Plane Whispering: of bevel, angle, and frog

[ivan]

I have been thinking and experimenting for some years, around the essential functional differences found in Japnese and infill planes, that contribute to a woodworking advantage over the modern cast iron type. Certainly a thicker blade helps. A Japanese blade may be 8x thicker and so 8x8x8 times* stiffer!

Like others posting here, mouths were widened and cap irons adapted, so they could still engage the adjuster when fitted with a thicker blade. Thick 'laminated' blades were made from a Samurai replacement blade, bonded to the detempered original with Locktite. The result was interesting enough to justify purchase of 5mm Hock and Lie Neilsen blades when these became available.

I beleive this to be important, for cutting loads the tip of the blade. This force can be resolved into two parts - one along the blade, pushing it against the adjuster, and the other at right angles, pushing the blade down into the work. This results in a tendency for the blade to pivot on the heel of the bevel, the edge digging in, and the body of the blade lifting from the frog**. This may be clearly demonstrated on a standard blade, by planing with a clock gauge on the blade itself, 50 mm or so up from the heel.

Matters are made worse by the standard 'bent metal' cap iron. Screwing this to a flat blade will bend the blade into a curve. This is not removed when the pair are fitted to the frog and clamped by the lever cap. The blade itself contacts the frog only close to the heel and under the lever of the lever cap. A chatter*** tool.....The two piece cap iron now made by Clifton is designed to prevent this, and also to provide a third clamping point.

The LN chipbreaker is well made, but still similar in principle to the bent metal original. No doubt that screwing the LN to a flat blade will cause the blade to bend (albeit less than the original). However the LN chipbreaker looks similar to that of an infill plane. Infill planes appear to have a much shorter lever cap (with a screw) which seems to clamp down, well up from the cutting edge, at the point where the Bailey blade is most lifted from the frog. When the infill plane's screw is tightened down for work, it may bring cap iron, blade, and frog all into intimate contact, to make a rigid whole. Could the infill experts comment on this guess, please?

A recent post referred to the work of Prof. Kato on the effect of chipbreakers on surface finish, which contains some photos which augment those in Leonard Lee's sharpening book. Kato's paper implies that the cap iron, or chipbreaker, should be 'sharpened' at 80 deg. and set at one shaving's thickness from the blade edge. A bit tricky if your best smoother's blade has a slight curve...It also implies that the standard chipbreaker settings of 1/64" to 1/16" would have no beneficial effect on surface finish whatever. Perhaps this is the reason low angle plane users don't seem to miss a chipbreaker when working on difficult grain?

Best Christmas wishes to all.

* stiffness increases as the cube of thickness - however in this example the 8x thicker blade has an 8x longer bevel so the increased resistance to cutting load is only 8x8=64 times. Incidentally, tapped out Japanese blades are supposed to show an improvement. Mythology? or local stiffening caused by pre stressing the bevel?

** put 10mm of a steel rule at right angles, over the edge of the bench, and prod the end, whilst pretending to be the lever cap with finger tips at 15mm and 100mm

***a vibrating blade produces a surface ripple

 

[Philly]

Ivan
An interesting discussion point!
There are many factors in achieving a flawless surface with a hand plane. Thickness of iron-when you think about it, regardless of the thickness of the iron, only one shavings thickness of iron is actually in contact with the timber. So a thicker iron really only helps on the stiffness/vibration absorbing front. I believe the way the blade is bedded is more important-good (and large) contact between the bed and the iron prevent chatter and unwanted vibration of the iron. I use woodies as well as metal planes and believe this is the most important factor in a successful plane.
The chipbreaker is another interesting area. There is an interesting article (with great pictures) in this months Good Woodworking by Jeff Gorman on the use (or not) of a chipbreaker. As you say, to actually work as a CHIP BREAKER it needs to be set about one shavings distance from the edge of the iron. Otherwise it doesn't really play much part. At least not in preventing tear-out (the stated purpose of a chipbreaker :roll: )
I believe they play more part in tensioning the iron, especially in planes with thinner irons. I know this is especially so with Jap planes.
A final thought-high quality planemakers Clark and Williams offer their planes for sale WITHOUT chipbreakers. And their planes are bevel down. Enough said...... :lol:
So in my opinion, a good plane needs:
Reasonably thick blade (blades 6mm and thicker are a waste of sharpening time)
A tight mouth (for the work the plane is to do)
A good fit between iron and bed (larger contact area the better)
A very sharp iron (often overlooked :lol: )
Cheers
Philly

 

[Anonymous]

I can't add much to the conversation on LV's and infills.

