Cheapest way to flatten chisels?

[Lasse Hilbrandt]

Im in the market for old chisels that needs restoration. I have found out that most of them are not flat on their backs. So far I have been flattening with my Norton wetstones, but it takes a hell of a time and wears a lot on my stones.

What is the fastest and cheapest way to flatten them ?

[Prashun Patel]

Worksharp with 120 grit Diamond lap plate. One of many ways. There's mine.

[Lasse Hilbrandt]

Worksharp with 120 grit Diamond lap plate. One of many ways. There's mine.

Prashun, Worksharp, is that the machine with the horizontal disc ?

[Patrick Chase]

Worksharp with 120 grit Diamond lap plate. One of many ways. There's mine.

Or the Veritas power sharpener, which is also an 8" disc grinder.

I've always had trouble getting chisels truly flat that way, though. The speed difference between the inside and outside of the wheel leads to grinding-rate differences, and I find that I have to do a fair amount of lapping afterwards to get a truly dead flat back.

Depending on how much your time is worth the cheapest solution overall may be "buy chisels that are already flat".

[Lasse Hilbrandt]

Patrick that defeats the purpose of restoring old chisels ;-) I already have the new Veritas chisels. Restoring I do for fun, but it would be even more fun if I could speed up the proces in the cheapest possible way.

[Phil Mueller]

Cheapest....a piece of plate glass or scrap granite or marble tile with 80 grit sandpaper. May not be the fastest, but keep in mind, only about an 1" really needs to be dead flat. I've flattened many garage sale chisels this way. Work up from 80 grit to 220 and move to the stones.
Actually, I run an old chisel over 220 grit first to see how bad it is. Then, depending on how bad, start with 80 or 100 or 150; the smallest grit to get it flat within a reasonable amount of time.

[Allan Speers]

Im in the market for old chisels that needs restoration. I have found out that most of them are not flat on their backs. So far I have been flattening with my Norton wetstones, but it takes a hell of a time and wears a lot on my stones.

What is the fastest and cheapest way to flatten them ?

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


Cheapest: Get a cement block. (they are flat due to gravity as they cure, just like plate glass.)

Rub your chisels until your fingers get numb, then switch to a finer-grit cement block. :)



I actually read an article once about an old timer pro woodworker, who actually did this.

[Patrick Chase]

Cheapest....a piece of plate glass or scrap granite or marble tile with 80 grit sandpaper. May not be the fastest, but keep in mind, only about an 1" really needs to be dead flat.

IMO this depends on the chisel. For, say, a paring chisel that gets used to clean out slots and dadoes I prefer to have (a lot) more than an inch. It's OK if it's a little bit concave and the chisel is flexible enough, though even in that case you have to remember to apply enough bending force so that it lies flat and doesn't dig in.

[Ray Selinger]

You should have added easy as well. When I find an old pitted rusty chisel I belt sand the back down as far as the pits. $1 for the chisel, $7 for the 6x48 belt . I've used 120 wet/dry paper to get the slight rounding out. Today the Eskilstunasteel, Berg and two Swedish patterned Footprints didn't require much. I only hone near the edge.

[Phil Mueller]

100% agree. For garage sale stuff, I usually hope for 1"...if lucky, you can get much more. Just not something I count on from a rust find.

[Robert Hazelwood]

The best way I have found is just to use sandpaper stuck to something flat, and make sure to use fresh sheets. I'd start with 80 grit, then 150, then 220, then go on to my 1000 grit waterstone and on from there. I've tried to find a better way, buying coarse diamond stones and waterstones, but I've found coarse sandpaper just works faster. And it's cheaper unless you are constantly restoring chisels.

If there is a lot of damage/pitting at the edge, I won't hesitate to grind back the edge (grind at 90 degrees) to get rid of defects. I've also put a few bad blade backs on a belt sander to get rid of the majority of problems, but that is risky.

[Jim Koepke]

Not much to add. I use the Veritas Mk.II Power Sharpening System, similar to the Worksharp, and have been able to do fine with the rotational differentiation. I also have a 4' long piece of granite from a monument maker (tombstone carver) with abrasive paper attached. I do not do as much flattening as I used to, but as far as I am concerned I have done a lot better spending a little time restoring the old than spending a lot of money on the new. Besides the enjoyment it brings, no one has offered to pay me money to not do it.

jtk

[Don Jarvie]

Norton has an combo oil stone, course and fine, that will make quick work of it.

