I just sharpened a card scraper

Re: I just sharpened a card scraper

Derek Cohen (in Perth, Australia)

Bill, and there I imagined that I was the guru of scrapers! Just goes to show that there is more than one way to go about this.

My favourite scraper is a piece of 3/16" thick O1 plane blade. This is hollow ground to a square edge on a grinder (I use 180- or 80 grit CBN wheels). Nothing else to do. Absolutely wonderful, and if you have not tried this, you are seriously missing out.

Paul advocates thin blades, so this is far from his method. With a card (Cabinet scraper in my world), I prepared the sides and edge with a very worn 600 grit diamond plate (probably now closer to 2000-3000 grit), draw out the steel, and then lightly turn a hook. 4 or 5 light strokes, and done ...

http://www.inthewoodshop.com/WoodworkTechniques/FoolproofSharpeningOfCard%28Cabinet%29Scraper.html

Regards from Perth

Derek

Re: I just sharpened a card scraper

John K Jordan

>>>My favourite scraper is a piece of 3/16" thick O1 plane blade. This is hollow ground to a square edge on a grinder (I use 180- or 80 grit CBN wheels). Nothing else to do. Absolutely wonderful, and if you have not tried this, you are seriously missing out.

That's exactly how the (expensive) StuMac scrapers are sharpened but with a 600 grit CBN. After hollow grinding they recommend using a fine hone flat on the sides, which I do. Excellent scrapers.

I use mostly curved scrapers since I use them on woodturnings. As you say, there are varied opinions on sharpening and turning the burr. I shape curved scrapers on a belt sander, grind on a 600 grit CBN, flatten, remove the grinder burr, then burnish. The scrapers eliminate almost all sanding on woodturnings.

Bill, the amount of force needed to turn a given burr depends somewhat on the diameter of the burnisher. I use three different ones and the one with the largest radius takes more force.

JKJ

Re: I just sharpened a card scraper

Derek Cohen (in Perth, Australia)

Bill, the amount of force needed to turn a given burr depends somewhat on the diameter of the burnisher. I use three different ones and the one with the largest radius takes more force.

JKJ

That's my belief as well. I use a polished carbide rod, about 1/4" diameter ...

Regards from Perth

Derek

Re: I just sharpened a card scraper

Barry Irby

I have struggled with this for years. I will go watch the video. Don't understand the last three steps. What is clean and straighten the burr? I may doing that when I wipe off the card, but I did not see that as a step.

I found and aid for this. What I do now is put a file in my vice so that it is horizontal. I use the wooden jaw of the vice to keep the scraper vertical and slideit back and forth to straighten and square the edge. This is a fresh fine sharp file I keep for this purpose. Then, In the past, I would clamp the card in the vice with about and inch or less exposed and use my carbide burnisher to turn a hook. Clamping the card fairly low allows for very forceful use of the rod. The rod is about 3/8" in diameter.

Recently I found a gadget that improves on my process. It's a block of hardwood with a rabbet in it. There is a hardened wheel set on a shaft at 90 degrees to the rabbet and the face of the rabbet is line with steel. Once you have filed the edge of the card, you slide it through the gadget against the steel face and in the crack created by the wheel and it turns the hook. Takes a second or two and works very well. I will look at it and see if it has any identifying markings.

I don't have one of the sticker scrapers or a CBN wheel so that would be a significant investment. Would like to try it.

Insight?

Bill Tindall, E.Tn.

Card scrapers and the ones illustrated by you all are ground 90 degrees. Fixed blade scrapers- chair scrapers, scraper planes, floor scrapers- are sharpened at 45 degrees and then the burr established. Why the difference?

For example, what would be the result if one used a beveled plane blade for a scraper instead of the 90 degree plane blade stock? Ditto for the lathe scrapers. What would be different if they were ground at a more acute angle?

Re: I just sharpened a card scraper

Bill Tindall, E.Tn.

watch the video. Save me trying to explain by words.

Re: Insight?

Derek Cohen (in Perth, Australia)

Card scrapers and the ones illustrated by you all are ground 90 degrees. Fixed blade scrapers- chair scrapers, scraper planes, floor scrapers- are sharpened at 45 degrees and then the burr established. Why the difference?

For example, what would be the result if one used a beveled plane blade for a scraper instead of the 90 degree plane blade stock? Ditto for the lathe scrapers. What would be different if they were ground at a more acute angle?

Bill, it is an illusion that card scrapers are square edged and fixed blade scrapers are 45 degrees. In reality, they are all similar to plane blades. All have a cutting edge with a cutting angle. The hand adjusts the cards, and those for the planes are prepared thus.

The card scrapers have a roughly 10 degree hook, but they are also angled to the wood, which increases the cutting angle (if the hook is a higher angle, one ends up canting over the card at a lower angle).

Fixed blade scrapers need a specific angle to work correctly. One can use the blade with just the 45 degree bevel, however it will not cut well (only beginners do this since they lack the experience to form the correct angled hook).

Now it is also possible to vary the angle on the blade in a scraper, such as a Stanley/LN/Veritas #112. Originally, I believe that the bevel angle was 60 degrees for maximum edge retention. Some prefer 45 degrees, and I have even used 30 degrees - the edge does not last as long, but the hook is easier to roll.