But I agree entirely on your comments regarding thin blade flex problems. I've had quite a few in depth discussions about that.

All things equal I generally believe a thicker blade is nicer to use.

Especally a thick laminated one, in a heavy metal plane. Very smooth.

Maybe a bit too ruff for some, but I've found modifying an old stanley to hold an old woodie blade successful. I tried to describe it here.
http://www.sawmillcreek.org/showthread.php?t=42167

I've done it to most of my bench planes. My #6 in particular, as rust pitted as it is, tuned and flatterned , is one of the best planes I've ever used.

But when it comes down to it, we're really just talking about slight improvements. A regular tuned stanley with its origional blade should be quite adequate..

 

[JesseM]

Maybe a bit too ruff for some, but I've found modifying an old stanley to hold an old woodie blade successful. I tried to describe it here.
http://www.sawmillcreek.org/showthread.php?t=42167

I wonder if you could somehow weld or attach another piece of flat steel stock onto any old blade to make it thicker. I guess attaching it would be the tricky part, but it would allow you to use those thinner blades.

 

[Anonymous]

Matters are made worse by the standard 'bent metal' cap iron. Screwing this to a flat blade will bend the blade into a curve.

No. Not with the LN blade as it is much thicker than the cap iron which will spring away from the blade as it is much thinner (ok, the blade might bow by a thou or two), not to mention that the gap between the blade and new LN cap iron is very small (<1mm?) and so the effect will be even less.

I just set this up in the garage with my LN4.5 blade and there is no defelection of the blade at all when the cap iron is tightened - well, none I can pick up on my DTI with a resolution of 0.01mm

 

[ivan]

Tony, the bit you quote above is about the standard cap iron on a standard blade. But if a LN blade is even just one thou off the frog, it's hard to see how the frog, as is often claimed, is 'supporting' the blade. Especially as the cutting force is trying to lift the blade away from the frog. Thinking about it, the same argument applies even if the blade is touching the frog.

I have come to think that maybe the lever cap should clamp the lot tight, no air gaps, to the frog. This would require a shorter lever cap (about 20 or 25mm shorter) - hence the Q to folk used to infill planes. Maybe I should just saw a bit off the wide end of a lever cap and see what happens, but I'm not usually that adventurous!

Jake, you should see the Anant I got to play about with, still has the loctite laminated pair of blades; your woodie blade looks a much better bet!

PS. No criticisms of LN intended - I have some myself - just an interest in what makes some planes 'special', and if it can be emulated.

 

[Paul Chapman]

Interesting post, Ivan.

My current thinking is that a thick iron, good cap iron, well-machined frog assembly and overall precision in the way these all fit together are essential for good performance.

I have four Record planes, #04, #05SS, #05.5 and #07 and three Cliftons, #4.5, #06 and #07. They are all fitted with Clifton irons and Stay Set cap irons. While they all work well on softer woods, when it comes to really hard woods and those which are otherwise difficult, the Clifton planes significantly out-perform the Records. Only yesterday I was planing some end grain beech on a shooting board. My Record 07 was struggling whereas the Clifton sailed through it like a hot knife through butter

The differences between the planes are essentially that the bedrock frog assemblies on the Cliftons are significantly better in their precision and the firm seating they provide for the blade assembly. When I insert the blade assemblies I can feel that they bed down with precision. The Cliftons are also heavier which helps with the overall momentum when planing.

