Cap iron set

[Patrick Chase]

Somebody asked in another thread how close people set their cap irons. I don't have a microscope here at home, but I was able to get a reasonable measurement using a macro lens at 1:1 magnification. My setup (minus camera) is shown in the second image. I used a camera (a Canon 1Dx II) with a pitch of 152 pixels/mm pitch, or 3.85 pix/mil.

I took the iron from my #3 and set it as I would for difficult tearout, by naked eye using the "reflection method" (i.e. close the cap iron down until there's a symmetric sliver of light showing). The attached image is from the center of the iron.

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The dark band in the middle is the back of the iron. The lighter section to the right of that is the "breaking face" of the cap iron, which is ground at 50 deg. The rougher section to the right of that is the bevel of the cap iron (this is a "new-style" iron that I haven't gotten around to reprofiling).

The answer is: 12 pixels, 3.2 mils. I double-checked my macro lens' magnification at closest focus and it's very close to 1:1, so I think the result is accurate to within 10% or so (I focused by locking the lens at closest focus and translating the camera with a geared macro rail, which you can see in the setup picture).

To be honest I'm pretty surprised, as I didn't realize I'd gotten down that low since I last measured this stuff. This iron is VERY minimally rounded, and the setback tapers to about 6 pixels at both corners (not shown). The setback is uniform to within +/- 1 pixel across the iron, with the aforementioned exception of the corners. I took the plane down to the shop and got clean shavings from Curly Maple and Mahogany.

To be clear this is the tightest set that I would ever use. I would not routinely work with an iron in this configuration.

BTW I have worse than 20:20 vision. This really isn't that hard to do.

[Derek Cohen]

Patrick, can you translate that into English for an illiterate, such as myself? What is the distance in both metric and Imperial (0.??mm and 0.??")?

Regards from Perth

Derek

[Normand Leblanc]

A year ago I did some test for this "capiron effect" and I measured the tiny distance between the blade edge and the capiron using a small microscope that you just plug into your computer. If I recall correctly, with anything past 0.01" I wasn't able to get the "effect" and 0.003" is most likely very close to the lower limit as mentionned by Patrick.

Here is a picture with a setting of 0.15mm or 0.006". Chip breaker on the left and the blade's back is the black strip.
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[Jim Koepke]

When my curious mind really wants to know, the poor man's way works for me:

https://www.tedpella.com/magnify_html/reticles.htm

This one looks like what is in my magnifier, the comparators in mine go down to 0.002":

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This is a bit fuzzy from enlargement.

https://www.edmundoptics.com/microscopy/magnifiers/contact-reticles/multi-scale-contact-reticles/

jtk

[steven c newman]

I try to kepp mine at 1mm from the edge.....seems to work well enough...

[Derek Cohen]

I recall the discussion from last year (?) - we had some difficulty in agreeing on distances. Part of this may have been a translation of metric and imperial, but I suspect that there are also other parameters that make it difficult to generalise. I mention some below.

I do not measure anything, and just aim for what seems like a familiar gap, then adjust it if it is not working well. I've looked at the distance of a working gap, and measured this as around 0.4mm (I never measure this small in Imperial). This works with a 45-50 degree leading edge and a 42-45 degree bed.

I would expect that there will be a small variation to this for others since the angle of the leading edge makes a difference, as does the wood used, and the angle of the bed. Still, most of us have set the limit of the distance at about 0.5mm to achieve the chipbreaker effect. Outside this and it is most unlikely to occur.

An indicator of being dialed in is the shape of the shaving, although thickness will affect very thin shavings insofar as they may not be stiff enough to stand up. Even so, it can be seen that the shaving is straightening up rather than curling into a ball.

It hardly needs to be mentioned that one does not need to set up a chipbreaker for all surfaces. Straight-grained woods do not warrant the effort.

How do your measurements compare here, Patrick?

Regards from Perth

Derek

[Patrick Chase]

Patrick, can you translate that into English for an illiterate, such as myself? What is the distance in both metric and Imperial (0.??mm and 0.??")?

Regards from Perth

Derek

0.0032", 0.08 mm. Like I said, REALLY low. I agree with Norman that it's close to the lower practical limit. It's also very close to the setting used in Kato/Kawai (0.004", 0.1 mm).

