Too much camber

[Kees Heiden]

At the moment I am on a planemaking binge. (I write about it on the fora, the blog, instagram, whatever, so it is hardly a secret anymore :D)

Anyway, I finished two jack planes, a 14" one with 2" blade and a 16" with 2 1/8" blade. I put a healthy camber on both of them, shooting for 8" camber on the short jack and more like 10 to 12" camber on the longer jack. Well, in reallity the short jack plane got more like 6" camber while the longer plane is more on target.

I hate it!

6" camber is way, way too much! But 10" camber ain't so great either. I am not a big muscular guy. Allthough I am pretty fit, I can't deny that I am a skinny guy who leads a sheltered office life. Pushing cambers like that through beech on the long grain is pure torture! I looked at the edge in my Record 05 and after many sharpenings it seems to have straightened out quite a bit. I can measure about 0.5 mm of roundness in the edge, which would calculate to something like a 22" camber. That's a maybe a little too shallow for effective wood removal, but it sure is a lot easier to push!

Anyone care to comment? Why are we always hearing a jack should have an 8" to 10" camber?

[Patrick Chase]

At the moment I am on a planemaking binge. (I write about it on the fora, the blog, instagram, whatever, so it is hardly a secret anymore :D)

Anyway, I finished two jack planes, a 14" one with 2" blade and a 16" with 2 1/8" blade. I put a healthy camber on both of them, shooting for 8" camber on the short jack and more like 10 to 12" camber on the longer jack. Well, in reallity the short jack plane got more like 6" camber while the longer plane is more on target.

I hate it!

6" camber is way, way too much! But 10" camber ain't so great either. I am not a big muscular guy. Allthough I am pretty fit, I can't deny that I am a skinny guy who leads a sheltered office life. Pushing cambers like that through beech on the long grain is pure torture! I looked at the edge in my Record 05 and after many sharpenings it seems to have straightened out quite a bit. I can measure about 0.5 mm of roundness in the edge, which would calculate to something like a 22" camber. That's a maybe a little too shallow for effective wood removal, but it sure is a lot easier to push!

Anyone care to comment? Why are we always hearing a jack should have an 8" to 10" camber?

A few thoughts:

- Roughing by plane is serious work even for professionals in good shape. I'm also an office dweeb though fairly heavily built, and I feel it for a couple days after a session with the cambered Jack or Scrub.

- Such cuts are typically taken on the diagonals, not along the grain. That may reduce effort depending on whether you were getting "gouge-out" (you can't really call it tearout at that point).

- A 2" wide blade with a 6" camber radius will take a ~60 mil deep shaving at full extension (such that the cutting edge corners are exactly flush with the sole), with a cross-sectional area of 0.08 in^2. That's a very substantial shaving.

- The 40-1/2 and similarly sized scrubs are typically set up with 3" camber radii, and take a 67-mil shaving with an area of .07 in^2, again at full extension. In other words, a Jack with a 2" wide blade and 6" of camber is in the same ballpark as a typical scrub.

- Roughing planes (both Jacks and Scrubs) end up set to take less-than-full-width shavings a fair bit of the time, and even a small reduction in width can have a huge impact on cutting forces. For example, if you retract the blade on the R=6" Jack such that it's taking a 1.5" wide shaving then you'd get 33 mil cut depth and a cross-sectional area of 0.03", i.e. less than half the cutting force at 3/4 of the width.

- Many people (me included) find that narrow-but-deep shavings are more efficient for roughing than wide-but-shallow ones. That's why I stick with fairly aggressive camber radii and back off the width when needed instead of just using a larger camber radius.

[Kees Heiden]

Across the grain is indeed a whole other kind of cut. I have one of these typical German narrow scrubs, indeed 3" radius. Works very well across the grain. But I don't do a ton of cross grain work, only for very wide panels. Most of the planing work I do is on narrower stuff, and working along the grain is better suited for that. Add to that the very deep furrows from the scrub, and I rarely use it. When I do need it it is a great tool though!

But why making 2" or wider jackplanes and then using less then 1" in the middle? I could have saved myself quite bit of timber and toolsteel...

[Stewie Simpson]

Kees. You should find the following of some interest. http://www.theunpluggedwoodshop.com/cambered-iron-or-a-broken-corner.html

[Derek Cohen]

Kees, the point of working cross grain (traversing) is to avoid the tearout that would typically be caused by a deep cut when planing with the grain. Plane across and diagonally (to avoid creating a hollow).

