Gngnggng!!! Flattening the backs of plane irons is boring.

[Anonymous]

I would have to dispute that the ruler trick is "a cheat"!

Polishing large areas of plane blade that do no work has always seemed unproductive.

Polishing and flattening are not the same thing David. The question is about flattening, not polishing. I have built some planes lately and flat backs are very important to plane performance

 

[Paul Kierstead]

I have built some planes lately and flat backs are very important to plane performance

That might be an interesting area to explore. Let us assume the back is flat enough very near the edge that the chip breaker will snug up to it. That is a very small area. Then, you put a very very small back bevel (aka ruler trick) on the blade, making it a highly polished back for a very small distance up the blade. Does it actually matter what the rest of the back is like, assuming it is reasonable (i.e. we are talking the regular production blade, not something that has not been worked since hardening and tempering).

 

[Anonymous]

Paul

I realise I mean the side of the blade that sits against the frog, which might be the back or the front of the blade depending on BU or bevel down. With traditional bevel down, the micro polish is fine, but the blade still must be flat before applying the polish

I do find that the better the polish on the back of the cutting edge, the better the blade takes end shavings on hard woods

 

[Paul Kierstead]

Paul

I realise I mean the side of the blade that sits against the frog, ...

Ahhh .... well now, that is a different story indeed.

 

[woodbloke]

My view is that whichever way you slice it, the back has to be initially flattened to get true or thereabouts, it doesn't have to be mirror polished. Coarse grinding marks, edge burrs, rust pits (if it' an older blade off a woodie) and other irregularities need to be removed before the polishing the leading edge can be done and it don't really matter what's used as long as the back becomes flat for the first 30mm say. After that the 'ruler trick' polishes the first 2-3mm of the blade to seat the CB correctly.
Agree with Tony that the polish on the back is crucial to obtaining a superfine edge. I now use a .45mm thick rule on my Extra Fine DMT stone and the edge is polished on the 'far' side of the stone so the width of the polished section near the edge is about 6mm or so. After I've finished on the stone, I give the flat side a few strokes on the leather stop just to complete the job

The pick shows the width of the polished edged I obtain - Rob

 

[Derek Cohen (Perth Oz)]

I now use a .45mm thick rule on my Extra Fine DMT stone and the edge is polished on the 'far' side of the stone so the width of the polished section near the edge is about 6mm or so. After I've finished on the stone, I give the flat side a few strokes on the leather stop just to complete the job

Rob

My view is that the front of the bevel must be honed to the same grit as the back of the bevel. Anything less and your best edge is that of the lower grit of the two.

Regards from Perth

Derek

 

[woodbloke]

I now use a .45mm thick rule on my Extra Fine DMT stone and the edge is polished on the 'far' side of the stone so the width of the polished section near the edge is about 6mm or so. After I've finished on the stone, I give the flat side a few strokes on the leather stop just to complete the job

Rob

My view is that the front of the bevel must be honed to the same grit as the back of the bevel. Anything less and your best edge is that of the lower grit of the two.

Regards from Perth

Derek

Derek - agree of course...should have said that the honed bevel is also honed on a DMT Extra Fine and finished on the strop. Both sides of the edge get the same treatment - Rob

 

[bugbear]

I posted an article on this topic not very long ago:

http://www.wkfinetools.com/contrib/dCohen/z_art/lappingBlade/lappBlade1.asp

Short story - sandpaper on a lapping board. Do it right and the process it quick, easy and cheap.

Regards from Perth

Derek

With regards to holding the blade during this dull process, I use a simple piece of scrap with a super-wide dado.

http://www.geocities.com/plybench/scrub.html#blade

(second photo)

Gives me a grip, keeps the "centre of gravity" of the pushing forces low.

BugBear

 

[Derek Cohen (Perth Oz)]

With regards to holding the blade during this dull process, I use a simple piece of scrap with a super-wide dado.

