Scraper not working correctly?

Re: Scraper not working correctly?

R.J.Whelan

>Alan ... what type of material are you trying to scrape? Very soft wood is not a great candidate for scraping.

Try your scraper on a piece of red/white oak and see if it works any better - if it does you'll know that your tool prep is at least close.

Good luck ... rj

Re: Scraper not working correctly?

Christof Hartge

>Hello Alan,

I'm quite sure that your scraper doesn't work the proper way.

20� is way to flat and a scraper can produce a much smoother surface than 220 grit, at least on hard woods.

What I do, to sharpen a scraper is very simple. Fit the card in the front or back vise protruding just 1/4" over the surface. Take a fine long file and joint the edge with one or two strokes, be careful by visual control that the file is rectangular to the bench-surface.

Clamp out the card and clean up all possible burrs on flat honing stone (medium grit). Quickly done.

Clean up blade and lay it flat on the bench surface, the edge protruding again 3/4 of an inch or so. Take a burnisher. The long edge of a chisel works very well for this taskalso, by the way. Now make three strokes away from youover the edge with the burnisherin a slight skew angle to the front side of your bench. Turn the blade make another three strokes. Blade is ready.

test it on the hardest wood which is in your shop. Lignum vitae for instance scrapes like plastic. Softer woods require a better edge on the scraper than harder woods.

Greetings, Christof.

Re: burnishing angle

Moses Yoder in White Pigeon, MI

>If you have to lay the scraper down to get shavings you are burnishing at too much of an angle. Try resharpening the scraper, and when you burnish put it in a vise (upright) and burnish in several strokes, starting at just about level for the first pass, a very small degree angle for the second pass, and about 5 degrees for the third pass. You want a very small but consistent hook. This is the most common mistake probably with scraping; people think they need to really put a hook on it, and actually a larger hook will break down more quickly, requiring more frequent sharpening. Different wood species will react differently and various hook configurations will work better depending and the wood, but a small hook burnished at a slight angle will work best for most hardwoods. The quality of the scraper steel will make a difference in the results also.

Re: Scraper not working correctly? *LINK*

Alan Womack

>I have created a page which shows my shavings, the results, and two movies in quicktime (8+ meg and 12+ meg) so just broadband users likely to look.

So what am i missing in my technique?

Alan


http://alan.firebin.net/card_scraper.html

Nice article here *LINK*

WoodburnBob

>Take a look at the link to the relevant WC article below. I think you'll want to pay special attention to the first of the three approaches. In particular, I think it's useful to know that success is dependent on:

1) filing/stoning a sharp perfect edge (if you dub the edge in the process, no amount of burnishing/turning the edge helps),

2) forming the hook (a step in the process often curiously left out of books and magazine side bars), and only then,

3) lightly bending the hook only a little.

Forming and bending are done with the burnisher in planes about 80 degrees apart from each other.

I think sharpening a card scraper proficiently is actually a fairly refined art requiring a degree of restraint and finesse. It shouldn't come easily to too many people.


Scraper article

Re: Scraper not working correctly?

Jack Guzman from Maine

>In the video "Handmade Dovetails with Tage Frid" Tage makes setting a burr on a scraper look real easy.---Jack

Re: Scraper not working correctly?

Alan Hamilton

>Alan (who spells his name correctly)

It's difficult--or impossible--to diagnose troubles such as yours from afar, but (the ubiquitous 'but'):

I agree with Moses that your troubles are very likely caused by a burr that's too large. Three or four strokes with a burnisher is plenty to draw out an edge; and two or three strokes--no more--are plenty to properly turn a hook.

I had troubles exactly like yours: my scrapers made wonderful wood dust, but no shavings, despite that I could feel the "edge" or catch a fingernail on it. I was making my edges way too big. The very first scrapes on wood (it didn't matter what kind of wood) the hook was either scraped off or bent to where it did little or nothing.

Alan (who also spells his name correctly)

Re: Scraper not working correctly? *LINK*

Alan Womack

>From some help on a FWW online article, and some members of oldtools, I've improved my shavings a bit by drawfiling the card scraper edge.

I've added the photo of the change in the shavings to my page from above:


http://alan.firebin.net/card_scraper.html

Re: Scraper not working correctly?

Jonathan Kaplan (OR)

>Alan,

I am by no means an expert, but after *a lot* of practice and a lot of failures I've become at least OK at using a hand scraper. It looks to me from your pictures that you are still not preparing the scraper blade well enough. Try to create a perfect 90 degree square edge (that's what the jointing of the edge does well, so you're probably there), with all three 'faces' (front, back, and the edge itself) well-polished (to do this, switch to whatever stones you use to sharpen, and, the first couple times at least, take it whatever grit to you normally sharpen plane-irons to). It looks to me from the pictures of the surface that your card scraper is not well polished... But I could of course be wrong.

At this point, if the scraper is ground perfectly square and the edges are well polished, even without pulling an edge on the scraper, you should be able to make (very small, albeit) shavings with it. If you can't get it to make shavings, it isn't well squared / polished enough. Rejoint it and try again.

If you can get it to make shavings without a burr, start playing around with putting the burr on it. I'd start out by creating a *tiny* burr on it. Pull the metal forward with your burnisher very gently (very slightly), fold it over to 90 degrees to the edge (again, very gently), and try it out. You should be able to make very fine shavings very easily at this point.

You can then play with making the angle sharper and making the burr larger, but once you figure out how to get the edge where you want it, it should good much more easily.

Hope this helps.

Very best,

jk