I had a discussion about 15 years ago with Paul Hamler about thick versus thin blades for scraper planes. He was (still is) a supporter of thin blades, at a time when LN was making a thick blade for their #112 and also a thick replacement blade for the Stanley #112. I explored this and wrote this article:

http://www.inthewoodshop.com/WoodworkTechniques/Thick%20verses%20thin%20112%20Scraper%20Plane%20blades.html

Both thin and thick blades made nice shavings ...

Regards from Perth

Derek

Insight not yet provided

Bill Tindall, E.Tn.

While your reply provided the opportunity to post your earlier study of scraper plane blades ground significantly different from what Paul recommends-35 vs 45 degrees- your reply did not answer the question I asked. Card scrapers prepared at 90 degrees. Fixed at something more acute, 45 degrees by Paul's recommendation. Why the difference card vs fixed?

Commenting on your study thin vs thick. Thin will be quicker and easier to file and less expensive to buy, presuming one bought spring steel stock for making scrapers. So if the use result of thin vs thick is the same, +/- screeching, thin would be preferred. As far as screeching, Paul's scraper planes did not screech in his demo. I agree that if screeching could not be avoided with some set of variables a change to these variables would be in order.

Re: I just sharpened a card scraper

Clint Searl

Card scraper>>File it; roll a burr with whatever's handy; use it. The rest is irrelevant. A sharp chisel with the original bevel and the edge rolled over also makes a dandy detail scraper. I use an old Stanley and a Craftsman.

Re: I just sharpened a card scraper

Dave Bair

My grandfather always had the best scrapers and never once sharpened them. He would recycle a tomato-sauce jar by putting it in a paper bag and dropping a hammer on it. The shards made excellent scrapers, especially for gunstocks, you just had to be a little careful when handling them.

Re: I just sharpened a card scraper

Bill Tindall, E.Tn.

Your claim, The rest is irrelevant, that being at least the two cleaning steps and the double roll of the burr that Hamler claims are important to improved edge life.

I would hope, without data to confirm, that Hamler has tested whether these extra steeps are important. I'm not satisfied with the longevity of my scraper edges so I am going to add these steps. The claim of work hardening at least seems plausible.

I was impressed with the amount of material Hamler was able to scrape with his prepared edge.

Re: I just sharpened a card scraper

Clint Searl

Perhaps "superfluous" is a more apt word that "irrelevant." Any advantage in advantage in possibly extending edge longevity isn't significant enough to obsess over the extra steps. I put a burr on both sides of a card scraper and redress when needed. Starting with an edge orthogonal to the plate only counts if both sides are burred. A burr rolled on the acute side of a beveled edge is just as effective, maybe more so as the hook may be deeper.

Moving goal posts?

Derek Cohen (in Perth, Australia)

Bill, you asked ..

Card scrapers and the ones illustrated by you all are ground 90 degrees. Fixed blade scrapers- chair scrapers, scraper planes, floor scrapers- are sharpened at 45 degrees and then the burr established. Why the difference?

For example, what would be the result if one used a beveled plane blade for a scraper instead of the 90 degree plane blade stock? Ditto for the lathe scrapers. What would be different if they were ground at a more acute angle?

I replied ...

it is an illusion that card scrapers are square edged and fixed blade scrapers are 45 degrees. In reality, they are all similar to plane blades. All have a cutting edge with a cutting angle. The hand adjusts the cards, and those for the planes are prepared thus.

Regards from Perth

Derek

Lots of considerations..

David Weaver

...where did david barnett go? I don't use scrapers a lot on furniture, but i use them on guitars and sometimes tools.

All of the factors (refinement of the edge, size of the burr, hardness of the scraper) are things that can be manipulated.

On the long duration end of things, a large burr on a semi-hard scraper can last a really long time (think the harder iron-style scraper blades in scraping planes), or you can sharpen a card scraper with an intentionally small burr and a very refined edge to try to blend in with planed surfaces by scraping with light final strokes and then burnishing with shavings.

Very refined in this case, to me, is using a washita stone for everything after the file. Most scrapers are soft enough that the washita cuts them very fast, but it definitely removes any file lines.

Refinement considerations are probably out the window if someone is going to sand the surface - who cares if there are small lines.

For really heavy work in something that blasts the burr off fast, I remember seeing a video of a guy on youtube scraping right off of a more coarse file, and he allowed the raised file burr (IIRC) to do the scraping work as a prep before sanding (so that he woudln't have to sand as much) rather than as a fine surface finish.

Everything works if it matches what you're doing.

Hamler's work was interesting (he's obviously some kind of savant) and I followed it for a while, but it disappeared quickly after figuring out the cap iron. You can just do the same volume of work (in volume of wood removed), often to a higher quality, with a standard bed plane and much less physical effort and much less regard to things like accidentally scraping across grain (oops), breaking off edges of stock or whether or not the wood is too soft to scrape in the first place.

Probable reason..

David Weaver

I think it's easier to roll a large burr on a 45 degree edge (and have it at an angle where a scraping tool can hold the iron) than it is to roll a large burr on a 90 degree scraper where rolling the large burr will often increase the angle that you need to hold the scraper to much more acute than 70 degrees or whatever a scraper plane likes to be bedded at.

Try rolling two similar sized large burrs on 90 degrees and 45 and see what angle you have to hold the scrapers to get the burrs to cut.

thanks good information