[Pat Barry]

How thick of a shaving are you typically taking with this close of a setting?

[Patrick Chase]

How thick of a shaving are you typically taking with this close of a setting?

2 mils or less. There are two limiters:

1. If the cap iron extends below the plane sole then bad stuff can start happening, particularly if you haven't been careful about whether the cap iron extends beyond the edge of the plane. If the cap iron is the same width as the iron then it's almost impossible to NOT have that happen on one side or the other when setting by unassisted eye.

2. Amount of relief/curvature on the ends should be less than the cap iron set, and that limits how deep of a cut you can take without risking tracking.

I would never set, say, a jointer this tightly. This is strictly for final smoothing on difficult wood.

[Patrick Chase]

A year ago I did some test for this "capiron effect" and I measured the tiny distance between the blade edge and the capiron using a small microscope that you just plug into your computer. If I recall correctly, with anything past 0.01" I wasn't able to get the "effect" and 0.003" is most likely very close to the lower limit as mentionned by Patrick.


Reiterating something I said in another post: I think Normand is right about the lower and upper limits. Back when I was measuring I never saw much effect from settings higher than 0.010"/0.25 mm. Too much above that and there's not much point to having a cap iron.

I had no idea I was getting as close as 0.003" until tonight. As I said in the other thread the lowest I'd previously measured was almost double that, though that was some time ago when I was just starting with close cap iron sets. I guess practice really does help. I suspect that closer sets would be impractical on a few levels (precision/straightness requirements for both the cutting edge and the leading edge of the cap iron, depth of cut limits, etc).

[Derek Cohen]

Patrick, I'd like to see the shavings you make, know what wood you are working, the angle of the leading edge of the chipbreaker, and the thickness of the shaving itself before reaching any conclusions. I will do the same and we can compare. Anything else is meaningless since you are taking one variable in isolation.

Regards from Perth

Derek

[Patrick Chase]

Patrick, I'd like to see the shavings you make, know what wood you are working, the angle of the leading edge of the chipbreaker, and the thickness of the shaving itself before reaching any conclusions. I will do the same and we can compare. Anything else is meaningless since you are taking one variable in isolation.

Agreed. To be clear, I'm not suggesting that anybody else should do this, I'm just answering a question that was posed in another thread. I'll post shaving pix in the morning (US time). As to the rest:

As I said in the original post, the "breaking face" on the cap iron is beveled at 50 deg. The plane is common pitch, so the overall angle is 95 deg, i.e. just past vertical.

I would never use a set like this with a shaving thicker than a couple thousandths of an inch. I use a significantly more relaxed set on, say, a jointer.

To be honest I'm starting to wonder if I've taken it too far. As I said earlier, when I started out I measured setbacks quite a bit and ended up with ~0.006" as a tight set and about double that as an intermediate set. I didn't realize that I'd drifted down this far since then. It works just fine for thin shavings on difficult wood, but I think I need to back it off to, say, 0.005" and see if I really sacrifice anything by doing that.

[Jim Koepke]

Interesting to have these kinds of discussions. Of course those who do not favor them can tune out.

One may never think about it, but it only makes sense if the chip breaker is set back 0.003" from the edge the plane will not be able to take a 0.005" shaving.

Also, if one is working a fairly easy piece of wood there may not be a need for a close set chip breaker.

jtk

[Todd Stock]

Chip stiffness varies as the cube of thickness (e.g., 0.004" shaving is about 150 times as stiff as a 0.00075" shaving), there's little chipbreaker effect for a fine chip even with a very close-set CB , while for thick chips (e.g., 0.003"-0.004"), the CB effect becomes more pronounced. The BU crowd can claim that it really does not matter (where the shaving is very fine, indeed), and the BD crew can say it does matter (when the chip is a whopper)...everyone wins.

Which I think is where we were a few years after LN reintroduced BU planes 20 years ago: gossamer chip...who cares? Thick chip...it matters.

[Pat Barry]

Interesting to have these kinds of discussions. Of course those who do not favor them can tune out.

One may never think about it, but it only makes sense if the chip breaker is set back 0.003" from the edge the plane will not be able to take a 0.005" shaving.