You need the back flat if you want a good edge so it's worth the time.

[jamie shard]

For sure, the best and fastest way is cheap sandpaper on a flat surface, then move up through the grits you already have for sharpening.

[Phillip Mitchell]

It's not the cheapest but not too bad at around $65; I lap my newly-acquired old chisels with a DMT XX coarse diamond stone. I think they say it's 120 grit. It's not too bad on chisels under 1". I have been restoring a handful of timber framing chisels (1 1/2 - 2") and it takes some elbow grease, but a lot quicker and more effective than waterstones. After it's lapped flat, I use a Tormek to either grind a new bevel or spruce up the current bevel if it's appropriate, then I go to the waterstones. I'm fortunate to have a Tormek that sits in the shop at work that I can use anytime I want.

[Luke Dupont]

I find sandpaper works quite well. I flattened the backs of my chisels with just 400 grit sandpaper, and it didn't take very long. But, if they're really out, maybe 240 or perhaps even 120 grit should work fine. I find that sandpaper cuts about as fast as diamond stones, if not faster; they just wear out quickly.

I haven't tried really coarse sandpaper, so I may be wrong, but I think if you go too coarse, it won't actually cut as effectively.

[Stanley Covington]

Depends on how bad the back is out of tolerance, and how skillfull you are.

If it is bad, and you want a flat back the whole length, use a grinder and Dykem to quickly cut down high spots. Keep it cooled with water, keep your finger right over the area being ground so you will feel it if it gets hot, and take your time. Apply Dykem frequently and check flatness against wet-or-dry paper glued to plate glass. Final lap on the paper and glass. If you screw it up, the chisel will be ruined.

Stan

[Lasse Hilbrandt]

Lots of different suggestions. Thanks. It seems like the most common is using sandpaper.
Do you guys glue it to the flat surface or just hold it down by hand ?
It seems to me that gluing will take to long as you have to change the sandpaper often ?

[Stanley Covington]

Lots of different suggestions. Thanks. It seems like the most common is using sandpaper.
Do you guys glue it to the flat surface or just hold it down by hand ?
It seems to me that gluing will take to long as you have to change the sandpaper often ?

http://www.amazon.com/ELMERS-Repositionable-Mounting-Adhesive-E454/dp/B000BKRLMO

[Luke Dupont]

Lots of different suggestions. Thanks. It seems like the most common is using sandpaper.
Do you guys glue it to the flat surface or just hold it down by hand ?
It seems to me that gluing will take to long as you have to change the sandpaper often ?

Gluing it would be best, I suppose. I haven't used it though. I've used tape, and it works, but you have to be careful; double sided tape may flex underneath and create an uneven surface. And just taping the edges down will allow the paper to buckle in the middle as the paper works its way loose on both sides.

What I usually do is tape it to my computer desk, which is quite flat, but I put the tape on the sides parallel to the motion I'll be working. That seems to work quite well, and I get a perfectly flat back. Experiment with different methods, but if you find it moving too much, or giving on you, you'll know to fix it or try something else.

I will admit; when touching a blade up (especially when working the bevel side, or plane irons), or even sharpening knives, I'll usually just hold the sand paper in place with my off hand, and never have a problem.

[Lasse Hilbrandt]

http://www.amazon.com/ELMERS-Repositionable-Mounting-Adhesive-E454/dp/B000BKRLMO

Thanks Stan. i just ordered some spray glue

[Jim Koepke]

Do you guys glue it to the flat surface or just hold it down by hand ?

I buy rolls of adhesive backed sandpaper.

Some of the problems with working the back of an iron or a plane sole is swarf buildup and rocking the item being worked.

I use a magnet to pick up the swarf. A brush or a vacuum could also do the work. Check the sole of a plane often. Depending on how the work is being done any distortion can be end to end or side to side. Did I mention checking often? Maybe every few strokes...

jtk

[Phil Mueller]

I use 3M Pro Grade Precision with no-slip grip backing sandpaper. Holds well to plate glass or granite on its own - maybe other surfaces as well (?).

