Diamond plate flatness and card scrapers

[Kicked Back]

I have an EZE Lap diamond plate, 600 and 1200 grit. Sharpening plane blades and chisels, followed by a strop, gets me nice sharp edges.

I'm really struggling to sharpen card scrapers such that I can take nice shavings with them. I have a proper burnisher and have tried multiple techniques.

On closer inspection, my diamond plate is very slightly concave. Haven't put a feeler gauge in, but let's just say 0.5mm or so. The problem is, it means the card scraper doesn't really get sharpened in the middle so well. And then I can't really strop a card scraper.

I was toying with the idea of getting a high grit waterstone to replace the strop, but now I'm not so sure the wonky diamond plate can keep the waterstone flat?

Any advice welcome. Thanks

 

[D_W]

file the bottom of your card scraper at about 20 degrees (toss out 90 degrees for now).

Hone across the diamond at about 10 degrees on the bevel side. Hone the flat face, draw a burr and use.

You can hone the flat face any way you want, it'll flex to the error on your card scraper.

I would prefer (on something like this) to follow the recipe I just gave, but use an oilstone instead as they're far superior to anything else for card scrapers - scrapers are saw temper or hard saw temper and an oilstone will cut them easily and leave a relatively high polish (drawing and burnishing will do the rest).

Too many people want to work the scraper top and bottom at 90 degrees to get four mediocre edges, but it's far easier to put a bevel like I described top and bottom with some separation (enough so you can do this visually without a jig) and make two excellent burrs instead. It'll save you time rather than taking more.

I mentioned honing across only because your stone isn't flat. You can also just let the edge on and off of the stone (as in, let the honing run past the edge), but diamonds cut deep and gnarly and on saw temper steel, it'll be even more so.

 

[Adam W.]

I use a mill file to create a burr and a burnisher to turn it. The burnisher also serves to take some of the harshness out of the edge for fine scraping.

Steve Latta uses this technique and he knows about card scrapers, but you'll have to buy his video from Lie Nielsen. It's worth the money, as he has a no nonsense approach.

Others may have a different opinion....obviously.

 

[Kicked Back]

file the bottom of your card scraper at about 20 degrees (toss out 90 degrees for now).

Hone across the diamond at about 10 degrees on the bevel side. Hone the flat face, draw a burr and use.

Thanks, a bunch of stuff I didn't know in there.

I'm a bit confused about what to reference for the 10 and 20 degree angles. It seems you mean with respect to the face (ie. face flat on stone = 0 degrees?)

 

[D_W]

Illustration of what I'm mentioning - the whole method - biasing the edge a little bit, will give you a huge head start if you're doing something like profiled scrapers (I generally use spring steel guitar angle gauges to profile fingerboards instead of sanding -as in, the gauge sets with different radius arcs on them are spring steel, so rather than using them to check progress, you can actually just roll a burr on them and use them to scrape a fingerboard dead on to the radius on the checking gauge - skip a whole lot of sanding and huffing dust. )

I refiled the edge on this scraper and honed both bevels and both faces opposite of them and then drew the burr and rolled them in a minute 20 (for all of it).

Sorry the first picture is from overhead a bit, but figure this angle is about 70 degrees or 20, depending on what you're referencing.

from the stone - higher angle - more or less microbeveling - rule number one in sharpening anything, if you don't actually get the sharpening or honing done at the edge that's doing the cutting then the results will be rubbish. I'm claiming this is 80/10 or something like that, it's only important that you lean the scraper a bit more toward vertical so that the stone is actually honing the edge and not some other steel that doesn't matter.

(that's the part you'll be doing across the stone. Do it vigorously for about ten seconds, then put finger pressure on the face of the scraper and hone the face with pressure biased make sure you're honing off all of the scuzz that may have been at the bevel edge).

If you do this with oil, then you can ignore the goofy "go find some oil" talk that waterstone folks would follow. I'd say you could also just wipe the scraper on your forehead, but you'd probably soon look like a pro wrestler.

About 10 strokes with a burnisher on the flat side just above the plane of the scraper and then a relatively light touch 90 degrees to the face to roll the burr. Roll a small to moderate burr - if you're going to roll more burrs out before refiling again, and you roll a huge rounded over burr on the first one, you've got nowhere to go with the next ones. You should be able to see and feel the burr.

First shavings from this (notice how bright they are - this was a sawn fingerboard blank that a wood supplier threw in on an order that I made).

scraping is all down the length, but turning the scraper at opposing angles (think plowing snow to the left or right side of a row).

The shavings look like this unrolled (the shiny side is on the outside = the inside is a bit dull from being crushed).

And the resulting surface without planing or sanding.

 

[D_W]

I'd normally say it doesn't matter what you use to sharpen, but I don't know of anything better than a single natural medium/medium fine oilstone. A diamond hone just doesn't cut it - the burr is more coarse and won't roll as smooth or last as long.

 

[IWW]

Hmm, it doesn't take all that much practice to learn to file/hone a 90 degree edge on your scraper. I agree that if you really, really can't do that then putting a slightly acute angle on is likely to get you a usable edge, but it's so much more economical of your time to be able to prepare 4 good edges at a sitting!

If you want to get a very fine edge suitable for fine work like cleaning up inlay etc, then I think some sort of HARD fine stone is mandatory after the file does the initial levelling/straightening (for less exacting work, just turn a burr off-file; as someone has already said the burnisher will refine the edge the file leaves somewhat). I would certainly not take a card scraper to my fine water stones - I use a Shapton pro, which is one of the hardest water stones around, but it's still far too easy to cut with a very narrow edge. Oilstones are the go, either man-made or natural - as DW said, the steel is not that hard & hones easily.

