PDA

View Full Version : Sharpening my card scraper is making me nutty



Tony Zona
05-06-2015, 10:06 AM
I need some tips on sharpening my card scraper. I love to use it, but haven't for a while. So I am attempting to sharpen it.

I follow Fine Woodworking's video, and other videos (some of which appear to be trash) and I still get dust when testing on poplar. This just struck me. Is poplar too soft to get shavings with a card scraper?

Anyway, can anyone please offer advice on sharpening this scraper?

david charlesworth
05-06-2015, 10:41 AM
Tony,
I suggest you look for the videos (2) by Brian Boggs. They are spot on. Called "Tune up a card scraper".

Two common faults.
1. Not getting the edge truly sharp.
2. Using much too much force on the burnisher.
3. Poor soft burnisher.

That's three!
David Charlesworth

Robert Engel
05-06-2015, 10:55 AM
Far as I know, you should get shavings on any kind of wood.
If you're getting powder then I would think you don't have a good hook formed.

I know you have to start out with a perfectly flat, square and honed edge before burnishing.

Like Mr. Charlesworth said, there's videos out there, then just practice it.

Terry Beadle
05-06-2015, 10:56 AM
Another good video is by William Ng on youtube.
https://www.youtube.com/watch?v=Nz6EpQu2HRo
One important tip is that it only takes a lite touch to turn the burr.

ian maybury
05-06-2015, 11:16 AM
Guess getting the geometry of the edge/corner honed on accurately must matter too - as in two truly flat faces/facets meeting at a consistent angle along the full length...

lowell holmes
05-06-2015, 11:21 AM
I use the attached method for sharpening a card scraper. You may have viewed it, but I find it to be foolproof.

http://www.finewoodworking.com/tool-guide/video/how-to-sharpen-a-card-scraper.aspx

What kind of burnisher are you using. I have a triangular carbide one similar to the one shown here.

http://www.traditionalwoodworker.com/Triangle-Burnisher-by-KUNZ-of-Germany/productinfo/580-13123/

Tom M King
05-06-2015, 1:46 PM
Reluctance is your problem. It takes pressure, and speed usually goes with enough pressure. Make SURE to keep hands and fingers Only on the pulling side. The back of a small gouge will work if you don't have a burnisher.

Jim Matthews
05-06-2015, 3:12 PM
Your suspicions are correct. Softer wood requires a more fine tuned edge.

I recommend trying a scraper that is filed,
ONLY as the serrated edge may better slice Poplar than a polished burr.

Try it on scrap, if you have some.

I think of card scrapers like a thoroughbred:
great when the conditions are just right.

Tom Bussey
05-07-2015, 9:25 AM
Scrapers do not work well on soft wood. Try just fileing it square and forgetting the hook for now.

lowell holmes
05-07-2015, 9:49 AM
I should add that all card scrapers are not equal. I floundered around using them until I purchased two from Lie Nielsen.
The come as a set of two and they have different thicknesses. I normally use the thinner one.

Using Pekovich's sharpening method, they will produce curly shavings. A freshly prepared edge should produce curls, not powder.
You have to produce a bit of bow in the scraper with your thumbs to accomplish this.

James Pallas
05-07-2015, 10:04 AM
IMHO card scrapers are an odd lot. I have had some that you could turn a burr with dental floss and I have one that you could not turn a burr with a 4# maul. It takes some experimenting with pressure and angle until you get the sweet spot for you. If I use another persons scraper I usually have to search around a bit to get it to work. It will be a light bulb moment when you find what works for you.
Jim

Jason Beam
05-07-2015, 10:58 AM
This might just be a case of too much instruction and not enough "getting to know what you have" situation. Micro knowledge, some call it. I would suggest you go through the filing and stoning process as instructed but ignore everything anyone tells you about rolling the burr.

Instead, take your burnisher and literally take ONE pass on the edge, then TRY it on some wood (yes, poplar is fine). See what it does - if it doesn't pull a shaving, change your grip - tilt it forward more, lean it back - take a dozen or so passes with different angles to see if you can find that hook. If ya can't, take ONE MORE pass with the burnisher and repeat - you should notice a difference in behavior. Keep doing this until you find two things: Good shavings at a comfortable angle and pressure. Then you're done. Until you're sure, you'll probably shoot past it - thus curling the burr back onto itself and it will not cut for crap then. You'll be back to dust. You have to find the sweet spot.

Once you've gone through this exercise, you learn a whole lot more than just following instructions by rote. Plus, you dial in the perfect edge for your scraper and your burnisher. If you repeat the above steps 3 or 4 times and don't see any improvement, I would change burnishers or increase your pressure just slightly (it doesn't take a gorilla grip to roll a burr).

You don't have to do this task every time you sharpen your scraper - just the first time or two till you get a feel for how to roll that burr for THAT piece of steel. Lots of scrapers behave uniquely so a variation on this process may be needed when you get a new scraper but by then you'll have done this enough that it's old hat and you won't have to be quite as methodical about it.

Tony Zona
05-07-2015, 12:12 PM
I tried for an hour and a half yesterday. No good results.

I dont have have a real burnisher, and tried a very hard steel rod, a lathe chisel and a screw driver.

My stores here don't sell burnishers or new scraper's. I tried to find them yesterday.

I'm going to keep at it. It's me, not the scraper, I'm guessing. Thanks for your help, people.

Mel Fulks
05-07-2015, 12:28 PM
If you know someone who does plastic laminate work ,ask for an old solid carbide 1/4 inch diameter trim bit. Makes a good
burnisher when glued with " shoe goo " type adhesive to a slight depression in the middle of a stick. Even if you have to
buy a new bit they are cheap and quite similar to what is used in some of the expensive gadgets.

Brian Thornock
05-07-2015, 1:21 PM
I always had mixed results with my scrapers. Then when we moved here to TX, we ended up buying a house just down the road from a carbide end mill manufacturer. I stopped in one day and asked if they had any broken end mills I could buy cheap. They gave me four or five for free, and I made burnishers out of them. I have never turned such a beautiful hook. The carbide is insanely hard and beautifully polished. A couple decent passes, and I was taking gorgeous fluffy shavings on bloodwood that my hand planes would just glide over. I had an extra one that I sent to a forum member and as far as I know, he had good luck with that after struggles as well. That experience led me to believe that a good burnisher is critical.

Jim Matthews
05-07-2015, 6:28 PM
If you're working with soft woods, it isn't you.