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



## MrJay (26 May 2007)

Ggngngngnnngggggngnnggnngngngngnngngngngngngn! I have nothing more to say on the subject.


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## Paul Kierstead (26 May 2007)

1) Ruler Trick

and/or

2) Stop when you get too bored. Use. Next time you sharpen, do some more.

Sometimes ya gotta know when enough is enough.


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## Woody Alan (26 May 2007)

Extra coarse DMT diamond stone, takes no time and the blade will be "flat"

Alan


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## Philly (26 May 2007)

Mr Jay you are right!
Tips - try the Japanese method. Take a piece of timber about 9 inch long and 2 inches wide and put this on top of the iron. Grip it with both hands and lap away. Seems to work quicker for me.
Also try to concentrate the pressure over the first inch of the iron.
As a final method - the previously mentioned ruler trick. A bit of a cheat though... :wink: 
Happy lapping,
Philly


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## Alf (26 May 2007)

45 micron diamond paste. 'Nuff said.

Cheers, Alf


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## MrJay (26 May 2007)

Gggngngngngnnngngnngggnngngnnn.


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## David C (27 May 2007)

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.

The ruler trick is also about maximising the probability that your wire edge will be properly polished away, and massively increases the reliability of plane blade sharpening on waterstones.

It is also very useful for card scrapers as demonstrated by Chris Schwarz in a recent Popular Woodworking, in fact for most edge tools *except chisels.*
David Charlesworth


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## Anonymous (27 May 2007)

MrJay":3p26ozvz said:


> Ggngngngnnngggggngnnggnngngngngnngngngngngngn! I have nothing more to say on the subject.



Currently, Veritas planes come with the back flattened and it appears finished to about 1000 grit waterstone level - no need ot do any work on the back at all on my latest plane


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## woodbloke (27 May 2007)

David C":1muyha46 said:


> 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.
> 
> ...



David - agree here...am currently reading Vol 2 of Techniques and am impressed. Of the top of your head, can you recollect which issue of F&C the article 'From Jack to a King' came from? - Rob


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## Philly (27 May 2007)

David
Would you recommend using the ruler trick instead of flattening the back of the iron? Knowing your high standards I can't believe you would recommend that.
Cheers
Philly


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## woodbloke (27 May 2007)

Phill - from reading MrC's book I gather that on a _new_ iron the back is flattened on a* very* course waterstone (much coarser than a blue DMT diamond) so that its pretty good to start with and then all subsequent back flattening ops are done with the 'ruler trick'. Stand to be corrected if wrong but I think that's how DC does it - Rob


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## Woody Alan (27 May 2007)

I have read DC's book and learned many techniques which enabled me to learn how to sharpen, thanks David. The one thing I would contend...only through the effects of the passage of time, is that a coarse waterstone is a waste of time,* for me!*. It is impossible to keep flat, the moment you try to flatten anything on it, having learnt this the hard way. The ironic thing here is that coarse or extra coarse diamond stones are recommended for flattening waterstones, well if it's flat enough to do that why not use the diamond stone in the first place? Having now used an *extra* coarse DMT http://www.japanwoodworker.com/product. ... t_id=13103 continuous stone 10mm thick flat steel base, I wouldn't use anything else for initial preparation. In saying that if you don't have many to do, my previous method was coarse oilstone, which stayed reasonably flat and would still recommend this to a beginner. The only negative about the diamond stone is the tactile feedback when working on it doesn't feel/sound good but you get used to it.

Alan (not wishing to start debate/argument just mentioning another method which some may find preferable)


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## David C (27 May 2007)

Rob,

Issues 28 & 29 I think.

Philly,

Back flattening of new iron is very important, for bedding or chipbreaker fit. However some L-N and Veritas blades are now flat enough to go straight to ruler trick. (Which I do on polishing stone only).

I use 800 g to flatten, it is quite true that most very coarse waterstones loose shape very quickly.

Diamond paste is very effective. I have had problems with rogue grits on some diamond stones.

David C


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## Woody Alan (27 May 2007)

David said


> I have had problems with rogue grits on some diamond stones



David is this experience of a fixed in the surface rogue piece of diamond or pieces coming loose and rolling around under the blade? if the latter I also found this on initial use, and found frequent rinsing helped, I assume it will settle down.

