Back bevel

[Mike G]

I've never used a plane with a back bevel, but I understand that this is more magical a thing than Harry Potter's wand. I've had a spare hour or two today, and with a bad back was pretty limited in what I could tackle. I had a little look at some of these:

https://thewoodhaven2.co.uk/viewtopic.php?f=21&t=7029

I've always said that any plane can be made to work, but one of these, a Rapier, might have just made a liar of me. At least, I can't get it to work unless the cap iron is set back from the cutting edge by at least 5 or 6 mm. The geometry is just wrong. So the plane is about useless, but the blade.....

The blade sharpened up pretty well, but it has quite a bit of corrosion in a couple of spots on the back (or is it the front?.........the face without a bevel) close to the cutting edge. It is compatible (ie identical) to my Stanley and Record number 4 blades. I doubt it has ever been sharpened, so there is a ton of wear left in it. It struck me that this would make it a good candidate for adding a back bevel and keeping for a better plane.

I'm not one for precision geometry when it comes to blade angles, so could someone give me a ball-park figure for the angle of a back bevel? How much material do I remove? Is it just a micro-bevel, or is it comparable to the bevel on the other side?

 

[AndyT]

I've never needed to try a back bevel, but if I was going to, I'd be as conservative as I could. The more bevel you make, the steeper the effective pitch becomes. This may be useful to eliminate tear-out but it will make the plane harder to push, even in mild wood.

So I suggest you aim for the smallest amount of steel removal to get past the pitting.

 

[Steve Maskery]

HI Mike,
Gosh I feel I can almost give advice on something hand-tool related! Whatever next?

On a standard Bailey plane, the cutting angle is set by the frog, which is usually 45deg. The bevel is downwards, so its angle is pretty irrelevant. As long as it gives clearance, it does matter if it a few degrees either side of the intended 30 deg. The cutting angle will still be 45deg, because of that frog.

With a bevel up plane (yes, I know, yours is not a bevel up, stick with me, please) the cutting angle is a combo of the bed angle and the honing angle. So if the bed (the equivalent of the frog) is, say, 18 deg and the honing is done at 32deg, you still end up with a 45deg cut. The centre of gravity is lower, but thecutting angle is still 45deg. Critically, changing the honing angle changes the cutting angle.

Using a back bevel on a bevel-down plane has the same effect. If you back-hone at 5deg, your cutting angle increases from 45deg (supplied by the frog) to 50deg (as if you had a York frog installed). The higher the cutting hangle, the better it will be dealing with difficult grain, such as burrs. It will be more of a workout, in the process, as it gets closer and closer to a scraping action. I've heard of (but never done it myself) of increasing the back-bevel to create 60deg of cut. That must be like shovelling snow.

The back-bevel can be as small as you like, indeed, it should be small, otherwise you have a heck of a lot of work to do to retore it to normal.

I shall read your progress on this with interest.

PS Andy has beaten me to it by being a lot more succinct

 

[Mike G]

Thanks guys. I suspect 5 degrees might still leave some pitting, but I'll give it a go sometime.

 

[johnward]

Is it related to the Ruler Trick, invented by a well known woodworker who's name escapes me.

John

 

[AndyP]

David Charlesworth

 

[Woodbloke]

the back-bevel to create 60deg of cut. That must be like shovelling snow.

Slightly off topic, but related, some years ago my daughter bought me a little bevel down, Mujingfang rosewood smoother with a 60deg cut and once set up, it's an absolute gem. Setting it up is the caveat though - Rob

 

[Argus]

the back-bevel to create 60deg of cut. That must be like shovelling snow.

Slightly off topic, but related, some years ago my daughter bought me a little bevel down, Mujingfang rosewood smoother with a 60deg cut and once set up, it's an absolute gem. Setting it up is the caveat though - Rob

Could not agree more.

Rutlands had a range of three of those little Mujingfang 'Hong-Kong' style planes as they were called, some 15 or 18 odd years ago, in ranging sizes and they are brilliant with the 60 degree pitch. The mouths on mine are closed off very fine with a brass strip. For an inexpensive plane (less than 20 quid at the time) they are good value and very well made.
On the downside, the steel in the blade is not the hardest, but by the same token it sharpens and takes an edge easily.
They did need some fettling, particularly the backs of the blades but these little planes are an absolute gem for awkward and rising grain and take a particularly fine shaving.

