Get the skinny on flat

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So what’s up with flat? Sure we know it’s important, but why? Many woodworkers demand that every tool they own be perfectly flat, because tools must be perfect if you want them to build perfect things. Often times the concept of flat takes on a mystical persona as the great savior to all your woodworking problems.

Often times flat does make things better, but to say flat = holy grail?

Nope!

This last weekend, I had the chance to hang out with a friend in his shop. He is looking to get into the whole hand tool game, and he was looking for a little help coming up with a sharpening game plan. The part that seems to snag a lot of beginners is how to keep your stones flat, and really to that, how important is flat?

Well I think it is very important, but the reason is practical. Not mystical, and I decided to try out a simple little exercise to get my point across. It seemed to work, so now I’m going to try it on you poor suckers.

What I did was take a piece of paper from a small note pad, and ripped the top quarter off like this.

The rip makes a jagged line. It was easy to make that messy edge, but try to repeat it with any accuracy. I asked my friend, and to tell you the truth, he really stunk up the joint with this project… Just like I expected he would. But it wasn’t his fault. A random edge like that is near impossible to reproduce accurately. The only good example is the other piece of torn paper.

The edge of this paper was mind blowingly easy to make once, but is hopeless to reproduce. In woodworking, that won’t do.

A flat edge is so much better, if you know how to do it, and it really isn’t much of a trick.

I then took the larger of the two pieces of paper, folded it over, and pressed down a nice straight crease into it.

The paper now tears in a sweet straight line if you are careful.

And leaves you with a nice flat edge.

While the free thinkers may complain that I’m trying to squish their groove, It’s not just the anal people that can see that the straight tear is far superior. It doesn’t just match up with its mating piece, it also matches pretty well with other pieces.

Well, not every piece, but the factory edges would mate with them pretty well…

But what’s also really nice about flat.

If you flip one of the pieces over, it still mates beautifully. Not so with the loosy goosy tear on the top. If you notice, when you flip the top one, the inaccuracies compound.

In real life, this can be a real problem.

So you lap the blade of your new smoother with a slightly hollowed out stone. Let’s say it’s hollowed by 0.002 of an inch. No big deal, that it leaves the back of the blade with a 0.002″ hump in it. Then you tune up the chipbreaker, and go to flattening the edge, and it gets the same 0.002″ hump in the middle. When you put the two together, you end up with solid contact at the middle of the blade/chipbreaker point, but you will have a 0.004″ gap on either side.

When you go to take you sweet 0.001 inch transparent shavings, you end up stymied by all the shavings getting caught in the edges of the chip breaker.

Flat stones are important.

And that is why we all stopped setting the chipbreaker close to the cutting edge…

So ya, ok, stones need to be flat. What about the bottoms of planes?

I’m still chewing on that one.

Perhaps I’ll work up the nerve to tackle that one another day.

How I flatten my stones. Part 2

I don’t know how many of you actually read what I write, but I’ve noticed that I do get a lot of hits on topics involving Sharpening, Lapping, or stone flattening.

Again, I don’t know if anyone reads it all, or if they stop after the first paragraph, and say, “this guy is wacked!”

Anyways, I’ve felt for a long time now that my description (HERE) lacked a little in getting through how easy the 3 stone system really is.

So I’ve fired up my low definition video camera, and made my second video. (I decided to play some music as cover noise in the event of any unexpected bodily noises…)

Flattening the three 1000 grit stones is just like what I explained before. The order that I work the stones is intentional. The rotation I do is a key part of the system.

I then move on to 8000, and finish with the 4000. Again intentional.

Annnnnndddd. You guessed it. The odd order of rotation that I follow? Ya that’s intentional too. If you number the three stones from 1 – 3. 1 on the left, 3 on the right, the order is;

1, 2, 3, 2, 3, 1.

The idea is to maintain a consistent average UN- flatness that each of the three stones is subjected to.

The first stone sees the stone when it is at its most unflat, and then when it is the most flat.

That’s all folks.