Like Luke, with other sandpaper, I tape the sides...taking care to pull it tight down to the surface. I use Gorilla Tape.

I've also used Spray Mount...art stores should have it. It does gum up your surface which needs to be cleaned off every few pieces of sandpaper. Goo Gone works well to remove it.

[Lasse Hilbrandt]

I buy rolls of adhesive backed sandpaper.

Some of the problems with working the back of an iron or a plane sole is swarf buildup and rocking the item being worked.

I use a magnet to pick up the swarf. A brush or a vacuum could also do the work. Check the sole of a plane often. Depending on how the work is being done any distortion can be end to end or side to side. Did I mention checking often? Maybe every few strokes...

jtk


Jim thats a good observation I havent thought about.

[Kees Heiden]

Even cheaper is loose SiC grit on a flat surface like a floor tile. Very quick to remove pitting when you regularly replenish the grit. I'm not so sure about getting a flat surface though. I still struggle with the whole flattening concept. Going from sandpaper to wetting stones usually shows a large discrepancy between the two.

[lowell holmes]

I would start with a belt sander and lightly sand the back. Then hone it on a granite plate with wet sandpaper. If you don't have a granite plate try a piece of plate glass.

I purchased a granite plate from Woodcraft. I really like it for sharpening jointer knives.

I also flatten chisel backs on diamond hones.

I really have not had much problem with the back of chisels. I normally will just flatten the bottom 1 inch portion of the back of the chisel. And, that is part of the sharpening.

[Patrick Chase]

Lots of different suggestions. Thanks. It seems like the most common is using sandpaper.
Do you guys glue it to the flat surface or just hold it down by hand ?
It seems to me that gluing will take to long as you have to change the sandpaper often ?

I use a very light coat of 3M Super-77 when I use sandpaper. After coating one sheet you can usually stick down the next few using just the residue it leaves behind. Stanley's Elmer spray probably works about the same, though I've never used that.

[Patrick Chase]

Jim thats a good observation I havent thought about.

The reason I didn't bring up PSA paper is because it's pretty expensive and you explicitly requested an "economical" solution.

For example P80 3M Stikit Gold is about $0.02 per square inch ($50 for a 25 yd by 2.75" roll). Similar quality P80 Al-Oxide paper is about $0.005 per square inch (Norton A275/3X at $35 for 50 9x11 sheets). The economics are about the same for other abrasives and quality levels.

The rolls are certainly user friendly though - The 3M Stikit ones in particular use a low-tack adhesive that's just about right for lapping. I'm not such a fan of the Klingspor rolls that LV carries - they're too tacky and prone to leaving residue.

[Andy McKenzie]

I spent some time this week working on a pair of inherited paring chisels. (New handles are on the to-do list, since someone munged up the old ones with a hammer...) One was only a little out of flat, and I started that one on 80 grit cheap paper from Harbor Freight. The other was terrible, and I started it on 60 grit, again from Harbor Freight. On both the rest of the progression was 180, then coarse, medium, and fine DMT stones, followed by a few passes on a strop. Both are now pretty near mirror finish, and I spent about 20 minutes on each one.

[Jim Koepke]

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/products_rolldrumsleeve-psa

The stock changes at times. The call in number has been very helpful answering any of my questions.

A putty knife and mineral spirits have been good at removing any adhesive residue.

jtk

[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/products_rolldrumsleeve-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.com/2011/08/10/chisel-backs-stop-lapping/

[Patrick Chase]

https://logancabinetshoppe.wordpress.com/2011/08/10/chisel-backs-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-Pak-Drywall-100-Grit/dp/B000CP0NBE/ref=sr_1_2?ie=UTF8&qid=1460138984&sr=8-2&keywords=3m+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.
335419
335420
335418

[Jim Koepke]

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

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.
335419
335420
335418

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.

[Patrick Chase]

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.

I actually agree with this and almost everything else you've directly posted in this thread. I'm pretty OCD (and upfront about it), and I know that a lot of what I do is way out into diminishing returns. For example I keep the backs of my mortising chisels flat, and there is basically no benefit to be had by doing that.

