Radiusing a cap-iron?

[David C]

David,

I do actually read what you say, but am frustrated by lack of useful information.

If faced with dense interlocked exotics, or difficult domestic species, what sort of C/B settings do you use, please?

I have used the 4 thou setting on the "Wood from Hell" , with success. I believe this may be gnarly Indian Laurel.

Actual figures, which could be tested, would be useful.

David.

 

[D_W]

David, I set the cap iron close enough that it will mitigate tearout without affecting the final surface quality. I have never measured the settings because nobody who actually sets the cap iron would ever have done that except for the kato and kawai video.

My normal setting is probably somewhere between 1.5 and 2x the thickness of the thickest chip I will take. That is a guess.

You are referring to kato and kawai, but I learned to set the cap iron before kato and kawai information came out. Only to find out that their paper detailing a method to set the cap iron for hand planes is the same as mine, not a prescribed number. This is preferred unless someones' eyesight is too poor to do it by eye and sense. To be clear, you are doing something that kato and kawai advised against, and not doing what they advised.

It is not a paint by number thing (setting the cap). I'm sure that on the try plane, it is set off more than a hundredth of an inch. If you listen to blog gurus, they will tell you that the cap iron doesn't work that far away (presumably because they have little practical experience), but they are clueless about using the cap iron on penultimate work where you might take a shaving of 8 thousandths or a hundredth in something like cherry. The same setting on a smoother would do little other than prevent an accidental deep shaving from an improperly set up plane.

They are set differently - heavy and not heavy use. You set the plane based on how it works best, and you develop a sense of what you need to see (in terms of how much bright metal from the back of the blade looks right to you when you set the cap iron). Anyone who is going to use a cap iron as a regular plane feature and not just an emergency preventer with thin shavings needs to learn that skill. It is different than just setting it tight and using at tight all the time - such a thing doesn't allow you a full range of shavings on a smoother.

What kato and kawai suggest in the hand plane related paper will parallel to setting the cap iron slightly further off so that it only engages a thick smoother shaving, but so that something sub 2 thousandth of an inch doesn't really get too much work from the cap iron. Such shavings generally don't need cap iron influence because they are not strong enough to lift a splinter from the surface of a board.

When Bill Tindall sent me a link to the video you're referring to, before it had been permanently hosted publicly elsewhere (it was just a shuffle of links in japanese on a blank white page), I voiced to him the concern that people would start creating all kinds of gadgets and fixtures to try to set a plane iron exactly at some specific thousandths of an inch, or that people would think 80 degrees is a good bevel angle for a hand plane (it's not). Bill relayed that he thought the video was good proof to goad people into actually trying to use the cap iron and mentioned repeatedly that K&K advised that the videos were for machine planing and should not be relied on for hand planes. There is no video for hand planes, so I guess their advice never gained any traction.

My explanation is not evasive. It is this - if you are having tearout problems, the cap iron is not close enough. If you are creating a surface that is fuzzy, crushed, or having too much resistance from the plane you're using, then the cap iron is set too close. If you are getting a good surface, a straight chip at a thicker setting for a given set, and little extra resistance (that is easily offset by the fact that the plane is not jumping in and out of the cut like it would be if it were tearing), then the set is good. Each plane's set will look a certain way to a user. If someone does nothing more than smooth, then they will only need to recall what one set looks like. If a user is doing more than smoothing, then they will need to become familiar with what a good set looks like from each plane. The coarser the expected cut, the longer the projection. The range is fairly forgiving with a 50 degree cap iron initial edge that is convex above where the cap meets the plane, getting inside the proper range is easy enough to do without resorting to shooting for specific distances with a measuring device.

 

[Beau]

I am afraid the logic is incorrect.

I judge camber by the light showing at either edge when the blade is offered up to a straight block of industrial plastic.

For squaring edges with a 2 3/8" blade this gap might be 10 or 12 thou".

If the timber is particularly dense and prone to tearout, K&K suggest a C/B setting of around 4 thou".

This leads to the outer edges of the C/B being over the edge of the blade. Something that I am not happy with.

This is solved by slight camber on the C/B which has no ill effects.

It may not be necessary in some people's view, but it is easy to do and has no down side.

This is not some theoretical argument, I have done it for many years.

David Charlesworth

David, you're still in the weeds. I don't debate you can work with the setup that you're using. You seem to be convinced that you've solved a problem and that my logic is lacking, but you have less depth in this subject and you don't realize it.

I figured when you brought this up that you were referring to a cosmetic issue (and you are - the fact that the cap iron goes past the edge of the iron is of no consequence in actual use, and you haven't yet figured that out). At some point you will.