BB

Like shavings, it doesn't exist until we see you and the blade holder together in action! How do we know that you are not making this up? :lol:

Regards from Perth

Derek

 

[Philly]

BB

Like shavings, it doesn't exist until we see you and the blade holder together in action! How do we know that you are not making this up? :lol:

Regards from Perth

Derek

LOL :lol:
Philly

 

[Paul Kierstead]

Let us assume that we are speaking of BD planes and the 'back' is the side facing up, i.e. the side opposite the primary bevel.

My view is that whichever way you slice it, the back has to be initially flattened to get true or thereabouts, it doesn't have to be mirror polished. Coarse grinding marks, edge burrs, rust pits (if it' an older blade off a woodie) and other irregularities need to be removed before the polishing the leading edge can be done and it don't really matter what's used as long as the back becomes flat for the first 30mm say.

Serious question (not rhetorical): Let us say you had some rough grinding marks, or a pit from rust 10mm back from the edge. Well assume neither has a feature which protrudes above the general plane of the area around it. What effect would that have on performance? Why does it have to be removed? I see edge burrs, since they stand up, but I don't see why small depressions not very very close (lets say 5mm) to the edge need to be removed.

After that the 'ruler trick' polishes the first 2-3mm of the blade to seat the CB correctly.

Whoa, that is totally different then what I meant by the ruler trick. I do a few very short strokes on an 8000 grit water stone. It is much smaller then 2 mm.

 

[MrJay]

Surely it depends on how bad the pitting. Hogging away an extra mm or so of depth across the iron in order to remove a teeny weeny bit of pitting would be cutting one's nose off to spite one's face.

Mostly we flatten only the first couple of inches precisely to avoid unnecessary effort and because a couple of inches is just about enough to provide a stable surface when flattening on the abrasive stone. I'd be wary going straight to the ruler trick type shenanigans because you'd risk introducing quite the little bevel by the time you'd got through all the rough stuff. Once you've got a good basic flat back then the amount of bevel you make using the ruler trick is hopefully going to be negligable.

Also, gngngngngngnngngngngnggnngngn!!! >8|

 

[woodbloke]

Paul Kierstead wrote:

Whoa, that is totally different then what I meant by the ruler trick. I do a few very short strokes on an 8000 grit water stone. It is much smaller then 2 mm

As I see it, a very narrow polished bevel produced by the ruler trick is tending towards putting a 'back bevel' on the iron, something that may not be required. In other words, if the rule used is quite thick and the distance from the blade edge to the rule is short, then a fairly steep angle on the polished bevel will result. Also this steep polished area of blade will prevent the CB from bedding down securely really close to the blade edge as some sort of gap may be present underneath the edge of the CB if it's brought too close to the edge. For me, a wide polished bevel is very easily achieved using a very thin rule and keeping the blade on the far side of the stone, there is then no problem in making sure the CB can be positioned very close to the front of the edge - Rob

 

[Paul Kierstead]

As I see it, a very narrow polished bevel produced by the ruler trick is tending towards putting a 'back bevel' on the iron, something that may not be required. In other words, if the rule used is quite thick and the distance from the blade edge to the rule is short, then a fairly steep angle on the polished bevel will result.

Ah, I did not explain myself well. I do use a very thin ruler; the key is that I use very few strokes. Since the ruler is thin and the strokes very short (and on the opposite side of the stone from the ruler), the angle is very shallow. The size is very small simply because I grind (in the sense of using the stone) very little metal away. The resultant bevel is not sufficiently large to interfere with the chip breaker, even if it is quite close. It is barely visible. This is how I understand (from watching the video) that DC intended it to be. I think he takes only a few strokes, and very short ones at that.

 

[woodbloke]

I tend to use a different approach as can be seen from the pic, the wider bevel ensures that it really is mirror polished, there's quite a lot of pressure and I use the full length of the stone, not sure that a short stroke is going to give me enough of a polish - Rob

 

[Derek Cohen (Perth Oz)]

I have been developing an growing, but increasingly strong, concern about the way the Ruler Trick is applied, according to my readings from forum members here and elsewhere.

