Finishing with a scraper as opposed to sandpaper...

[Bill Hicklin]

By accident more or less I arrived in the same place as Alan, since my junk-store acquisition of an old Stanley No 12 veneer scraper plane. The iron in it is much as Alan describes, and I frequently use it by hand. (the scraper plane, BTW, is a great tool for thinning squirrely-grained backs and sides).

[Randy Roberts]

I've got one of Al's scrapers and would agree that for a lot of uses it lives up to the "Ultimate Scraper" name.

The other thing I've really liked for a final pass for scraping is a blade that is used in a surgical instrument called a dermatome blade. They are used for split thickness skin grafting, and have the sharpest edge I've ever come across. They are very thin and flexible and conform to a radius easily. They are the closest thing to heaven I'll ever get. I have to keep telling myself to barely touch the surface, or it will fold the edge over. It's more caressing the surface than scraping. About 30 passes in one direction turns a slight burr, and then 30-40 the opposite direction turns a burr the other way. I love these things as much as Al's. The problem is I ran across these on a scavenging expedition when a hospital was clearing out old stuff in their warehouse and when I reached the manufacturer to get more, they were 54.00 apiece.
I've been working on trying to get them to sell me the flawed reject blades for two and a half years now, as I just want the edge it has, but every time I get close, someone in the chain gets transfered or has been replaced and I have to start all over.
My thinking is if I could get them for a buck or two apiece for the cosmetic rejects, that I might be able to sell them as a fund raiser for the forum here. I'll continue trying but it's been frustrating so far. Meanwhile I husband them for just the final finish scraping.

[Steve Senseney]

Randy, could we have a picture? or part number?

[Alan Carruth]

I set up the tool rest on one wheel of my grinder so that it's more or less pointed along the radius of the wheel: if the scraper is .2" thick, then you want the surface of the tool rest .1" below and parallel to a line that points to the center of the shaft. Mark Aron, the guy who's making these, came by and we made a short video on sharpening and using them, which I imagine will be posted on Stew-Mac's web site when they get them in the catalog.

Alan Carruth / Lurhier

[Tim Douglass]

How large a wheel, Alan?

[Randy Roberts]

Steve,

Here's a picture of the dermatome blades next to the scraper Al generously shared with me when I visited a few years ago. (I'm not sure it's his final design)

[Alan Carruth]

Tim Douglas asked:
"How large a wheel, Alan?"

Just a normal bench grinder: I don't think the diameter of the wheel matters much, so long as you get the anlge pretty close to right.

That picture of Randy's shows the scraper with the edge not ground. That's the right general size and shape, though.

Alan Carruth / Luthier

[John Aguilera]

I just registered to this board - greetings - I recognize many of you from Delcamp, OLF, and other guitar building forums -

Alan -

I am interested in your new scraper design. Can you please let us know when it does become available ?

[Matthew Lau]

Dermatome scraper!
I'm not surprised that it's so pricy.

Anyways, Al, ever considered an autographed, limited edition?
I know that I'd probably buy one.

[Charlie Schultz]

Hi John and welcome!

[Alan Carruth]

John Aguillera asked:
"I am interested in your new scraper design. Can you please let us know when it does become available ?"

It should be in the catalog any time now. If you're like me, you get those pretty regularly in the mail, so you'll probably find out about as soon as I do.

Alan Carruth / Luthier

[Andrew Porter]

Now available

http://www.stewmac.com/shop/Tools/Scrap ... =3&xsr=868

[Chuck Tweedy]

Nice!
Great video Al - Thanks.

So no turning of a burr on the edge? Just a keen 90 degree edge and then go to town then?

[Christ Kacoyannakis]

Those dermatome blades look a bit like disposable straight razor blades. There is a Japanese company called Feather that makes blades and razors (also surgical blades). Guys, these things are the sharpest things I have ever shaved with. They have several different kinds, pro-guard (with wire wrapped around it to protect you) professional, professional light and professional super. I have only ever gone as far as professional light because when I use that, I lose too much of my face. These are very reasonably priced, and for 24 dollars, you get a package of 20. You may get the same result, and even if they are not exactly the same, they are only about a dollar or so a piece.

http://www.classicshaving.com/Feather_Razors.html

[Mario Proulx]

Damn! I now have scraper envy.... <bg> Cool stuff, Al! Must to add one to my next SM order!

Christ, looking-over that web site makes me almost want to shave again. Almost....

[Dick (DT) Trottier]

I checked a bit into the history of sandpaper. Seems mass production of sandpaper was developed in the early 19th century. I'd guess that prior to that it would have been a much different discussion, scraper vs. sandpaper (or glass paper as it was). Can you imagine making your own sandpaper? Or maybe buying ready-made from your local Glasspaperologist! Much easier to recycle a broken saw blade into scrapers...

[Chuck Morrison]

I've seen many old guitars that had the finish sunken slightly in the softer parts of the top grain. I've taken it (right or wrong) as a sign of a thin finish on an older instrument. I'm not as thrilled seeing the finish sunk into back/side grain though. I guess I'm 1/2 and 1/2 on the sanded/scraped look.

For what it's worth, for most finishes (Gloss) I've tried, rubbing the finish out early, before full cure, will usually result in this kind of sinking. A finish like KTM-9 can be rubbed out nicely the day after the final coat but it will "groove" by the end of the first week on spruce/cedar. Wait a couple weeks (or longer) before rubbing out and keeping a glossy flat surface is more likely.

Oh, and I did pick up one of Al's scrapers. Thanks for all the info on how to sharpen it. Now I just need a really fine grinding wheel...

Guitar players are used to seeing sanded surfaces, which will either be perfectly level, if you did it right, or have the softer parts slightly below the level if you didn't. A scraped top on a guitar is a terrible flaw, from their perspective, and, since it looks so bad, it must sound awful, right?
Alan Carruth / Luthier

[Chris Reed]

I checked a bit into the history of sandpaper. Seems mass production of sandpaper was developed in the early 19th century. I'd guess that prior to that it would have been a much different discussion, scraper vs. sandpaper (or glass paper as it was). Can you imagine making your own sandpaper? Or maybe buying ready-made from your local Glasspaperologist! Much easier to recycle a broken saw blade into scrapers...

I believe dogfish skin was used as a proto-sandpaper. The name may not translate well; a dogfish is a small shark found in UK waters (and probably elsewhere), maybe 24 inches long. Sold in British fish-and-chip shops as rock salmon or rock eel. Well, would you eat a dogfish?

[JC Whitney]

Al - the new catalog arrived on my doorstep this week, and your sharpeners caught my eye. Very nice indeed. Being a cheap yankee, since seeing them I've been daydreaming about a sharpener that could produce that sort of edge. So far I'm thinking a half round file (chainsaw blade file?) seated in the bottom of a groove matched to the thickness of the scraper blade... [Edit] Just looked closer at the recommended sharpening method. Seems that the radius of the blade is much larger than I had imagined. Hmm...

[Michael Lewis]

Alan, what would be wrong with sharpening your scraper by stoning the sides on a diamond block? That would leave the original hollow grind intact, though, the scraper would eventually become a bit thinner given enough time.