The cutting edge

In our recent discussions between Ralph and I about sharpening, I often mentioned the importance of tweaking the edge with a micro bevel if the edge seems to crumble too fast for a given wood. He mentioned on numerous occasions that he never saw any references to that in older text, so what gives?

So here is my take on this.
There always was, it just wasn't called micro bevels like we do today...

Let me try to explain this.

Every text I ever read about sharpening always makes mention of two angles;
The grinding angle and the whetting angle. 

Top the primary or grinding angle, need to be shallow.

Bottom, angle A is the primary, B is the secondary.

You want to add a third one? Be my guess, but its not necessary...

So what are they and why bother with two angles??

You need a shallow angle to penetrate easily into the wood. That shallow angle is referred to as the primary bevel or the grinding angle. It is usually between 20 and 30 degrees, as seen in older text. Today we seems to favored 25 degrees (smack in the middle).
If you are using a chisel for paring, 20 would be fine, but it would crumble pretty quick if you were chopping mortise.

Nobody really likes to spend too much time sharpening, we all rather spend our time actually working wood.

The next angle is the secondary angle or referred to as the whetting angle in older text. That is the angle that we use on our stones after the grinding operation. Which grinding is usually done on a mechanical or electrical grinder, but I do mine on stones as well, as I am not a big fan of a hollow edge, produced by a round wheel. A bigger wheel will give you a shallower hollow, but it is still there.

Why that second angle? Because if will significantly reduced the time required to sharpen, since we are not doing the whole bevel again, AND perhaps more importantly, it will beefed up the edge (more metal behind the edge)

That small land of steel at a higher angle makes a lot of difference for the edge retention, but it is too small to make much of an effect on how the tool feels into the wood. If you were not adding that small secondary bevel and instead were to sharpen two chisels, one at 25 the other at 30, you will find a  difference in how it penetrate the wood. Now touch up that 25 degrees by adding a 30 degrees micro bevel and compare it to the other still at 30. The one with the whole edge at 30 will be harder to push still than the one with the micro bevel of 30.

I called that secondary bevel MICRO, because really you do not need to have a wide land of steel at that secondary bevel to affect its performance.

I know some would argue that what we call micro bevel today are really a tertiary bevel (3rd one) but to me that is semantic.
I do my edge usually at 25 then tweak the edge by whatever work for the wood I'm working with. The exact angle?  Don't know don't care!

What does that mean? If my edge is crumbling too fast, I'll simply touch up the edge with a steeper secondary bevel.
I do strop my edges often as I work, an habit I picked up from my carving days.
It keep my edge sharp longer and delay the inevitable trip back to the stones...

Other than that, that is all I do.
Oh, I do the back first real good the first time around (past pitting at the edge), then...
i'll just continue to polish it to remove the small burr introduced by whetting.

I do not care to take my edge to a blinding shine level, I stop at my finest stone, a 6000 grit waterstone, and I most certainly do not test my edges on any of my body parts. Nail, hair on my arms etc, paper or whatever (those test proves nothing, except that you are about to cut yourself and probably damaged that edge :-)

I'll have you know on good authority that blood cause rust on tools, so clean up immediately, save the tool, don't worry about your body parts, i'll grow back right?

 I simply look at the edge under a strong lite trying to catch reflections and I test the actual edge on a scrap piece of pine.

My all times favourite knife.

German chip knife No 8  

Bought that knife in 1998, has been sharpened a bazillions times by now...

Can you tell if its sharp or not?

Same picture, blown up.

See the white bright white spots on the edge??

These means that there is sufficient thickness to reflect light, 

it is overdue for sharpening :-)

Why pine? Being a softwood, the end grain crumble easily if the edge is not properly sharpen.
Once I got a shiny burnished surface left on the end grain cuts, I am done!

First cut with nicked edge shown above.

Cut easily still, but look at the scratches left 

After a couple strokes on my 6000 stone

Better but I can still see lite spots on the edge

A few more strokes followed by stropping.

Pretty good, it is leaving a burnished surface

BUT... I will tweak that edge depending on how it react to the wood I am working on, by raising the edge a tad. Whetting angle, secondary bevel, micro bevel, whatever you want to called it...

Brazillian hardwood, forgot the name.

