Cheapest way to flatten chisels?

[Patrick Chase]

The price of PSA paper can depend a lot on what you are buying and from whom it is bought.

I have had good service from these folks:

http://www.supergrit.com/products/pr...drumsleeve-psa

Their "gold" Al-Oxide paper prices out at $0.015 per square inch, or about triple the cost of non-PSA sheets. It isn't much more of a deal than 3M 216U.

The F-weight Alumina-Zirconia stuff looks really interesting though. That's the same abrasive family as the Norzon belts that many people recommend for heavy lapping work, but with PSA and paper instead of cloth (which may improve flatness). I think I'll order some...

EDIT: Whoever set up their web storefront was laughably incompetent. I particularly like the way it clears all of your information (name, address, payment, etc) every time you adjust order quantities.

[Patrick Chase]

So this isn't exactly the "cheapest" way, but here goes:

I get the chisel roughly flat using a 150# diamond disc on a Veritas power sharpener. If it's really nasty I'll have at it with a grinder as Malcolm suggested, though that's a last resort. I usually use a flat-sided CBN wheel when I do that.

The next step is to true the back on either a Sigma #120 waterstone, or 125 micron 3M 675L diamond microfinishing film if I'm in a hurry or the steel is difficult. I've also used sandpaper at this step, but I don't find it to be enough of an improvement over the Sigma stone to be worth the added cost. The 675L film is in a class by itself for speed - it's like starting with a fresh XXC diamond plate for every chisel. It's also in a class by itself for cost (and not in a good way) at $5 per 3x6 sheet when bought in bulk.

From there I usually work through a series of diamond pastes on surface-ground mild steel plates, typically starting at 45 um and ending at 0.5 um (~20000 grit). I sometimes use diamond lapping films instead though I prefer the results from the plates/paste - the films (esp the PSA ones) have a little bit of "give" and that leads to ever-so-slight dubbing.

With that said, I'd rather spend my time using tools than fixing them up, so I avoid chisels that aren't flat to begin with these days.

If you aren't completely "retentive" about flatness then Charlseworth's technique on harder waterstones (Sigma Power, Shapton Pro, etc) works well.

[Jim Koepke]

EDIT: Whoever set up their web storefront was laughably incompetent. I particularly like the way it clears all of your information (name, address, payment, etc) every time you adjust order quantities.

That may be what got me to use their telephone number. It has been a few years since I ordered anything.

jtk

[Tom McMahon]

https://logancabinetshoppe.wordpress...-stop-lapping/

[Patrick Chase]

https://logancabinetshoppe.wordpress...-stop-lapping/

Clearly sufficiently skilled craftsmen could and did get good results with convex chisels, but the step from that fact to "you shouldn't flatten your backs today" is akin to arguing that we shouldn't use cars or planes because people used to be able to get from point A to point B by horse.

Also, some of his arguments display fundamental misconceptions about cutting mechanics. Take for example the claim that the chisel's path will "bisect" the back<->bevel angle. That's (somewhat) true when taking a deep cut perpendicular to the wood's surface, but that doesn't happen If the back of the chisel is registered against a broad surface as in many paring cuts, or if the cut is shallow such that the bevel side yields more easily than the back side. That's precisely why the standard advice is to "sneak up" on your baseline when chopping, such that the small amount of wood on the bevel side doesn't exert enough force to push the chisel off-line. I have similar reactions to a few of his other claims, but unfortunately am at work.

[Chuck Nickerson]

Here in the US the home improvement stores sell Drywall Screen (NOT the Drywall Sandpaper). They are 3"x9", cheap, and come in grits 120, 150, and 220.
For me they were a game-changer.

[Patrick Chase]

Here in the US the home improvement stores sell Drywall Screen (NOT the Drywall Sandpaper). They are 3"x9", cheap, and come in grits 120, 150, and 220.
For me they were a game-changer.

Those are also really useful for stone flattening on a budget. The trick is getting them to lie flat...

http://www.amazon.com/3M-99440-Pro-P...drywall+screen

[Prashun Patel]

Wow, that's good info Chuck. Thanks. Like Patrick I wonder how you get them flat?

[Ray Selinger]

I use a granite plate I was given. It's a handy two sheet size. Someone mentioned glass shelves as a source. A light misting of 3M 77 is enough hold the 120wet/dry. Either the water or the oil on the wet/dry makes lifting easy. I then use a single blade razor blade to scrap the granite. Rather than change the paper, I've taken to sprinkling 90grit silicone carbide on it when it loses it's bite. It makes short work of flattening water stones. Just make sure to wash it off.

[David Bassett]

... What is the fastest and cheapest way to flatten them ?

First, remember the old saying: fast, cheap, or good, pick two.

Since you've picked fast & cheap, I'm surprised no one has mentioned the HF 1" x 30" belt sander / grinder. (Lasse, I'm not sure what your HF equivalent is over there. You must have someone importing cheap Chinese tools. Or, maybe you can find something similar you can order directly from Asian.) Ron Hock even shows a way to mount it for a horizontal grinding surface in his sharpening book. It's on their website for $50 right now, but it seems like $30 with coupon is it's more usual price. Add in a few grits of metal cutting belts and you'd be set to quickly remove a lot of metal for pretty cheap.

[Malcolm McLeod]

"fastest" and cheapest" don't belong in the same sentence.

Sure they do:
"You can have your 'chisel' (insert anything) good, fast, and cheap. Pick two!" - Anon.

[Tom McMahon]

Patrick, I was going to write a big long reply but I decided it's just a waste of time, it's all been said before. So instead here is a picture of my chisels and some of my work and I will say that I have no idea whether any of the chisels have flat backs or not, I suspect not.
IMG_20160408_150939148_HDR.jpg
IMG_20151224_104746282.jpg
IMG_20151220_160521478.jpg

[Jim Koepke]

Tom, I suspect most of your gouges and carving tools do not have flat backs.

jtk

[Patrick Chase]

Patrick, I was going to write a big long reply but I decided it's just a waste of time, it's all been said before. So instead here is a picture of my chisels and some of my work and I will say that I have no idea whether any of the chisels have flat backs or not, I suspect not.
IMG_20160408_150939148_HDR.jpg
IMG_20151224_104746282.jpg
IMG_20151220_160521478.jpg

Wow, those are indeed terrific pieces. Maybe someday...

With that said, the fact that you replied that way means you missed the entire point of my post: Of course you can do terrific work with horrendously dubbed chisels. IMO it takes more skill and is all the more impressive as a result, but that doesn't make it the "best", "right", or "most productive" way to set up your tools as that article you posted argued. It just means that you're so good that you can overcome that particular handicap. My hat is off, but I won't be emulating you in that regard any time soon, thanks.

[Tom McMahon]

Patrick, I don't think I missed your point but maybe. I do think you missed mine probably because I never really said it. Here's what I believe right or wrong. A chisel only needs to be flat enough to do the job you are trying to do. Spending the time to flatten a chisel to the third decimal place only makes sense if the surface you are going to jig off of is flat to that same tolerance. In 48 years I cannot think of a single thing I tried to do with a chisel that failed because the back of the chisel wasn't flat enough. For almost every job a chisel with an ever so slight back bevel to get the edge past any pitting will make no difference and in some cases is an advantage. In all honesty I can't think of a single thing I do that needs a dead flat back on a chisel or would even make it faster or easier. In most cases if I make an error with a chisel it digs in or rips out some grain which a flat back wouldn't help. I'm not saying to purposely put a back bevel on all chisels, I'm saying if they will sharpen don't worry about how flat they are.