I still think however that that article went too far in the other direction. Some of the arguments like the one about "bisecting the bevel" were just plain bogus, and it seemed to argue that there was *no* benefit to a flat back. I think that anyone who's ever used a chisel to pare a tenon cheek knows that flatness helps, at least up to a point (though you could reasonably argue that a chisel isn't the best tool for that).

EDIT: Note that I ended the post you first replied to with "if you're not totally retentive about flatness..."

[Lenore Epstein]

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-Pak-Drywall-100-Grit/dp/B000CP0NBE/ref=sr_1_2?ie=UTF8&qid=1460138984&sr=8-2&keywords=3m+drywall+screen
What have you done in the past? I've used drywall screen to sharpen the edges of Plexiglas wax scrapers (for ski bases) by clamping a length of 2x4 lengthwise an inch or so in from the sheet's edge and using the wood as a 90 degree guide. The screen is thick and stiff enough that I had no trouble with movement, so clamping further away from the edge might keep as much as a few inches of it flat so long as you didn't bear down hard. I'd get it out and try it for you all if my waxing kit weren't stored away...

[Lasse Hilbrandt]

Without flat backs how do you remove the wire edge on the back?

[Kees Heiden]

The wire edge sticks out a bit. You fold it back to the bevel side and do some more rubbing on the bevel. All this bending and rubbing ultimately cuts it loose.

[Patrick Chase]

I still think however that that article went too far in the other direction. Some of the arguments like the one about "bisecting the bevel" were just plain bogus, and it seemed to argue that there was *no* benefit to a flat back. I think that anyone who's ever used a chisel to pare a tenon cheek knows that flatness helps, at least up to a point (though you could reasonably argue that a chisel isn't the best tool for that).

Now that I have more time, here's another gem of an argument from that "chisel backs, stop lapping" article: "I did a little research and found out that properly made chisels should actually be concave along the length of the back. Think Japanese chisel. Traditionally, toolmakers would harden and temper the chisel before the bevel was ground. This way, after the heat treatment, they could identify which side of the tool had warped concave, and grind the bevel on the opposite side. Doing so would put only the very edge of the chisel in contact with the stones when chasing the burr. This made perfect sense to me, as it focussed the work only where it was needed, just like a Japanese chisel."

On a related note, black is white, up is down, we've always been at war with East Asia and never with Eurasia, etc.

Of course the obvious problem with that argument is that everything it says about Japanese chisels is completely backwards. Japanese chisels are concave in the center of the back (i.e. in both axes), not "along the length". They're made that way to make it easier to work the entire perimeter of the blade back rather than just the leading edge as the article claims. The lengthwise edges are generally prepared flat or somewhat convex, rather than being "concave along the length".

[Patrick Chase]

What have you done in the past? I've used drywall screen to sharpen the edges of Plexiglas wax scrapers (for ski bases) by clamping a length of 2x4 lengthwise an inch or so in from the sheet's edge and using the wood as a 90 degree guide. The screen is thick and stiff enough that I had no trouble with movement, so clamping further away from the edge might keep as much as a few inches of it flat so long as you didn't bear down hard. I'd get it out and try it for you all if my waxing kit weren't stored away...

I've had OK luck clamping the ends with blocks, though as I implied above I found it to be a hassle. I'd rather use loose SiC grit at that point.

[Kees Heiden]

Now that I have more time, here's another gem of an argument from that "chisel backs, stop lapping" article: "I did a little research and found out that properly made chisels should actually be concave along the length of the back. Think Japanese chisel. Traditionally, toolmakers would harden and temper the chisel before the bevel was ground. This way, after the heat treatment, they could identify which side of the tool had warped concave, and grind the bevel on the opposite side. Doing so would put only the very edge of the chisel in contact with the stones when chasing the burr. This made perfect sense to me, as it focussed the work only where it was needed, just like a Japanese chisel."


I think that quote came originally from the Iles brothers in England. There is a problem with this idea though. Many of the older chisels in the 19th century and earlier were laminated. So it would have been impossible to choose the bevel side until after hardening depending on the concavity. You would end up with a lot of chisels with the lamination on the wrong side. The brothers Iles learned their trade in the twentieth century when chisels were ususally made from solid steel.

