5 degree back bevel on iron?

[jerry nazard]

I am curious about the practice of raising the working pitch of a smoothing plane by honing a back bevel on the iron. It seems that I occasionally read about this in discussions regarding micro bevels, but really never hear of anyone actually doing it. Until Santa brings me a BU smoother, or I add some shims to a frog, it seems that the back bevel would help me with some pieces of white oak that need finish surfacing. Any thoughts?

-Jerry

[Joshua Layne]

moves the angle of attack closer to a scraper - can't really hurt IMO, but you may not get paper-thin shavings off of your plane with the back bevel. I am a neophyte neanderthal, so take what I say with a grain (or bucket) of salt.

[Sam Takeuchi]

If you must, back bevel can get the job done, but angle should be according to the material you are working on. You might have to go 10 degrees or even 15, start with 5 and gradually go up until you get satisfactory result.

There isn't a whole lot of thoughts to discuss really. It'll work, I've done it before and many others too at one point or another. If you have a spare blade, I suggest you put back bevel on the spare one.

[Jim Koepke]

My experience with a back bevel is nonexistent. My most recent surprise came about by trying to compare the feel of a Bailey and a Bedrock plane. The mouths were set impossibly tight and the blades were as sharp as I could make them.

My old type 6 #4 is taking some incredibly thin and tear out free shavings. Of course, this plane has not been tried on a lot of woods, but it seems a very sharp blade taking as light a cut as possible has always worked pretty good for me.

jim

[Pohgunn Ooi]

G'day mates,

I don't use any back bevel for my irons and all my bench planes are bevel down woodies, mainly Mujingfangs and HNT Gordon.

But I have reversed the iron and use them. The Mujingfangs have about a 45 degree bed and its iron has 30 degree microbevel. Reversing the blade worked well for knots.

Reversing the blades for my 60 degree smoother made them function like a scraper. This has worked well for me on some tough grains.

I would recommend trying it out before using a back bevel because getting rid of the back bevel would be removing quite a bit of steel.

Cheers

GUNN

[Steve Hamlin]

A back bevel is certainly effective for more awkward grain, though at the expense of slightly reduced surface quality (but much better than sanded or torn out) and reduced edge life (since this is for finishing, you're going to be touching up the blade frequently anyway, so this doesn't matter.)

I wouldn't bother with 5° though which will only give you an effective pitch of 50° (york pitch) but jump straight for middle (55°) or even half (60°) pitch. This is more practicable on a narrower plane such as a #4 rather than a #4 1/2, as the increased pitch does make the tool harder to push, and of course the more effort required, the poorer the control possible.

I have a #4 with a back bevel of around 25° - 30° (I freehand, so couldn't tell you exactly what it is) for recalcitrant ebonies and rosewoods. Works like a charm.

Of interest may be David Charlesworth's DVD Furniture Making Techniques: Five Topics in which he discusses the use of high effective pitch and back bevels.

[Randy Klein]

I put a back bevel on all my irons, BU and BD, using my self-made jig. For my 4-1/2 smoother, however, I use a 10 degree back bevel which gives me a 55 degree effective angle. Works great and since I'm taking thin shavings anyway, it doesn't require much more effort while planing. I say go for it. Worst case is that you hate it and either need to grind it out or get a new iron.

[Jeff Willard]

I put a back bevel on all my irons, BU and BD,...

On a bevel up iron? What am I missing?

[Steve Hamlin]

On a bevel up iron? What am I missing?

This would allow a shallower effective pitch without (significantly*) reducing edge durability. Just have to ensure the clearance angle isn't reduced too much.

* reduced clearance angle will I think increase the wear bevel effect. But since the wear bevel will manifest on the honed backbevel, its removal doesn't involve as much work as when it's on the flat (which may itself by why Randy uses it.)

[John Schroeder]

I've increased the pitch on my stanley smoother to 55 degrees with a very small back bevel. I get super performance with much reduced tear out, and with when taking very fine shavings it doesn't seem more difficult to push or control.

I really did it based on several data points. The first is that I often work with difficult woods and couldn't avoid some tear out no matter how fine the shavings and sharp the iron. Moving up to 50 helped, and 55 pretty much eliminated it.

Secondly, a sharp edge is the intersection between two planes and as it wears it rounds off evenly. Thus you have to hone completely through the rounded portion so that the main bevel once again intersects with the perfectly flat back. A back bevel allows you to resharpen faster and take off less metal from the iron. This idea is explained much more thoroughly by Brent Beach here, along with some great illustrations that help clarify the concept: http://www3.telus.net/BrentBeach/Sharpen/bevels.html

There is also a nice discussion of back bevels with a lot of back and forth, and a reference to Brent's research here:
http://www.sawmillcreek.org/showthread.php?t=93632

Thus I use the ruler trick as described by David Charlesworth to put a microbevel on the back of my BU jointer. It doesn't change the included angle, but it does reduce the amount of iron that you have to take off and yields a sharper edge for me in less time (mostly using scary sharp). Note that this only adds about 0.5 degrees to the angle on the back of the plane. Very minimal and easily enough removed if desired. This is definately not appropriate for sharpening chisels though, as they need a completely flat back.

Happy sharpening!

[Randy Klein]

On a bevel up iron? What am I missing?

A few reasons, one to strengthen the edge of low bevels, such as the one I use for shooting. Second, easier removal of the wear bevel. Keep in mind, that it's only 3 degrees at most. I describe the jig I use here. It enables me to hone both sides rather quickly.

[jerry nazard]

Well, I honed a ~10 back bevel on an iron, loaded up a Millers Falls #4, and gave it a try. Seems to do the trick - no tearout on some white oak that was giving me problems. The plane was noticeably harder to push, and the shavings were mostly small broken up chunks rather than continuous pieces. A most interesting experiment! Thank you to everyone that posted for sharing information.

-Jerry