Also, if one is working a fairly easy piece of wood there may not be a need for a close set chip breaker.

jtk
.003 setback is at 45 degree blade angle so that might limit the shaving to only about .002 maximum shaving thickness. I'm curious though, how much clearance there is in front of the chipbreaker to the front of the mouth with it all set that close. Also, Patrick didn't show a Bailey style chipbreaker, would that make a differrnce?

[Graham Haydon]

This is interesting, however I think I'll expand on a point I think Derek was hinting at. The value of setting a cap iron properly is to get clean surfaces. I think there is most value in posting pictures of a surface that has issues and the shavings produced, then an adjustment, an improved surface and the shavings produced.
Knowing where the sweet spot is, has many things in common with planing square or cutting straight. It just has to be learned.
I do see merit in the detail and information you are presenting, please keep the conversation going! But many old books and tradesman had it right. You set it close. How close? You'll work it out with practice. The biggest lesson with the cap iron was not to dismiss experienced workers who had found success with it. That's not a slight at you, just a human condition of being dismissive of how to get the best out of tools. I'm sure I've done so myself as have others https://blog.lostartpress.com/2007/12/31/chipbreakers-the-no-6-way-to-reduce-tear-out/

[Brian Holcombe]

I've certainly had boards that misbehaved to the point where a setting that tight along with a light shaving were required. Planing curly cherry recently I was using such a setting for finish planing.

[steven c newman]

Right now, all I'm working with is a bunch of Curly Maple..
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Not really concerned about see-through shavings, either..
364977
Would take way too long to make a bunch of bevels....( most of the shavings there on the floor are from doing two bevels, the "noodle"-like shavings are from the Stanley 45
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Noodles")
364978
Dry fit, needs the last bevel planed..
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1mm set back on the chipbreaker. The "other" item in this set up is the lever cap. It helps to stiffen the chipbreaker.

[Patrick Chase]

.003 setback is at 45 degree blade angle so that might limit the shaving to only about .002 maximum shaving thickness. I'm curious though, how much clearance there is in front of the chipbreaker to the front of the mouth with it all set that close. Also, Patrick didn't show a Bailey style chipbreaker, would that make a differrnce?

In practical terms I agree, but... Kato/Kawai took a 4 mil shaving with a 4 mil cap iron setback (~2.8 mil "depth of set" taking bed angle into account), so clearly it's feasible to work with the cap iron extending below the sole of the plane.

The catch is that in their setup the wood was narrower than the iron, so they didn't have to worry about what happens at the edges. In the real world our cap irons are generally so close in width to the iron that they extend a tiny bit past one corner or the other when we set the cap iron by naked eye. That protruding corner will gouge the wood if your cap iron set and shaving thickness are such that the cap iron is below the plane sole.

[Patrick Chase]

I've certainly had boards that misbehaved to the point where a setting that tight along with a light shaving were required. Planing curly cherry recently I was using such a setting for finish planing.

Hah, how did I know you would turn out to be a member of the "aggressive set (when needed) club".

EDIT: I've certainly seen cases where I get shallow tearout with ~2-mil shavings, and moving the cap iron "all the way up" as shown here pretty much kills those dead.

[Patrick Chase]

Answering the second part of Pat's question...


I'm curious though, how much clearance there is in front of the chipbreaker to the front of the mouth with it all set that close. Also, Patrick didn't show a Bailey style chipbreaker, would that make a differrnce?

I use a pretty wide mouth when I'm setting the cap iron close like this. I don't know how wide, but easily > 1 mm.

One thing to note is that the steepest part of the cap iron face is also pretty small here, on the order of half a millimeter. It's just tall enough to break the shaving, and no more. That in turn minimizes its impact on clearance.

IMO a Bailey style cap iron helps by presenting a continuously curved surface to the shaving. The tip of a Bailey-style cap iron is generally around 40 deg (depending on maker), so even if you grind in a 50 deg breaking face as I did here there isn't a terribly sudden transition to the rest of the cap iron. In contrast the iron in the picture goes from 50 to ~25 deg at that first corner, which is non-ideal. As I said it needs to be reprofiled, I just haven't gotten to it yet.