I have two jacks, one a woodie I built and the other a Stanley #605. Both have 2" wide blades. The woodie has a 8-9" radius and the #605 has a 9-10" radius.

Regards from Perth

Derek

[Kees Heiden]

Well, you certainlky can get some horrible tearout across the grain too! I remember some wallnut boards with a big knot. In and around the knot, the scrub made quite a mess and I had to resort to epoxy in the end to repair the damage.


Right now I feel that camber is a very personal issue. Tom Fidgen from the link Stewie posted seems to like a shallow camber on his jack plane too. You just have to find the balance between workout and result in the kinds of cuts you take on the kinds of wood you use.

[Stewie Simpson]

Kees. My personal preference is to round off the corners of the blade; the depth based on a moderate blade set for that type of plane; and leave the cutting edge in the middle straight, or with a very slight camber. Each to there own when it comes to personal preferences.

Stewie;

https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcQ2uNIb2x73mijrIIIwnjP4H1x3PtQYL NOVaRtjwKT9TvSwmsmN

[Kees Heiden]

My Record 05 is much like that. I now remember again that I started with the usual heavy camber, then quickly grinded the centre a lot flatter. And then used it a ton, sharpened often and it only got flatter over time.

I much prefer a plane that doesn't buck in a plane stroke, or where I have to lean with all my might to get it through. So for me, personally, I think I like shallower cambers.

[Nicholas Lawrence]

Anyone care to comment? Why are we always hearing a jack should have an 8" to 10" camber?

Stewie is always saying hardly anyone actually prepares stock by hand anymore, so maybe it is one of those things people repeat because they heard it somewhere and have never actually done it. I don't really know.

I work in a small place in my basement, and have no room for power tools, so what I am able to do I do by hand. I am no expert but from the "self taught - still learning" perspective of someone who has flattened and squared some larger boards without power assistance, I can tell you it does not make a lot of sense to me to expect to take a heavy cut with a two inch blade, and do so reasonably cleanly. And if you can do that once or twice, can you do it dozens and dozens of times, up and down both faces of a six foot board?

There is a reason Stanley made their scrub plane about an inch wide. And that was for use by guys who worked with their hands for a living! I use the scrub for heavy stock removal. Then I don't ask my jack to take more than kind of a medium cut. I have never measured the shavings, but what comes off my jack is usually a little thicker than a good piece of paper. Maybe a hundredth of an inch or so? Then on to the try or jointer, with a thinner cut, and on to the smoother with the little fine shavings everyone likes to post pictures of.

This approach seems to work for me because it gets the problems in the stock corrected quickly enough that it does not take me hours of planing thousands of strokes at .001 to remove a 1/16 of an inch of cup or twist, and still leaves a nice surface at the end.

[Stewie Simpson]

Kees. Excellent work with the mouth opening on your new Coffin Smoother.

http://seekelot.blogspot.com.au/

[Chris Hachet]

Kees. My personal preference is to round off the corners of the blade; the depth based on a moderate blade set for that type of plane; and leave the cutting edge in the middle straight, or with a very slight camber. Each to there own when it comes to personal preferences.

Stewie;

https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcQ2uNIb2x73mijrIIIwnjP4H1x3PtQYL NOVaRtjwKT9TvSwmsmN

This is my aproach also.

[Stewie Simpson]

Stewie is always saying hardly anyone actually prepares stock by hand anymore, so maybe it is one of those things people repeat because they heard it somewhere and have never actually done it. I don't really know.

Nicholas. If you re read my previous comments you will note that I stated most woodworkers will have at least a 12 inch lunchbox thicknesser in their workshop. That's all I have available; and I don't use a power jointer. The use of a power thicknesser does not remove the necessity to pull out the winding sticks and hand planes to remove any cup and twist within the primary face of the board before you feed it through the power thicknesser.


I work in a small place in my basement, and have no room for power tools

Nicholas. I would assume by that comment you would be using power tools if you had a larger work area.

regards Stewie;

[Derek Cohen]

Kees. My personal preference is to round off the corners of the blade; the depth based on a moderate blade set for that type of plane; and leave the cutting edge in the middle straight, or with a very slight camber. Each to there own when it comes to personal preferences.

Stewie;

https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcQ2uNIb2x73mijrIIIwnjP4H1x3PtQYL NOVaRtjwKT9TvSwmsmN

Stewie, Kees is referring to the set up of a jack plane, not a smoother. Clipping corners is not appropriate for that situation. Only cambering will work.