As far as the downside goes, if you've taken a hundredth off of the cap iron at the edges, the plane has lost the ability to control tearout on a straight ground blade without gaining any additional capability on a cambered iron.

One other aside, and that is that Kato and Kawai never prescribed 4 thousandth for any hand tools. The professors who did the work were very specific that the testing shown in the video (and the related paper) is to support development of machine planers (like the super surfacer). They wrote a separate paper that was intended to help people set the cap iron on a hand plane and it says no more than to suggest that examination of the quality of the shaving (when it begins to straighten) and the resulting surface are key for setting a cap iron properly. In practical use, there is never or nearly never a time that a cap iron on a hand plane should be set to 4 thousandths of an inch.

If you ever were to try to do that, you'd never get the part of the iron that you've cambered in the cut, anyway. The plane would become too difficult to push and not stay in the cut before you got to a shaving thickness equal to the cap iron set (you'd be only 1/3rd or 1/4th of the way to the parts you've doctored ever even seeing the cut). But beyond that yet, unless the mouth on your plane is large and the wear sloping away, you can't even get the cap iron down to the level of the sole, let alone beyond. It can only come within a few thousandths of an inch of striking distance.

As far as practical, I've been using the cap iron to reduce tearout since before there was any cap iron videos from K&K. When the video came out, I figured there'd be people who would take it too literally and believe they could or should set a cap iron equal to shaving thickness. I was in contact with Bill Tindall before the university who owned the videos ever even made them available - they were effectively locked away because they didn't want them to be available in the public domain. I was goaded by warren mickley, that's the reason I learned to use the cap iron, and goaded by the realization that people knew more about using planes 200 years go when they had to do it to eat. I rode the wave of "small improvements" before that for a while, including in making my own infill planes, only to find out I should've been paying more attention to how people did things when they had to be good at them to survive. I don't refer to theory, I refer to practice. Some things in practice are superior to others. In this case, you're on the wrong side of it, but the consequences are small, you're lucky.

Sorry off topic but what an astonishingly rude and arrogant post D_W. I have met David and visited his workshops. He works to very high and exacting standards and does not force his ideas down your throat but shares his experiences which is a far better way to teach people than just being rude.

 

[D_W]

Sorry off topic but what an astonishingly rude and arrogant post D_W. I have met David and visited his workshops. He works to very high and exacting standards and does not force his ideas down your throat but shares his experiences which is a far better way to teach people than just being rude.

I am familiar with his teaching material, I've purchased some of it and it is very good.

This is a topic i know more about than David and have worked much more deeply in, and am weary of it it going the wrong direction. I'm sure 9 out of 10 topics related to woodworking, David knows more than I do. Perhaps it's 99 out of 100, who knows? But this is not one of them and sometimes accurate information needs to be stated more bluntly when someone is on the wrong side of correct but still telling you that you have swiss cheese logic.

If you choose nice over right, then that's your choice. It's not what I would choose.

 

[memzey]

I am afraid the logic is incorrect.

I judge camber by the light showing at either edge when the blade is offered up to a straight block of industrial plastic.

For squaring edges with a 2 3/8" blade this gap might be 10 or 12 thou".

If the timber is particularly dense and prone to tearout, K&K suggest a C/B setting of around 4 thou".

This leads to the outer edges of the C/B being over the edge of the blade. Something that I am not happy with.

This is solved by slight camber on the C/B which has no ill effects.

It may not be necessary in some people's view, but it is easy to do and has no down side.

This is not some theoretical argument, I have done it for many years.

David Charlesworth

David, you're still in the weeds. I don't debate you can work with the setup that you're using. You seem to be convinced that you've solved a problem and that my logic is lacking, but you have less depth in this subject and you don't realize it.

I figured when you brought this up that you were referring to a cosmetic issue (and you are - the fact that the cap iron goes past the edge of the iron is of no consequence in actual use, and you haven't yet figured that out). At some point you will.

As far as the downside goes, if you've taken a hundredth off of the cap iron at the edges, the plane has lost the ability to control tearout on a straight ground blade without gaining any additional capability on a cambered iron.

One other aside, and that is that Kato and Kawai never prescribed 4 thousandth for any hand tools. The professors who did the work were very specific that the testing shown in the video (and the related paper) is to support development of machine planers (like the super surfacer). They wrote a separate paper that was intended to help people set the cap iron on a hand plane and it says no more than to suggest that examination of the quality of the shaving (when it begins to straighten) and the resulting surface are key for setting a cap iron properly. In practical use, there is never or nearly never a time that a cap iron on a hand plane should be set to 4 thousandths of an inch.