The ruler trick

EDITORS NOTE *** This post is experiencing 3rd party photo hosting “issues”, that will be addressed as time allows. ***

 

If you do not know what the ruler trick is (and I’m not talking about the one with the floating hammer…), you can read about it here as written by its creator David Charlesworth.

The ruler trick is one of those ideas that is as brilliant as it is simple. It’s been endorsed by many of the true woodworking greats of our time, and for the beginner it removes one more road block from the challenge of sharpening a plane blade. Besides that, it really does work!

Well… for plane blades that is.

You don’t ever want to use it on a chisel, because you often need to register the chisel on it’s back, and the slight back bevel it creates would lift the cutting edge off the level of the back of the chisel.

There are also some, (myself included) that feel that any kind of back bevel on a low angle bevel up plane shortens the life of the cutting edge.

In this light, the ruler trick is only useful for bevel down planes.

So do I use it for my bevel down planes?

I have in the past, but then it occurred to me that it really does not jive with my mentality for developing better hand tool skills.

Here is the thing. I am a creature of habit. One accidental use of the ruler on one of my chisels would result in me having to regrind the chisel back past the back bevel, and I have no plans on that kind of waste of metal. I also expect that I be able to sharpen my chisels and bevel up blades to the same finely honed edge of my bevel down blades. If I am able (and I think I am) why add the extra step?

If I am not able, why wouldn’t I want every opportunity to improve the edge of my chisels by getting extra practice with my bevel down blades? (I should mention that in my opinion the bevel down blade is the easiest to sharpen anyways)

Finally, I think the ruler trick is of the most benefit to anyone that has less than flat stones. I don’t think I need to harp any more on how incredibly whacked out OCD I am on stone flattening…

Ya,

Not going to go there…

Edit. I wrote this a few days ago, but didn’t get the finishing touches done until now. Since that time, some great news was posted HERE about Mr. Charlesworth. The Coles notes are that as many in the hand tool world know, he as been terribly ill, but recently has made a full recovery, and is back to teaching. This is great news as he is one of the true leaders in woodworking. The DVD’s I have of his are some of my favorites. Even though I don’t agree with his every point.

Finally, while I voice my opinions that contrast those of many of our wood working hero’s. It should be remembered that I am just another guy with more tools than skills. The Hero’s of whom I speak are superior to me in every conceivable woodworking aspect, and I don’t expect that will ever change.

Take my opinions if you will, but only for what they are worth.

The Veritas flat back test

EDITORS NOTE *** This post is experiencing 3rd party photo hosting “issues”, that will be addressed as time allows. ***

 

Today I made a discovery that made me a little happy.

A good while back I read about someone who did not lap the backs of their Veritas blades because they felt that just doing the “ruler trick” was enough. It seems that since I bought my Veritas Skew Rabbet Plane, I had bought into this way of thinking. When I pulled the blade from the plane I could see right away the dull grey back of the blade.

My first thought was, “I can do the test now!”, and that is a little weird. Since when did I start enjoying lapping the backs of blades!? I guess this stone flattening kick I’ve been on lately is to blame for that. If you have been reading along you won’t need another reminder of all I’ve written about it.

The big thing, is today I can show how flat my 3 stone system really is. (Yawn…)

Here we have my unlapped skewed blade, with a little crud along the cutting edge, as well as the thin back bevel from the ruler trick.

A quick test on the 1000 stone give some interesting data. Are my stones as flat as the Veritas blade?

No, they are not. You can see in the middle of the blade between the cutting edge and the hole, a small area that is not overly affected. I should point out that when lapping, I do put a little extra pressure on the cutting edge side since that is the side that matters.

While my stone was not as flat as the blade, I would say that it is not that far off from a blade that is flattened to ±0.0002”, and for that I am pretty happy.

A little more on the 1000, and it’s all a consistent finish.

I move on to the 4000 stone, and very quickly I’m left with a mirror finish.

A little more with the 8000 and we are done.

Well not really, I still had to sharpen the darned thing so I could get back to work.