[Patrick Chase]

I think that quote came originally from the Iles brothers in England. There is a problem with this idea though. Many of the older chisels in the 19th century and earlier were laminated. So it would have been impossible to choose the bevel side until after hardening depending on the concavity. You would end up with a lot of chisels with the lamination on the wrong side. The brothers Iles learned their trade in the twentieth century when chisels were ususally made from solid steel.

IMO there's no question that a concave chisel is easier to work with than a convex one. That's true regardless of whether you flatten it: If you do flatten it then you end up having to remove about 3x less metal from a concave chisel to correct any given amount of runout. If you don't flatten it then you can still pare without having to lift the chisel, and you can still chase the burr easily. For that matter you can easily make a concave chisel "flatten out" if it's flexible enough.

[Chris Parks]

Coincidence, there has been a lot of talk about flattening chisel backs on another forum, I can't link but I am in Australia so you can work it out. One of the suggestions there was to get a flat plate sander, turn it upside down and clamp it in the vise and go at it with whatever grade of paper you want to use. Another one is buy some diamond discs from Ebay, make a platter of MDF, attach a mandrel to drive it from a drill press chuck and put a piece of MDF on the DP table that the platter can be lowered flush with the top of, instant, variable speed horizontal grinder complete with tool rest. The MDF might have to be substituted for something more durable over a longer term but it gets what is needed for a quick try out.

[John Kananis]

Diamond paste on MDF. Get the waterbased stuff from Gramercy. Quick, cheap and very good (IMHO). My water stones are rarely used any longer.

[Warren Mickley]

There have been a few suggestions that historic practice involved stones that were not flat and chisel backs that were not flat. I would like to see documentation of these ideas beyond wretched flea market finds. The only 18th century writing on this which I recall just now is Salivet (1792). He says that the stone should be kept flat through careful use and that the back should be carefully abraded flat on the stone.

If someone buys new planes or plane irons every year and constantly buys auction and flea market chisels, plus a new set every other year, I can see that flattening would be a chore. For a woodworker, flattening backs is a rare chore. I have chisels and plane irons in constant use since the 1970's and 80's; I can't recall the time spent on the back of tools that I have sharpened five or ten thousand times each. I have worn a few plane irons from new down to nothing, but I don't think I have replaced one in the time since the "ruler trick" was invented.

[lowell holmes]

Just curious, are you flattening the entire length of the back.

Normally, I only flatten the bottom inch or so of the back. I have antique Stanley chisels as well as Lie Nielsen and Narex. Some of the old Stanley chisels may require more.

[Jim Koepke]

I don't think I have replaced one in the time since the "ruler trick" was invented.

Was it recently "invented" or was it something rediscovered?

It would not surprise me to find woodworkers used this "trick" in the past.

jtk

[David Bassett]

... The only 18th century writing on this which I recall just now is Salivet (1792)....

The Jointer and Cabinet Maker, (by Anonymous, edited & augmented by Joel Moskowitz & Chris Schwarz, and republished by Lost Art Press), says an apprentice or journeyman could be fined for not flattening the shop's stones. In another section it talks of a sloppy apprentice leaving a bench stone dished and uses it as an example of someone unlikely to advance or succeed in the field. The original text is from 1839. Also in a footnote, they (Joel, I think) talk about how sharpening on grind stones and bench stones was so common in so many trades in that day it is omitted as obvious from most texts of that era. They list a few other mentions in old literature too, so the concept was known "back in the day".

[Stewie Simpson]

The Jointer and Cabinet Maker, (by Anonymous, edited & augmented by Joel Moskowitz & Chris Schwarz, and republished by Lost Art Press), says an apprentice or journeyman could be fined for not flattening the shop's stones. In another section it talks of a sloppy apprentice leaving a bench stone dished and uses it as an example of someone unlikely to advance or succeed in the field. The original text is from 1839. Also in a footnote, they (Joel, I think) talk about how sharpening on grind stones and bench stones was so common in so many trades in that day it is omitted as obvious from most texts of that era. They list a few other mentions in old literature too, so the concept was known "back in the day".

