Tungsten carbide scratcher for tuning ?

[isorry123]

Hey,

Want to get a scratcher for tuning. I know the traditional metal scratchers are imported from Italy and need to be sharpened periodically.

I also known that Dremels and engravers are not appropriate.

Has anyone tried a tungsten carbide scribe ? They have replaceable tips and are very similar to the typical metal scratchers

 

[debra]

Such scratchers can be fine for reeds on the outside, but they may a bit thick for scratching reeds under the valves.

 

[KiwiSqueezer]

I hope I'll be corrected if I'm wrong, but I believe that the desirable shape of the tip of a reed scraper is a circular plane, at right angles to the tool's long axis, not a sharp point. (Sorry, having difficulty with description - think of a cylindrical log, sawn across). The edge between the end of the tool (the circular plane) and the side of the tool does the cutting, and thus needs to be sharp. Thus the tool is sharpened on its end face.

Tungsten carbide comes in many grades. Most are far more brittle than hardened and tempered steel, and achieving a sharp edge is not trivial. Keeping the edge sharp is even more problematical, because the stuff tends to crumble. Sharpening requires very fine diamond abrasive plates (say 1000 grit, or finer), and the edge must not be 'rolled' when sharpening. My experience is with machine scrapers, both steel and carbide, used to finish precision surfaces: it's far easier to sharpen steel, although it's required more frequently. With carbide, it's taxing to get an edge free from irregularities that mar the surface being scraped. Under magnification, the edge looks like a mountain range, because of tiny bits having flaked off. Note that most carbide lathe tools are not 'sharp' - the edge would be too fragile. (OK, I know some are - this subject gets complicated...).

Steel is much more forgiving. Properly hardened high-carbon steel ('silver steel' in UK, 'drill rod' in USA) is plenty hard enough: it makes good lathe tools and milling cutters, within limits, and is the material from which gravers and files are made. High carbon steel loses hardness when heated (from the friction of cutting at speed) - that's where 'high speed steel' comes in... Carbide is at another level, as far as hardness preservation at elevated temperature is concerned.

I had a carbide-tipped scriber once. I fumbled it and it dropped, on its point, a few inches onto a hard surface. A depressing 'Click!", and that was the end of the point.

Long preamble. The message is to make your own scrapers from silver steel (pushed into a wooden handle). It's cheaply available in many diameters from engineers' suppliers. It's easy to shape it to your requirements, before hardening. Its heat-treatment is very easy, and is described on the 'net (or even in books...). Don't take some folks' advice to recycle old drills - their shanks usually aren't particularly hard (unless carbide).

 

[isorry123]

Interesting write up thanks. What attracted me to the tungsten scribe was that the points are replaceable - so keeping them sharp is not important

Didn’t know that about the point shape though -

 

[JKJ]

This page looks like useful information for anyone interested in tuning accordion reeds. George Bachich discusses in great detail things to consider about tuning as well as some of the tuning tools including files, scratchers, the dreaded Dremel, and some of the other things he considers useful.

HOW TO REPAIR ACCORDIONS 3

Check out http://accordionrevival.com!

accordionrevival.com

JKJ

 

[tcabot]

While it was interesting to read kiwisqueezer's musings, I've actually tried this idea a while ago and it works like a dream.

So hard & sharp that you never need to put any pressure on the reeds. Extra hard bayan or bandoneon reeds? Scrapes like butter. Sharpening? Forget about it, you might do it once a year, but so far mine hasn't gone blunt. Because it doesn't lose the edge, it tends to be quite consistent with the amount of steel it takes off. Because you're not using any significant pressure to scrape, you don't chip the cutter. Simples.

You'll never want to touch steel again. I mean who wants to cut steel with steel ? Are you also planning on cutting cheese with a cheese knife? A knife made from something hard, like parmesan might be OK to cut brie, right?

Circular shape is probably the best, but I suspect that a TCT rod will be harder to source & sharpen and will cost a small fortune. When I was looking to experiment, a rod was working out as ~£30, while a dozen of engraving tips were £3 taxed & delivered from China.

1) You want it thin to be able to fit it in the plate slots, so get some dirt cheap 15 degree TCT engraver bits with a 3.175 shank. For example:
Huhao engraving bits
* I've used Huhao-branded TCT router bits and forstner drill bits for over a decade. Excellent stuff. Never let me down.

2) As you can see, the cutting ends are pointed & the tips are too thin for scratching and break too easily, so you want to break off the top 1-2mm, depending on how wide you want your scraper to end up. After that, bump the broken tip on a diamond honing plate to put a square edge on it. Took me 5 minutes on cheapo off-brand diamond sharpening plate.

