Thread: New Scraper ?

Very interesting.

I was going to reply to the other thread about the scraper that this is something I want to but have yet to figure out (the sharpening part).

I'm sure it is pretty simple once you've got it in your head, but I've read several articles, seen clips on Youtube, and watched The Schwarz's video - and not produced a burr that is what I expect to be achievable. No nice shavings.

I've only had a couple of tentative attempts at it - so much else to learn

I haven't heard anyone talk about using the edge of a piece of glass ... but when I think about it, I've done that at some stage in my life - scraping away at something with the broken edge of a cup or plate.

But in any case ... the video from the website:

[ame=http://www.youtube.com/watch?v=a7XRbfbpXiE]Carruth Ultimate Scraper - YouTube[/ame]

Hi pmcg,

Stick with it. I try to turn the edge with only one or two heavy passes, with a 3 corner burnisher, to reduce metal fatigue.

The glass is 3,4&5 mm x 70-75 mm square

Once you get a card scraper sharp you will wonder how come you had so much trouble before. Polish the face (at lleast near the edge0 and file the edge square and straight like jointing a saw, polish the edge, keep it square across and straight, then lay the scraper flat on the bench andwith a slight angle(almost flat) to the face burnishe the edge. Clamp the scraper in a vise and run the burnishe square across, now run the burnisher across at a slight angle (drop one end) and with gentle pressure burnish the corner. Most people have trouble because they don't get the edge straight and square (look across it in good light and you should see a narrow even rectangle) or they use too much pressure and too great of an angle off of 90 degrees. Glass works too. You may need a bit of lube if you feel your burnisher dragging on the scraper, I use the collet ends of carbide router bits stuck in a handle for burnishers.

My scraper never makes it to the vise, it gets held flat on the bench with sholder and fingertip power. This gives me a better view of the burnisher angle and the edge can be re- turned anywhere , shop or site.

At the risk of sounding lke an old carmugeon (which I am, I admit), I reckon that Caruthers scraper is gilding the lilly big time. The first thing that occured to me is how will you resharpen the thing? I've no doubt it will work alright out of the box, but given our siliceous woods down here, it will dull sooner or later, if used seriously - what then?

This is a timely post, - see the current AWR for a short article by Anton Gerner on sharpening card scrapers. I think he's done an excellent job, particularly because he shows 3 levels of preparation, depending on what you want to do with the scraper. The file/burr process he starts with is dead easy and gives you a marvellous paint-removing tool.

IMO, card scrapers are one of woodworking's great inventions - so simple & so effective in their right place. (And the best place for most of us is on hard woods, they just don't work as well on soft woods, though luthiers seem to be able to manage them!). As someone else says, getting the burr right is a skill that takes a bit of initial mucking about, but when you finally get it, it's one of those revelatory moments in life. I think the most common fault beginners make is over-doing the burr. Once you get the edge square & polished, a couple of light passes is all it takes. (A useful hint is to rub your finger on the side of your lower nose or ear lobe, which are both areas rich in large sebaceous glands, then wipe it over the burnisher. Sebum is an excellent lubricant, and prevents the burnisher from binding. If you are squeamish about body fluids, light oil does just as well, but you have to walk over to the oil can. )

Try your scraper after a couple of light to firm passes of the burnisher, to see if it will cut at a not-too steep angle. If it won't catch & cut until laid over at 45 degrees or more, you are definitely over-doing it. You can burnish the burr off & redo it. I wouldn't worry about metal fatigue, on the contrary, reburnishing a few times work-hardens the metal & gives you a tougher edge. I usully re-burr 3 or 4 times, sometimes more, between re-sharpenings.

Happy scraping, and you can even learn to like the smell of cooking thumbs when hand-scraping lrge areas......
Cheers,

IanW is spot on. Once you have the edges square everything becomes easy. If there is some rounding that's when it will be difficult to get the correct burr. With an oilstone in a wooden case to was easy to run it against the side of the stone using the box to keep it square.
It's one of the most versatile tools there is and probably the cheapest. Especially for Ian; he probably has more scraps of saw steel lying around than anyone.
Cheers,
Jim

Originally Posted by jimbur

....t's one of the most versatile tools there is and probably the cheapest. Especially for Ian; he probably has more scraps of saw steel lying around than anyone.
Cheers,
Jim

Bang on, James...

In fact, you can make very servicible scrapers out of the floor scraper blades Bunnings sell. For 12 bucks, you get enough steel to cut out about a dozen cards (using a 1mm cutoff wheel & clamping the scraper between a couple of bits of straight steel to act as a guide & heat sink). They are 0.8mm thick, so on the less-flexible side, if you prefer the thinner, more flexible type. Lee Valley scrapers seem to range from 0.4mm to 0.8mm. The first scraper I ever had was a Sandvik, which was about 0.8 mm thick, so I like them that way....