Of my Records, the best one is the #05 SS. I bought this second-hand. It is quite a bit older than my 35 year old other Records and it has a much better machined frog and therefore the blade seats better. However, it's still not as good as the bedrock frogs on my Cliftons.

Better irons and better cap irons will, in my experience, make a significant difference to performance but a good frog assembly is, I think, essential for ultimate performance.

Cheers :ho2

Paul

 

[woodbloke]

JesseM wrote:

I wonder if you could somehow weld or attach another piece of flat steel stock onto any old blade to make it thicker. I guess attaching it would be the tricky part, but it would allow you to use those thinner blades.

Agree with much that has been said here. I have an old T5 Record jack withe a machined frog offering a greater area of contact for the blade. This is still the standard Record offering and seems to perform adequately.

I was leafing thro' some back copies of F&C the other day and noticed that someone had addressed the problem of thinner blades by epoxy glueing a piece of thick brass onto the back of a standard blade and then filing away the excess to regain the profile of the blade. Dunno wether this would work - Rob

 

[Steve Elliott]

When the infill plane's screw is tightened down for work, it may bring cap iron, blade, and frog all into intimate contact, to make a rigid whole. Could the infill experts comment on this guess, please?

I've looked at this issue on about a half dozen older infill planes by Spiers, Norris and Mathieson. In every case the pressure of the lever cap did <i>not</i> clamp the blade down onto the infill bed. The blade typically rests only on the heel of the bevel and from the lever cap screw on up. (This part varies from plane to plane.)

I've made some chipbreakers that have such a small amount of curvature that the blade rests down flat on the infill bed. Pictures of them can be seen at the bottom of this page on my website:
http://planetuning.infillplane.com/html ... lanes.html

Mod edit, original URL returned. Sorry, the SPAM filter kicked in. Adam
Once Steve has made some more posts this will clear, that is how the filter is setup. DaveL

 

[Adam]

And I can't get it to undo it, even thought it shows it to me as ok, anyway this is the link
http://planetuning.infillplane.com/html ... lanes.html

Adam

 

[bugbear]

In every case the pressure of the lever cap did <i>not</i> clamp the blade down onto the infill bed. The blade typically rests only on the heel of the bevel and from the lever cap screw on up. (This part varies from plane to plane.)

Yeah; I'm sure it's commonly assumed that blades "bed down" on the frog, but detailed observation show that they commonly don't.

The observed fact that some planes with VERY desirable performance don't have "fully bedded" irons is conterintuitive.

However, I think the "old guys" knew it, since a tip in a (old...) magazine for a woody with a too-closed mouth is to insert a leather shim at the top of the bed, so that the blade pivots around the arris of the bevel, thus opening the mouth (a little).

As the sole or the blade wears, the mouth will open, and the shim can be removed.

However, while the shim is there, it is self-evident that the blade is not "fully bedded".

BugBear

 

[engineer one]

these discussions are always interesting, but i think you are not quite right Ivan about the tendency to lift the blade away.

surely as the blade is moving through the wood, it is digging in, and tending to be pushed against the frog at the bottom, whilst the top is moving forward, thus the clamp/chip breaker/ whatever we have decided to call it, being placed about the horizontal centre of the blade with the clamp at the top, and the flat surface really near to the edge, is stopping this happening.

even bevel up planes have a similar device to stop the blade"bending"
and smaller apron type planes have a cross bar which is also to help this.

after experiencing a number of wooden planes, in my view unless they are built as a kit of parts, rather than a hollowed out solid object, there is always going to be a problem at the beginning with the frog and the aperture being as smooth and flat as one would prefer. i think that is how "infill" planes got developed.

i would have thought that the bending moment is lessened because of the cutting action of the blade, it only becomes important when the blade is not properly sharpened.

paul :wink:

 

[bugbear]

I would have thought that the bending moment is lessened because of the cutting action of the blade, it only becomes important when the blade is not properly sharpened.
paul :wink:

If that analysis were enough, the only factor governing plane performance would be blade sharpness.

And Ivan isn't just saying he thinks the blade might lift, he's saying he's measured the thing lifting.