Look at the clean pore holes, cuts are shiny, burnished

AND I do not put any back bevels what so ever on my edges thank you very much... Not on my plane irons, and never on my chisels.
I may be lazy but never that lazy (ruler trick) ... :-)

Bob, sharpening his keyboard with help from Rudy.

That is his little stool to go up on the couch.

Its starting to shows some signs of puppy chew...

Must really puppy proof my shop... :-)

About the sharpness levels required on moulding planes

My next posts about using them (building a moulding stick jig and making a Linenfold panel are currently in the holding pattern.  Heather is back at home having completed her first round of palliative care radiations.

She is having all kinds of side effects from it, none pleasant, but it should go
away within weeks to months, no two people being the same.
So for now, I'm playing nurse to her and don't get much shop time...


In the mean time I want to address a conversation I'm having with Ralph regarding how shiny these blades should be...

Like I said earlier, these H&R comes in a varieties of slightly modified forms:
- Various bedding angles (pitch) from Common (45) to Half pitch (50) all the way to York (60)
These various angles are to better address the types of wood you are working with.
The British planes, perhaps because their furniture makers were using more often exotic woods brought back from the "empire" and beyond (Think Mahogany, Rosewood, ebony etc),  made theirs with higher pitches (50 to 60) than the North American makers, who made theirs more often at common pitch (45 ish)
Look at the angles found on a small samples of mines.

Ralph reported that the one he is sharpening is working so so in pine but make beautiful work in cherry, and has some issues in oak (normal since being more stringy).  That would be normal. That one currently with its pitch angle, sharpening level on his blade (he like them shiny), and its bevel angle all are apparently currently tweaked to work better in close grain hardwood (Maple, Birch, Cherry etc).

So what can you do different to make it perform better in say, softer woods like pine or stringy woods like oak??

First understand that some of the criteria's affecting its results are fixed (like the pitch of the blade and the blade being straight or skewed.

That leave us with only two other variables:
- The sharpness level on the blade, and
- its bevel angle.

So back to the original question: Just how sharp should you make it?
Sharper fix a multitudes of sins, but in this case, it cannot overcome the plane limitations (up to a point).
That leave us with the realization that you would need either a different pitch plane, or using a skew iron one.

Doing some research on line, I saw some advocating sharpening their moulding plane's irons to a bazillions grits (talk about shinny, should use sun glasses :-)

In my experiences, it does not make much differences. The higher the pitch, the more of a scraping action than cutting. What is more critical is how durable that edge is. That's why the blades came originally at various bevel angles between 25-30 degrees.  A lower bevel angle, bedded at a lower angle, translate into more of a paring action, I.E. it cuts easier, but the edge is more fragile and can crumble faster if used in harder woods.

Conversely in planes with higher bed pitch (toward York) the scraping action is murder on the edge, hence why the bevel angle is raised higher toward 30 to beef up behind the edge (more resistant).

BACK TO SHARPENING

A higher polished blade is going to stay sharper longer, because the level of shininess indicates less visible scratches, it should crumble slower.

But, the problem with high level of shininess is that it can easily mask a subtly rounded edge...

Understand that sharp is simply two FLAT surfaces mating with ZERO thickness. Of course that is impossible to attain, but when you approach that zero thickness, comes a point when you cannot discern anymore light reflection at the edge, because it is then too narrow to reflect light at you.

You can work for hours raising that edge to a high level of sharpness, and very shiny, just to kill it in one NY minute by poor stropping action, burying the edge in the leather and rounding the end ever so slightly... And you may not detect it, until you attempt to cut wood.

Moulding planes irons profiles poses some challenges sharpening them because of their irregular shapes.  Good news is you only have to touch up that bevel edge rarely after first working on it, you then maintain the edge sharpness by touching only the flat back. Yes occasionally you may have to touch up the bevel to take out chips etc. but not very often if you are careful.

Ever notice that a stock scraper profile is cut almost straight across with a file, then sharpened simply by working the flat faces?  We take a similar approach with our moulding plane's iron.
ALWAYS TAKE CARE NOT TO change the profile of the cutter while sharpening, work on the flat!

When I originally sharpen mine, I start with 220 Grit sand paper, then move on to my diamond paddles (black and red) and give it a quick strop on a leather strop with LV green compound, that's it! Plenty shiny, (look at the last edge pics on Step 2 initial assesment)   When using them, I will then tweak its edge depending on how it react with the wood.