Honing is the critical step, you need to concentrate to keep that edge square (or within a very close approximation). My method is to put the scraper on the stone & turn it about 10 degrees to the direction I'm moving it back & forth. That helps me to keep it vertical to the stone's surface. Because the steel is soft, it doesn't take very long to polish the edge - the less time you can spend on this step the less likely you are to round the edge over.

I think the best advice of all is to just persevere - it'll click all of a sudden & you'll be rolling copious shavings off so easily you'll wonder what the fuss was all about....
Cheers,
Ian

 

[Ttrees]

I don't think the hone is at fault, as I've often sharpened a scraper.. or I could say
flattened a hollow oilstone with a beater hand plane iron.

It seems like a reluctance to file back to a square edge is the problem.

Even if what you say about the hone creating that profile is what the issue is...
Not sure how long of a stroke you are making, but surely running off the edge would
counter this from happening.

If you are using a block for registering the scraper off the file and hone,
note that these blocks wear, and you are faced with the decision whether to plane off a sparkly shaving

 

[Blackswanwood]

I was shown how to do it on a course by Chris Tribe. Helpfully he shows how to do it his way (which works for me) on Youtube

 

[Kicked Back]

Illustration of what I'm mentioning

Thanks for the detail, that's clear now.

Interestingly, rosewood fretboards is what I'm trying to tackle. I'm turning a burr with my current method but it just tears out the slightly cross-grained rosewood. Will try yours and report back. Do you think I'm likely to get significantly worse results from using a diamond stone over the oil stone in terms of shaving quality?

 

[Ollie78]

Not sure your issue is the abrasive itself.
It took me a while to get the hang of turning a burr to the proper angle.
As others have said you can turn a decent edge straight off a file, granted it wont be super smooth but it shows that the sharpness is coming from the burr not the "flatness" of the edge exactly.
Too much burr or turned to much angle it won`t work nicely, not enough and it won`t do a proper shaving. Once you crack it its pretty easy.

I normally do a few passes on my waterstone before doing the burr. I have an arno burnisher which is really good and easy to use as it has the angle built in so you just hold it square.

Ollie

 

[Kicked Back]

I was shown how to do it on a course by Chris Tribe. Helpfully he shows how to do it his way (which works for me) on Youtube

That's the method I can't get to work acceptably. But maybe his plate is flat...

 

[Ttrees]

I'd like to try making a burnisher from an old file like Rob has to see the results sometime.

 

[D_W]

Thanks for the detail, that's clear now.

Interestingly, rosewood fretboards is what I'm trying to tackle. I'm turning a burr with my current method but it just tears out the slightly cross-grained rosewood. Will try yours and report back. Do you think I'm likely to get significantly worse results from using a diamond stone over the oil stone in terms of shaving quality?

I can test on this fingerboard, but I think if you have something like a 1000 grit diamond, it'll do just fine.

 

[D_W]

I refiled, same method, and worked across the width of the diamond hone.

The burr is a bit more toothy, but similar results.

The smoothness of the result from a common low cost Arkansas stone is just much nicer, though.

 

[D_W]

it boggles my mind that we've gotten to the point where someone has to pay to learn to sharpen a card scraper.

 

[Blackswanwood]

it boggles my mind that we've gotten to the point where someone has to pay to learn to sharpen a card scraper.

No one has to.

Chris Tribe showed me on a course he used to run for beginners which was about sharpening and fettling tools. I chose to go on the course and for me it was good value for my money.

The ethos of the course was to try different methods and mediums for sharpening to find the one you were happy with and don’t get sidetracked by sharpening zealots who feel those that don’t use their chosen method are stupid. It’s a shame Chris had retired as he was a great tutor and is one of nature’s gentlemen.

Of course you don’t find any sharpening zealots on this forum

 

[Adam W.]

Nor any sharpening gurus, for that matter.

 

[D_W]

The ethos of the course was to try different methods and mediums for sharpening to find the one you were happy with and don’t get sidetracked by sharpening zealots who feel those that don’t use their chosen method are stupid.

Experimentation is good advice. (I also like the advice of avoiding the "the guy i like, i bond with him, you know, he does it this way, so it's the only way".)

Brosharpening.

 

[D_W]

I'd like to try making a burnisher from an old file like Rob has to see the results sometime.
View attachment 124390

I wouldn't get too infatuated with something like that unless you have no other options. Three different people have sent me their end-all-be-all "best ever" burnisher, and a guy who teaches hand tools here (And who isn't as good with them as I am - which is boggling, too) swears by a triangular burnisher and sold me one early on.

High polish high hardness round something, rod, screwdriver shaft, whatever. I just use a round piece of rod that hock sells that's low temper and high polish. It wasn't expensive. I'd make the same thing with scrap rod now instead of buying, but I don't know that the average person could make it worth their while (no harm in testing high polish screwdrivers, though - aside from the scraper may mark them if they're underhardened - if they were, though, they'd be flexible like saw temper).

Crown burnisher is the only thing I've had (First one I got) where the entire rod isn't actually high hardness - and the scraper will actually cut into it near the handle - first one I ever bought probably 16 years ago - it's the peg in my leg vise pin board now.

I think the average person trying to round over a file or something probably spends a lot of time doing it and either draws the temper or doesn't end up with a good polish.