BugBear

 

[engineer one]

ok bugbear i kind of skipped that part, but what are we talking about
0.0001/0.5mm???

at that point it is easier to determine the actual effect.

paul :wink:

 

[ivan]

Thanks to all for your thoughts. And best wishes for the New Year!

I had a look at the Good Woodworking article on Xmas eve, Philly, whist SWMBO was doing the last shopping. Jeff Gorman appears to fall into the "traditional chipbreaker position" camp (1/16" back form the edge) Which according to Prof. Kato's photos, has no efect at all on surface finish. So he's efectively just comparing two different sharpening angles.

Tony, fitting the standard Stanley/Record/etc cap iron to a standard blade results in the "flat" back of the blade being curved alomg its' length by around 20 thou. You can still slide a feeler gauge under when it's fitted to the plane. The exact amount depends on the initial curvature of the cap iron.

The LN must bend as it's stressed by bing screwed to its' bent cap iron - being thicker it bends less, and stiffer because probably tempered harder. (Try a bit of engineers blue to check your bedding)It will also lift less in cutting as it is thus stiffer - but still in comparisons, traditional japanese and infill planes are reported to have particular advantage.

Steve, How did I miss this! (I found Kato at cablespeed.com, presumably a mirror of your site) Great minds think alike... ccasion5: Ho! ho! Indeed the forum is a marvelous place to learn. Your photos make the point exactly. I was thinking of trying to sharpen a LN cap iron at about 60 deg and then turn a small burr, scraper-wise, at the required 75-80 deg. A gentle flattening of the burr might then result in a cap iron capable of being clamped to iron and bed with no airgap or possibility of flutter. I was also wondering if I was wasting my time; seems not.

Engineer one - Try my ruler experiment above. Consider the blade as a beam, mounted as a very uneven see saw, with the heel (arris) of the bevel as the pivot point. Cutting pushes the sharp edge down, and creates a tendency to pivot, resisted by the length of the blade, clamped firmly at the top. Unless the blade itself is perfectly rigid (a materially impossible condition) it will bend up allowing the edge to bend down.

Bugbear/Engineer one, in cutting softwood with clock gauge on the blade (standard Stanley) , the needle can be readily seen to flutter, so probably a thou or two. It's hard to measure exactly on a moving plane. It moves rather more as you lean into a difficult patch, and gets quite excited if you try to slice through a knot...that's wot I calls digging in...I think you can probably hear the flutter as the Bzzzzp you get as you plane - planes with thick irons are much 'swishier'. Thus I conclude that Mr Bailey may have been a carpenter, not a cabinet maker. The Bailey works quite well when tuned up as long as you don't stress it, or expect the almost optically smooth surface of a Japanese plane. Standard Cliftons and LNs are much more versatile, but I was curious to know what takes some traditional designs to a higher level. Could be Steve has already got the answer - thanks!

 

[David C]

Ivan,

I was disappointed by the Jeff Gorman chipbreaker/capiron article, due to the lack of a close setting to the blade edge.

I slightly camber the front edge of my chipbreakers, what I would call a "big" curve, maybe 10-12 thou of light at each side when offered to a flat surface. This enables me to set very close indeed to the cambered blade edge in the centre.

Difficult to know how close it gets. But certainly within a few thou", if I concentrate.
While not conforming to the Japanese research, I feel that something is acheived in Type 1 chip production.

I will try to remember to test this in the new year as it should be easy to do. (Closest possible set and then well back).

Bevel up planes are entirely dependent on choosing a suitable effective pitch and getting on to Type 2 chip production for difficult timbers.
Bevel down planes also cope best with difficult timbers when the EP is adjusted with a back bevel. once this is done the C/B has no function other than blade adjustment.

Personally I am not concerned with total blade support for thick blades. The vital area is clearly the heel of the bevel.

I would be very surprised if the improved L-N C/B induces a significant bend in a thick blade?

These are all fascinating issues!

best wishes,
David Charlesworth

 

[ivan]

Thanks for your observations, DC.