This is very much like what carvers do all the time.  We stop and strop often our edges, changes the bevel angles as required for the wood and the type of work we do etc.  It soon becomes second nature and you go thru the steps quickly without thinking much about it.  We are talking minutes changes, no drastic modifications requiring grinding a new bevel angle, think micro bevels.
Either that OR change tools for the wood.  That's why carvers have so many gouges/tools tweaked for various jobs in various woods.

Similarly, you may find you need more H&R of various design (Skew, higher pitches etc) depending on what kind of woods you uses.

BOTTOM LINE

At the initial stage, work on the bevel, ensuring there is no pitting at the edge, go ahead and flatten the back (past pitting at the edge), polish it to whatever degree you like, but since we are often touching up the flat often to keep it sharp, you should keep using the last grit you use or you will kill all that shininess you work so hard to attain initially.
Of course the higher the grit, the more work to maintain the edge (slower).

SOOOOO, we have to find a compromise between blinding shiny and shiny enough to work and easy to maintain.

Truth be know, moulding planes do not required super sharp edges to work correctly, so don't waste you time going nutso on them, make shavings instead and look at the profile left.  Uses that as the ultimate determination of having achieved the right amount of sharpening for this plane bedded at X angle for this type of wood.

Before you go back and sharpen some more, try different woods, see a difference?   If its better, stick to that type of wood...or...get another plane (pitch, skew etc)

And remember stick with clear grain, straight grain woods.
Working on the edge of wood (end grain)? Good luck with that!!!
Some wood may be possible, but they were never designed for that.
Scraping and sanding will fix that surface left on the end grain.

All that to say, understand the tool and its limitations.

Bob, working at his computer "bench"

Meanwhile, back to the cabinet swapping...

I have  been working at it for the past few days here and there.

I was debating with myself how I was going to cut the long stopped groove for the machine hinges (2). Should I excavate them by hand or power? Router or drill press? In the end being solid maple I opted to go with power :-)

Since I long got rid of my Sears fixed router, I currently only have a small 1/4 Bosch Colt trim router. Plenty powerful, but I do not have many bits for it and the size required would have necessitated numerous pass to cut a wide enough and deep enough groove. Noisy, noisy, so I went with the drill press and a Forstner bit. Much faster and quieter :-)
Why a Forster bit? Because it is one of the few bits that can cut overlapping holes, even at an angle.

Sizing up the proper bit.

1/2 inch it is.

After setting the depth stop on the quill...

a series of holes are drilled.

The fence interfered with the drill's column, so I free handed it

A quick clean up with a chisel. Then cut the opening wider at the 

mouth to allow the hinge to swing fully up.

Once one hinge was installed, I doubled checked my spacing 

with the machine, then cut the other one.

  After both hinges were fastened, using the previous holes on one side of the old groove, I marked and drilled pilot holes for the remainder screws.

Using a small gimlet I predrilled for the screws

One last check with the sewing machine, everything OK, but it doesn't fit right in the large opening on the top, since I now need to trim it a bit.

More markings and more trimming later, everything fit as it should.
Including the smaller flip board up front.  I had to cut a rabbet deeper on the front flip panel front edge to sink the machine lower up front.

Then realized that the back was sitting a bit lower than the top?
Checked the older top, it was a bit thinner, cut a recess for the hinges, that lowered the hinges in the top low enough to raise the back of the machine up.

Now need to fill the previous holes, and

Then do some veneer patching, near the hinges and by the small flip up board.

Reattach the top and fix the top surface.

Not done yet. Now need to ensure there is some support holding the machine in the lowered position.  Otherwise, the machine is hanging only by two pins secured by a set screw on the pin's shaft of the hinges. I would not put all my trust in that.

Not sure what I can do, most cabinet I looked at seems to only hang the machine by these 2 posts ? Whatever I do must not interfered with the sewer's legs under the cabinet. And if there is room, maybe a drip guard for the machine oil...

Machine flipped down

View from under, I want to put some thing to restrict it.

It is only holding by a set screw on the rear posts (2).

Although the top is solid wood, I put in  couple of solid wood patch to hide a couple boo-boos on the top. Good practice for later work on a few more of my wife cabinets :-)

Need to sand the top and refinished.
Then deliver to happy friend.