If you ever were to try to do that, you'd never get the part of the iron that you've cambered in the cut, anyway. The plane would become too difficult to push and not stay in the cut before you got to a shaving thickness equal to the cap iron set (you'd be only 1/3rd or 1/4th of the way to the parts you've doctored ever even seeing the cut). But beyond that yet, unless the mouth on your plane is large and the wear sloping away, you can't even get the cap iron down to the level of the sole, let alone beyond. It can only come within a few thousandths of an inch of striking distance.

As far as practical, I've been using the cap iron to reduce tearout since before there was any cap iron videos from K&K. When the video came out, I figured there'd be people who would take it too literally and believe they could or should set a cap iron equal to shaving thickness. I was in contact with Bill Tindall before the university who owned the videos ever even made them available - they were effectively locked away because they didn't want them to be available in the public domain. I was goaded by warren mickley, that's the reason I learned to use the cap iron, and goaded by the realization that people knew more about using planes 200 years go when they had to do it to eat. I rode the wave of "small improvements" before that for a while, including in making my own infill planes, only to find out I should've been paying more attention to how people did things when they had to be good at them to survive. I don't refer to theory, I refer to practice. Some things in practice are superior to others. In this case, you're on the wrong side of it, but the consequences are small, you're lucky.

Sorry off topic but what an astonishingly rude and arrogant post D_W. I have met David and visited his workshops. He works to very high and exacting standards and does not force his ideas down your throat but shares his experiences which is a far better way to teach people than just being rude.

No point being too precious about things like this IMHO. This is a forum for sharing opinions and learnings. DC and DW are both big boys, I'm sure neither will be crying into their pillows

Now how about a nice and friendly "what sharpening method is best" thread?

 

[Carl P]

D_W -

Thanks for your explanations, they are much appreciated, I think I've got it now, just need to try it in practice. For a fuller context, what radius is the camber on your jackplanes?

Cheerio,

Carl

 

[David C]

Well its a pity that the K & K recommendations are not public.

The video shows quite clearly the use of 4 tho shavings and 4 thou C/B settings. (With a C/B edge at 80 degrees). The rig in no way differs from a hand plane except that the blade pitch was 40 degrees. The cutting was slow and the mouth infinitely wide.

I have used a very similar set up, 45 degree pitch and 70 degree C/B front edge.

I never use a straight blade in anything but a rebate or shoulder plane etc.

It is a shame that DW does not have the facility to estimate small measurements.

There was a comment about fine shavings not producing tear out. This is not true. A one thou shaving will produce plenty of tear out in a difficult wood. Yew is a prime native example.

I do not presume to teach about the K&K findings as I don't know enough about them yet. I just report what I have done so far. David may well have more experience here but I would prefer it if he did not tell me I can't put a small camber on a squaring/finishing blade, because it works fine.

best wishes,
David

 

[Corneel]

Sure you can radius your smoother, jointer and tryplane. You just don't need to radius the capiron accordingly. When the capiron sticks over the edge a little in the corners then that doesn't matter, it's only a cosmethic issue. That part of the edge won't get in the cut anyway.

Cambering capirons only brings extra work (the camber will lift the corners of the capiron of the back of the cutting blade, so you must redress the fit again to prevent shavings creeping under the capiron). And when you decide later on to make the edge a bit straighter again, you would have to repeat the whole process again.

And Dave's advice how to set the capiron without prediscribed dimensions is actually very accurate. Much more accurate then dimensions, because it is situation depended. Look at the result and use it as feedback for your setting. Still got tearout? Set it closer. Terribly increased resistance and a dull surface? Set it a little further away.

 

[D_W]

Well its a pity that the K & K recommendations are not public.

The video shows quite clearly the use of 4 tho shavings and 4 thou C/B settings. (With a C/B edge at 80 degrees). The rig in no way differs from a hand plane except that the blade pitch was 40 degrees. The cutting was slow and the mouth infinitely wide.

I have used a very similar set up, 45 degree pitch and 70 degree C/B front edge.

I never use a straight blade in anything but a rebate or shoulder plane etc.

It is a shame that DW does not have the facility to estimate small measurements.

There was a comment about fine shavings not producing tear out. This is not true. A one thou shaving will produce plenty of tear out in a difficult wood. Yew is a prime native example.

I do not presume to teach about the K&K findings as I don't know enough about them yet. I just report what I have done so far. David may well have more experience here but I would prefer it if he did not tell me I can't put a small camber on a squaring/finishing blade, because it works fine.

best wishes,
David

I never said you shouldn't camber a blade, I said you shouldn't camber a cap iron. I don't have any straight blades other than joinery and rabbet planes. I don't have any profiled cap irons because I don't own any planes that have profiled soles other than moulding planes.

