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Scraper sharpening

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I've watched many video tutorials on this and there seems to be conflicting advice. Some say apply moderate pressure, and some say only use the weight of the burnisher itself? what do you do?

Personally, I'm still really bad at sharpening a scraper, and only get good results maybe 1/3 attempts, but have found I get better results when applying moderate pressure.

I have a Bahco scraper, and a Crown HSS burnisher
 

Osvaldd

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Im using a 22mm spanner as burnisher, medium pressure. It used to be frustrating experience sharpening scrapers, but with enough practice now I can sharpen one is less than 30s with 100% success.
cheers
 
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Osvaldd":2p91ys21 said:
Im using a 22mm spanner as burnisher, medium pressure. It used to be frustrating experience sharpening scrapers, but with enough practice now I can sharpen one is less than 30s with 100% success.
cheers
Really? I would have thought a spanner would be far too soft.
 

Osvaldd

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I tried everything(other than a commercial burnisher), drill bits, screwdrivers, pliers, hss rods, chisels etc.. a spanner is giving me a perfect burr every time. I'm using old timey ones, maybe they are a bit tougher than modern ones. And holding a spanner with two hands while burnishing an edge gives me more control and stability.
 
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Osvaldd":jbdq0sr1 said:
I tried everything(other than a commercial burnisher), drill bits, screwdrivers, pliers, hss rods, chisels etc.. a spanner is giving me a perfect burr every time.
Well if it works, that's all that matters :)
 

Cheshirechappie

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I think the key to reliable scraper sharpening is in the preparation. Once a scraper has been used and the burr 'refreshed' a few times, you have to get things back to basic. You have to do this with new scrapers, some of which come with rather rough sheared edges.

Firstly, grip the scraper in the vice with the edge needing attention uppermost, then file off the old edge, using a 6" (or thereabouts) smooth cut hand or flat file, finishing by drawfiling. Then apply the edge of the scraper to a fine sharpening stone, and polish the filed edge. Do the same on each face by the edge. The aim is a clean, 'straight across' edge surface with dead sharp 90-degree corners between the two faces and the edge, with both edge and faces close to the edge polished.

Then grip the scraper edge up in the vice again. With the burnisher (or whatever - I've used a proper burnisher, screwdriver shanks, a small gouge and largish HSS drill bits with equal success), held parallel to the bench top, work the edge quite hard to really - erm - burnish it. A bit of lubricant (oil, spit, whatever) helps. The scraper will cut at that, quite finely - useful for a final clean-up. For a more aggressive cut, once the edge is burnished at 90 degrees, angle the burnisher about 5 to 10 degrees, and give a couple of medium pressure strokes across one edge. Angle it about the same the other way, and do the other edge.

The burr can be 'refreshed' (usually at slightly increasing angles) several times, but eventually you find yourself tipping the scraper at more and more of an angle to the work to get it to cut. Then it's time to re-file and polish the edge, which doesn't actually take that long (provided you can find the file!).
 

Bm101

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Cheshirechappie":1p7v386b said:
I think the key to reliable scraper sharpening is in the preparation. Once a scraper has been used and the burr 'refreshed' a few times, you have to get things back to basic. You have to do this with new scrapers, some of which come with rather rough sheared edges.

Firstly, grip the scraper in the vice with the edge needing attention uppermost, then file off the old edge, using a 6" (or thereabouts) smooth cut hand or flat file, finishing by drawfiling. Then apply the edge of the scraper to a fine sharpening stone, and polish the filed edge. Do the same on each face by the edge. The aim is a clean, 'straight across' edge surface with dead sharp 90-degree corners between the two faces and the edge, with both edge and faces close to the edge polished.

Then grip the scraper edge up in the vice again. With the burnisher (or whatever - I've used a proper burnisher, screwdriver shanks, a small gouge and largish HSS drill bits with equal success), held parallel to the bench top, work the edge quite hard to really - erm - burnish it. A bit of lubricant (oil, spit, whatever) helps. The scraper will cut at that, quite finely - useful for a final clean-up. For a more aggressive cut, once the edge is burnished at 90 degrees, angle the burnisher about 5 to 10 degrees, and give a couple of medium pressure strokes across one edge. Angle it about the same the other way, and do the other edge.

The burr can be 'refreshed' (usually at slightly increasing angles) several times, but eventually you find yourself tipping the scraper at more and more of an angle to the work to get it to cut. Then it's time to re-file and polish the edge, which doesn't actually take that long (provided you can find the file!).
Ah right. I've only ever filed it the first time I got it. I thought you could just use a diamond plate when it needs touching up from scratch after that(every 3rd/4th refresh)
 

Cheshirechappie

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If you can get the edge back to 'straight across' flat and polished, with nice, sharp, 90 degree edges just on the stones, that's fine - just have a look at what you've got and decide whether it's bad enough to need filing.

I use an oilstone rather than diamond stones, and prefer to file so as not to wear a groove in the stone. But do whatever works for you with the gear you've got!
 

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There's a bit of a revolution taking place amongst card scrapers.

Many years ago I can clearly remember most craftsmen made their own by cutting a square from a retired saw plate. These were pretty soft (by design) so the hook didn't last all that long, but it made preparing and sharpening your card scraper really easy. Actually, I should qualify that, it made routine preparation very simple, but initial preparation after cutting a scraper from a saw plate was a long job as all the ruffles from the metal cutting sheers needed stoning flat and polishing.

Then Bahco card scrapers took over, most cabinet makers I know use Bahco 0.6mm card scrapers. These were a little harder than saw plate stock so the hook lasted longer, but they're still soft enough that sharpening is fairly straightforward. What's more they came fully prepared apart from the burr.