As I understand it the original text was only 100 pages; by Anonymous.

the revised text is 370 pages.

never let the truth get in the way of a good story.

[David Bassett]

As I understand it the original text was only 100 pages; by Anonymous.

the revised text is 370 pages.

never let the truth get in the way of a good story.

I don't understand your point.

As I said, the original text was edited and reprinted and the book was augmented. I believe Joel did the historic information in the introduction and footnotes that provide context to a modern reader unfamiliar with that earlier era. Then an entire section was added where Chris Schwarz builds the projects assigned to Thomas, the story's apprentice, and provides extra directions for those want to try them. Since the 1839 portions of the text talk about flattening stones, it is another, slightly more recent, mention than the one Warren gave.

[Kurt Cady]

As I understand it the original text was only 100 pages; by Anonymous.

the revised text is 370 pages.

never let the truth get in the way of a good story.




"The complete text of "The Joiner and Cabinet Maker," unabridged and unaltered. We present every word of the 1839 original (plus a chapter on so-called "modern tools" added in a later edition), with footnotes from Moskowitz that will help you understand the significance of the story." From LAP.

370 would include all of the other stuff in the book

[Patrick Chase]

The Jointer and Cabinet Maker, (by Anonymous, edited & augmented by Joel Moskowitz & Chris Schwarz, and republished by Lost Art Press), says an apprentice or journeyman could be fined for not flattening the shop's stones. In another section it talks of a sloppy apprentice leaving a bench stone dished and uses it as an example of someone unlikely to advance or succeed in the field. The original text is from 1839. Also in a footnote, they (Joel, I think) talk about how sharpening on grind stones and bench stones was so common in so many trades in that day it is omitted as obvious from most texts of that era. They list a few other mentions in old literature too, so the concept was known "back in the day".

I wonder how much the practical meaning of "flat" has changed, though.

There is no such thing as a perfectly planar surface, so for the most part when people say "flat" they really mean "sufficiently planar that I can't tell the difference with the tools at my disposal". In my case that usually means "I can't see light under my Starrett straight edge".

Does anybody have a sense for what an 18th or 19th century cabinet maker's definition would have been?

[David Bassett]

I wonder how much the practical meaning of "flat" has changed, though....

I'm sure it's changed and I'm also not sure we shouldn't have equal or more concern about "smooth". We shouldn't sell short the very refined skills of craftsmen past and I suspect they could achieve flatter with their tools than most of us could with those tools, but they also didn't have cheap granite surface plates, precision ground straight edges, etc. that come up in many of these "flat" discussions. (Which is why I was staying out of this discussion. I only jumped in when I knew a second historic reference supporting the point Warren was making.) BTW- I'm convinced, from the references, they did worry about flat and, I'd bet, they had a much better idea what "flat enough" is than most of us do. Given time is money, I'm sure they didn't go beyond flat enough (for their current job.)

[Jim Koepke]

Given time is money, I'm sure they didn't go beyond flat enough (for their current job.)

The world was different then. How many people bought a set of tools at the local hardware store. Most likely a person 'in the trade' bought tools as they went. The first part of all of it was being an apprentice in a shop. A lot of the time they had wasn't worth as much as the journeymen in the shop. They were likely learning about sharpening as one of their first steps after tending the glue pots and sweeping the floors. If they liked the trade they maybe bought a chisel when the money and need came together.

jtk

[Warren Mickley]

Today we have people who put pencil marks on a stone and consider it flat when their flattening tool obliterates the marks. This is completely divorced from the real concerns of how the flatness of the stone affects performance of the tool. The most important thing in sharpening is discernment: what can you notice about the performance of the tool. The stone is flat enough when the tool does what you want.

We have people putting a camber on the tool by counting strokes rather than by actually looking at how the plane is performing. This is what we call cookbook learning: follow this recipe to the letter; don't bother getting a feel for the process, don't follow your intuition or worry about the actual taste of the food.

The advent of the sharpening jig has caused a great increase in the need for flattening. Rather than using the stone in such a way as to minimize uneven wear, many today give no thought to wear and run the tool on a very small patch of the stone. They are content to spend time repairing the damage for the next tool.