Regards from Perth

Derek

[Derek Cohen]

Kees, have you used a jack plane with strongly cambered blade before building these planes?

Regards from Perth

Derek

[Tom M King]

Get a little momentum going before the iron hits the wood.

[Stewie Simpson]

Stewie, Kees is referring to the set up of a jack plane, not a smoother. Clipping corners is not appropriate for that situation. Only cambering will work.

Regards from Perth

Derek

Derek. As I mentioned; each to there own when it comes to personal preferences.

regards Stewie;

[Tom M King]

Each cut doesn't have to be full depth. Just take what you can get. A rounded camber gives you the ability to take as deep a cut as you can, and then get it more leveled out by taking the tops off the ridges between the "gulleys".

[Sean Hughto]

I have a 12 lunchbox and no 'lectric jointer, just like Stewie mentions. So I need to get one face relatively flat before sending it through the planer. I also like to use wide board and slabs in my work that are far too wide for the 12" lunchbox, so I have no choice but to get all the way their by hand. I depend on my scrub (40) with a lot of camber - a 5 1/2 with some camber but nothing even close to what you are talking about at 8 or even 22 inches -and a 7. The scrub, with its aggressive camber is narrow for a reason. The physics maths will tell you that to do that much work, you need to do it across a smaller area. My 5 1/2 has no more camber than that imparted by the aggressive use cambering by hand on stones imparts - bellied and proud at the middle, but not even something that would be very noticeable to a non-woodworker looking at the blade. The 7 has just a normal light camber. I work on diagonals and across the grain or focusing on high spots of a given board at first, then proceed through the typical actions of planing while using my benchtop, winding sticks, and long straightedges to gauge my progress. In short, I've never been a fan of an aggressively cambered jack in my own work. Maybe if I used more pine.

[Tom M King]

332306The motion, and attack method, is easiest learned with a scrub plane. You don't place the plane on the wood and push. You hit the surface fairly violently. Shavings don't curl nicely out the top of the plane like you want them to with a smoothing plane. Shavings fly a couple of feet into the air. Once you get the feel for it, it transfers to other planes.

I already had this picture using a plow plane in here. You don't need shavings two feet in the air from a plow plane, but hopefully it gives you an idea.

[Stewie Simpson]

Can I draw you guys back to the fact that Kees is not discussing a Scrub Plane; he is specifically talking about Jack Planes. The choice between rounding off the corners vs using full camber are the 2 optional choices being advised to Kees at the present time. I reiterate advised; because at the end of the day, it will be Kees who will have the final say on what cutting edge profile he decides to use on his Jack Plane irons.

regards Stewie;

[Sean Hughto]

Stewie, with all due respect, he is asking about "too much camber" and his dislike of pushing a 2" blade with significant camber. He asks: "Anyone care to comment? Why are we always hearing a jack should have an 8" to 10" camber"

My comment is: yes, that is too much camber on a jack. Huge camber requires a narrower blade, i.e., a scrub.

[Stewie Simpson]

Stewie, with all due respect, he is asking about "too much camber" and his dislike of pushing a 2" blade with significant camber. He asks: "Anyone care to comment? Why are we always hearing a jack should have an 8" to 10" camber"

My comment is: yes, that is too much camber on a jack. Huge camber requires a narrower blade, i.e., a scrub.

Sean. My apologies; I missed reading that part of your comment.

Stewie;

[Nicholas Lawrence]

My comment was not meant to suggest there is anything wrong with using power tools. I really don't know whether you are right about what most people do or not, it is simply something I have seen you mention more than once, and I think it is a good point.

Whether or not I would if I had space I do not know. I don't build anything except projects for my own family, and I have come to enjoy working without the noise, dust, and other things that come with electricity.

[Kees Heiden]

Yes, I have used cambered blades before, just never really meassured the camber. This time I thought to do it extra tidy and actually meassured them.

My largest complete handtool project ever was my dining room table. I used the scrub, a wooden 20" Fore plane with quite a bit of camber and my Record 05. I have also done quite a few smaller porjects, or parts of projects with the handplanes from rough to ready. I also have a thicknesser/planer combo, so when I feel lazy or hurried, I use that.

Yesterday evening I came to the conclusion that 8" to 10" is too much for me.

[Stewie Simpson]

Whether or not I would if I had space I do not know. I don't build anything except projects for my own family, and I have come to enjoy working without the noise, dust, and other things that come with electricity.