I had not previously put a radius on chipbreakers fitted to radiused blades, as until reading Kato, I thought 'a close setting' (1/64 or about 16 thou) a good deal more than any curvature! (2-5 thou I guess, enough to taper a typical shaving out to zero thickness at the edges).

Kato shows that 'as supplied' the LN chipbreaker is not capable of preventing chipped or torn grain, although this is easily remedied by 'sharpening' it at around 80 deg. It distorts the blade much less than the Stanley (this latter ~20 thou). Last night I looked at my LN41/2 which has a 50 deg frog, and is fitted with a ground down blade from a LN No. 8 (this a measured 4.8mm). This blade is flat, tested with arm of M&W eng. square agaist light. When fitted with a standard LN chipbreaker it's less than 1.5 thou off the frog (my smallest feeler) but bluing shows only the heel and lever cam area touch the frog. There is almost an overall contact when using a 2 piece cap iron.**

The Bailey design, when accurately executed, places all responsibility for resisting digging in, chatter, and blade flutter, on the stiffness of the blade. As the mid length of the blade moves upward, away from the frog under cutting load, this just highlights an area of potential weakness in the design. Having observed this, it seemed appropriate to think "I wonder if it would be beneficial if the lever cap could clamp the lot rigidly to the frog". Perhaps DC is right, and if you already have a thick blade, this is just gilding the lilly....

**Unfortunately the Clifton 2 piece is pressed from mild steel and does not have a LN style pecision finish. As bought it may not be flat, this specimen had to be lapped flat, or it too would distort the 4.8mm thick blade. The additional, third clamping point, where the two pieces join, provides a modest aditional clamping pressure at the spot where the blade is most likely to lift from the frog. This would of course be much increased if the lever cap was a bit shorter....!

 

[David C]

A thought that comes to mind.

Redesign the lever cap and make a solid 1/4" - 3/8" brass one, like Brian Boggs did for his Stanley spokeshave tune up, then use centre screw only to crank whole lot down flat on frog surf. Stanley frogs are far from flat so surface would need work.

As well as not being precision ground I think you will find the 2 part C/B has only one point of contact near the pin on the join.

The theoretical considerations are very interesting, but a sharp high quality thick blade with fettled c/b and flattish sole does all I need.

Have you looked at the details of the recent, radical Bridge City lever cap arrangement.

David

 

[engineer one]

looking carefully does it matter????

it seems to me that unless you are continually taking vast thickness of shavings then the movement has little real effect with thin shavings.

i also wonder whether the common practice of planing at an angle to the wood and thus the blade intersection also reduces the actual effect of any bending.

i think certainly for those beginning, the problem is trying to take too much wood off, ie too thick a shaving, hence the value of the dc cambered blade idea. it is also surely why scrub planes have such thick blades.

patently a thinner blade will tend to dig in if it is set too coarse which is why many have problems if not trained.

or have i been eating too many funny sweets again :twisted: :lol: :roll:

paul :wink:

 

[MikeW]

I think most of this is nice info to read...even to study. I also think as Paul alludes to, it only applies to planes set for a ranker cut than a typical smoother is--there is no chip failure below a certain thickness and at 50 degree effective cutting pitch or less.

One reason I find this info a nice read is that a smoother taking a non-breaking chip is used so little on a project when one is talking total time used. And should I get to a finished surface while taking a thicker chip, so much the better. Most time with the woods I work, this is not possible and so the smoother and or scrapers work their magic on most work.

Most of my planes do not have a chipbreaker/cap iron set very close--some simply do not have one anyway--yet chip failure still occurs. Rarely does tearout occur once I am no longer using a wide mouth setting and a rank cut.

I tend to use less than well behaved hard woods, so perhaps it is less rank a cut anyway which helps minimize tear out. That or I lead a charmed life--hah! Point being any tear out I typically have is eliminated by either the smoother alone or a finer set plane followed by a smoother.

What I am unsure of is what use is measuring any flutter [and how much of this "measurable flutter" caused by the movement of the measuring device and plane as opposed to true movement of the iron] to me?

Take care, Mike