[Brian Holcombe]

My backs are flat enough that my wear bevel disappears each time I sharpen. I assume that requires a very flat back and stone. I also cannot imagine that deviates very far from historic requirements

[Jim Koepke]

My backs are flat enough that my wear bevel disappears each time I sharpen. I assume that requires a very flat back and stone. I also cannot imagine that deviates very far from historic requirements

Well said, I tend to keep an eye toward removing the wear bevel when honing a blade, but it seems more profound reading it.

jtk

[Brian Holcombe]

Thanks Jim!

I didn't see Warren's post before submitting mine (we must have been typing at the same time), but basically driving at the same point. His example is a good one, I'm learning to make sushi currently and the rice is the most delicate part of the task. My last attempt was to follow a recipe exactly....which I did....the rice was beautiful and tasted horribly plain. Next time I will follow my gut and add what I thought it was missing.

Same for camber and flattening backs, ect. If you're getting a good pattern, and your stone is working nicely and the wear is disappearing then you're right on. If it's not and your getting multiple patterns and your not accomplishing anything then something is wrong. I haven't checked flatness on a stone or chisel or plane blade in my shop, but they're flat to be doing their job well, if they weren't or at least weren't flat enough then I would get a new wear pattern each time. Diagnostic equipment is great, when you need it, but otherwise it seems to get in the way of doing the job well and developing intuition.

[Stewie Simpson]

My own experience with using Early 1900s Nos taper irons suggests there is little to be gained by spending too much time trying to flatten the back of these irons. They are far from flat as seen on more modern manufactured irons.

Far better to limit this work just shy of the cutting edge, on a needs basis.

http://i1009.photobucket.com/albums/af219/swagman001/2nd%20attempt%207%20inch%20smoother/_DSC0152_zpsb42dsvf8.jpg (http://s1009.photobucket.com/user/swagman001/media/2nd%20attempt%207%20inch%20smoother/_DSC0152_zpsb42dsvf8.jpg.html)

As such, if early craftsmen also saw a need to focus more of their attention on the bevel side of the iron, were they overly concerned if the honing stones they were using were out of flat.

Stewie;

[Patrick Chase]

Today we have people who put pencil marks on a stone and consider it flat when their flattening tool obliterates the marks. This is completely divorced from the real concerns of how the flatness of the stone affects performance of the tool. The most important thing in sharpening is discernment: what can you notice about the performance of the tool. The stone is flat enough when the tool does what you want.

Yeah, there's a critical distinction between "flat" and "flat enough", and I intentionally didn't ask about the latter :-).

Pencil marks on a stone are useful when it's badly out of flat and you want to be able to get a rough idea of when you've reduced the dishing to the point of working the entire surface. You're obviously right that it's neither a sufficient nor a reliable indicator of "flat enough".

[Patrick Chase]

My own experience with using Early 1900s Nos taper irons suggests there is little to be gained by spending too much time trying to flatten the back of these irons. They are far from flat as seen on more modern manufactured irons.

Far better to limit this work just shy of the cutting edge, on a needs basis.

Stewie;

Plane irons have different flattening requirements than chisels (the topic of this thread)...

[Mike Jaureguy]

As far as "flattening" the back goes, I start with a Worksharp @ 80 grit until the Sharpie test is passed. Remember now all I'm doing is trying to flatten it. Then another Sharpie test on flat granite tile with 3M "sticky" 80 grit( I think they call it "professional grade". The sticky-Post-It-note style works perfect for keeping it from shifting). After that, it is "flat"(certainly for W/W purposes), the entire back. Now then, since it is flat, I just start polishing; the next task(s) is to just make smaller scratches out of bigger ones, with successively finer grits; whether I do the whole back or just an inch or so, depends on the phase of the moon, and my patience.. At this point, I am also doing the bevel, alternating bevel to back. Each successive swap to a finer grit and back to bevel swap, cleans up the preceding wire curl. I do most of this on the Worksharp, much quicker and smoother. As I approach the final honing stages, with as fine a grit as I desire, I use my honing guide and fancy stones, as I desire, maybe a leather strop and/or rouge of various super fine grits. However, with older or 'beater' chisels, the Worksharp does a very commendable job, for most of this back-to-bevel swapping procedure, especially since the steel itself may not be of the finest quality, and therefore not hold a fine edge for any length of time. But, oh, those first few swipes on a nice wood piece !!!! The same technique for plane irons. I will try the drywall screen mentioned in earlier posts, nice and cheap, maybe even mount it on a Worksharp. If I didn't have the Worksharp for all the 'grunt' work, I'd just use successive grits of paper on the granite plate with the honing guide.:)

