I haven’t gotten the hang of forming and turning a burr on my card scrapers. Would I be better off using scrapers made from softer steel, and who sells them?
At the Lee Valley website it says, “Most cabinet scrapers are sheared from spring steel, hardened to Rc38-42.” I don’t where they found such scrapers; they all (including mine) seem to be Rc48-52.
Can I soften the edges by heating them with a torch?
Janet
Replies
Janet,
I had trouble getting a good burr on my scrapers at first also. Then in my reading I came across an article that said to draw the burr in two steps. I have had much more sucess with the following method. After filing the edge square, first I draw a burr downward twards the edge then roll that same burr back 90+ degrees to its final location. This seems to create a more serious burr for me. I do not know if this the accepted method or not, but it works for me. Good luck.
Janet,
Instead of using softer scrapers, I suggest you learn how to sharpen a card scraper properly. To get a good hook, you first need to joint the edge with a file, then refine the edge and adjacent faces on a stone before rolling a hook with a burnisher. You must use a burnisher (not a screwdriver, etc) for today's super-hard scrapers. EDIT: Start with the burnisher at 90-degrees, using medium pressure and take a few strokes (I usually do 3-4), then tilt the burnisher up to 15-degrees and take another few strokes, then do the same on the other side.
Good luck. Sharpening a card scraper continues to be one of the activities that will always gather a crowd trying to learn how to do it well.
Actually, I'm not certain that I have even created the burr, never mind turning it. Does it take a lot of muscle to create the burr?--because maybe I'm not applying enough pressure while burnishing.
Janet
Clinton's analogy of using the same amount of pressure when hand-planing is a good one - I wish I'd thought of it.
You could of course take the temper out of the card, but I bet the edge wouldn't last long enough to be useful. The edge tends to get work hardened which may have compounded your problem. Take a file and remove the work hardened edge. I saw a man at a show with a neat little gig in which a file was set in a slot in a block of wood allowing him to run the card against the file...a sure fire way to file the edge perfectly square. He said, and I've found that you can feel when the file is cutting into the unhardened metal all the way along the edge.
I agree with the other commenter that forming the edge is a two step process after you've filed the edge. To be clear lay the card flat on a surface and pull a burr out parallel with the card's flat surface above the edge. Then put the card in a vice and burnish the edge out perpendicular to the face, more or less.
I use a screw drive as a burnisher. It may be less than perfect, but it's better than nothing.
Peter
Card scrapers are in my opinion the hardest hand tool to learn how to sharpen, but once you get the hang of it they are one of the easiest tools to sharpen. The key in my oipinion is having a good burnisher. I tired all differnent kinds from HSS drill bits to auto engine valves. I finally broke down and called Hock tools and got one of their burnishers. Ron Hock answered the phone and gave me great advice on how to use a burnisher. He said that when drawing and turning the burr, you need to use about the same amount of pressure on the burnisher as you would use to hand plane a piece of wood. You need to be firm but not so hard that you're standing on the burnisher. Be careful, if you use too much pressure you will slip off and slice the dog crap out of your hand. Beleive me I watched all the FWW videos about how to sharpen a card scraper at least a dozen times and still coudn't get it right. Don't give up though, it is a skill well worth learning because card scrapers are so incredibly useful.
Maybe I need to buy a new burnisher. Mine is a small jeweler's burnisher which, come to think of it, would be used on soft metals like gold and silver.
Janet
Janet,
That sounds like a good place to start.
This burnishing tool (http://www.stewmac.com/shop/Tools/Scrapers/Scraper_Burnisher.html?tab=Pictures#details) is set into a block of wood. It is similar to the jig that Brian Boggs used in his video, except the wood is shaped so the tool will be used at the correct angle for both drawing and turning the burr (see pictures).
I ended up buying the Hock burnisher, but will make a jig for it.
Janet
David Marks has a very useful video on sharpening hand scrapers...using his method I actually have learned to do it properly and effectivELY
Neil
Neil,
Is this an online video, or a "boughten" one?
I am not familiar with David Marks, but I see he is in Santa Rosa, CA. Next month I'll be near there (visiting family in SF). Hmm....
Janet
David use to have a show on DIY called Woodworks, one of the major influences for my journey into the wonderful world of wood butchery...the video is for sale on his website..well worth the money and of course you can easily resell it.
Neil
There is a video on the FWW site and an article in the archives that will tell you all you need to know. What no video or book can tell you is how it feels when you turn the burr over and how much pressure to use. That only comes with experience. My card scraper is about 1" smaller that it was originally from all the times I re-filed it while learning the process. You need a good hard burnisher. One thing that suprised me when I finally got it right was how small the burr felt when it scraped effectively. My early attempts made a burr too large. I could definately feel it with my fingernail, but a large burr will wear out faster or break when compared to a smaller burr. If it's too large it won't cut at all because it has rounded over. You want a hook, not a bumper. When I resharpen my scraper, one side always seems to cut better than the other three. That side is usually the one where the burr "feels" the smallest, ie. my fingernail catches the least on that edge.
Click on the link below for my favorite How-to for card scraper sharpening. I've watched Tom do this in person, and seen the results, he's good!
http://www.woodworking.org/InfoExchange/viewtopic.php?t=7941
Janet,
A softer scraper would be cause more problems than it would solve. Even a hard scraper doesn't stay sharp for very long.
Ask 100 woodworkers how to sharpen a scraper and you will get 100 slightly different answers. The following link has some information on the subject.
http://rlmillard.typepad.com/my_weblog/2008/03/index.html
Rob Millard
http://www.americanfederalperiod.com
Why, Rob, you must be something of a Luddite! Great web site.
You emphasize the importance of using a light touch in places. I'm going to practice some more.
Janet
Janet,
Thanks.
Those projections that become the burr/hook are fragile, so a light touch when flattening them out in the second burnishing step, really helps produce a good cutting edge.
Rob Millard
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