Cheers,

Just a wild guess Ian
Cheers,
Jim

Originally Posted by IanW

At the risk of sounding lke an old carmugeon (which I am, I admit), I reckon that Caruthers scraper is gilding the lilly big time. The first thing that occured to me is how will you resharpen the thing? I've no doubt it will work alright out of the box, but given our siliceous woods down here, it will dull sooner or later, if used seriously - what then?

This is a timely post, - see the current AWR for a short article by Anton Gerner on sharpening card scrapers. I think he's done an excellent job, particularly because he shows 3 levels of preparation, depending on what you want to do with the scraper. The file/burr process he starts with is dead easy and gives you a marvellous paint-removing tool.

IMO, card scrapers are one of woodworking's great inventions - so simple & so effective in their right place. (And the best place for most of us is on hard woods, they just don't work as well on soft woods, though luthiers seem to be able to manage them!). As someone else says, getting the burr right is a skill that takes a bit of initial mucking about, but when you finally get it, it's one of those revelatory moments in life. I think the most common fault beginners make is over-doing the burr. Once you get the edge square & polished, a couple of light passes is all it takes. (A useful hint is to rub your finger on the side of your lower nose or ear lobe, which are both areas rich in large sebaceous glands, then wipe it over the burnisher. Sebum is an excellent lubricant, and prevents the burnisher from binding. If you are squeamish about body fluids, light oil does just as well, but you have to walk over to the oil can. )

Try your scraper after a couple of light to firm passes of the burnisher, to see if it will cut at a not-too steep angle. If it won't catch & cut until laid over at 45 degrees or more, you are definitely over-doing it. You can burnish the burr off & redo it. I wouldn't worry about metal fatigue, on the contrary, reburnishing a few times work-hardens the metal & gives you a tougher edge. I usully re-burr 3 or 4 times, sometimes more, between re-sharpenings.

Happy scraping, and you can even learn to like the smell of cooking thumbs when hand-scraping lrge areas......
Cheers,

I'll have to go to the libary to see the vidio. My understanding, from the blurb, is that the edge is not burnished. It is hollow ground as needed.

I have old planer and spindle knives, I'm going to try at least grind one edge to see how it works.

FWIW:

The new scraper is 1/8" thick.

Ground against a 8" (200mm) diameter grinder it would create a dip between the top and bottom edges 1/2 thou deep.

s = R-sqrt(R^2 - l^2) where l=thickness/2.

Paul.

Before hollow grind, it is prepared much the same way as a traditional card scraper so it should have a clean un-ragged arris in this state. But what happens when the burr is formed on the grinder? Does it push this arris out to form a fine cutting edge? Or do you end up with a ragged burr off the grinder? If the former, I wonder how easy it would be to exceed to the latter? He doesn't show the quality of the surface under raking light and under a finish and this is what I'd like to see. I'm always suspicious of anyone claiming a cutting edge from straight from a grinder is sufficient for any tool ('cept turning), especially one producing a show finish.

I know that if I haven't got my card scraper tip top, even though it was burnished and not ground on a wheel, the first coat of shellac across the surface usually tells me quite emphatically that there is problem with the scraper.

mic-d, yes, my first thoughts were along similar lines, but given that this scraper is probably produced on highly sophistacted machinery, it's conceivable that they could get a pretty good edge on it, using a very fine diamond grit to finish the hollow edge. But my next thought worried me more - how does your average user restore that edge when it gets dull? There's no way I could freehand the edge of a straight scraper across a grinding wheel & end up with anything other than a rough paint remover!

Since it's trumpeted as being designed with people like luthiers in mind, one can reasonably assume it's capable of doing a very good job initially, but do you just chuck it away when it no longer cuts, or send it back to the factory for re-sharpening? Neither alternative seems like a good idea to me, but if people are happy to chuck away saws whenever they become dull, who knows......?

Cheers,

Agree with Ian and Mic-d. You could easily end up with a rough scraping tool.
Cheers,
Jim

Originally Posted by IanW

mic-d, yes, my first thoughts were along similar lines, but given that this scraper is probably produced on highly sophistacted machinery, it's conceivable that they could get a pretty good edge on it, using a very fine diamond grit to finish the hollow edge. But my next thought worried me more - how does your average user restore that edge when it gets dull? There's no way I could freehand the edge of a straight scraper across a grinding wheel & end up with anything other than a rough paint remover!

Since it's trumpeted as being designed with people like luthiers in mind, one can reasonably assume it's capable of doing a very good job initially, but do you just chuck it away when it no longer cuts, or send it back to the factory for re-sharpening? Neither alternative seems like a good idea to me, but if people are happy to chuck away saws whenever they become dull, who knows......?

Cheers,

You guys, I'm assuming we have some sharpening skills. I always assume I can do something untill proven wrong. Then I have another go.

This interests me because I've used glass and know it works.
I'll make one of these in the next couple of days.