All this to say that if your stones are flat, even a goof ball like myself can make quick work of lapping the backs of blades and chisels.

And now, I’ve got a panel to raise…

How I flatten my stones

I guess this is part #4…

If you want to bury yourself in text, as I wax not so eloquently about the value of stone flattening, there is more than just this post!  Oh yes my dear friends there is more. Much, much more. You can start with “How do you flatten your stones?“. If that wets your appetite, move on to “How do you know your stones are flat? “. If that doesn’t gag you, you will be ready for “Lap a chisel back in 6 minutes“. When you regain conciseness, run for the hills!

Or, you can continue here for desert. Much of this post is from an old forum post I made.

Here you go!

Here is my sharpening station with the 3 Norton stones I use. From left to right my 1000/8000 (I’ll be calling this my “8”), 1000/4000 (AKA “4”), and finally my 1000 grit stone (AKA “1”).

You will notice some lines on all the stones. Those are areas I have recently sharpened. Once I have marked the full stone it is time to flatten it. On a side note I generally only use the “1” for 1000 grit sharpening as the 4 and 8 are more expensive stones, they also are best left flat so that they can flatten the 4000 or 8000 surface when they need it.

Here you can see in the second frame, I have flipped over the 8 and 4 and marked a bunch of lines so we can see the progress.

I start by taking the 8 and rubbing it’s 1000 side against the 1000 side of the 4. I rub up and down just at little overlapping ¼ to ½ of an inch about 10 times. I then move the 8 to the 1 and rub again. Then I return the 8 to its place.

I then take the 4 and rub it against the 8, move it across to the 1, and return it to its place.

This first frame here is the result, I repeated the steps using the 1 to get to the second frame.

I find that when the pencil marks are this faint you are pretty darned flat, but one more round would probably remove them completely.

So what is actually happening here? Its all about the rule that 3 is a crowd. Your stones will generally be either concave (dished) or convex (errr humped???). If you have 3 stones chances are one is one way and the other two are the other way. So let’s pretend you have to concave and one convex.

Rub #1 convex against #2 concave, and then #1 convex against #3 concave. Very little will change here, but then when you rub #2 and #3 against each other the high points (circled) will be removed first, and those two stones will relatively flatten out.

Now #2 and #3 gang up on #1. When you rub #1 against #2 (and then #3) only the center of #1 touches the center of #2 (and #3) removing the bulk of the hump in #1 and returns both #2 and #3 to a much less dramatic concave shape. #2 and #3 flatten each other out again, and go to work on #1 again.

And so on and so on. At some point they will all even out.

I know it’s a little hard to absorb, and it’s just as hard to explain, but it works. It really, really works. It’s also one of the more affordable options. You need stones already, so however you do it, you will have a 1000, 4000, and 8000 (I’m assuming). All you need is 2 additional 1000 stones, or in my case with the combo stones 1 more 1000. You just need 3 individual stones that have a 1000 grit surface (3 is the critical number. Not 2, not 4, not 6). Once the 1000 grit sides are flat, you can then use them to flatten the 4000 and 8000 grit sides of the stones. It was suggested to me a while ago that you could save some money and time by just using the 1000, 4000 and 8000 surfaces with this system. I got to thinking that this could be a great option if it only works. So I tried it…

It seemed fine for the first week. After a month or so, I had a new blade that needed lapping, and was very surprised at how much trouble I was having. Slowly over time, the stones were going out of flat. The 1000 had severely rounded off both the 4000, the 8000 because they couldn’t cut as fast. It took a while to get them all back to flat using my old method, but once done. Lapping the blade was amazingly fast again.

Continue to next segment?

Editors note – I’ve added a video demonstrating the 3 stone system in a new post. There is also some additional description that I think may be helpful.

The video may as well be on this post as well…

Lap a chisel back in 6 minutes

In previous posts Here, and Here. I’ve been discussing the issue (or non issue) of flattening stones. I’ve tried to show how and why many popular systems are not effective, but have neither offered a better solution, nor even proven that it is necessary.

