Camber for plane blades, how much is enough/too much

[Robert Engel]

Yes, Robert, you are missing something. For a smoother a rounded edge means the cut will feather to nothing at the edge. If you just round the corners, the edge of the cut is not as abrupt as a flat edge, but still noticeable nonetheless. Rounded tracks instead of square tracks. In addition the problems with having the iron slightly tilted to one side are much more severe with an iron that has rounded corners than one which has a nice sweeping curve. If you are not planing boards that are wider than the iron, it does not matter very much.

They are not cambered but rather upturned a few thou. I don't get tracks so whatever I'm doing works. Just saw the word "feathered" guess that describes it better.

Guess I'm just saying a cambered blade is for rapid material removal ala a scrub plane and is most useful in a jack.

All the rest can just have the corners feathered or eased.
Maybe I'm missing the core of the discussion, but a cambered plane is not necessary to eliminate tracks

[Warren Mickley]

I think the ideal for a smoothing plane is nice rounded arc all the way across the width so that it cuts roughly .001 in the center and nothing at the very edge. That way the feathering is very smooth, gentle all along, not concentrated in the last 1/8 or 1/4 inch of the cut. In addition the penalty for a slight lateral adjustment problem is merely that the cut is a little off center in the plane, not that the plane is making an angled cut as is the case for a "flat" edge with upturned corners. In fact with an arc shape, how the cut is centered in the plane is an extremely sensitive diagnostic tool for lateral adjustment.

For a jointer plane, a arc shape gives a much more effective tool for flattening an edge that is very slightly in wind.

[Mike Holbrook]

Good link Stewie, to the Fine Woodworking article/video. I think the picture of the smoothing plane blade, against a square with light behind it, illustrates what Warren is saying. The curve in the blade on a smoother may be so small as to not be visible without the square and extra light. "Historically" unless the "historians" were checking blades in the same manner the curve might not be noticeable. It seems to me that very few used/flea market finds have blades that are in the condition that a tradesperson 100 or more years ago would have left them in.

Warren makes a great point about the virtues of a gradually curved vs flat plane blade surface, in my humble opinion. I believe the same principals apply as we move towards planes set up to do medium and coarse work.

[Jim Koepke]

It seems to me that very few used/flea market finds have blades that are in the condition that a tradesperson 100 or more years ago would have left them in.

There was a period of change in the craft trades and a couple of major wars that interrupted the transference of knowledge and tradition through the period these older tools have existed. During my lifetime I have met many people who though a blade could be brought to full sharpness on a coarse grinding wheel. It doesn't surprise me that so many of "grandpa's old planes" were taken off a shelf to smooth the edge of a sticking door. Certainly the first thing such a tool needed was a run over the bench grinder, wiping away any of the historical remnants of sharpening.

jtk

[John Sanford]

Excuse me for being dense, but why would one use CNC, i.e. Computer Numeric Controlled wheels unless you have a CNC grinder? Do you mean CBN, i.e. Cubic Boron Nitride, wheels?

[Mike Holbrook]

Sorry John, yes CBN wheels.

[Mike Holbrook]

I wonder if others have the issue of a cambered blade not fitting well in the standard/small mouth of Stanley planes? Admittedly I may have been experimenting with too much camber. Still I am having issues, particularly with LV's blades made for Stanley planes, which I believe are slightly thicker. I have been considering increasing the mouth size on the planes I plan to use with the more cambered blades but I thought I would ask what fellow posters have done to resolve issues of this nature first.

I have Veritas BU planes which I have been planing to use as my less cambered planes. Considering the easier to adjust mouths on these planes though I may have things backwards. There is the issue of the thicker wider bevels that need to be ground into BU blades to achieve cambers. I am aware of Derek's method of achieving this with a secondary bevel. I am also aware that CBN wheels grind faster hollow grinds and might make cambering BU plane blades a more approachable goal.

[Tom M King]

No trouble with standard Stanley irons being cambered in Stanley planes. I have one of each, and multiples of some, but have had no need to "upgrade" the irons for my uses.

[Jim Belair]

No trouble with standard Stanley irons being cambered in Stanley planes. I have one of each, and multiples of some, but have had no need to "upgrade" the irons for my uses.

Ditto. I have a Stanley #4 that I use as a scrub and it has more than 1/8” of camber on it.


Camber shouldn't effect the fit of an after market blade since with it the edges of the blade project less than the nominal shaving thickness. The purpose of camber isn't to take thicker shavings, its to taper those shavings at the edges.

[Sean Hughto]

On smoothers and jointers of any sort, a camber imparted in the sharpening process on stones by finger pressure and extra strokes as you near the outer edges is plenty. For a jack a little more perhaps. And for a scrub, a lot more. Getting too fiddly with much more detail if you asked me.