[Aaron Rappaport]

I'm surprised nobody's mentioned carefully using the curved part - the face - of a bench grinder's wheel. Well, someone did describe using it to remove high spots, but the hardest challenge in back flattening is pitting. Pitting makes virtually the entire back a high spot. Nevertheless, if one carefully grinds 1/8" wide concave strips out of the back of the blade over its first inch or so, then the remaining high spots can be brought down much more quickly on a diamond stone or sandpaper than if those latter two mediums are used alone.

A cautionary note: This is to produce users, not necessarily good-looking blade backs. Unless one "feathers" the width (and thus the depth) of the concave strips to decrease gradually to zero as the grinder wheel moves away from the blades tip, this method can easily leave some grinder marks, but they will be well back from the business end of the blade, and they'll go away over time, or they can easily be removed when the blade is finally sharpened back to them by repeating the process. It's definitely a method to practice with a beater blade before using it on something more important to you.

Someone here or over at woodnet linked to a blog that described this in pictures, which work way better than words, but I seem to have not saved the link.

[Robert Engel]

I haven't run into a chisel needing more than 300 grit to flatten.

If you have a chisel that is THAT out of flat to start with 80 grit, most likely is it abused and/or poor quality so you maybe be ahead to just buy set of decent chisels.
You may still have to flatten the backs, but it will be a much easier process.

[bridger berdel]

Flatness of chisel backs is a good thing and helpful..... sometimes. In some cases having a very gentle convexity to a chisel back geves you a fine control of lifting the edge off of the surface or even to avoid diving.

[Patrick Chase]

Flatness of chisel backs is a good thing and helpful..... sometimes. In some cases having a very gentle convexity to a chisel back geves you a fine control of lifting the edge off of the surface or even to avoid diving.

The counterargument is that you should always use the right tool for the job. For the sorts of uses you reference that would be either a carving chisel or a bench chisel on its bevel.

[Aaron Rappaport]

Here is the link to hollowing out the back of your chisel with a bench grinder in order to make it easy to flatten it: http://timmanneychairmaker.blogspot.com/2014/01/tuning-up-and-re-handling-old-chisels.html . He describes it a lot better than I did. I've found it to be an incredibly fast and cheap way to flatten a back. You certainly can't find a cheaper abrasive per use than a grinding wheel.

[Benjamin Amadon]

Hello,

I'm in the same boat with a few vintage Stanley 750 really badly out of flat and I started experimenting a combination of techniques that seems to work fine and pretty quickly.


First I check the flatness with a surface plate and engineers blue. Then I remove the high spots with a Dremel that has a grinding wheel attached. Then I check again and repeat. This video gives good information of the process

https://youtu.be/bY7Nctvbpn0
When I have enough high spot I switch to a sanding disk on the Dremel and repeat the same process to get rid of the potentials hills and valley created previously.

When all is done I switch to a Lapping plate with 90x grit. I just received Veritas lapping plate tonight and tried it. Well I'm impressed how quick it goes without any dubbing. I worked with wd40 to lubricate. On my first trials I had the grit breaking down too quickly (less than a minute). Then I decided to put less pressure and the results were very nice. Low pressure had no significant impact on speed but allowed the grit to keep on for much longer until it started to break down and bring a nice matt grey.

I really like this method that brings the blade ready for polish. In the past I tried diamond plate but they wear, sandpaper but it wears and creates dubbing at low grit, water stone but I had loading and section

I think I will experiment with diamond paste soon on Veritas honing plate.

Also I not too worried about my lapping wearing, I know it will but when it will arrive, I will control it on my surface plate and hand scrape it

Benji