3) Fashion some sort of a handle for it. Long & thin is best. If you're really low on funds after buying £3 worth of tips, you can take a 6mm wooden dowel, drilled out for the 3mm shank & sharpened like a drawing pencil to stop the wood from getting in your way. Insert the tct tip, wrap some string around it, caveman-axe-style and drown it in CA glue.

4) The most keen eyed of you will notice that the cutting tip is not a round rod. That's a bit of an issue, but the way round it (ha! did you notice the pun?!) is to cut a flat on the wooden handle and align it with the flat on the tct tip. It is, in fact, an old leatherworking trick, where you want to hold a diamond-shaped awl at a constant angle to your workpiece: impossible to do it by eye if it's in a round handle, but very easy to do it if you file a flat on the handle and let your fingers register against it. You very quickly get used to presenting the scraper with its flat face to the reed, using the flat as a reference. You can even use it "upside-down" and scrape with the very pointy bit for fine-tuning piccolos.

 

[tcabot]

Dang. Having re-read my post I've realised that I'd be better off keeping them a secret, making these TCT scrapers and selling them at £50 a piece.

"New generation professional accordion reed scrapers designed using AI-enhanced technology"

How do I delete a post?

PS fwiw, the tct bits you've linked to in the original post ain't no good for scraping reeds as debra has suggested. Too fat and not pointy enough. They do, however, make a fantastic general-purpose marking tool and usually cost a couple £ delivered. Been using them for over a decade. Broke one (my fault) and lost one. Otherwise going strong.

PPS I've used tct cutters for wood turning for years, including turning fine detail in African blackwood. While they do chip sometimes, and I agree that they are never "truly sharp" from an engineer's point of view, they perform beautifully in real life conditions and do their job better than steel. The only steel turning tools I still have are the parting tools. But I only do very small-scale turning like chessmen, so never have to hog off a lot of wood, where you'd really want a steel skew. I'm drifting off topic here.

 

[JKJ]

You'll never want to touch steel again. I mean who wants to cut steel with steel

I haven't use those you mentioned, but just want to comment that steel tools are definitely used to cut steel all over the world. I use both steel and carbide bits on my metal-cutting lathe. HSS (high speed steel) bits, properly sharpened, generally cut steel and other metals better than carbide. They cut cleaner and with less force than my various carbide insert tools. The key is in proper sharpening.

I think a sharp HSS tool would work fine scratching accordion reeds. That's what a tuner I know uses. From what I've read, it's important to actually remove metal when tuning reeds, rather than just push metal to the sides by scratching a groove, so perhaps a very sharp pointed tool of any type might not be best.

As for woodturning, of which I do a lot more than metal turning, with one exception I prefer HSS tools, skews, gouges, parting tools, etc. Again, sharpening is key. (I sharpen my spindle gouges on a 1200grit CBN wheel on a Tormek, other tools with 600grit CBN) With 5 seconds of my custom honing technique all tools are arm-hair shaving-sharp. In my experience HSS cuts far cleaner on wood than any of the carbide tools I've tested, with the exception of the excellent Hunter carbide tools which I prefer for some face work including bowls, platters. and hollow forms/lidded boxes - used as "cutting", not "scraping" tools.

I teach a lot of woodturning and we always use HSS tools.
(Frankly, carbide scrapers of any type are not used by the high-end woodturners I know.)

I mostly prefer delicate spindle work but in case anyone is interested, here are a few examples of face work (where the grain runs perpendicular to the axis of rotation):





Working with steel, I made this last week - a tuning hammer for my piano tuner, custom made to his specs.
I used both metalworking and wood lathe tools, steel and B&W Ebony for the handle.
With the exception of a tiny boring bar, all tools were HSS.
(Sorry, I think I posted some of these recently in another thread.)





JKJ

 

[tcabot]

I can sharpen steel very well - just ask the hand surgeon who stitched my thumb back onto my hand a few years ago . High carbide steel is what gives you a real edge. HSS is more of a sharp screwdriver - only has its place when you're spinning things very fast.

And I know that steel cuts steel (however, I suspect that parmesan cuts brie too, if you sharpen it well enough). TCT is harder and holds the edge a lot better when you're talking about scraping reeds though. And accordion reeds are not exactly made out of mild steel, are they. More like hardened CS95.

For turning, HSS gives a fantastic finish. Carbide doesn't. Makes a big difference for a bowl, but this does not matter when the work is small and hand-polished for final finish.