Nicholas. I can fully understand your preference to work in an environment that lacks the noise and dust levels created by power tools. Where I am able too, I also have a preference to use hand tools. Some of the Australian Hardwoods I work with have a janka hardness more suited to being thicknessed by machine vs trying to manage it all using hand planes.

Stewie;

[Warren Mickley]

I think the best way to arrive at the best camber is by how it suits you, not by measuring some radius. I would tailor the camber so that when you are using a softwood you are using most of the width. That means that when you are planing a more demanding wood you are not using the full width.

The traditional method is to use a fully rounded camber. For a given amount of effort, this configuration removes a larger volume of wood than an iron that just has the corners rounded off.

[Brian Holcombe]

I actually have no idea what the camber radius if my Jack plane is but it's A full radius. I increase the cut for softwoods and decrease it for hardwoods. 1" wide shavings are fine, what I'm looking for is a deep cut without much tearout, and with a straight grained wood I am looking for zero tearout.

For taking the wind out if a board I don't need a really heavy cut and so I take lighter cuts. For thicknessing I take a fairly heavy cut both at an angle to the board or running with the grain depending on what I'm doing.

I don't own a thicknesser or jointer, so I do that work by hand.

[Pat Barry]

Question of usage for the scrub plane. I don't use much rough sawn lumber myself, but I always thought that the scrub plane was more of a grunge tool to get rid of the dirty surface before using better tools for more surface refinement. Therefore, it seemed to me that once you have the surface basically scalloped all over from diagonal and crosswise scrubbing, the job was done. How far do you guys go with this scrubbing anyway? Are you using it to take out cupping and twist completely as well as the rough sawn surfaces?

[Patrick Chase]

Each cut doesn't have to be full depth. Just take what you can get. A rounded camber gives you the ability to take as deep a cut as you can, and then get it more leveled out by taking the tops off the ridges between the "gulleys".

This was one of the points I was trying to make in my post, but perhaps it didn't get across clearly: You don't have to take a full-width shaving. Just back the depth adjuster off until you get to something you can handle comfortably.

At that point the question of camber radius becomes one of preference between deep-but-narrow and shallow-but-wide shavings. IMO deep-but-narrow works better for roughing, but I see a pretty wide range of (implied) opinions in this thread.

[Patrick Chase]

I actually have no idea what the camber radius if my Jack plane is but it's A full radius. I increase the cut for softwoods and decrease it for hardwoods. 1" wide shavings are fine, what I'm looking for is a deep cut without much tearout, and with a straight grained wood I am looking for zero tearout.

VERY well stated IMO.

[Patrick Chase]

Stewie, Kees is referring to the set up of a jack plane, not a smoother. Clipping corners is not appropriate for that situation. Only cambering will work.

Regards from Perth

Derek

I agree with Derek here, but I think that "only cambering will work" is too strong. A lot of things will work, the question is whether they're optimal. FWIW I have a #5 set up with 6" camber, a 5-1/4W set up with 12" camber, and a second #5 set up with a flat blade with relieved corners. I find that I prefer the 6" #5 for aggressive roughing, but that may just be me.

[Patrick Chase]

Stewie is always saying hardly anyone actually prepares stock by hand anymore, so maybe it is one of those things people repeat because they heard it somewhere and have never actually done it. I don't really know.

Nicholas. If you re read my previous comments you will note that I stated most woodworkers will have at least a 12 inch lunchbox thicknesser in their workshop. That's all I have available; and I don't use a power jointer. The use of a power thicknesser does not remove the necessity to pull out the winding sticks and hand planes to remove any cup and twist within the primary face of the board before you feed it through the power thicknesser.

FWIW I'm in the same boat as Stweie - I have a lunchbox (DW735 with Shelix head) but no jointer. I have access to very nice jointers at my place of employment (we have an employee "playpen") but usually flatten the first face by hand.

[Tom Vanzant]

Pat, I use my scrub primarily on edges to reduce board width when ripping is over-kill and planing would take a lot of passes...also handy to rough out a beveled edge.

[Patrick Chase]

The physics maths will tell you that to do that much work, you need to do it across a smaller area.

