Mechanics of chipbreakers and high cutting angles in woodworking planes. Abstract.

[ian maybury]

Hi Kees. Just to pitch the 'shaving centered view' again: The plane having been moved forward by the force applied by the user (which isn't necessarily a simple horizontal 'shove'), I guess the shaving doesn't terribly care what type (of plane) is involved.

It just experiences being cleaved off, and contact with various surfaces. Which act on it as they do. The resulting force balance(s) (actions and reactions) then largely determine what happens on the workpiece, the form of the shaving and the handling of the plane...

We likely do a lot of unconscious simplification of the dynamics of what's going on when we think, but there are also potentially a lot of irreleveant considerations in the mind models we work with too. The above for example thinks of the forces as acting in the vertical plane, but there is potentially lots going on in other directions too. (although it may or may not influence the above)

[Kees Heiden]

Absolutely! There are plenty of design parameters influencing the experience like the handles, the weight, the center of gravity, the solidity of the plane etc, but I don't think the shaving cares if the bevel points up or down.

[Bruce Mack]

Thanks Winton. I got up at 5 AM with my pinched nerve and tottered to the computer to try a seated position. Your humor restored order.

[David Weaver]

(winton says a lot of words and they're all parsed up)

Winton...here you go and bring this post up after the fight is over...and I have no more fight!!

Plus, after all of those quotes come out in a reply, it's almost impossible to parse the post!!

(I noticed I spelled "your doing it wrong", wrong. That's my favorite place to misspell that, from an old inside joke. Me and some folks used to always misspell that because it irritates the reader. "your wrong" or "your doing that wrong" It has a different meaning than "you're doing it wrong", though, but I should've done it elsewhere since this place doesn't have that convention - I'd love to get it going, though )

What else can I say, me likey stanley profile. Think quarter round with the 2-3mm bit, still sharp at the edge, closer to the profile of a stanley chipbreaker once the front edge is rounded, though - just not as tall. Just do the old paul sellers roll on the front edge of the thing.

If you love the 12k chinese hone, go to woodcraft in person and look for one that appears to have stretch marks on it. Those are the hard ones that will give that polish. The is a Polish (not polish) seller on ebay who sells them, and sometimes they are good and sometimes they are too soft and slurry. They won't do what is in that picture if they slurry - they're more like a 4k/5k stone if they slurry. You'll have to get up off of your bevel to use them, though - too slow otherwise in non slurry mode. I have had four of them, only one of those four stones was really good, two were "eh.." and the fourth was junk - I cut it up for a nagura, and it's not even good at that.

And for the elimination - well, cap iron and tearout or whatever the subject, elimination is really satisfying!

(I knew when ellis put that picture in that some day, someone would take my article and say "hey look, it doesn't work, there's still tearout" - it's happened twice so far)

I can tell the conversion is coming soon...winton will soon be using mostly stanley planes with the cap iron set.

[Warren Mickley]

Stanley capirons certainly aren't made of "uniformly high quality and properly heat treated steels". No idea what they are made of, but it is a rather soft, gummy metal that creates huge and persistant wire edges when you work on the bevel. So that would explain their sagging under the constant pressure of the levercap over a 100 years or so.

Do you have any data on this sagging?

I have a small amount of data provided by my five planes. Three of the cap irons are over 100 years old; the other two are 31 and 41 years old. None of the cap irons have been altered in the last 30 years. I checked these cap irons this morning and it appears that they are all still functional, that none of them relaxed over the weekend. I am not anticipating that they will relax in my lifetime.

I do have one more interesting bit of information. The cap irons in the Seaton chest (1796) have a small strip of steel welded to the iron at the tip..

[David Weaver]

I've also never noticed much on my cap irons, except for one plane. I received an 8 that came to me in parts from ebay (early on in my woodworking fiddling) that had a cap iron that was worn through in the middle. The mouth had a similar level of erosion, I don't know what the plane had been used for. I guess the mouth erosion isn't that uncommon, but the fact that the cap iron was worn through only in the middle was odd (and rude that the seller couldn't be troubled to mention it).

In the last two and a half years, I haven't had any issues with stanley irons seeming too thin (no matter how hard the wood) nor any cap irons seeming anything other than totally solid in the cut. If anything, the whole assembly (the plane with the irons properly set) will stop me in my tracks if the cut is too deep, or skip on a board at the start of a cut, but not chatter or feel flimsy.

[Kees Heiden]

Only one example. A #7 type 11. Shavings would find its way under the cap no matter what, as soon as it was set close to the edge. I've reworked it several times to no avail. Bending it a bit in the vise cured this problem. So it is just one example, and I'm not even 100% sure if it was due to sagging.

I don't have many planes, so I am not the best person to ask about all manners of things that can go wrong with a plane.

[ian maybury]

Guess there's numerous possibilities for issues with the traditional layout chip breaker. One birthday present in the mid 60s was a small Stanley plane - can't remember the size. I can agree that the steel in the chip breaker felt soft. Against that the format can't be helpful - long slots often lead to funnies. Especially if there's residual stress about from punching and/or similar. Add lots of heavy tightening (with the screw bearing only on the edges of the slot) and it might not be hard for it to belly somewhat and end up taking a set...

[David Weaver]

The body of the cap iron should lay flat against the iron, and the two ends of the hump should be in contact with the iron when the cap iron is tightened. There's really no great reason for it to be hard - it needs for the small hump to be sprung somewhat. The rest of it doesn't deform unless someone does something to abuse it while it's apart.