[Jim Koepke]

It is also possible to remove some metal from the top of the front half of the mouth of a Stanle/Bailey style plane without opening the mouth. This will help some with clearance issues.

jtk

[James Pallas]

Interesting thread. I have a few questions for the experts. First I'll say I get the cap iron set up. I experimented and know it works. My question is this. You have a piece of lumber, rough, that looking at the long edge it looks like QS with lots of reversals. You have to start somewhere so you go with a jack Wide open mouth cambered blade and you get major tear out. Do you go straight to your smoother and flatten the whole piece with tiny shavings or just how do you do it. You are going to end up taking a lot of material with tiny shaving at some point. What is your approach?
Jim

[Brian Holcombe]

Hah, how did I know you would turn out to be a member of the "aggressive set (when needed) club".

EDIT: I've certainly seen cases where I get shallow tearout with ~2-mil shavings, and moving the cap iron "all the way up" as shown here pretty much kills those dead.

Absolutely and that is the kind of situation I had in mind.

[Brian Holcombe]

Interesting thread. I have a few questions for the experts. First I'll say I get the cap iron set up. I experimented and know it works. My question is this. You have a piece of lumber, rough, that looking at the long edge it looks like QS with lots of reversals. You have to start somewhere so you go with a jack Wide open mouth cambered blade and you get major tear out. Do you go straight to your smoother and flatten the whole piece with tiny shavings or just how do you do it. You are going to end up taking a lot of material with tiny shaving at some point. What is your approach?
Jim

It depends. I almost never use a jack for prepping stock unless I have a ton of material to take off, which is then considered poor planning on my part. So I use it instead when I have a board that's out of flat by a lot.

I'm normally starting with a try plane to joint the face then smoother.

I've had a few slabs that required me to use a smoother start to finish, they were truly miserable but fairly rare.

[Warren Mickley]

I use a double iron jack plane and a double iron trying plane to prepare stock. In traditional work the smoothing plane is used to clean off finished work. After joinery and such the timber accumulates scuffs, maybe dirt or markings. This is removed just before assembly with the smoothing plane, one or two passes.

[Brian Holcombe]

This one gives me nightmares still, easy enough with a smoother but tore out with literally everything else.

https://brianholcombewoodworkerblog.files.wordpress.com/2017/07/img_6958.jpg

[Patrick Chase]

Interesting thread. I have a few questions for the experts. First I'll say I get the cap iron set up. I experimented and know it works. My question is this. You have a piece of lumber, rough, that looking at the long edge it looks like QS with lots of reversals. You have to start somewhere so you go with a jack Wide open mouth cambered blade and you get major tear out. Do you go straight to your smoother and flatten the whole piece with tiny shavings or just how do you do it. You are going to end up taking a lot of material with tiny shaving at some point. What is your approach?
Jim

Depends. I have a Jack set up with a minimally-cambered blade, and I can (and do) use relatively close cap iron sets with that, the key word being "relative". Obviously I'd take deeper cuts and use a larger cap iron setback than I demonstrated earlier in this thread. I also use relatively tight sets on jointers.

I think the key thing to keep in mind is that at each phase you don't want to leave deeper tearout than the next plane down can easily remove. The Jack shouldn't leave tearout much deeper than the jointer's depth-of-cut, and the jointer shouldn't leave tearout much deeper than the smoother's depth-of-cut. You don't need to completely eliminate tearout until you get to the smoother, and trying to do so will slow you down as it will force you to use finer sets and take shallower cuts early in the process when your main focus should be on getting the right geometry as efficiently as possible.

[Stewie Simpson]

In practical terms I agree, but... Kato/Kawai took a 4 mil shaving with a 4 mil cap iron setback (~2.8 mil "depth of set" taking bed angle into account), so clearly it's feasible to work with the cap iron extending below the sole of the plane.

IMO. Ignore that advise. Same applies to those that advocate a capiron clearance of 0.1mm. You will choke the movement of shaving.

[Patrick Chase]

IMO. Ignore that advise. Same applies to those that advocate a capiron clearance of 0.1mm. You will choke the shaving.

Thanks for the misleading, out-of-context quotation, Stewie.

All, the rest of the post he quoted (http://www.sawmillcreek.org/showthread.php?256590-Cap-iron-set&p=2712229#post2712229) explained why it's a bad idea to have the cap iron extend below the sole. There's no disagreement here, just certain folks being disagreeable and manufacturing controversy.