Today, may just be that day…

I’ve put together a little demonstration here. I call it a demonstration rather than an experiment, because I knew what the outcome would be before I started.

Editors note – I’ve noticed that I did not include any instruction on lapping technique in this post. The reason is that you can find it else where, and it really has nothing to do with the speed of my process. It’s all about the stones today.

I found a couple of my old Narex chisels that for whatever reason had never been sharpened, or lapped. The larger is 20mm wide (a little over 3/4″) and a smaller one that no longer shows its size in metric but is about 5/8″. The rules of the game are this. Lap the back of one chisel with my flattened stones until done.

Then lap the second chisel for roughly the same amount of time with some “new to me” stones that have been flattened to a less stringent level.

I know who is going to win in this little game but I want to be fair here, so I’ve chosen the larger chisel for my stones, and the smaller chisel for the new stones.

So let’s get started with the wide chisel. First I just quickly rub the back on my 1000 a couple of times just to see where the high spots are. It looks like there is a hollow in the middle of the blade.

Now I do the same thing, but this time I’m looking to remove the old milling marks. I could go further, but I don’t know if it is really necessary. The blade will register on the flat just fine in use just like this.

Next I go to the 4000. I’m spending about the same amount of time, and again, just trying to remove the scratch marks of the 1000. Look closely at this pic vs. the previous. On the 1000 the scratch marks go from front to back. On the 4000 I went from side to side. It’s easy to see when the 1000 marks are gone. You should also notice that the size of the lapped area has not changed much. That is because the 1000 and the 4000 are almost exactly the same shape so the touched only in the same areas as the 1000 did.

And then on to the 8000. Again I spent about the same time as the other two stones. Again note the absence of the 4000 grit scratches, and that the lapped area has changed little in size. I do see a very thin strip of light on the sharp edge of the blade. I suspect this is a very light burr.

This whole process according to the time stamps on the pictures took 13 minutes. The majority of that time was me fumbling with my camera. I’d say that 6 minutes is more than realistic for a total working time.

Now on to the smaller chisel on the new (suspect) stones. My plan is to work this chisel no more than the last.

A quick swipe on the 1000 to see the lay of the land. Seems to be a little more hollow on this one.

Getting to this point took roughly the same amount of time as the other chisel.

Switch to the 4000, and again a similar amount of work gets me here. The first thing to note is that the lapped area has grown a fair amount. The second is on the blade edge. Can you see that darker grey strip the full length of the edge? This stone completely missed the cutting edge, but removed a bunch off the back further down. Not good.

On to the 8000. This time the lapped area doesn’t change much so we can assume it is the same shape as the 4000, but look at all the scratch marks that are left over from the previous stones, and the unlapped area on the cutting edge now has caught the reflection of the light. It’s still there, this chisel at a glance is lapped, but in truth is not much better than when I started. It’s hard to say what stone was not flat, and it could be that all three were not flat. For sure we know that the 4000, and the 8000 were similar is shape, but the 1000 was not the same.

I wouldn’t bother to try, but if I continued using those stones, I suspect that properly polishing them would have taken at least half an hour or more because of the extra work those stones would have to do removing extra material.

I’ve been accused of being anal with my stones, but the time I take flattening is no where near what I would invest in lapping blades with un-flat stones. Let’s look again at the popular flattening systems in their best light and applicable cost.

Sand paper on a flat surface. Your kitchen counter top would be free, but not very flat. Lets go with the granite slab from Lee Valley. At $36.00 the price is right, and with a tolerance of ±0.0001″ it is the flattest surface I can find (the Veritas straight edge is only ±0.001″). The problem is that sand paper is notorious for not sitting flat, and being costly in the long run.

Norton Truing stone. Video of the Christopher Schwarz method of flattening his truing stone. $29.00 (if you are considering buying one, PLEASE watch the video first!!!)