But in the past few years there's been a trend towards thicker (0.8mm and above) scrapers made from much harder steel.

I find the sharpening and preparation techniques that served me well for thirty or forty years with my Bahco type card scrapers don't really work on these new scrapers. I suspect you really need a carbide burnisher to work efficiently.

I still prefer the Bahco style 0.6mm card scrapers. But that's a personal choice and I appreciate others may feel differently, for one thing Bahco don't make them in Sweden anymore. They still come fully prepared apart from the burr, and they still come with that really useful plastic slip case that protects the edges, but they're a lot more expensive these days, around about £15 a pop which I think's extortionate!

Incidentally I once worked in workshop where one of the craftsmen had the Arno Carbur. Even though we were all pretty scornful about such new fangled fripperies the fact is we all wanted to borrow it! If I were using today's super hard scrapers then I'd definitely get a carbide burnisher, and even on normal scrapers they do speed things up as you only need a couple of strokes to form then turn the burr.
 

D_W

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transatlantic":2b22q2bf said:
I've watched many video tutorials on this and there seems to be conflicting advice. Some say apply moderate pressure, and some say only use the weight of the burnisher itself? what do you do?
You're reading about peoples' assessments of their methods, but what you really want to know is what result you're looking for.

I use a hock bar, but I'll use anything that's polished. I generally use prepared 1095 scrapers rather than saw scraps (but I will use saw scraps if they are laying around and have been prepped, too - must be from a good saw, though).

There's nothing special about the hock bar. Use a file and stone fast enough to prepare the edge quickly so that you're not needlessly trying to roll a burr on a rounded edge, clean the edge up reasonably well so that there are no snags and then draw the metal out and roll the burr.

My personal thought is that if I have a good clean corner, I will roll with relatively light pressure (not feather pressure like honing a razor, but only a fraction of what I can apply) for the first burr so that I haven't rolled a giant hook over. You give yourself room to work then when rolling subsequent burrs rather than rolling a large burr from the start that's at a steep angle and then having nowhere to go.

Feel for the burr (the result) and don't worry about what people say about their interpretation of their own pressure. Note what it takes to roll the first fresh burr in a way that it's not gigantic and broken apart and where you don't need to roll the card really steeply to get it to bite. That will maximize the amount of time you have before having to back to the file and refresh the edge.
 

D_W

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by the way, the first burnisher that I had was the crown burnisher. Mine has soft spots on it, and I thought maybe I was doing something wrong because the cards would beat it up.

I replaced it with a triangular burnisher because a local guru here told a friend of mine "it's the only one anyone should have". Since its corners are sharp, or you use a large flat area, it's either really light pressure or a lot to get it to roll. I don't get on with it, but will use it if it's closest by when I'm holding a card in hand. The hock rod is just a simple rod, it's hard and polished.

My crown burnisher makes a good pin for my front vise. I know what spots on it are properly hardened, but there's no reason to put up with that. Anything close to the handle is soft.
 

xy mosian

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As recomended by the old guy who taught me to sharpen a scraper, many years ago, I use a blunt saw file ground and polished. It works well enough for me.

Anyone care to share tips on sharpening curved edge scrapers?
xy
 

D_W

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How tight of a curve are you working into sharpening the curved edge scraper? I try to track the edge of a curved scraper with a reasonably fast stone until it's fresh and then use something less aggressive and work some polish to the edge. It has to be done freehand unless you want to make a rube goldberg machine.

I'm not convinced a harder piece of profiled steel wouldn't be better, but I don't use scrapers on tight curves more than necessary. Profiled scrapers and patternmaker's incannel gouges (two things people probably try to avoid using) are pretty nice to have when making guitars, though.
 

yetloh

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Hi Transatlantic,

I've sent you a PM which I think you may find helpful.

Jim
 

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custard":2o6frj61 said:
I still prefer the Bahco style 0.6mm card scrapers. But that's a personal choice and I appreciate others may feel differently, for one thing Bahco don't make them in Sweden anymore. They still come fully prepared apart from the burr, and they still come with that really useful plastic slip case that protects the edges, but they're a lot more expensive these days, around about £15 a pop which I think's extortionate!
Made in Portugal according to the one I got last year. Unless we're talking about scrapers, I paid £6 from D&M.
The one I use most was a home made one. Cut from an irwin hardpoint saw plate, it looks terrible but is easy to sharpen and holds an edge for a while. It was the first scraper I used (and got used to) so I find the stiffness/flexibility ideal. I'm not sure of the thickness, the only downside is it gets hot very fast.
As for sharpening, I watched the first video I encountered (happened to be wood whisperer). Found it got good results so just stuck with that.
For burnishing, I use an old gouge and a bit of oil. My irwin saw plate scraper requires a small amount of pressure, using the weight of the gouuge alone does nothing. I've never sharpened the bahco as it comes ready to use (as Custard mentioned) and currently dont know where it is #-o

edit: someone posted an excellent sharpening guide here a while ago, but I cant remember who it was.
 

Ttrees

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transatlantic":tca9lval said:
I have a Bahco scraper, and a Crown HSS burnisher
You haven't mentioned what file you are using.
A nice wide "farmers own" single cut file is really smooth cutting.
I like to use a block to register square.
4.jpg

7.jpg

From what I see, most folk who aren't getting the results they want, its down to the filing.
I use a sawplate straight from the file in the metal workshop for occasional wooden things.



xy mosian" Anyone care to share tips on sharpening curved edge scrapers? xy[/quote said:
 

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