Comments on: Curved Cutting Edge Equals Tight Shoulders

By: xMike

xMike — Fri, 27 Apr 2012 14:38:02 +0000

“Add to that oil stones that might have been slightly dished…”
That, I think, is the crux of the matter – When I was a little sprite watching my Dad and uncles work, no one had ever heard of Japanese water stones or diamond plates – they used two-sided (Carborundum) oil stones lubed with coal-oil or kerosene and the stones were ALWAYS dished from use.
Yep, Carborundum – they only used Arkansas stones for straight razors.

By: Dale Smith

Dale Smith — Sat, 06 Feb 2010 16:48:14 +0000

If you drawbored a joint like this with a gap on one shoulder, would it still seat the way you want?

By: Chris F

Chris F — Fri, 05 Feb 2010 18:18:37 +0000

Not sure about historical evidence for this specific technique, but there is evidence for gaps on the inside shoulders of M&T joints. If you look at Peter Follansbee’s joint stools, quite a few of them have a gap at the inside shoulder specifically because this forces the visible shoulder to be tight. See "http://pfollansbee.files.wordpress.com/2009/03/interior-of-stool-pegs.jpg?w=509&h=341" for instance.

By: Christopher Schwarz

Christopher Schwarz — Thu, 04 Feb 2010 23:56:59 +0000

David,

This is a tough question on myriad levels. The earliest texts on planes say that the irons were sharpened straight across for jointers.

Were they really? We do not know.

As anyone who has worked with hand sharpening for a long time can tell you, sharpening a 2-1/4" or 2-3/8" iron straight — dead straight — is frustrating. It’s easier to sharpen a shallow camber. Add to that oil stones that might have been slightly dished and you get a situation where we are taking about how many angles can dance on the head of a pin.

Are cambered jointer irons covered in the 18th c literature? Not that I know of.
Are they covered in the 20th c literature? Absolutely.

Is a very slightly cambered iron something that would be detailed in an 18th c text?

Not sure. Ask again later.

Does it work? Yes. Like crazy. Not just in one instance, but in many many instances over many years.

Chris

By: David

David — Thu, 04 Feb 2010 23:49:39 +0000

I was just wondering, is there any historical evidence for this? I’m not saying I’m opposed, I love a cambered iron. I’ve just never taken or had the opportunity to examine any really old planes, when did the use of a cambered iron start? I recently read (to be honest, I can’t remember where I read it) that the scrub plane is a recent invention, ie. within the past two hundred years, possibly less than one hundred years). Before that, the try plane was the one to use, with the jointer being a completely different animal. From what I remember from the article, the difference was the width of the iron, and camber (apparently jointers were never cambered to ensure a tight joint). Is having a cambered iron historically accurate?

By: Christopher Schwarz

Christopher Schwarz — Thu, 04 Feb 2010 23:28:30 +0000

Jeremy,

I run down the center of the leg. And yup, you get a gap on the inside. And I think this is just fine.

Chris

By: Jeremy

Jeremy — Thu, 04 Feb 2010 22:01:46 +0000

Chris, did you line up the crown of the plane iron with the centerline of the entire leg, or of the mortise? Maybe I’m overthinking this, but I’d be concerned that running a crowned jointer plane down the true centerline of the leg, rather than relative to the mortise, would result in the leg face being "taller" on one side of the mortise than on the other. Then you’d get the effect you want on the side of the mortise closer to the edge, but a gap on the other side. Of course, if you’re telling me that just doesn’t happen on this scale of work, I’ll take your word for it!

By: Richard Dawson

Richard Dawson — Thu, 04 Feb 2010 21:49:39 +0000

George wrote, "Next time I sharpen my #8 jointer, it gets a crowned profile…"

I guess this means I need to get a #8 jointer. Oh well, OK.

Great idea.

Richard

By: George Walker

George Walker — Thu, 04 Feb 2010 21:39:31 +0000

Ok, you convinced me. Next time I sharpen my #8 jointer, it gets a crowned profile on the blade. I’m sure after I execute a few joints at the bench I’ll be kicking myself for not doing this years ago. Thanks again.

Goerge Walker

By: david brown

david brown — Thu, 04 Feb 2010 21:39:02 +0000

If you properly undercut all four shoulders, it shouldn’t show on any of the edges.