how to crown plane blade....

[stickdoctorq]

I have several plane blades where I need to either round the corners or crown the blade.

However, I am only just getting the hang of getting a good edge (thank god I bought the Lee Valley jig....I was using the cheapo side clamp, and the difference between that and the Lee Valley is just night and day) while sharpening the blade straight, using either waterstones or scary sharp.

What is the suggested method for creating rounded corners on a blade, or creating a crowned blade?

Should I just take a file or paddle, and shape the corners, then sharpen the corners as best I can freehand?

That would deal with rounded corner blades, and I would still be able to sharpen the bulk of the blade with a jig...but what about a crowned blade? Is there some kind of jig, homemade or otherwise, that will help sharpen a crowned blade?

I guess what I am asking for is any suggestions that people may have for how to create and sharpen rounded corner/crowned plane blades, and for any jigs that can be used for creating/sharpening said blades....

Thanks all for any help you can give...

Jason

[A Dubya]

Hey Jason,

Knocking the corners off your blade, using the edge of your sharpening stone (not the face), lightly drag the edge of your blade from parallel to 45 deg on the stone, using a "pull" stroke.

Only a tiny amount off rounding is required (32nd -64th), the more you take off the corner, the narrower the usable blade width becomes. Lap and sharpen as you normally would after the corners are knocked off.

For a specific radius'd blade, I'll draw the radius on the back of the blade with an alcohol marker. Grind the blade to the radius line. Sharpen and lap by hand on the stones. I'm not sure there's an affordable jig out there for sharpening various radius'. If there is, I'd also be interested.

Cheers,

aw

[Conan the Librarian]

That's easy enough to do, in fact, some would say it's hard to avoid. :-) Simply apply more pressure with your left hand with one pass, then with the right hand with the next one. Repeat until desired effect is achieved.

Chuck Vance

[Lowell Holmes]

[Jeff Gorman]

"stickdoctorq" wrote

: I have several plane blades where I need to either round the corners or : crown the blade.

Planes with rounded corners produced terraced surfaces, the internal corners of the terraces being rounded. It is very difficult to square the edge of a board with a straight-edged blade.

Apart from use on a shooting board, a very slightly convex blade has always been the tradesman's tool. For information, please look at my web site - Planing Notes - How To Plane A Square Edge.

In fact a check will probably reveal that edges intended to be straight are slightly convex. Indeed it is quite difficult to generate a perfectly straight edge.

You will see that the cambering needs only be very slight. It does produce a very slightly rippled surface, usually flattened by the glasspaper.

Where an absolutely flat surface was required (eg for a veneer ground), the old hands used a toothing plane with a dead straight edge.

Jeff G

-- Jeff Gorman, West Yorkshire, UK Email address is username@ISP username is amgron ISP is clara.co.uk Website

[Conan the Librarian]

My technique is pretty similar. I only use a jig when I'm re-doing a bevel angle or fixing an edge that has been chipped. For freehanding, I apply pressure only on the pullstroke; I hold the iron in my left hand with my ring finger and thumb on either side and middle and index fingers on top. I lock my wrist and draw the iron from right to left. I'm standing so my arm is away from my body so it is free to move piston-style while my wrist is locked.

Absolutely. I used to rely solely on jigs until I started buying specialty planes with irons that don't work well with jigs. That's when I realized that I needed to learn to freehand, and I've tried many different approaches (side-to-side, pushing and pulling, etc.) before settling on this one.

For me the best thing has been to gain enough confidence (and having my sharpening station always set up and ready to go) so I am willing to hone on a regular basis.

Chuck Vance

[Lowell Holmes]

I have always applied pressure with the right hand which makes it a push. I'm going to try your method of pulling and see what happens.

Like you, I keep my hones out when I'm using the handtools. None of my chisels hold an edge all day and it is so easy to touch them up if the hones are out, it doesn't matter much if the edge needs some help. I find it breaks the tension (that I don't realize is there) during a session to stop and fix a chisel.

[A Dubya]

I got thinking about this thread.

I hand plane every component of a project. So, I guess I do my fair share of hand planing. I have a good selection of hand planes, from shop made and store boughts to antiques. blah blah blah

I can't think of one that I've "crowned". I've made planes and shaped blades for a specific job (created a specific radius). I'm trying to figure out why you'd reduce the width of your cutting edge by crowning.

On any type of plane blade other than a jointer, I'll knock the corners off, to prevent any cutting marks. I go to the extreme to maintain a 90 deg cutting edge, and sharpness.

The serious question then: what is the benefit for someone to "purposely" crown a blade. Eg: take a scary sharp 2" blade with the corners knocked off, perfectly 90deg cutting edge, that gives you a shaving of a thou or thou and a half the full width of your blade, then "crown" it, now you have a cutting edge of less than 2".

Serious question to those who purposely "crown" a blade.

Cheers,

aw

[Swingman]

Here's one "old fashioned" reason explained on Jeff Gorman's site:

[Alan W]

In Leonard Lee's sharpening book he shows using a bench grinder and mounting the blade to a pivoting stick which allows you to rotate the end of the blade back and forth across the grinding stone. Your stick is affixed at the center of a large circle and the end of the blade is on the diameter of this circle. It gives you an arch to work the blade against the stone.

Alan

[Mike G]

Crowning is a time honored, a very long time, way of removing lots of stock fast with minimum resistance and tear out.

If you to have a chance to take examine some really old antiques, say something made in the 18th century, and could get a look at hidden parts, say the sold wood back panel, underside of drawers, etc you would find the distinctive marks of a crowned plane.

It may not be everyone's cup of tea but it is a well proven method.

[Lowell Holmes]

That will produce a crown I would expect in a scrub plane. The crown in my

604 Stanley is barely discernible. The plane will surface a flat board without leaving any noticeable marks. Rob Cosman addresses the issue in the preview on his dovetail VHS..

[A Dubya]

...thanks for the posts and the link. A different school of thought....

Cheers,

aw

[Rodney Myrvaagnes]

Since I have an 1830-ish razee jack that was crowned when I got it, I have not needed to. It is used for flattening large glued-up panels of not-very-hard woods, by scrubbing across the grain.

For surfaces that need to be smooth, the resulting furrows are takken out with a smooth plane.

If I were to copy this jack plane in boxwood (which I have been tempted to do because I like it so much) I would certainly crown the iron.

Rodney Myrvaagnes NYC J36 Gjo/a

"Curse thee, thou quadrant. No longer will I guide my earthly way by thee." Capt. Ahab

[Father Haskell]

Since you can set it deeper for rapidly hogging lumber without killing your arms, you still have a 2" edge.