Going back to the OP's original point, yes, previously I did keep a spare No: 4 blade, clearly marked as such with a back-bevel to increase the cut to approximately 60 degrees simply to deal with wild grains as an alternative to places where a card scraper would not work as well. It was not as successful as the Mujingfangs though....


.

 

[Pete Maddex]

I find a close set chip breaker the easiest solution.
Really difficult stuff my scraper plane or small parts one on my scraper shaves gets used.


Pete

 

[Phil Pascoe]

Is it related to the Ruler Trick, invented by a well known woodworker who's name escapes me.
John

It may be commonly named after him but I doubt very much he invented it.

 

[Mike G]

I find a close set chip breaker the easiest solution.
Really difficult stuff my scraper plane or small parts one on my scraper shaves gets used.


Pete

Indeed, Pete, although I tend to reach for a card scraper first.

Chip breaker.......Isn't that an Americanism? I think we have cap irons, don't we?

 

[Steve Maskery]

I know it as a back iron. The cap iron is the bit with the lever. At least, that's what I've always known them as.

 

[johnward]

Is it related to the Ruler Trick, invented by a well known woodworker who's name escapes me.
John

It may be commonly named after him but I doubt very much he invented it.

Agreed Phil. Wrong wording by me. But forgive my ignorance, are the ruler trick and the back bevel the same thing. I use the ruler trick regularly but am unable to confirm if it makes a difference or not!!

John

 

[Phil Pascoe]

Much the same thing. I think the ruler is actually no more than a honing guide.

 

[Woodbloke]

Agreed Phil. Wrong wording by me. But forgive my ignorance, are the ruler trick and the back bevel the same thing. I use the ruler trick regularly but am unable to confirm if it makes a difference or not!!

John

Without getting into a sharpening discussion, these are different things; a 'back bevel' so called is when you take a standard bd plane iron (honed say at 30deg) and reverse it so the bevel now faces up. If a miniscule bevel is now honed at the same angle that's a 'back bevel'. When the blade is returned to the plane in the normal bevel down position, the 'back bevel' cuts with a scraping action.

The 'Ruler Trick' is used after initial honing and prevents the complete back of the blade being polished; instead the blade is raised by a fraction of a degree using a thin, springy steel rule so that only a couple of mm of the back near the edge is polished.

Apologies if straying into 'egg sucking' territory - Rob

 

[johnward]

Thanks Phil and Rob - I'm unsure of the reasoning or benefit of the 2 proceedures but will carry on with the ruler trick just incase it does some good!!
John

 

[Woodbloke]

Thanks Phil and Rob - I'm unsure of the reasoning or benefit of the 2 proceedures but will carry on with the ruler trick just incase it does some good!!
John

I always use the RT and if a very thin rule is used and placed around 70mm or so (this is the width of my 3M 'scary sharp' film) from the edge the back is still (for all practical purposes) flat. If you do the sums to work out the angle that the blade has been raised by (I did once :eusa-whistle: ) it's considerably less than one degree - Rob

 

[Dr.Al]

Thanks Phil and Rob - I'm unsure of the reasoning or benefit of the 2 proceedures but will carry on with the ruler trick just incase it does some good!!
John

I always use the RT and if a very thin rule is used and placed around 70mm or so (this is the width of my 3M 'scary sharp' film) from the edge the back is still (for all practical purposes) flat. If you do the sums to work out the angle that the blade has been raised by (I did once :eusa-whistle: ) it's considerably less than one degree - Rob

I found this quite interesting, from one of the youtubers I rate more highly than most: https://www.youtube.com/watch?v=2U3Jd1oET_M

 

[Mike G]

Agreed Phil. Wrong wording by me. But forgive my ignorance, are the ruler trick and the back bevel the same thing. I use the ruler trick regularly but am unable to confirm if it makes a difference or not!!

John

Without getting into a sharpening discussion, these are different things.......

I beg to differ. The ruler thing produces a back bevel.....just a very shallow one.

 

[Pete Maddex]

I find a close set chip breaker the easiest solution.
Really difficult stuff my scraper plane or small parts one on my scraper shaves gets used.


Pete

Indeed, Pete, although I tend to reach for a card scraper first.

Chip breaker.......Isn't that an Americanism? I think we have cap irons, don't we?

