Camber on a BU smoothing plane?

Re: Camber on a BU smoothing plane?

David Charlesworth

Joe,

You will either have to relieve the corners or use camber.

You will be surprised by how much more camber you have to put on the bevel up blade, relative to a regular 45 degree pitch blade. This is because of the low bedding angle.

Personally I like camber, you certainly won't screw anything up.

best wishes,

David Charlesworth

Re: Camber on a BU smoothing plane?

Curt Putnam

I suggest starting with simply relieving the corners. It's easier and not as major an operation as is cambering. Of course, if you are good with a grinder then go for it. If you are going to do it, I'd suggest dedicating a blade. Check Derek Cohen's site for an article on just how much camber is required.

Re: Don't be misled

TomD

It is certainly true that the lower the angle the more camber that is required. But in order to hide your tracks, let us say that you want to take a 1 thou cut so you have a vertical depth of 1 thou, and a projection on the bedding angle of a 45 degree plane of 1.44. So you are talking a camber of 1.44 thou over the width of your blade. That is barely visible, and not something requiring a major re-grind. If you then decide to reduce you depth of cut for a finer finish, to say 5 tens, you are going to loose a fair chunk of working width as the curve retreats into the plane.

With a 20 degree bedding angle your projection will about double, your camber would need to be 2.92, in order to expose 1 unit of cut. So 2.92 thou for a 1 thou cut.

(http://www.blocklayer.com/riserun.aspx)

Of course it isn't a perfect world so you may want to add a little more camber since the exact projections are not worth fighting over, and you want to eliminate your tracks. but 4 thou, say, is still less camber than the thickness of a sheet of paper.

As mentioned every camber setting is only good for one projection. This kind of precision led Toshio Odate to have a special set of diamond stones made to allow him to actually work these minute arcs, for one set of circumstances, and to consistently polish off marks from different grits during sharpening.

Re: Don't be misled

Tony Wilkins

I too was going to mention Derek Cohen's how to on cambering a BU plane - it's truly excellent. I see where TomD is coming from and don't think you need to go to extremes with the camber. I would try a little and a little more till you have it zeroed in.

Re: Camber on a BU smoothing plane?

Derek Cohen (in Perth, Australia)

Hi Joe

The camber you use on a BU blade is just a little more than you would use on a BD plane. It is not worth fretting over the numbers - just use the BD amount as a starting point, then experiment with whether you need more.

The real issue is how to achieve this camber on a BU smoother (since this is what you plan to use). The question I ask is whether you are using a high cutting angle in the BU smoother (since this is the advantage of using BU smoothers)? Assuming that you are, the next question is whether you are using a single bevel (for example, LV sell blades with 38- and 50 degree primary bevels) or a secondary microbevel on a 25 degree primary bevel?

My recommendation is only to use a 25 degree primary bevel, add the desired secondary angle to this, and camber the secondary (micro) bevel. The reason is simply that cambering a full and high angle primary bevel requires removing significantly more steel than when cambering on a low 25 degree primary bevel. This process makes it really quick and easy to camber a BU blade.

Note that this method of honing requires a honing guide. I routinely use one on BU plane blades, and freehand all else.

See my website (under Sharpening) for an article on all this. I will try and add it here if I get a chance later - I'm tapping this on my iPad at Joburg airport en route to Cape Town.

Here's the link: http://www.inthewoodshop.com/WoodworkTechniques/TheSecretToCamberinBUPlaneBlades.html

Regards from Johannesburg

Derek

Re: Camber on a BU smoothing plane?

Joe in a Cleveland suburb

Thanks for all the info guys.

Derek, I had forgotten about your site. Thanks. It's a great source of information.

Thank you.