I think that's an oversimplification. If you do the math, you'll see that the following all remove roughly the same volume of wood per cut:

- A #40-1/2 scrub (1.5" wide blade) with a 3" radius. Cross sectional area of the cut is 0.07 in^2

- A #5 (2" wide blade) with a 6" radius. Cross sectional area of cut is 0.08 in^2

- A #5-1/2 (2-3/8" wide blade) with a 10" radius. Cross sectional area of cut is 0.08 in^2

The choice between the 3 boils down to "wide-but-shallow" and "narrow-but-deep", and that strikes me as a fairly complex question that can't be reduced to simple math.

[Tom M King]

332323332324
Question of usage for the scrub plane. I don't use much rough sawn lumber myself, but I always thought that the scrub plane was more of a grunge tool to get rid of the dirty surface before using better tools for more surface refinement. Therefore, it seemed to me that once you have the surface basically scalloped all over from diagonal and crosswise scrubbing, the job was done. How far do you guys go with this scrubbing anyway? Are you using it to take out cupping and twist completely as well as the rough sawn surfaces?

This is exactly what I use a scrub plane for-scrubbing a piece before putting a good iron in it. I bought this ECE Scrub plane new. Weathering is from sweat, and wear in front of the iron is from use. Notice the wear pattern on the iron. It still throws wood even when dull, although like any other plane it works easiest when sharp.

You probably can't see the edge of the iron in that small picture, but it shows more wear near the bottom of the arc on the cutting edge. That's because most cuts are not full depth. I think there is some confusion about how a plane with a big camber is used. You rarely take a full cut. The extra depth is there to take as much wood as you can take. It would take an awfully good touch to be able to vary the depth of a pass with a wide iron with only the edges rounded. I expect I have a decent feel for using these planes, but doubt I would have a good enough touch not to jamb the straight iron to a stop sometimes.

I don't vary the depth of cut with an adjuster, but rather in hand by not putting the plane all the way down. I can see where this would not be as easy with a plane without a front handle. Just like the picture of that plow plane, there are two ways to use a plow plane. You can set the depth stop with each pass, or control the depth of cut in hand until you reach the right depth by the stop. I don't do a lot of fiddling with the depth stop. In that picture, it was in the hogging out stage without using the depth stop.

[Steve Voigt]

But why making 2" or wider jackplanes and then using less then 1" in the middle? I could have saved myself quite bit of timber and toolsteel...

Lots of good stuff in this thread. I'm glad to see that most agree that significant camber and less-than-full width shavings are the most efficient way to work.

As to the question above, we use a larger plane because it makes flattening easier. The larger surface area doesn't follow the hills and valleys the way a scrub plane will. Of course, you can still use a scrub plane if that's your preference; you just have to be more attentive, and you will probably end up doing more of the work with the try plane.

[Zach Dillinger]

Lots of good stuff in this thread. I'm glad to see that most agree that significant camber and less-than-full width shavings are the most efficient way to work.

As to the question above, we use a larger plane because it makes flattening easier. The larger surface area doesn't follow the hills and valleys the way a scrub plane will. Of course, you can still use a scrub plane if that's your preference; you just have to be more attentive, and you will probably end up doing more of the work with the try plane.

100% spot on. Fore planes are the only way to work, and every other way is wrong. #sarcasm

[Sean Hughto]

I was serious about the general proposition cause my own muscles tell me so. The "maths" comment was a bit of a joke.

[Jim Koepke]

Wow! This seems to be a hot issue. All these posts in half a day.

A lot of it seems to be going over my head.

My one plane with any significant, intentional camber is used for scrub work. Some may have unintended camber that require putting to wood or checking with a square to detect.

How much camber is on my plane with intended camber? I wouldn't know.

We often hear of camber being used to prevent 'plane tracks.' Then we get into a discussion about full width shavings. This doesn't make sense to me. A full width shaving with a cambered blade is just as likely to leave tracks as an noncambered blade. Maybe I am not understanding the conversation.

To eliminate plane tracks on my work, a sharp blade and super thin shavings seem to do the job. This is only for the final and few shavings on a surface.

When using my #5-1/4 that is set up as a scrub, there is usually not much more than half the edge engaged in the wood. Fast work on a lot of thick shavings. The chips seem to peel right off and fly all over the place. A word of warning, keep your mouth closed. DAMHIKT!

jtk

[Graham Haydon]

Kees, I think I'm likely to go with a more moderate curve to the iron. Not having to prep stock by hand at work I had no experience of what would be best. Working mainly by hand is not a very paint by numbers way of working. I think as long as someone knows that a jack iron is best curved it's then just a case of more radius on the iron for softer easier working woods and less on harder working woods. Same goes for traversing or with the grain. You work with what you have in front of you.