If I had to give an estimate, I'd say that the cap iron setting is probably 1 1/2 times what K&K's video said. Maybe. In my estimate I'm somewhere between 1 1/2 and 2 times the thickest shaving I'll take at a set. I don't generally take shavings thicker than about 4 thousandths, but I definitely don't take a 4 thousandth shaving with a cap set 4 thousandths away (which, IIRC, was one of the tests in K&K because it's too much work and surface quality suffers).

I think observation of the surface and shaving is far more important, you'll get a sense for what you want to see in terms of light reflection when using the cap iron. When goaded by warren mickley years ago, I decided to put my infill away (which I had made and thought was as close to anything could be for smoothing - 55 degrees and a mouth between 3 and 4 thousandths and an enormously thick iron - 1/4"), it took about a week for me to recognize what the projection should look like so that I wasn't jamming things up - my first instinct was to set the cap iron too close. When I say be able to recognize, I mean set the cap iron by looking at it without then hitting the wood with the plane and finding out it needed to be adjusted one way or another. At the end of the two weeks, I knew I'd never use the infill again and setting it by eye has never produced an unreliable result since then. That's what I'd suggest people would do.

I might be able to track down the paper from K&K for hand planes, I probably have it in my email. I believe, based on some of the settings that K&K recommend that their assertion of a good surface is a bit looser than we'd tolerate.

FWIW, at the time, i tried the cap iron on everything I could find with leading edges between 50 and 80 (that includes japanese planes, high angle western planes and common pitch planes, of course). I thought the discovery of the cap would finally make it so that I could get the brightness of the japanese plane without any tearout, but I still think they are more tedious to set the cap iron on because it's not affixed to the iron, and the tension from the cap iron makes their adjustment more difficult than a single iron alone. That's too bad.

If someone came along and offered me what I paid for the materials for my infill smoother (I realize this isn't germane to the discussion, but I'd love to find a victim...er buyer), I'd be glad to sell it. Unfortunately, that's about $300.

re: the yew, I haven't planed yew, but I've found that the woods that are the most trouble are the ones where the early wood and late wood are vastly different in hardness - those usually have crumbly earlywood. That can be anything that was dried improperly, or more commonly things like truly quartersawn cocobolo (which is a bear to plane cleanly on the face of a board - some samples aren't like that, though, either, so maybe the ones that are trouble are also improperly dried). Is that the issue with yew? with the bad cocobolo, that early wood crumbles even under a smoother shaving and breaks out as dust, and it's necessary to scrape it or sand it. Most of the stuff I've used isn't as bad, though. I guess large surfaces of ash can be a problem, too, but not quite so much as that.

 

[D_W]

D_W -

Thanks for your explanations, they are much appreciated, I think I've got it now, just need to try it in practice. For a fuller context, what radius is the camber on your jackplanes?

Cheerio,

Carl

David C is going to want to strangle me when I say this, but I don't know. I set the radius where they are the most efficient in woods ranging in hardness from cherry/walnut to ash/beech/maple/oak. When I make a new jack plane, I grind the corners off of the iron and profile it until it looks right to me. I'd guess 6-8" radius, but it may be steeper/shorter than that. It's definitely not the 3 that many scrubs are set at.

I'll take one apart tonight and draw an arc with the iron and measure it.

The jack is the plane that I set the cap iron close on the least by far. I always set it to be used on the try/jointer and smoother, though. Always the same every time for a given type of wood (for example, I set the caps a little closer with ash or curly oak than I would with cherry - they are more trouble, and you can't take as thick of a shaving with them as you can with cherry.

 

[D_W]

https://www.youtube.com/watch?v=2yYnjUhVvzk

I have one comment to add on the jack. On medium hardwoods, I like the shaving to be somewhere around 2/3rds of the iron width. I had just made this plane (the mouth is a bit tight and could be another half mm or so - you can feel a little resistance from it). The shavings shown are 2 hundredths thick at the middle. I'd have chosen the location of the strokes more carefully if I were trying to make the board flat (it's not like it's flat when I'm done), but the purpose of the cut was to feel for poor fit in any part of the plane and make sure it works without rattles or clogs.

You can ignore the rest of the blabber in the video. I wanted to do an assessment of the plane itself since I built it in real time on the videos, which includes an honest assessment of any shortcomings, and then I had some point I wanted to make about the chisel I used to mortise the handle, and that was probably something nobody will find useful. I think it may have had something to do with tool familiarity and finding things out for yourself with your hands and eyes - two things i'm a fan of.

Knowing the thickness of the shavings and getting their width gives an idea of the camber, though.

 

[D_W]

D_W -

Thanks for your explanations, they are much appreciated, I think I've got it now, just need to try it in practice. For a fuller context, what radius is the camber on your jackplanes?

Cheerio,

Carl

After checking last night, the radius is about 6 or 7 inches.