Editors note – Sadly the link no longer goes anywhere. It was a video of Chris smashing his Norton Truing stone with a hammer. The simple point. It’s a worthless product. WORTHLESS I TELL YA!!!

Diamond plate. Option 1. Diamond stone from Lee Valley measuring ±0.005″ That’s 5 times less flat than the straight edge. $109.00 That’s big money for something that is 25 times less flat than a Veritas blade back. You will be almost guaranteed to mess up a blade if this is what you flatten your stones with.

Option 2. DMT Dia-Flat Diamond Coated Lapping Plate from Lie-Nielsen measuring an impressive ±0.0005″ but at a price of $195.00 you won’t want to loose it, and you will still be 2.5 times less flat than the veritas blade back.

Of all these options I’d say the DMT will give you the best result. I would say that my option is at the very least as effective as the DMT, but I can’t prove it. Why? Because I’m not prepared to drop 200 clams to get something I don’t need.

This post has been rather labor intensive, and I’m starting to fade. I can’t believe that what seemed like a quick little topic has now morphed into 3 going on 4 posts… I hope that at the very least I have provided a decent argument for the value of flat.?

Next time for sure! I’ll show my flattening system.

Continue to next segment?

How do you know your stones are flat?

A good friend of mine has suggested that I’m a little anal retentive about my stones and sharpening.

He’s wrong. I’m anal retentive about just about everything.

He really should get his facts straight before making such a comment.

With that in mind, lest I appear the hypocrite, I’ve been attempting to confirm that there is at least some factual information behind my radical opinions, and apparent war with popular opinion. (Say that five times fast!)

There are smart people somewhere in the world with fancy equipment that can test for flat to increments that are unfathomable to people like me, and despite my warm and honest looking face, I will ever be able to borrow some for use in my shop. So what is the common man’s best method?

If I was testing a piece of wood I’d use a straight edge. Just place the edge on the wood and move one end. It will pivot on the highest point.

I went out and got a 12″ straight edge for this application. It didn’t take long for it to dawn on me that my stones are abrasive, and rubbing against it would quickly make my straight edge not so straight.

By the way, if anyone is looking for a 12″ swerve edge I may be able to help them out.

My next idea, didn’t come to me as an idea, it was a problem.

Flattening the backs of blades is a job I don’t like doing. The only thing I like less is flattening planes. Flattening blades can be a slow process and gives you much time to think about what you are doing.

Your coarse (1000) stone has two jobs. Remove the scratch pattern from the milling process, and define “flat” for the rest of the job.
This can take a while but it’s worth it.

The next stone (4000) has one job. Remove the scratch pattern of the 1000.
This I’ve found can take forever! The problem I’d have is that it would initially only remove the scratches from part of the blade. By the time the 4000  had removed all of the 1000 scratches it would take 2, 3, maybe 4 times as long as the 1000.

When I’d get to the 8000 I’d be near the point of tears as it would take even longer still.

What the heck was going on!?

It seems my stones were not as flat as I thought they were.

What I’ve come to accept is that your stones do not make your blades flat. They make them into the mirror image of the stone. If your stone is concave at all, the blade will come out convex. Same thing it the stone is convex. When you move to another stone, if it is not the same shape as the first stone, it will first need to re-establish its version of flat before it can remove the previous scratch pattern.

At this point I’d discovered that the 4000 and 8000 actually had 2 jobs. Remove the old scratches and not screw up the shape determined by the 1000 stone.

Essentially the 3 stones need to be virtually identical in shape to “flatten” your blades quickly and easily, but this has nothing to do with true flatness.

But the problem still remains that we don’t have a way to confirm that the stones are flat.
Back in the days that I used sandpaper on glass to flatten, I read about the idea of rubbing two stones against each other. On a whim I tried it out. I took two matching 1000 grit stones that had been freshly lapped on the sandpaper, marked a bunch of pencil lines on either and rubbed them together. Because they were both shaped by the same sand paper, they would be the same shape. When facing each other they become opposites. Concave facing concave does not mate, and the same with convex. Only if they both were truly flat would the pencil lines wear off evenly because the opposite of flat is still flat.