[James Pallas]

Thank you Warren, Brian and Patrick. My experiments came out much the same, closer with the cap iron, smaller shavings until you get what you can work with.
Jim

[Brian Holcombe]

I use a double iron jack plane and a double iron trying plane to prepare stock. In traditional work the smoothing plane is used to clean off finished work. After joinery and such the timber accumulates scuffs, maybe dirt or markings. This is removed just before assembly with the smoothing plane, one or two passes.

Warren do you always work from rough sawn stock? It seems like everything I source as of late has been skip planed and so it has been fairly easy to joint, but of course makes other things more difficult (Id rather have the thickness than the convienence).

[Warren Mickley]

Sometimes I buy rough stock, sometimes machine planed thick enough to allow for truing. As to James' question, we could do everything with a smoothing plane, truing from rough, but these other planes (jack, trying, jointer) are designed and set up specifically for the stock preparation tasks and are thus more efficient.

The smoothing plane's functions are small trimming and cleaning of boards that are already in great shape, too nice to sand. Generally no more work on a figured board than a plain board.

[Brian Holcombe]

Sounds like my available choices then, all depends on what is at the yard. When I can get rough stock I usually start with a jack plane.

I probably shouldn't be citing extreme cases, like the aforementioned slab, that is an exceptionally rare case. Heavy tearout was left in the slab from the skip planing, I had to get down past that point before clean passes could have been taken, at which point I had completed the truing. Had that board been left without planing it would have likely been a much easier piece to work (but of course much harder to sell to the general public). Once bad tearout happens it is more likely to continue tearing out until the structure has to be restored by a clean cut.

James if you are careful to avoid tearout in your prepping process by using the appropriate cap iron setting you will not experience extreme tearout. When I do start with a jack plane that to has a cap iron setting to avoid heavy tearout, it's certainly not nearly as tight as a smoothing plane, or even as the try plane but it's doing some work all the same.

[Mike Baker 2]

Are we talking cap iron here, or chip breaker? Because for the life of me, I can't figure out how to get a cap iron any closer to the edge of the iron than the hole in it that slips over the little screw will let you.
Very confusing discussion. Or perhaps I'm confusing the two, but they sound like they are being used interchageably in this thread.

[James Pallas]

I keep hearing that you can just leave the mouth open and depend on the cap iron. I have found that in Jack plane work, not smooth plane, that the mouth helps. If you have say a ten inch radius iron where the cap iron is not close I will close up the mouth so I can take a wider shaving with less tear out. I don't think it makes much sense to take a 3/4 " wide shaving with a jack when you can control some with the mouth. Of course wood planes can't do this.
Jim

[Brian Holcombe]

I like the keep the mouth respectably close, which is wider for a jack plane than it is a smoothing plane.

David Weaver made my wooden jack and try planes and so adjusted the mouths to accommodate use with a close set cap iron, they're not super tight like would be for a smoother but they're not wide open by any means, both are about 1/16". By comparison my smoothers are usually set to allow a shaving to pass and not much more. My double iron smoothers being looser than those with a single iron.

[Robert Engel]

37 posts ........and counting.

[Normand Leblanc]

Are we talking cap iron here, or chip breaker? Because for the life of me, I can't figure out how to get a cap iron any closer to the edge of the iron than the hole in it that slips over the little screw will let you.
Very confusing discussion. Or perhaps I'm confusing the two, but they sound like they are being used interchageably in this thread.

Maybe it's the terminology. So here it is.
365034
Yes, chipbreaker and capiron are both used.

[Nicholas Lawrence]

Are we talking cap iron here, or chip breaker? Because for the life of me, I can't figure out how to get a cap iron any closer to the edge of the iron than the hole in it that slips over the little screw will let you.
Very confusing discussion. Or perhaps I'm confusing the two, but they sound like they are being used interchageably in this thread.

When I started trying to fix up an old plane that belonged to my grandfather, the tool dealer who was kind enough to give me some advice explained the parts, and told me that the part labeled as the "chipbreaker" in Normand's helpful diagram was actually called the "cap iron." He explained that if I called it a "chipbreaker" everyone who dealt in tools would immediately know I was ignorant, and try to sell me junk instead of good tools. To add to the confusion, some sources I have read refer to the same part as the "back iron" and I even saw it called the "top iron" once.