Ok I will call it a cap breaker to annoy both sides of the pond ;-)

Pete

 

[Woodbloke]

Agreed Phil. Wrong wording by me. But forgive my ignorance, are the ruler trick and the back bevel the same thing. I use the ruler trick regularly but am unable to confirm if it makes a difference or not!!

John

Without getting into a sharpening discussion, these are different things.......

I beg to differ. The ruler thing produces a back bevel.....just a very shallow one.

Indeed Mike, you're correct, 'tis just that the RT back bevel and the one I described above are used for different purposes - Rob

 

[Andy Kev.]

I have a general question about back bevels as one thing has always puzzled me.

Assuming that you have got the back behind the cutting edge flat and given that you have set the desired angle with the secondary bevel, does the angle of the back bevel make any difference? Is my assumption correct that the purpose of the back bevel is simply to provide the last bit of sharpness to the cutting edge? But … if you’ve flattened the back and removed the wire by pulling with the back flat on the stone, haven’t you just achieved the ultimate age that the back bevel is intended to provide?

Or am I missing something obvious?

 

[DaveL]

The back bevel increases the pitch of the blade as it is cutting the wood. The action is approaching scraping which helps with wood with a twisty grain, reducing tearout.

 

[Pete Maddex]

I have a general question about back bevels as one thing has always puzzled me.

Assuming that you have got the back behind the cutting edge flat and given that you have set the desired angle with the secondary bevel, does the angle of the back bevel make any difference? Is my assumption correct that the purpose of the back bevel is simply to provide the last bit of sharpness to the cutting edge? But … if you’ve flattened the back and removed the wire by pulling with the back flat on the stone, haven’t you just achieved the ultimate age that the back bevel is intended to provide?

Or am I missing something obvious?

I think you are confusing the ruler trick with a back bevel.
The ruler trick gives you a tiny angle less than a degree I seem to remember where as a back bevel it 10+ degrees or more depending on how difficult your wood is.

Pete

 

[Andy Kev.]

This is where I get confused. See Steve Mastery’s post above. For bevel down planes, it all seems to be down to the angle of the frog. I have to admit that I see no difference in principle between the effect of the ruler trick and a back bevel.

 

[spb]

The ruler trick does create a tiny back bevel, but does it for different reasons and with different effects. The purpose of the ruler trick is just to avoid having to flatten more of the back of the iron than absolutely necessary to get a sharp edge, but the bevel it produces is so small and at such a small angle that it doesn't change the cutting characteristics in a noticeable way - you might end up with a 46 degree effective pitch, say, instead of 45, but you're unlikely to ever feel a difference in how the plane works.

A larger back bevel will have the same effect as the ruler trick, but also changes the cutting angle to a much greater extent so that it does make a noticeable difference on difficult grain - the increase to 55 or 60 degrees changes things much more.

 

[Andy Kev.]

Thanks. Now I understand. I’ll bear the back bevel in mind for when confronted with outrageous wood.

 

[johnward]

The ruler trick does create a tiny back bevel, but does it for different reasons and with different effects. The purpose of the ruler trick is just to avoid having to flatten more of the back of the iron than absolutely necessary to get a sharp edge, but the bevel it produces is so small and at such a small angle that it doesn't change the cutting characteristics in a noticeable way - you might end up with a 46 degree effective pitch, say, instead of 45, but you're unlikely to ever feel a difference in how the plane works.

A larger back bevel will have the same effect as the ruler trick, but also changes the cutting angle to a much greater extent so that it does make a noticeable difference on difficult grain - the increase to 55 or 60 degrees changes things much more.

Many thanks for this explanation of the difference between the two plane blade treatments. I shall stick to the Ruler Trick as it ensures a better edge while maintaining an almost normal cutting angle.

John

 

[Loghead]

I never tried the 'Ruler Trick'. I can't get out of my head the idea that introducing a back bevl as described would result in a 'knife edge' rather than a 'chisel edge' to my iron.

I believe DC used the trick to reduce the need for flattening more of the back than was really necessary.

I achieve this by keeping a stone specially for this, and I hang the plane iron over the edge, so I only need flatten about 1/2 an inch, plenty of room for the chip breaker, and it works fine for me. Naturally the flatting moves back over time and subsequent honings. This tip was given to me in the 1950s, by an old-timer, in the shop I first went to when I started. Then I went and joined the RN!

I never use abrasives in my normal woodworking. Sharp irons, and some recourse to bevel up planes have got me through so far.

