Plane iron camber?

[Bill White]

I have (and use) Stanley #s 3, 4, 5 1/2, and 7.
Share your thoughts on cambers for the irons if you will.
The 3 has no camber now, 4 has a straight and slight cambered irons, 5 1/2 has a little larger camber, and 7 is open to suggestions.
I see and hear soooo many variations, and just trying to arrive at a consensus.
Bill

[Tom M King]

All my bench planes are either Stanleys, or Records. I use cambers on 3's from 3 thou to a thou and a half. 4, I don't think I ever measured, but I expect a thou or a little more. I have them set to match various old work we replace new boards beside. I don't know what a 5-1/2 has as an intended use, but my 5's are about a 8 to 10" radius. My 7 has a camber of a little less than a thousandth. The 8 is the only bench plane I keep with a straight iron. My method is mostly by eye, and measuring the shaving thickness. I like them to take a shaving all the way across the width of the iron, with these depths at the middle of the shaving, or otherwise what's that size plane for. Jacks are the only ones that might get the cutting depth changed in use. Once I set all my bench planes like I like them, including not only shaving thickness, but mouth opening, breaker distance from edge, I don't mess with it again. I keep a 4-1/2 set to take about a half thou, and set up for curly wood.

The picture is a shaving taken from a small piece of Yellow Pine with a block plane. It was taken to compare paring chisel shavings. I don't have any other pictures of measured shavings.

The picture of the exterior steps shows those done with the 3 with the 3 thou cut, but not using the full width of the iron, to match other boards on that old house. It was taken with a strong late afternoon cross light, to highlight the texture, which makes it look a lot more severe than it actually is.

[Jim Koepke]

I see and hear soooo many variations, and just trying to arrive at a consensus.

A quote from the movie "Angels & Demons" seems appropriate here, "God answers all prayers. Sometimes the answer is no."

The area of sharpening seldom, if ever, produces a consensus. Then just when one seems to have a firm position, they change their way of working.

My practice has been to not camber blades. Recently more rough cut lumber came into my shop and one of my junk box planes was turned into a scrub plane. A scrub plane's work relies on the blade being cambered.

Some folks like every blade in every plane to have a touch of camber. Some like to keep it straight.

There isn't a wrong or right to this. It is something each person has to determine for them self.

Cambering can help to eliminate tracks, but as you see in Tom's post, cambering can be used to leave tracks or change the name to texture and it is a different story.

jtk

[Christian Thompson]

All my plane blades have at least some camber on them. My 5 has a lot of camber and my 4 and 7 have very slight camber. If I had a dedicated jointer plane (vs. now where I use my 7 for edge jointing and face planing) that would probably get a non-cambered blade. But I like to have at least a little camber on anything I use for face planing to avoid plane tracks.

[John Vernier]

I also put camber on just about every plane. I sharpen freehand, and judge the cambers by eye, so I don't worry about edge radii. If I don't like a result, I change it at the next sharpening. I don't grind the shape of the camber, but develop the curve while honing on a medium stone (Washita, usually).

My jack planes have a lot of camber, maybe rounded back 3/32 at the corners. It's amazing how much less effort it takes to level a board with a plane set up like this, compared to a straight-bladed jack.

My jointers have a lot less camber, less than 1/16 back at the corners. I keep a no.8 pretty much dead flat, just the corners of the iron rounded. I use this for the last few passes if I'm trying to get a table top dead flat. It doesn't get a lot of use, frankly.

I used to sharpen my smoothers like that too - just round the corners of the iron. That was easy when I used a sharpening jig. Nowadays I just freehand a barely perceptible camber, and I think it feels better in the cut that way, as well as being faster to set up.

[lowell holmes]

Also, camber allows you to square edges that are not square on a board. I need to go back and put some camber in some irons. I have good replacement irons in my planes. I can camber the old irons and then have the option of going either way. Hmmmm

[David Ragan]

My #4 1/2 smoother is set up using the "Odate crowning plates" that put a slight camber on them. Just enough so the edges don't dig in.

My #5 has a much more noticeable camber on it for (almost) hogging off wood. Of course, as has been mentioned, the scrub plane has the most pronounce camber.

I also would really like to be able to sharpen confidently freehand, but, alas, I use guides.

[don wilwol]

I sharpen freehand, so I tend to just rock my smoothers from side to side just enough to not leave tracks. Expirence has given me the number of "rocks", and it can vary slightly with iron hardness.

I like cambered jacks. I have a few different degrees of camber in the arsenal. Its all by eye and hand, so I have no measurements.

Jointers get the same treatment as smoothers.

