back bevel

Re: back bevel

Paul in NJ

>Jerry,

If you put a back bevel on a bevel down plane blade, i.e. a Stanley or LN #4 for instance, you increase the effective cutting angle of the plane by the amount of back bevel you add. To increase the effective cutting angle for a bevel up plane you just increase the angle of the primary bevel. Increasing the effective cutting by using a back bevel may help with the tear out of difficult grain. Another use of the back bevel is with pitted plane blades. Rather than flatten the entire back which is tedious if you have rust pits, you add a back bevel to get to clean metal.

An easy way to back bevel is with David Charlesworth's ruler trick. You simply put a 6" metal machinist's ruler on top and at the end of your honing stone. The ruler lifts the back of the blade as you are honing and automatically adds a slight back bevel.

Paul Dzioba

Re: back bevel

mikew

>Hi Jerry,

To add to Paul's excellent explanation, on a bevel down plane that is bedded at 45 degrees, placing one of those 6" rulers on top of a 2" wide stone, flat, and with the plane back laying on the stone so the edge is on the opposite side of the stone from the ruler, back on the ruler and honing will give a couple degree back bevel.

This makes the effective pitch on that plane 47 degrees or so, depending on how far the blade's edge projects past the ruler's edge. Using a honing guide is a good way to add more back bevel consistently. So for instance, adding a 10 degree back bevel now makes the effective cutting angle of that plane with a bed of 45 degrees equal to 55 degrees, and so forth.

All that is needed to achieve the effecacy of the back bevel, is to hone one about 1/32" or a little less. Doesn't take much.

One if the issues with using back bevels is consistency, which is why without a honing guide Charlesworth's method is a good one, but anything can be used, if used with consistency.

Back bevels are a good way to plane wood that is tearing out, such as wood with reversing grain. It is, though, less than ideal unless you either always work in such wood, have a couple planes for this use, or have more than one iron for said plane--which isn't a bad idea for a smoother anyway. The reason a second blade is a good idea is if you decide to now lower the effective cutting angle by removing the back bevel you have to grind it out.

Take care, Mike

Re: back bevel

Jerry Thompson

>I am still a little confused. Does the back bevel go on the back of the plane iron, i.e., the opposite side of the bevel?

Re: back bevel

Greg Sloop, Portland Oregon

>Yup. From the perspective of the plane it probably should be called, more appropriately, a "front bevel."

In short, the main bevel trails the cutting edge of the iron. The "back bevel" would be in front of it. It would increase the effective cut angle from say, 45 degrees to 45 degrees plus the back bevel angle.

Clear as mud? :)

Cheers,

Greg

Re: back bevel

Frank D. in Montreal

>Paul,

The ruler trick gives a back bevel but I think it only gives a 1 or 2° angle. Usually back bevels are around 5 or 10°, so a ruler isn't quite thick enough for this. I know I'm splitting hairs a little here, but I just thought I'd point it out.

Frank

Re: back bevel

les winter

>I have a question.

When you hone the main bevel, you create a burr and you remove it by backing off on the back side.

After you hone the main bevel and you hone a back bevel, how to do you get rid of the burr from the back bevel?

thanks

lw

Back bevels of just a few degrees

Steve Elliott

>I'm a convert to using back bevels on plane blades because it speeds up sharpening and gives me a keener edge than I've been able to achieve without a back bevel. The quality of honing I can get on a tiny back bevel is better than I can get when I have to hone the flat back of the blade.

I usually use a back bevel of 2 or 3 degrees even when I don't want a higher cutting angle, just for the speed of sharpening and the final edge quality.

Re: Back bevels of just a few degrees

Frank D. in Montreal

>Point taken Steve,

I made a distinction between back bevels for ease of sharpening and back bevels to help with tearout. I once described David Charlesworth's ruler trick on another forum as a back bevel and he showed up to say that his ruler trick was not a back bevel as is normally undertstood (used to raise the effective planing angle, which the ruler trick didn't accomplish to a signifiacant degree). It is a back bevel though, I just tried to make a distinction between the two for the person posted the original question. Oh well... :)

Re: back bevel

William Duffield, on the Cohansey

>Strop the blade across the palm of your hand a couple of times on each side, until you don't feel the drag from the wire edge. For the faint of heart, you can use a leather strop, or a piece of hard maple instead of your own leather. I used to use the knee of my blue jeans, but that led to premature denim failure and more cutoff shorts than I really needed.

Re: back bevel

mikew

>What William said.

In reality, the burr created in making the back bevel is insigificant in size, extremely weak and will at the slightest provocation break free. Which is what a light stropping causes it to do. I often use my shirt or jeans. Couple swipes and that's it.

If one were to seriously remove metal in creating the BB, it would require more attention.

Mike

Re: Back bevels of just a few degrees

Adam Cherubini

>Don't laugh at me but I've found it helpful to remember that the sine of 1 degree is 17 thou (.017) So if the ruler is .032 and 2" from the edge that's one degree. Moreover sine is pretty linear at low angles, so you can just multipy by .017 to get the sine of 5 degrees.

So you'd need a ruler .10" thick, 1" from the edge to get a 5 deg back bevel.

I think about this stuff when I'm sawing a tenon shoulder. If I loose the line by .010 over 2" I figure I'm off 1/4 of a degree.

Anyway, don't laugh at me.

Adam

Don`t laugh?

Bob Hackett

>It would help if you could find a decent hat.;^)

MB

Re: Back bevels of just a few degrees

Paul Kierstead

>Actually, that is pretty handy. I got the sin/cos of the 'major' angles ground into my brain years ago, but never really though to stick 1 degree in there. Though woodworking would be a lot easier if it were in grad...

Well,

Bill Houghton, Sebastopol, CA

>I guess thinking about the sine of 1 degree being 0.017 is less distracting than thinking about how putting beer in hot hide glue is a waste of good beer.

Re:But "DID YOU INHALE?"

kevin French, Antrim NH

>If you did, I don't think it counts as a waste.