Have you had any luck sharpening a card scraper...


woodbutcher
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...with anything other than an actual burnishing tool? I have tried screwdriver handles, prybar shafts, anything that seems like it would be harder than the scraper, but nothing I have tried gives me anything i can snag my fingernail on, much less take shavings with. I am fully prepared and intend to buy a dedicated burnishing tool, I was just wondering if anybody has had success sharpening their card scrapers with anything less. I have heard and read that you can. Not working for me though.

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I used the shaft off an old HSS drill mounted in a dowel handle and a Crown round rod for awhile with equally decent results.  I use goose-neck and other scraper shapes and found the Veritas Tri-Burnisher to be a good fit for this tighter curves.  If you have an old valve out of a car motor around I have heard of folks using those.  Any material used should be harder than the material you are using it against. 

William Ng drowns his scrapers in oil but, I find a tiny bit to be adequate.  I do not know that your failure to achieve a burr is the burnisher's fault yet.   As mentioned, even a screwdriver should give you a good burr.  It just won't do it very well very long and can gall.  The fact that you are not getting one at all makes me focus on the prep prior to trying to lay one on.  the video above has got it well covered.

Here's another.

And another.

 

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The hardest thing about sharpening a card scraper is overcoming reluctance.  You have to press down hard, while drawing it across as fast as possible, but still under control enough to not hurt yourself.  I think the "fast" part generates some heat, and also helps to even out the human error part that comes into play when trying to go too slow.

I was at a Bob Ballard talk where he told a story about Prince Charles going diving with him somewhere in the North Sea.  Prince Charles was sitting on the edge, while the crew was piling his equipment on.  They were strapping on something like 80 pounds of weight.  Prince Charles said that he had calculated that he would only need about 40 pounds.  Bob Ballard said that he told him,  "Yeah, that first 40 pounds is to overcome bouyancy.  That other 40 pounds is to overcome reluctance".

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There are a ton of videos on this subject and they all have little twists to them.  I found Marc's to be very good.  Keep it simple.  Square the edges with a mill file, there are various aids out there to help you achieve a square edge.  Once this is done I never go back to the file.  From here hone the edge and face of the scraper with a 1000 grit to 3000 grit stone, use the edge of the stone to hone the edge of the scraper to avoid putting ridges in the surface of the stone.  Again there are various aids you can use to keep the edge of the scraper square to the stone.  I use a Veritas tri-burnishing rod, recommend you purchase a proper burnisher.  Lay the scraper down flat on the edge of your bench and draw the metal out with a few quick swipes across the face side. The drawn edge will be Shiney!  Hold the burnisher perpendicular to the edge, then tilt around 5* and draw across the edge about one or 2 times at the most.  Done!  When you stop making shavings burnish the face and the edge again.  The angle that you burnish determines the angle you have to tilt the scraper to cut.  I have found I can re-burnish the scraper many times before needing to re-hone on the face and edge.  I use oil when I remember but that is usually not the case when I re-burnish the edge.  You should be able to re-burnish all 4 edges of a card scraper in under a minute!  Curved scrapers use the same procedure, just a little trickier to handle.  The first time you hone the scraper after filing it will take awhile due to the scratches from the file.  Afterwards, it's a minute or two on the stone and back to burnishing.  The finer the stone you use the finer the shaving and smoother the finish on the wood, just like a plane iron.  I find a 3000 grit stone gets me to light sanding with 180-220 grit paper.  Some people scrape and the wood is finish ready.

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Screwdriver is no good.  You really do need a burnisher.  If you wanna take all the guesswork out of it, get the Veritas burnisher...the one that's egg shaped.  Can't remember exactly what they call it but it is absolutely auto-pilot.  If you can't turn a hook with that thing then you can't butter a piece of toast. LOL

I have a standard burnisher and the Veritas...and unless I'm sharpening a curved scraper I grab the egg nine times out of ten.

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5 minutes ago, derekcohen said:

Regards from Perth

Derek

Derek, how many times would you say you can turn a new hook before you have to go back to the stone and establish a new square edge and start over?  My initial hook on a fresh edge will last a fairly long time, but even just the second one seems to dull (break?) almost instantly.  I realize it's a much weaker hook but having to square my edges for every sharpening is annoying.  Any tips?

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11 hours ago, Eric. said:

Screwdriver is no good.  You really do need a burnisher.  If you wanna take all the guesswork out of it, get the Veritas burnisher...the one that's egg shaped.  Can't remember exactly what they call it but it is absolutely auto-pilot.  If you can't turn a hook with that thing then you can't butter a piece of toast. LOL

I have a standard burnisher and the Veritas...and unless I'm sharpening a curved scraper I grab the egg nine times out of ten.

 

Eric.- this burnisher here the one youre referring too?

 

 

http://www.leevalley.com/us/wood/page.aspx?p=32633&cat=1,310,41070

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Don't know why the OP is having some difficulty, but some other sources are Christopher Schwarz and Mike Peckovich from Fine Woodworking. Christopher has a great article on sharpening scrapers and there is a video online at finewoodworking.com by Mike (but it might just be available to FWW online members). Either of these provide step by step guidance on scraper sharpening and even I was able to understand.

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I'd second @derekcohen's suggestion about using a light touch. When I first started, I thought I really needed to bear down with the burnisher to turn the edge, and I was never able to achieve a good edge on my scrapers. It was only after I watched a video recommending a very light touch on the burnisher that I was finally able to get acceptable results.

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I really got into the card scraper during the sculpted rocker build.  What an incredible time-saving tool.  To take a surface that's rough from a rasp to something quite smooth and ready for sanding with so little effort.  A must have in my woodworking toolkit.  Admittedly, I use a burnisher.

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