[Tom M King]

I bought the Mitutoyo micrometer specifically to measure shavings, I'm 90% sure in 1982 to answer that question by a scientist friend of mine. At that time Mit was considered cheap but okay stuff, and well less than half the cost of Starrett, or Brown&Sharpe. I've checked the accuracy a number of times over the years, and it's are still dead on. You have to be careful not to cheat with micrometers on a shaving. You can keep squeezing, and get a thinner "measurement".

I never thought much of just rounding off the corners of an iron. The idea is to make the part taken to be as smooth a transition as possible, from one side to the other. No camber will result in right angle ridges, that are obvious even at one thousandth or less.

I mostly only use American woods, so the stock irons work just fine for me. I've never used the wood that Derek uses.

The pictures show an ECE scrub plane that was bought new-wear on finish from sweat. We use it to scrub dirty beams before putting a good iron in the wood. That's not a shadow at the mouth, but wear. I don't know what the radius is, but it's way more than a Jack.

[Jim Matthews]

Most of the lumber I buy has been skip planed, so two sides are close to parallel and flat.
I don't use the scrub plane much, it takes off heavy shavings.

With the exception of my try plane (about 18" long) all my blades are
ground square across, with the corners knocked back, so tracks are less common.

My try plane will take a heavy 64th off at the center - nothing at the sides.
The blade is 2 5/8" wide. I would say it's a 5" radius, if I was forced to make a SWAG.

My smoother, block and jointer planes are all squared across - no camber.

[Winton Applegate]

Always, always at least a smell of camber.
Finish planes mostly just the corners relieved a little so they don't leave tracks.
Even the #7 when used for jointing edges a little camber makes for a more controllable and accurate cut when you want to take just a whisper off here and there for the final joint of a thick hard pair of boards that are too hefty to "spring" so they have to hook up flat.
Then for the other planes if you are trying to cut off a lot of thickness to get something roughed flat or in particularly hard wood then more and more camber until you can achieve your goal in the least amount of time with the least effort.

For instance rough planing bubbinga or purple heart or the Aussie super woods with no camber and a heavy cut will kill you effort wise and keep you sharpening every few strokes especially with the grain but cross grain the edge doesn't dull nearly as fast but the effort required is still just too heavy.

So CAMBER ?
as little as possible but as much as you need to.

[ian maybury]

I ran a similar thread some time ago, and got lots of helpful input.

The sort of conclusion that seemed to emerge to the camber question was 'it depends'.

The big distinction seems to be machine use/non machine. Lots of camber eases stock removal with a scrub or a jack (almost magically so) when shifting significant quantities by hand before finishing with a smoother - which last may have the minimal amount of camber required to prevent corner marks. (could be as little as several thou) Or multiples more (or use the jack) if the aim is to produce a rustic finish with visible plane tracks.

When doing most stock removal by machine, then it could be about setting up for those exceptional jobs where hand tools are more convenient (than using the machine), or alternatively of setting up primarily only to remove planer/machining scallops - which latter only requires minimal depth of cut and camber of a few thou to suit.

Jointers can be a variable feast. Some seem to set them up with more camber for e.g. shifting lots of material off the top of large surface like a bench to flatten it, or much less/minimal camber for realigning edge joints.

Blocks (especially the wider Veritas variety) can be set up with a little camber to function as a small smoother, or straight for trimming jobs and the like. It will make sense to keep a dedicated jack/BU jack or whatever sharpened straight for use on a shooting board too if you use one.

So as ever it's about choices - determined by your type of work, methods, style and preferences. Which picture as ever in woodworking only clarifies over time, so there's of the nature of a journey about it where we guess as best we can what we need and wait to see how it works out. Apart from a scrub plane (which actually was something of a revelation in terms of how effectively it could shift wood) i've as a machine user set everything up (apart from a small block and shooting board BU jack) with moderate cambers of a few thou - but will put more on as/if the need arises. It's not even clear that we necessarily need the full collection of plane types, especially if we machine work most of the time.

[Bob Glenn]

I have a Stanley #8 that I use for edge jointing and flattening panels. I bought a Hock blade for it and have kept it ground perfectly straight. I use that iron for jointing. The stock iron has a slight camber at the corners to prevent tracking when flattening panels. Takes just a minute to switch irons. Both my smoothers have the corners eased a bit to reduce tracking.

[Jim Matthews]

So CAMBER ?
as little as possible but as much as you need to.

What did Einstein say, "A scientific principle should be as simple as possible, but no simpler."

[Bob Glenn]

What did Einstein say, "A scientific principle should be as simple as possible, but no simpler."

Brilliant!!!!!!