Back Bevel for Plane Irons

[Richard Gillespie]

Oh no, another sharpening question (groan). However, I've been thinking (that's where I go wrong every time), how did the craftsman of past century's sharpen their plane irons? I know they used grinders, both dry and wet as well as oil stones to hone with. I can't say however I've ever seen a iron come out of an old plane with the back polished to a mirror finish. On the other hand, I can only think of seeing one or two irons that had back bevels.

It's been my practice, with both old and new irons, to flatten and polish the backs to a mirror sheen. That's a time consuming process that has gotten very old to me. A number of old irons I've seen aren't close to flat and some are pitted. With many of the pitted irons you have little choice but to grind off the pits where and when possible.

In fact I have a number of planes I've put aside for later because I dread working on the backs of the old irons. I'm beginning to think that back beveling might eliminate the need to polish the backs of irons. The only problem I can foresee is the difficulty in duplicating the back bevel during future sharpening.

Anyone have an opinion they would like to express on this. Based on the sharpening hearsay I'm discussing here, I expect an arrest warrant be issued for me by the sharpening police or at least getting flamed a little. :rolleyes:

[Tyler Howell]

I've heard a back bevel is a great way to get rid of nicks and pits. A method to get repeatd angles is a turn or two of masking tape on the iron.
Let us know how it turns out.;)

[Daniel Fisher]

Using a back bevel minimizes or eliminates the need for polishing the back. The purpose of polishing the back is to create a smooth surface to mate with the smooth surface of the front bevel. A smooth back bevel will do this, but if the angle is too steep, the effective angle of the plane iron will be drastically changed.

Also as pointed out, consistency is a problem. David Charlesworth, the English handplane expert, uses a back bevel. He creates the angle by placing a 6-inch metal pocket ruler on one side of the waterstone and lays his iron on that, moving it back and forth sideways to create the back bevel. This produces a very small, slight angle.

[Rob Millard]

I put a back bevel on all my Bailey type metal planes to increase the bed angle, making them better able to handle difficult grain. I also put one on my LN No.9 miter plane to do just the opposite, reduce the bed angle, making it plane endgrain more easily. The only time I have done it to overcome pitting is with molding planes. On my bench planes, I grind the primary bevel at a little under 25 degrees, and put a back bevel of around 5 degrees. I do the back bevel by eye and feel, just as I do the primary bevel.

Rob Millard

[Harry Goodwin]

I have lived in ignorance of back bevels on plane irons and chisels. I don't intend to join in unless some other probem appears in flattening the back. A trip to a flat course stone and followed by fine stone will help. Once it's flat it will be easier. I've even been discouraged from lifting that flat back on a strop. A polishing wheel really does a nice job on the bevel side.

[Joel Moskowitz]

The back of a chisel must be flat or the chisel won't work properly. So if you can sharpen a chisel properly - sharpening a plane blade is exactly the same only wider.
there is no point to flattening any more than the bit right next to the edge - even a 1/16" is fine.
I've never ever had the urge to put a back bevel on anything - I know it makes it easier to plane difficult wood but so far I havn't had any problems and controling a back bevel seems to me a royal pain and not worth the trouble.

[John Weber]

I use the Charlesworth method of sharpening my plane blades and my Tormek for my chisels. The chisels are hollow ground at the desired angle, and then polished with the leather wheel. For plane blades, I flatten the back with a 1000 grit water stone (leaves a matt finish). The primary grind is 23 degrees, followed my a 33 degree 1000 grit hone, a 35 degree 8000 grit polish, and a 8000 grit back bevel polish using the "ruler trick". Sharpening is fast and repeatable, and the grind only needs to be re-estabilished every 5 sharpenings or so. My results have been excellent. 80% of the work is on the back and that is a one time deal. I highly recomment his first DVD. With 2 stones you can basically get excellent results.

I'm a strong believer of back bevels.

John

[Richard Gillespie]

The back of a chisel must be flat or the chisel won't work properly. So if you can sharpen a chisel properly - sharpening a plane blade is exactly the same only wider.
there is no point to flattening any more than the bit right next to the edge - even a 1/16" is fine.
I've never ever had the urge to put a back bevel on anything - I know it makes it easier to plane difficult wood but so far I haven't had any problems and controlling a back bevel seems to me a royal pain and not worth the trouble.

Joel; I couldn't agree more with you regarding chisels. IMHO their backs must be dead flat to work right.

Plane irons are another species. I've acquired, over the years, 38 metal body planes, two transitional and about 20 woodies. I've seen irons so pitted they had to be discarded. Others, the pitting occurs on the backs where they rest on the frog edge. Those, you can usually grind the pitting off. More often than not, irons with high spots in the middle that won't let you polish the edge and irons convex across the backs that make it difficult to flatten all the way to the edge. These occur were the frogs were never properly flattened across their face or bearing surface and years of being clamped down have bent the iron.

The thought of back beveling is contrary to what I was taught about sharpening but in a way makes sense. I suspect our ancestors used the fastest way possible.

[Joel Moskowitz]

Richard,
you are talking about a special case - a damaged iron. In that case you really have only three choices, replace the iron, thin it signifiantly as you flatten a good portion of the back in trying to get clean metal at the edge, or using a back bevel. In that case I certainly understand the back bevel. I don't actually know how many planes I have - it's a lot - however I don't use most of them and the ones I do use are usually in good shape or I will replace the iron. However if you actually want to get lots of planes in usable condition quickly a back bevel is a good solution - although it makes each successive sharpening more work.
My point on the chisels and plane irons is that for irons that are basically in good shape a back bevel (except when it is done for a higher effective angle) takes a lot more time to maintain then just sharpening the way you would do a regular chisel. and sharpening a chisel quickly is an important skill. Why have two procedures?

[Mark Singer]

Flattening the back takes a bit of time ....but is not required for additional sharpening....The single bevel is what I have had te best results with as well.

[Mike Holbrook]

This sounds something like a micro bevel but on the other side of the plane iron, or am I missing something?

I have found it very easy to get a little off on the micro bevels that come on LV plane irons and end up with a problem that is hard to correct. I have been trying to grind a 25 Degree bevel over the LV micros. Coloring the blade bevel helps but it has still been quite difficult to deal with those ticky little suckers.

[Roy Wall]

This sounds something like a micro bevel but on the other side of the plane iron, or am I missing something?



That is correct.......just a degree or two to make a really "flat" edge on the back without all the work....