[Gary Muto]

Hi Gary,

Thanks for your comment. Chatter has the habbit of being triggered somehow. It appears suddenly somewhere in the middle of a board. The Stanley plane isn't known as the most chatter resistant design ever made. Especially with the thin original blades you can have some trouble now and then.

In the situation I wrote about, I tested the Stanley plane on a piece of curly wallnut. 45 degree to 55 degree gave no chatter problems, and resulted in a smooth results. Likewise with the capiron settings of 0.3 to 0.1 mm from the edge, no problem at all, smooth surface. But the 60 degree cutting angle suddenly produced a remarkable amount of chatter. Because you write about resonance, would it be some kind of harmonic resonance where the cutting action excites a frequency which happens to be the same as the natural frequency of the plane blade? But why didn't the chatter happen at 55 degrees, which is the same blade, bedded the same way, only with a slightly different backbevel?

Then I ripped the board in half so it was 2cm wide, and the chatter went away. The same plane setup, the same wood, no chatter. Reducing the cutting width reduces the forces on the edge. These things sure get complicated!

BTW, the chatter had no influence on the tearout.

Kees,

I agree on the chatter not being related to tear out.

The excitation does not have to be at the same frequency as the natural frequency as the blade. The blade (system) will resonate at its natural frequency regardless of the input frequency. Shortening the depth of cut for example will increase the system stiffness and resultant reaonance. Typically it is easier to get more displacement with lower frequencies so I suspect that this is happening here. I am making general statements here but I think they are accurate.

[Winton Applegate]

Stanley capirons certainly aren't made of "uniformly high quality and properly heat treated steels". No idea what they are made of, but it is a rather soft, gummy metal that creates huge and persistant wire edges when you work on the bevel. So that would explain their sagging under the constant pressure of the levercap over a 100 years or so.

Ha, ha,
No gummy saggy butt steel on my LN BU.

Serious question now . . .
? Was there one or more HIGH End, boutique, made right, built to last and work well, double iron planes . . . you know for the impatient, intolerant girly men like me that want a well make plane and don't know that "too much" is too much to spend on a plane.

For instance kind a like these but with a chip breaker but back in the day.

[Kees Heiden]

Infill planes?

i think the older Stanleys were damned good planes.

[David Weaver]

I'd agree with kees, the Stanley planes are high quality. Winton, I think most of the old infill planes would've met your description.

I also can only think of one cap iron that's hardened at all, and that's the one in the command set, and it's very mildly hardened. They're otherwise but steel, and I haven't yet used one that works as easily and as well as the stamped Stanley cap irons.

Oh, and given the choice between the two (take a stanley 6, for example, and an 18" spiers infill - other than for the fact that the spiers infill is worth more, I'd have a stanley 6 if I could only have one plane. I have both - well, my spiers panel is only a spiers copy built from a shepherd kit, but I'd suspect it's working far better and is far tighter than most vintage spiers planes).

[Derek Cohen]

Hi Winton

High cutting angles have a place, either with a BU with a high included angle or a BD with a high bed. As do back bevels, and close set chip breakers. They all work and are just choices.

I continue to find it so interesting that I cop flack on this forum for suggesting a high included angle in a BU plane on squirrelly grain, and then on the Oz forum I cop flack for suggesting a close set chip breaker!

In a current thread on the Oz forum the discussion had turned to high angle frogs (everyone) vs chip breakers (me), and so I posted the following ...

"These photos were taken on the spur of the moment, so it is not intended as an experiment. Still, you can see the result. The chip breaker was set close (about .3mm). The wood used is a scrap of Fiddleback Jarrah from my chair build. This stuff just tore out with the spokeshaves during my build, which forced me to use rasps. Here I am using it with the LN #3 with a 55 degree frog planing into the grain (look at the side), just to make it more difficult.




Above: the surface quality is excellent. No signs of any tear out.

Here is a close up of the shavings - pretty typical straight shavings when the chip breaker is working ...



With just a rub of wax, the finish is pretty good (just for reference, the board is rotated, so the grain is now forward) ...



(One of the forum members argued that the reason for the LN's performance was that its high frog and high cutting angle. Consequently I posted the following ...) ....

I took a few more photos, which will add to the information, and I will use to respond to your observation/question (not sure which it is).

Returning to the interlocked section of Fiddleback Jarrah, the LN#3 (with 55 degree frog) planed into the grain again. This time the chip breaker was pulled back to 1/16", where it was out of the way. In part this was to test the belief held by Stewie that the high bed/frog (i.e. cutting angle) was responsible for the earlier results.



You can see the change in the shape of the shavings. They are no longer straight but curly.

A close up of the surface reveals tearout throughout - not nearly as good as when the chip breaker was also used with this plane ...



Now I switch to another #3, a Stanley with a LV PM-V11 blade and LV chipbreaker. The leading edge now has a 45 degree secondary bevel and is placed about .3mm from the edge of the blade.



Note how flat/straight are the shavings ...



What of the surface quality?



Well, it is not as good as the LN with 55 degree frog and closed up chipbreaker, but it is a whole lot better than the LN with the chipbreaker pulled back

The lower angle Stanley is easier to push than the higher angle LN. However the difference would be negligible with waxed soles.

The other factor is that the cutting angle does make a difference, and is additive to the chip breaker effect - which is something I have been banging on about for the past few years. There is no doubt that both have an effect, and that the effects can be additive.

Regards from Perth

Derek

[David Weaver]

It looks like the cap iron is too far from the edge. What do you get if you put it about half as far away?

In working something like that with a stanley plane, I'd take a penultimate set of shavings like you've taken and then back off the cut depth to half or less and take a few passes. That should eliminate the tearout that's still there, but if it doesn't, I'd advance the cap iron forward.