I just tried using a piece of broken glass as a scraper for the first time (after hearing that this is what violin-makers use) and holy moly! It’s like a butter knife. Even though I’m using some of the hardest densest wood in existence (ironbark).
You make them with an old piece of picture glass (2mm or so thick), and break rectangle roughly matchbook-sized from it.
The way to break it is using a cresent profile file to gouge a nick where you want the break to start and then lining that knick up with the edge of your table (nick upwards) and gently pull down on the overhanging bit to snap it.
You can also make curved ones by not using the table and instead using your hands and twisting like you would when opening a jar on its side.
Probably a good idea to wear gloves when the learning and glasses. And to keep a vac handy in case your break leaves any shards (though it does seem to break really cleanly).
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Ummm. Just get a steel card scraper and learn to sharpen it. I'm sorry, but unless I'm stranded on an island with nothing but a container of window glass, it's not a great solution.
I don't have to sharpen this and it cuts so much better with very little force and I can make whatever shape I want and I can see through it for better accuracy.
And the best bit? I don't have to strain my hands both bending and moving it.
To each their own but I definitely see the reason they're favoured by instrument-makers after only one use.
I reckon try it before you knock it. 😄
Plus it's a great way to recycle broken glass.
It's great to hear that you found a useful technique for woodworking using a broken piece of glass! However, it's important to take safety precautions when handling glass, such as wearing gloves and keeping a vacuum handy to clean up any shards. Home Bargains Employee Portal
I did write that, Sara, along with glasses.
Brings back memories of my father and grandfather who always used to use glass scrapers and swore they were better than steel.
I'm entirely convinced they're correct after only a couple of hours!
I have a luthier buddy who buys glass microscope slides to use as scrapers. They're super cheap and he always has a pile lying around ready to go.
! I didn't even think of this! I have a bunch of microscope slides! :D genius! I'm going to make a holder for them.
Darn just tried my slides and they're blunt compared to the freshly broken stuff. Maybe some times they grind the edges a little?
Funny that you should mention this... I almost mentioned in my comment below that I seem to recall from years ago that if I scored/snapped too many glass scapers, such that they sat around unused for months, they would be "dull" compared to a freshly-snapped piece of glass. I'm guessing that something happens to the sharp burr after sitting exposed for a while, but I'm out of my depth here; we'll have to let one of the materials scientists weigh in on this.
Huh! That is interesting given how inert glass is. Wonder why.. Definitely just sitting? Not jostled in a drawer or some such?
I've had a few small offcuts of 1/8" glass on a shalf with my planes for years. Fantastic for small flats. A 1.5" square has 8 cutting edges. I touch off the corners with a diamond hone meant for saving chipped glassware to stop them from leaving tracks.
Glass naturally fractures to an edge that is far sharper than what's possible by machining steel. That's how super sharp obsidian (volcanic glass) tools were made by prehistoric people. Obsidian is still used today in specialized surgical scalpels. Of course the downside is that glass looses its edge after only limited use.
A very easy and safe way to cut glass is to score the surface with a glass cutting wheel like this:
https://www.amazon.com/Fletcher-Terry-01-122-Steel-Cutter/dp/B000BZZ022/ref=sr_1_17?crid=33BVY5C9GGAAY&keywords=glass+cutter&qid=1679421428&sprefix=glass+cutter%2Caps%2C75&sr=8-17
After scoring the top surface, tap the underside of the glass (under the score mark) with the ball end of the cutter and simply snap it off over the edge of your table/bench as the original poster suggested. This ensures a straight edge, assuming that you scored it straight, and generally avoids the issues of flying shards of glass from errant breaks. The link is for a well-known Flether USA-made $9 cutter, but there are cheaper versions available, as well as other styles. Picture framers and glazers have used cutters like this for years.
As for the usefulness of glass as a scraper, years ago I used it extensively while employed by a picture frame manufacturer and it worked very well. As noted by others, when the edge eventually dulls simply rotate/flip to a new edge (I used to tape over a worn-out edge so as not to inadvertently try to use it), and throw it away or recut the edges (if still large enough) when all edges have worn out. I hadn't considered trying to cut a curved edge to use when scraping concave surfaces, but I'll be giving that a try the next time I have a need.
Good to know the scoring works because that's how I normally cut glass! That would make it easier to match curves. ☺️
Glass has been used for centuries, here is a type of scraper that is used just as you would a piece of glass.
https://www.stewmac.com/luthier-tools-and-supplies/types-of-tools/scrapers/stewmac-ultimate-scraper/