Bob, modding sewing machine cabinet

Using marking gauges

If you ever uses one, you probably discovered that there seems to be a few way to buggered up a straight line and your lines may not be as crisps as you would have like.

First some basic maintenance
The head should be able to lock securely and square to the head, if it doesn't, you will never be able to uses it to its potential and it may earn flying lessons :-)
Refer to my earlier Marking gauges post to troubleshoot and evaluate various designs. If your antique gauge is missing its shoe, you will damaged the beam, make one. Especially if you feel you have to crank it down very tight to stop wiggles.

Notice the metal wing part sticking out from under the head? It is a loose shoe pad, shaped like a flattened U to stay put when loosening the head to move it. Its shape also prevent it from turning when cranking the screw. Often MIA in antique gauges, if it came with it.

Next take a hard look at the pin, cutter or pencil: they should be sharp, but their shape and position would also affect its use.
A conical pin, is going to scratch wood cross grain no matter what. Hint it is sometimes referred to as a scratch gauge, vs marking gauge.  Shaping that pin like I shown you earlier is how you fix that.

But that introduce, yet one more variable, the effect of the half cone shape on the gauge. It is acting like a wedge, either pulling the fence tight against the board or pushing away from it.

So what do you do? The short answer depends on what you are trying to mark and why.
The shoulder line should be straight, the V shape toward the waste area.
Marking the walls of a mortise, you would want the straight edge on the outside walls, but if you are now marking the matching tenons, ideally, it should be reversed.

Reverse for tenon, the straight wall should be on the inside.

Before you start flipping around those pins back & forth, you should instead invest or make, a few more, gauges dedicated to their function. If you happen to make the marks with the ramp side on the wrong way, don't sweat it, just be aware of where your true references surfaces are. But keeping the above information in mind will make your work more precise.

Using the gauges

First having taken the habit of establishing witness or joiner markings on you face and reference edge, make sure to always gauge (set the fence against) the reference edge.

They can be push away from you or pull toward you, but you should use a trailing motion, that is to say the gauge is slightly tilted up or down sideways (depend if coming or going) not straight across like a panel gauge. That's the reason for the top of our reshaped pin being like an arc, and the usual wear pattern shown on the gauge beam.

I replaced these pins years ago. That is about as much projections as I like for my pins

And just like using a marking knife, the biggest mistake is to try to make your final mark all at once. Instead, try 2, 3 marks. First one with a light touch, just to establish the cut, following ones (I always do at least 2) a bit stronger to deepen the mark. You will have less trouble following the grain that way .  Personally I prefer mostly to pull toward me, you get more control when working toward your core. Just remember to push the fence tight against the board, especially when the pin wedge shape is working against you.

Talking of mortise & tenons, they are usually centered on my stock. In order to find the center, just make a small mark from either sides, if you are centered, the marks will line up, if not, just remember that the offset is double the error. 

When marking my baseline for dovetails, I reach for my wheel type gauge, it is easier to roll over the board edges as I go around all 4 edges. It is also cutting cross grain all around, a task where wheel type excel. 

When marking tenons or mortise, I reach for my appropriately shaped pins on different mortise (or tenon) gauges.

Now you can start to understand why I have a "few" gauges :-) That and the fact that I like to keep them set throughout a project. Because you never know what you may have to redo or forget to do, before you change the setting...

The marking knife and marking gauges are what your cutting tools will follow next. May as well uses the mark left to our advantages.

Deepening the wedge side of the mark (don't touch that reference straight line, it's your finish shoulder) allow the saw to track straight across (called a 1st class saw cut) the ramp actually tend to push the saw against the straight shoulder. This also illustrate why the marks should be reversed for tenons vs mortise walls

  

Regardless of how ragged your cut, notice the sharp shoulder lines left. Easily cleaned up with a sharp plane to the exact shoulder lines. 

  

Understanding how to cut a crisp line and then using it to our advantages is what these tools are all about. When making or buying one make sure the head lock solidly, no wiggles, reshaped the pin if required and be mindful of the pins orientation.

Wouldn't that be easier to always use a cutting or slicing gauge instead of a pin type gauge? 

Not really, a thin knife edge will require more frequent sharpening, the modified pin last longer and we can better use the wedge shaped through to our advantage.