First off, I think that the concept of David's is inspired and has a place in the strategies of sharpening plane blades (never, as hopefully we all agree, with chisel blades). This place is with blade backs that are either too pitted to be honed without resorting to a significant amount of grinding, and those blades that are warped and too out-of-flat to be much use without, again, resorting to a significant amount of grinding.

The Ruler Trick, in my opinion, is not a method for removing the wire edge, and it should not be used when the back of a blade is flat enough to hone flat with a reasonable amount of effort. Be lazy and you will condemn yourself to extra work thereafter and forever. It is not a short cut to preparing "normal" blades.

The problem with a "large" degree of micro backbevel (say 5 degrees or greater) is that it alters the angle of attack for a BD blade. Of course, at certain times we seek this deliberately, but that is, as we say, a different kettle of fish. The advantage of a higher degreed micro backbevel is that it is shorter/narrower and does not impact on the area of the blade as much as a shallow (1-2 degrees) micro backbevel, as created by a thin steel ruler. These micro back bevels, as described by David, are wider than one realises (do the geometry for yourself). And even though they are slight to begin, they extend further back into the blade than I am comfortable with when time comes to re-hone the cutting bevel. The only way that I can remove a wire edge at this point is to use the Ruler Trick again (since the back of the bevel now lies below the level of the blade back). Frankly, I do not want to do this because I prefer to strop my blades as I work (BD and BU blades alike), and I cannot do so if there is a micro backbevel (well I can, but I cannot control the angle at which I need to strop).

So, for the majority of my plane blades, I consider the Ruler Trick inappropriate. Again, let me emphasise that there is a place for the RT, but not in the situation I outline above.

Regards from Perth

Derek

 

[woodbloke]

Derek of Oz Wrote:

This place is with blade backs that are either too pitted to be honed without resorting to a significant amount of grinding, and those blades that are warped and too out-of-flat to be much use without, again, resorting to a significant amount of grinding

Derek - I agree that old and pitted warped blades need quite allot of work before the 'Ruler Trick' can be applied. However I don't have any serious problem with a wide and very shallow bevel produced after a while. I also strop the front honed bevel and have no difficulty in removing the wire edge. The pic in a previous post on this thread shows how wide my polished back edge has become but it's not a problem, the main thing is as I see it is that the CB should mate exactly on the polished back surface - Rob

 

[Anonymous]

So, for the majority of my plane blades, I consider the Ruler Trick inappropriate. Again, let me emphasise that there is a place for the RT, but not in the situation I outline above.

Derek

Absolutely. I spent about 10 minutes polishing the last inch or so of each of the blades on my LNs to a nice polish (using end grain of oak to assess the finish until I could take 6" long shavings) and will never have to polish the backs again. I cannot see a need to polish more than the last inch of the blade.

I have used the ruler trick in the past, but I would suggest, like Derek, that it should be used as an exception (blades that are badly pitted etc.) rather than the rule.

As with all things in life, a bit of effort pays off in the end :wink:

 

[David C]

Derek,

I too am concerned about the way the ruler trick is so frequently misunderstood.

It was precicesly for reliable polishing away of the wire edge that I invented it!

The band of polish on my blade backs never exceeds 2 mm wide, and has no impact on back iron/chipbreaker fit. The angle is 2/3 of a degree which has no significant effect on effective pitch.

It works brilliantly for alll edge tools except chisels.

I find it significant that it is promoted by both Rob Cosman and Chris Schwarz.

David Charlesworth

 

[Paul Chapman]

I think it is also important to find a honing technique that you are happy with. At our recent get-together, Rob, Newt and I were playing about with different planes. Clifton for me, Norris and Calvert Stevens for Rob, and LN for Newt. Our honing techniques are also slightly different. I use an extra fine DMT stone followed by a leather strop with jewellers rouge and Vaseline, but without the ruler trick. Rob uses the same but with the ruler trick. Newt, I think, uses a DMT extra fine and now also a ceramic stone (not sure whether he uses a strop as well). On some very difficult wood with interlocked grain, all the planes produced outstanding results with no tearout. Our honing techniques are slightly different, but the results are equally good - and that's what matters

Cheers :wink:

Paul