Anyhow, some years ago, a lot more people learned that if you adjust the thing cleverly, it will actually break chips, so it is once again allowed to call it a chipbreaker.

[Patrick Chase]

When I started trying to fix up an old plane that belonged to my grandfather, the tool dealer who was kind enough to give me some advice explained the parts, and told me that the part labeled as the "chipbreaker" in Normand's helpful diagram was actually called the "cap iron." He explained that if I called it a "chipbreaker" everyone who dealt in tools would immediately know I was ignorant, and try to sell me junk instead of good tools. To add to the confusion, some sources I have read refer to the same part as the "back iron" and I even saw it called the "top iron" once.

Anyhow, some years ago, a lot more people learned that if you adjust the thing cleverly, it will actually break chips, so it is once again allowed to call it a chipbreaker.

I've started following Warren's lead on that one, and try to use "cap iron". I figure he knows the history better than any of us, so his terminology is almost certainly accurate.

On a related note: Warren, thanks for your posts in this thread. I'm learning from you as always.

[Mike Baker 2]

Normand, thanks. I was calling the lever cap the cap iron, and the chip breaker, well, the chip breaker. Now I understand.
Much appreciated.

[Pat Barry]

I've started following Warren's lead on that one, and try to use "cap iron". I figure he knows the history better than any of us, so his terminology is almost certainly accurate.

On a related note: Warren, thanks for your posts in this thread. I'm learning from you as always.
Maybe. It could be all chip breakers are cap irons but not vice versa? Double iron planes have cap irons, Bailey planes have chip breakers ( I believe it's right in the patent wording ).

[James Waldron]

Patent wording? An exercise in obfuscation and nothing more. I have established through exhaustive testing that 999 angels can dance on the head of a pin, but that there are never that many around who wish to do so.

[Pat Barry]

Patent wording? An exercise in obfuscation and nothing more. I have established through exhaustive testing that 999 angels can dance on the head of a pin, but that there are never that many around who wish to do so.
Obfuscation? Are you taking lessons on obscure terms from Patrick now?

[Patrick Chase]

Obfuscation? Are you taking lessons on obscure terms from Patrick now?

That's "entry level" obscurity at best. Obfuscation is one of my favorite words, though, as it describes so much of what people actually do...

[Patrick Chase]

This one gives me nightmares still, easy enough with a smoother but tore out with literally everything else.

https://brianholcombewoodworkerblog.files.wordpress.com/2017/07/img_6958.jpg

I meant to say this earlier but forgot: That is a very nice, continuous shaving, considering the source. It's one thing to get shavings like that from straight-grained Alaskan Cedar, but quite another from a reversal-ridden slab like that.

[Nicholas Lawrence]

Are we talking cap iron here, or chip breaker? Because for the life of me, I can't figure out how to get a cap iron any closer to the edge of the iron than the hole in it that slips over the little screw will let you.
Very confusing discussion. Or perhaps I'm confusing the two, but they sound like they are being used interchageably in this thread.

If you have decent internet and google "unc tv woodwright's shop" they have a streaming video channel where you can watch full episodes of the Woodwright's shop. I did not know about it until Jim Koepke just posted it in another thread. Season 31, Episode 5 is "Hand Plane Essentials" with Chris Schwarz. It is pretty good information, but the discussion around the 18 minute mark will give you an idea how the conventional wisdom about the chipbreaker has changed in recent years (not that I use a closely set chipbreaker on a jack plane).

[Todd Stock]

I acknowledge freely that I have had hard feelings against Mr. Ballou for abusing me and calling me a logarithm, which is a thing I do not know what, but no doubt a thing considered disgraceful and unbecoming in America.

-Ollendorf (Roughing It, Mark Twain)

[Mike Baker 2]

Nicholas, thanks for that link!

[Brian Holcombe]

I meant to say this earlier but forgot: That is a very nice, continuous shaving, considering the source. It's one thing to get shavings like that from straight-grained Alaskan Cedar, but quite another from a reversal-ridden slab like that.

Thank you!

[Pat Barry]

Thank you!
DI'd you by chance make a video of your flattening and smoothing for this piece Brian? If so, is it on your website?

[Brian Holcombe]

Nope and nope.

For a slab like that I need entertainment and so I was watching episodes of Californication while planing away in the late evening hours.