[Kees Heiden]

One thing for sure, 6" radius is really too much for me. Even 8" is pushing it. Or I must be content with 1 cm, wide shavings of course.

I just had a quick look. My old fore plane (18" long 2"iron) has a camber around 14". That is something I can push all day long in hardwood. So I am going to regrind my new jack plane irons. The small one with more like a 10" camber, the larger one with 14". And then I'll see again how I like them.

A problem with testing on softwood is the quality of softwood overhere. Most of it is full of knots.

[Lasse Hilbrandt]

Kees a way to get softwood in a better quality is to buy large roof construction wood and then resaw

[Kees Heiden]

Next time I need some, I'll keep your tip in mind Lasse.

[Jim Koepke]

A problem with testing on softwood is the quality of softwood overhere. Most of it is full of knots.

Knots are a different matter all their own. Planing around or through knots is akin to walking through no man's land, you are not likely to get out in satisfactory condition.

jtk

[Brian Holcombe]

Hah! I like that line Jim.

[Mike Holbrook]

I have several planes, #5, 5 1/4, 5 1/2..with 8" cambers. I don't think I would go for 6 though. Like Steve Voigt said, I find a wider/longer plane is more stable. The whole blade does not necessarily produce part of the shaving.

Jim I don't think the camber on a smoother is designed to do the same thing as the 8" camber on a jack. The smoother can make a subtle enough hollowed surface that it isn't visible to the naked eye. One might actually argue that any plane ultimately has to lean either towards a cambered (convex) or hollowed (concave) surface. The same idea of matching two edges for glue ups with a little light between them so we are sure we are not leaning the wrong way.

I have been in classes where students were trying to take oak down fast,. The 8" cambered blades were much faster for all those who tried using them.

[Patrick Chase]

I have several planes, #5, 5 1/4, 5 1/2..with 8" cambers. I don't think I would go for 6 though. Like Steve Voigt said, I find a wider/longer plane is more stable. The whole blade does not necessarily produce part of the shaving.

Jim I don't think the camber on a smoother is designed to do the same thing as the 8" camber on a jack. The smoother can make a subtle enough hollowed surface that it isn't visible to the naked eye. One might actually argue that any plane ultimately has to lean either towards a cambered (convex) or hollowed (concave) surface. The same idea of matching two edges for glue ups with a little light between them so we are sure we are not leaning the wrong way.

I have been in classes where students were trying to take oak down fast,. The 8" cambered blades were much faster for all those who tried using them.

6 vs 8 doesn't make all that much difference. At full width it's the difference between a 45 and 60 mil shaving. If you look at how wide a shaving you can take for any given level of effort (cut cross-section) the differences are *really* small, on the order of 10%.

[Pat Barry]

6 vs 8 doesn't make all that much difference. At full width it's the difference between a 45 and 60 mil shaving. If you look at how wide a shaving you can take for any given level of effort (cut cross-section) the differences are *really* small, on the order of 10%.
I suspect that you have done the surface area calculations correctly but I do think that real wood adds another, more difficult to model, dimension to the problem. In other words, the fibrous nature of real wood, coupled with the depth of cut, would significantly increase the required shear force in a non linear fashion. This needs real world testing to prove one way or the other but the cited user experiences above should not be discounted.

[steven c newman]

Dungeon Shop has three jack planes I use a lot:
Millers Falls No. 14....no camber
Stanley No.5c corners only and barely any in-between
Corsiar No. C-5...8" camber....the Scrub Jack.

Each get used as needed. I think I have sharpened the scrub jack's iron twice.....once when I made the cambered edge, and once maybe a year later.
Had a small scrub plane, with a 3" radius.....way too many strokes to do a board. Scrub Jack takes a wider bite.

[Mike Holbrook]

Certainly, as we often allude to, the type work any individual is doing at a given time has to make a major impact on whether a Jack with an 8" radius or a smoother with an invisible camber will be most useful. Lately I have been making tapered legs from dry 2" square oak stock, and trying to get useable boards out of some rough sawn twisted/bowed/cupped... cherry. If I was: flattening dimensioned pieces, finishing pieces that had been through a planer, working sawn pieces off a table saw or pieces cut with a well sharpened hand saw...less camber might be all I would need.

There is also the type surface the woodworker wants to end up with. I do not think a rough surface is a "worse" surface just because it is rough.