As it turned out, my glass was not flat, because the pencil lines would consistently wear off faster in some places than others.

But now I could always just rub the two together until all the pencil lines were gone and then they would be flat. Right?

Well no.

Any error in hand motion could cause one stone to round, just a little, and the other to dish out to match. And besides, this seems a little backward to have to work your stones out of true so you can flatten them (hopefully) against each other.

Well this is really getting long winded, so I’m going to wrap up today’s post with the closest thing I can find to the every day man’s version of a flatness test. It’s not a test you will want to do every day, as it could get expensive.

Get yourself a new Veritas plane blade (preferably one that fits a plane you own. Or even better, buy a plane that fits the blade!!!). They are lapped to ±0.0002” across the blade back and really are as flat or flatter than I’d ever expect to get my stones. What I’m saying is that if your 1000 stone does not remove the old milling marks evenly, your 1000 stone is not as flat as the blade was. It’s that simple. Unfortunately, you will need a new blade for every test, so as I said, it could be expensive.

Two posts in and I still haven’t provided what I believe is a viable solution to the flatness issue. What is worse, is that I still haven’t given a halfway good reason why you should be this anal about flatness.

I’ll get there, I’m just slow…

Continue to next segment?

How do you flatten your stones?

Who hasn’t either seen this question or posted this question on a woodworking forum?

Most answers involve 1 of 3 methods.
1. Sandpaper or silica on a flat surface
2. Norton Truing stone
3. Some kind of diamond stone

If you have seen any other answer, there is a good chance it was me who replied. The method that I use is not unknown in sharpening circles, although for some reason it is not taken seriously.

I have a very special rule when getting tips from others. If they say that their way is the “best” or “only acceptable” way to do something, I shouldn’t take their tip too seriously. So I’m not going to say that my way is the best (although I am thinking it) because with all the complaints and questions about the topic I think a lot of people could benefit from this very simple system.

Every system has its pro’s and con’s, so let’s have a look at them.

1. Sand paper or silica on a flat surface.
This was my first system. It seemed like a no brainer for a beginner with its low start up costs, and sandpaper is easy to find at any store. BUT, sandpaper is an ongoing cost that even with the cheap stuff (that is almost useless), will quickly add up.

Sand paper also tends to lift (like it’s doing the wave) as you move the stone causing the edges of the stone to round. Years later some of my stones are still rounded some on the edges.

But the biggest issue I found was in trying to hunt down an acceptably flat surface to place your sandpaper on. You can try your luck on your kitchen counter top, but trust me, it’s not flat. The top of my table saw looked promising, but it’s got a small hump in the middle. Bought a glass lapping plate from a well known tool store, but found that it was both bowed, and rather flexible (2 very bad qualities). You could buy a granite reference plate, at least it’s going to be pretty darned flat, but not perfect (whatever that means). The thing is that you are still shelling out more coin over and above the sand paper. That = good money after bad.

2. Norton Truing stone. Warning! Warning! – Uncontrolled Rant to begin in 3. 2. 1. 0!!!
I have to be honest here… The first time I saw this product I thought it was one of Lee Valley’s April Fools jokes.
Talk about your oxymoron! Right up there with Crash Landing, and Intelligence Agency. So I just have to ask, “Assuming this hunk of silicon carbide in a durable hard resin is actually flat. After using it to flatten your stones, it’s not going to be flat anymore… How do you flatten your truing stone?”

OK, rant over. Forgive me if you are a believer?

3. Some kind of Diamond stone.
I’ve never used a Diamond stone to flatten my stones. The main reason is that they are CRAZY EXPENSIVE!!!

I came very close to buying one once, but in a fit of thriftiness, I chose my current system.

Soooooooo, what is this system?

I’d tell you now, but I’m getting Typer’s Cramp.

And we still need to find a way to confirm that said stones are flat when we are done “flattening” them.

…and that’s got Monday written all over it.

Continue to next segment?