One last point, something rarely mentioned in the literature is the length of the pins sticking out. Too long they will chatter or tend to deflect and affect accuracy.  Too short the beam will experience more wear than necessary. So what is the correct length? That will depend on how you naturally tilt the gauge in use, so pay attention on how you use it and keep it as short as possible, while clearing the beam off your piece in use. Most gauges often come with the pin sticking out way too much. A long pin is nice for repeated sharpening, but it should be sticking out on top, not at the cutting edge.  Wheel types do not have this problem, the distance from pin to beam is fixed, even after numerous sharpening (we only touch up the flat back remember?) Use that distance as a starting point if you have both types. And remember you cannot have too many gauges.  

What about those measurements found on some beams? Oh please, we do not need yet another source of measurement errors! Set them to your tools, gauging blocks or adjust the fence until the mark is centered on the stock, no measurements involved in these operations! Just about the only time I will set my gauge with a measurement would be when using a panel gauge, and that is a slightly modified animal for its task.

Bob, gauging the snow in his driveway, wondering if its worth getting the snowblower out...

How do you measure up?

This may sound corny, but your biggest source of measurements errors come from your measurements themselves. Solution? Don't measure but whenever possible uses gauging sticks, story pole, setup blocks etc. Make it fit is the name of the game

Uses you available tool width, instead of measuring & transferring measurements (double the chances of errors)
Who care if your 1/2 in chisel made overseas is an reality a metric chisel labelled somewhat close to 1/2 in, but not really...  Uses whatever you have to your advantage.
If I need an 1/2 in mortise, I will set my mortise gauge using my so called 1/2 in chisel, that it is a smidgen wider or smaller, I could not care less. And I will then make my tenon to fit my somewhat 1/2 in mortise by sneaking up to the fit.

What about digital measuring gismos, aren't they inherently more accurate? Not really, they will give you a close approximation, never an absolute, and probably never twice the same exact measurement yet within the stated accuracy.

                                     
You see, the problem with measuring devices is always in the interpretation or interpolation, both from a human or some sort of electronic transducer.  Real life examples rarely fall exactly on the tick marks, more as in somewhat in between... as in 2 little bar and a smidge past the big number 5.  Read it again but tilt your head slightly the other way and it is now more like 1 little bar past whatever. Parallax errors anyone? Even when you are aware and compensate for it, no two people are going to measure and interpolate the same.


What about converting back and forth between measuring systems such as Metric and Imperial?  Now you are asking for troubles, rockets blew up on the launching pad and space exploration probes have missed the mark completely because of it! Stick to whatever you are familiar with.


What if you were to take your piece and mark it where it will fit? Ah, but what about the thickness of your line? How about sneaking up to the exact length...


Have you ever tried to shave off a smidgen with a power miter saw? Good luck and watch out, it could get seriously dangerous in a hurry.  On the other hand using a shooting board and a sharp plane it is very easy and safe to do.


Need to remove a few thous from a board thickness? If your plane is set to remove a know thickness per pass it is easy to do. One caveat here, trying to measure a fluffy shaving with a micrometer can quickly becomes an exercise in frustration. The pressure you exert with your micrometer or caliper will affect its reading. So don't get worked up about it. and give me an analog device over a digital one any day!


Ever tried to read off a measuring tape to check if your assembly is square during a glue up?
Heck of a lot easier using pinch rods, or gauging sticks and more accurate too (Hint it is because there are no actual measurements involved).


Ever used a story sick or pole? Once you understand how it is used, you will be amazed at the number of information it can carry, and accurately too.
Another source of errors is by using various instruments. Stick to monogamy here, uses the same measuring tape, rulers, try square whatever you are using. Every time you switch instrument you introduce yet more variations.
Setting your tools, calipers, marking gauges etc. using known dimension; Setting blocks, specialized gauges, are a lot easier than trying to lift measurements of a ruler for example

Learning to use and trust your senses, it is amazing how much accuracy we have "built-in" at our disposition.  You can resolve a few thous difference with your fingers (you still have ten, right ? :-) or by seeing light between a know flat surface and an object. Starting to see the light yet?


And talking of senses, if your nose is smelling burning and your ears are hearing screaming noises from your planer or drum sander, you are probably taking too much of a cut or are experiencing bind up, pay attention to your senses!
Or I suppose, I should say "You should come to your senses!"


Bob, staunchly refusing to convert to Metric, long live my foot :-)