Can’t get a camber on my plane iron

[Helvetica]

I’m edge jointing some cherry and in one area I managed to plane a hump into the edge that I’m having trouble getting rid of. I tried to hone a camber into my jointer plane blade but when I hold the edge against a straight edge it’s flat.

Ok I’m using water stones. 1200 and 6000. Primary bevel is 20° and flat. Micro bevel is 25° and I spend more time at the edges to hone a camber, but it doesn’t seem to work. I tried 10 strokes at the outer edge, 7 strokes halfway, and 5 dead centre. Tested the plane, then tried that again twice plus trying to make an ‘X’ in the stone by a la Charlesworth. Blade still looks flat to me.

Any feel for where I’m going wrong? The plane sole seems flat. The plane blade isn’t kryptonite. The stones were flattened with 220 grit on plate glass.

Stumped.


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[thetyreman]

try a higher angle, I would try 30 degrees then if that doesn't work 35.

 

[Ttrees]

That's a very low primary bevel, doesn't Charlesworth recommend 23 for a primary bevel?
Never honed a plane iron at those angles, but reckon your not getting camber as quickly/at all because your having to remove more material.
Nothing wrong with a barely noticeable camber for what your doing, you just have to scoot the plane overhanging the edge more than you would with the camber.

Tom

 

[ED65]

What has bevel angle got to do with the problem the OP has chaps?

Helvetica, are you perhaps expecting more camber than there's going to be given the grits you're working on? With the stones you're using you're removing thousandths of an inch in old money, a few hundredths of a millimetre, this is so little that the curvature of the iron is actually hard to see with the naked eye.

Try looking along it like you'd sight the edge of a board, that can make a very slight curvature easier to notice (assuming it's there).

But, there's no need for camber if you're just removing a hump on an edge! Anyone who uses non-cambered edges on certain of their plane irons (including their smoothers and jointers) can remove a hump just the same as those who camber all their irons.

That aside, if you want a camber you want a camber. Just do more strokes with pressure exerted to each side. Oh P.S. if you're using a honing guide that has a wider wheel than others it might be interfering with the process.

 

[Ttrees]

Thinking the problem is probably more steel is in contact with the waterstone, and the stone is wearing away.
Have you ever honed a bevel at that angle ED65?
I'd reckon the secondary bevel gets large pretty quickly with a primary bevel at 20 degrees.

Agreed about not needing the camber for this, and indeed preferable if you want to eliminate tearout.

Tom

 

[ED65]

There isn't noticeably more steel in contact with the waterstones because the angle is a mere 5° shallower than typical. Helvetica said he's doing a microbevel, it's only a tiny amount of steel being worn away in either case.

But I suppose stone wear is a possible issue here given the nature of many waterstones, hadn't thought of that.

Have you ever honed a bevel at that angle ED65?

I'm sure I've done a bench plane's iron at that angle at some point if it came into my hands with a primary grind of ~25°. I do maintain the single bevel on my low-angle block plane's iron at that angle so it remains as low angle as possible. I don't normally do secondaries (micro or otherwise) and I'm not using waterstones though, so really not related.

 

[Ttrees]

I remember when I used a honing guide, had no grinder, and had a piece of timber for setting the plane iron with an Eclipse style guide, as close as I could replicate Charlesworth.
I was setting the plane iron in the jig exactly the same every time to the line (instead of a stop block)
One of the last times I remember it took me about a half hour to even get a burr on a Washita.

I should have either ground the huge secondary bevel away
(A small secondary bevel is a big deal when you use the jig.)
Or figure out a temporary solution to make do until I got grinding again...
I was thinking of creating an increasingly steeper secondary bevel every time, but was a bit
stumped on how much to increase it by and it just seemed a bit too much to remember to make sense.
I think I may have tried this, but didn't give it a fair go more than likely.
What was most silly about it all, was resisting the urge of dismounting the iron from the jig to grind the primary again, and carrying on honing because of the time wasted allready (hammer)
It would have been much quicker to just bite the bullet, dismantle the jig, regrind the primary
bevel, and reassemble the iron in jig again.

Funnily enough the reason I finally ditched the guide was to produce a flat iron.

Having a grinder is the answer.

If you've went through this before, as many have, it seems good training for freehand honing, as in..
You know it is a waste of time to try and persevere with honing the secondary bevel if it needs regrinding.
Freehand is easy with a freshly ground primary bevel (with the sliver of secondary left)
Don't persevere with a larger secondary bevel, grind it away if you're learning.
Keep the bevel tiny.
Tom

 

[Helvetica]

Sorted. Thanks for the advice.

I believe the relative softness of water stones and the low primary angle meant it needed more strokes to get that camber happening. I think I had negative camber from planing mahogany then not sharpening the blade since!

The reason I want a camber is to remove more material where I choose, by just moving the centre of the plane mouth over the high spots. I think I would find it harder to control by just putting pressure on either side of a flat blade. This way I can keep my thumb centre behind the knob and guide it with my fingers with pure downwards pressure.

Removing the hump across the width was still tricky. The sole has a tendency to rock if you’re not paying attention.

Anyway, all edges now with a little spring, and glued up. Thanks for the interesting discussion! Here’s a photo of the edge in question and the glue up:

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[David C]

Helvetica,

That's quite some glue up!

If you have a modern thick blade, it can be difficult to camber with point finger pressure alone. (O strokes in center would be better)

When starting with a new blade, I now cant the blade by supporting one edge on a strip of 0.5mm plastic ( about 1/2 inch wide). This removes triangular shapes at the edges. (Repeat on other edge) After this a few strokes at the apex, or meeting point completes a nice camber. This is done on a coarse 800 grit stone. (600 or 700 or 1000 g will all do.) Your 1200 stone is too fine to remove much metal.

Angles are important. I grind at 25 degrees, shape and get wire edge on 800 stone and polish on 6,8,or 10 thousand grit.
The shaping bevel should be kept as narrow as possible, this ensures rapid sharpening.

The 800 work can be done at 30 degrees and the polishing work at 32 degrees. (I use 33deg and 35 degrees.) A2 does not like low angles.

I realize this may sound complicated, but it is not. Approx 4 mins to resharpen a plane blade.

The process may be seen best on my Plane Sharpening DVD which is available from me, or Lie-Nielsen who also have streaming.

 

[ED65]

I'm reminded of why I love diamond plates so much 8)

No dishing, no maintenance and fastest cutting by a country mile. And in normal carbon steels at least you don't have to worry about how wide your secondary has become, you can maintain a single flat or convex bevel forever and never visit a grinder again, barring accident. But then I think that's also the case with oilstones, despite being supposedly too slow to make this practical.