Arkansas stones, they are bound together better.
Hi,
@lorenzojose long and very interesting post, thank you!To clarify a little my previous post here’s the page, where are those empty links (very bottom of the page):
http://www.vanedwards.co.uk/rentools.htm
These pages are not indexed (?) in internet wayback machine. It might be put offline, because it might be an integral part of property lute making courses, that Mr van Edwards sells, but also because it might be (as @lorenzojose suggested) a certain health hazard.My intention is not to find another sharpening “sensation” or re-invent any wheels. I am just asking about what I have wanted to ask for a long time. About buffing wheels I read here and there previously:
http://www.classicalguitardelcamp.com/viewtopic.php?t=45513&start=15
see:
“My great breakthrough from sharpening carving chisels was a buffing wheel in the drill press”.
But in the same post some other guys say that they use “as little” as just a two-sided benchstone anad a strop only, and are fine with that.Mr van Edwards also warns agains using oil with any stone – probably it could contaminate small pieces of fine work. Is it a so big concern really? And does it make sense to use let’s say Arkansas stone, or any “traditional” oilstone with water?
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