Cheers

John

 

[Pete Maddex]

David Charlsworth the ruler trick leaves a back bevel of 2/3s of a degree, not wourth wourrying about.

Pete

 

[Woodbloke]

David Charlsworth the ruler trick leaves a back bevel of 2/3s of a degree, not wourth wourrying about.

Pete

I did the trig sum a few years ago and found it was even less than that if I recollect. I'm rubbish at sums though so could be way out - Rob

 

[9fingers]

A typical 0.5mm flexi rule and projecting the iron say 50mm gives and angle of 1 in 100 or mathematically

Arctan 0.01 which equals 0.6 degrees

I might not use hand planes but I can do sums!

Bob

 

[Woodbloke]

A typical 0.5mm flexi rule and projecting the iron say 50mm gives and angle of 1 in 100 or mathematically

Arctan 0.01 which equals 0.6 degrees

I might not use hand planes but I can do sums!

Bob

Yebut my 3M films are 70mm wide so it's going to be less than 0.6deg, init? - Rob

 

[9fingers]

I just plucked some numbers out of the air eg a you tube video

Angle =arc tan (ruler thickness divided by iron overhang)

Bob

 

[Mike G]

Well, it took me 2-1/2 years to pluck up the courage, but I have finally put a back bevel on a spare plane iron. I'm still experimenting with it, in particular, with whether it works with a close set cap iron, but with its very first try I was able to take a good shaving without tear-out from a piece of oak I couldn't plane with anything else. I'm soon to start on a big oak dining table, and I really want to be able to plane the top confidently without any chance of tearing out chunks. I think I may have added a useful weapon to my arsenal.

 

[PAC1]

I use a No3 with a high frog angle (55 degree) to tame rogue oak so your back bevel should be in the same ballpark. Logically a back bevel of 5 degrees should not work with a close fit cap iron as the mating surface is creating a gap to clog up with shavings, but I will be interested to see how you get on.

 

[Mike G]

I use a No3 with a high frog angle (55 degree) to tame rogue oak so your back bevel should be in the same ballpark. Logically a back bevel of 5 degrees should not work with a close fit cap iron as the mating surface is creating a gap to clog up with shavings, but I will be interested to see how you get on.

I've put the cap iron at the back edge of the back bevel, rather than overhanging it. As I was bringing a rusty old iron and cap iron back into use, I also prepared the mating surface of the cap iron, which seats well. At the moment, I can't see any difference between locating it there or a little further back.

Does your No.3 have an original built-in angle of 55 degrees, or is this some sort of special?

 

[TomTrees]

I use a regular Bailey's too, with a 50 degree honed edge on my cap irons,
open mouth as not to clog the plane, (clogging being only noticeable when cap iron is honed beyond 45 deg)
and a very fine camber on my smoother (obviously)...
as my cap irons aren't honed super steeply, i.e enough to have influence
when set further back.
If the leading edge of the cap were less than 50 degrees, the smoother wouldn't be able to have any camber at all,
so it's the bare minimum.
One can note the shaving straightening on both panel plane and smoother, when the cap iron is set correctly.

Those are the three things which need to be in sync to work,
ps, I don't see the want to file the mouth on my planes, i.e profile the area of casting where the shavings come out.
If one doesn't believe in the cap iron, and still set on having a tight mouth, then breaking that rule will have to address the above, which I've no wish to try, as I reckon it would cause extra friction,
kinda like what one may first experience when honing a panel plane's cap steeper, and still having a tightish mouth.
(very difficult to push)

All the best
Tom

 

[PAC1]

I've put the cap iron at the back edge of the back bevel, rather than overhanging it. As I was bringing a rusty old iron and cap iron back into use, I also prepared the mating surface of the cap iron, which seats well. At the moment, I can't see any difference between locating it there or a little further back.

Does your No.3 have an original built-in angle of 55 degrees, or is this some sort of special?

It was a standard from LN pre Covid. Now you have to buy a standard plane with 45 degree frog and pay extra for a high angle frog. Whether a LN high angle frog would fit other makes of Bench plane, I do not know.

 

[Sheffield Tony]

Just a word of caution - some plane irons are laminated. On a cheap Acorn #3 I played with, the hard layer is not terribly thick. Don't get too carried away with your back bevel or you might find it doesn't hold an edge so we'll.