The secret to cambering Bevel Up plane blades

Derek Cohen (Perth, Oz) · Posted: Sat Oct 20, 2007 6:59 pm Post subject:

Hi Brent

Thanks for adding those points, especially the bit about "If we can camber a bevel down iron, we can camber a bevel up iron".

In summing up, I must explain a little more where the motivation for the original article came from...

When it comes to handplanes, I am torn between using BU and BD types. I enjoy the woodies I have, mostly HNT Gordon and Mugingfang, all bevel down planes. To prepare these, I grind a hollow bevel on a high speed grinder and then freehand them on waterstones. Nothing special. You will find this surprising perhaps, but I hate sharpening! One of the reasons I do research on it is because I am trying to find an economical method. KISS rules. I strop on leather as I work to maintain the edge. These BD planes work for me as I like their balance and the Gordon planes have the performance needed to work Australian timber.

There are a couple of reasons why I make the effort to get on top of BU planes. Firstly, these are exceptionally comfortable and balanced planes. This makes it easy to use them well. Secondly, they are capable of being tuned to work at very high angles of attack, which is essential for most of our hardwoods. I think that a lot of hobbyists enjoy their ability to use different cutting angles.

But ... they need to be prepared differently to BD planes. They are not the plane for someone who is not prepared to do things in a slightly obsessional way. Very Happy

I spent quite a while trying to treat the BU planes as if they were BD planes. I ground bevels on the bench grinder to 50 degrees and then tried to freehand them on waterstones. I could get sharp edges, but they were straight edges only. Eventually I had to accept that these planes needed to be treated differently. Since the secondary bevel is so important (unlike BD planes, where the frog angle is all important), these planes need to be prepared with a honing guide (the exception being the 37 degree included angle. There I hollow grind at 25 degrees and then freehand). I really am quite lazy and a honing guide is not my preferred style, but I have spend quite a bit of time working with various guides, especially the Veritas, and using one can be quick and painless. Still, I wish I didn't need to use one, and this is where the ambivalence lies. This thread was about coming to terms with this issue and accepting what needs to be done to use BU planes with camber.

Happliy, only a jack requires a radical camber. A smoother and jointer can be done as easily as a BD plane.... just as long as you prepare the primary bevel at 25 degrees. The subsequent cambered microbevel needs to remove significantly less metal than cambering a full face high angle bevel. Thus the door to cambered BU blades is opened, and one of the main criticisms levelled at BU planes is now a thing of the past.

So the BU planes are technical to prepare, and this will contiinue to polarise users. Some will rail against this and see it as unnecessary fussiness. Others will just accept it as the entry fee to use a style of plane that is rewarding in use and performance.

I like both types of planes - there will always be pros and cons with each. It should not be about one or the other. One man's meat ....

Enjoy the rugby.

Regards from Perth

Derek

ivan · Posted: Wed Oct 24, 2007 3:23 pm Post subject:

Just another way of saying both work OK and neither constitutes an absolute of precision!

David C · Posted: Thu Oct 25, 2007 7:38 am Post subject:

Derek,

"Not liking sharpening" is a bit of a snag.

Being comfortable with sharpening is one of the most important things in woodworking.

Standard bench planes are actually easier to set up for difficult timbers.
A very narrow 15, 20 or 25 degree back bevel is easy and quick with an Eclipse type guide.

Eclipse type is acually much simpler, easier and less cumbersome to use than the Veritas, once you get used to it. Veritas will do skewed blades, but so will many others.

Adjusting of Squareness on chisels and plane blades, straight edges, cambered edges of varying profile (except scrub) are all straightforward, and the ruler trick massively increases the probability of a really sharp edge by correctly honing away the wire edge.

In the time it takes to remove a plane blade and strop it one might as well have sharpened it.

I don't know how much you travel but a few days would give me the opportunity to get you to love sharpening.......? It really is not that difficult.

Think how much more time there would then be for making!

best wishes,
David

bugbear · Posted: Thu Oct 25, 2007 8:08 am Post subject:

David C · Posted: Fri Oct 26, 2007 8:17 pm Post subject:

BB,

I don't think 2 to 4 minutes using £5 guide and two waterstones counts as elaborate.

Although I do acknowledge that 1 to 2 minutes might be the target for freehand oilstone users.

David

Derek Cohen (Perth, Oz) · Posted: Sun Oct 28, 2007 2:10 pm Post subject:

I spent a little time over the past week playing around with profiles for the LA Jack. The radical camber I posted here originally produced a typical Jack shaving of 1/32" thick and approximately 1 1/4 - 1 1/2" wide. However I was not satisfied with the profile and thought that it could be improved.

The original profile had a radius of 5 1/2". I finally settled on a radius of 8 1/2". This is the difference on the template:

Here is the profile in the mouth of the LA Jack:

The shavings are wider now, about 2":

.. and with a miniscule loss of thickness (still efectively 1/32" thick).

I think that I will keep this one.

Regards from Perth

Derek