Alan


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## Philly (27 May 2007)

David
Yes, fair enough. I am familiar enough with your methods, having read your books and seen your DVD's  
I have been making my own irons for my the planes I have been making recently. Flattening the backs of the irons IS the most boring task but it MUST be done - there is no other way of getting round it. You are only putting off the inevitable :lol: 
I have had reasonable success with a 240 grit waterstone - yes it does go out of shape quickly but it does cut quick. Sadly my coarse diamond stone is now finer than the fine diamond stone I have. They do break down too quickly for my taste - especially at the price! 
I have used the finer grit diamond pastes - maybe its time to try the coarse.
Best regards
Philly


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## Colin C (27 May 2007)

Philly 

What daimond stones have you used ?


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## MrJay (27 May 2007)

gngngnnngngnngnngngngnng!!! >:|


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## Derek Cohen (Perth Oz) (27 May 2007)

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


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## Philly (27 May 2007)

Colin
It is a Smiths stone. Real nice, worked great for a long time and now it leaves a very fine polish. But it is the coarse stone........ :roll: 
Derek
Your article reminded me of Mike Dunbars similar approach. Ally plate, lots of sandpaper. If it works.........  
And I just remembered your magnetic base tip - a brilliant idea!
Cheers
Philly


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## Anonymous (27 May 2007)

As I said earlier, LV blades come pre-flattened these days (looks to be about 1000 grit equivalent ot me). Easy way to avoid flattening and you could buy 4 blades for the price of one course DMT stone

Of course, you could ignore this advice and flatten away whilst I plane......


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## Anonymous (27 May 2007)

David C":138t9lo5 said:


> 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


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## Paul Kierstead (27 May 2007)

Tony":3pl4rs5n said:


> 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).


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## Anonymous (27 May 2007)

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


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## Paul Kierstead (28 May 2007)

Tony":289982kv said:


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



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


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## woodbloke (29 May 2007)

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


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## Derek Cohen (Perth Oz) (29 May 2007)

> 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


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## woodbloke (29 May 2007)

Derek Cohen (Perth said:


> > 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
> 
> 
> 
> ...



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


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## bugbear (29 May 2007)

Derek Cohen (Perth said:


> I posted an article on this topic not very long ago:
> 
> http://www.wkfinetools.com/contrib/dCohen/z_art/lappingBlade/lappBlade1.asp
> 
> ...



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


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## Derek Cohen (Perth Oz) (29 May 2007)

> 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


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## Philly (29 May 2007)

> 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:
> 
> ...



LOL :lol: 
Philly


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## Paul Kierstead (29 May 2007)

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.



woodbloke":3497el99 said:


> 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.


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## MrJay (29 May 2007)

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|


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## woodbloke (29 May 2007)

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


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## Paul Kierstead (29 May 2007)

woodbloke":ehc66eh9 said:


> 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.


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## woodbloke (29 May 2007)

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


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## Derek Cohen (Perth Oz) (30 May 2007)

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


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## woodbloke (30 May 2007)

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


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## Anonymous (30 May 2007)

Derek Cohen (Perth said:


> 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:


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## David C (30 May 2007)

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


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## Paul Chapman (30 May 2007)

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


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## woodbloke (30 May 2007)

Derek- even with a wide polished bevel, the angle I make on the back is 0.73deg, this is using a rule which is .45mm thick and the edge is 35mm away from the rule. I'm with David on this one as I can't see that such a miniscule bevel makes any real and significant difference -Rob


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## Derek Cohen (Perth Oz) (30 May 2007)

Hi Rob

A very low angle for the micro back bevel actually produces a _wider_ mbb. 

My point is that the Ruler Trick is fine _if_ you intend to do so each time. But, if like myself on most occasions, you hone freehand, then wish to renew the edge by stropping, etc, then it is difficult to do without some degree of dubbing the blade. For a couple of years I would use the RT religiously after each honing, and it worked very well because I only used a honing guide. I have no problem with its use in this contect. My understanding is that this is how David conceptualised its use. I no longer use it much since I can remove the wire edge by honing/stropping alone. And I prefer not to have a mbb since it is easier to "feel" for the very early signs of a wire edge if a mbb is not used.

Note - this is _not_ about getting an edge sharp. This is about the _ease _of freehand honing. It is also not about the ease of honing the first time one creates an edge (since Rob Cosman demonstrated in one of his DVDs), but about the refreshing of this edge as one works.

Regards from Perth

Derek


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## woodbloke (30 May 2007)

Derek - penny's finally dropped ....no honing guide. _Now_ I understand  - Rob


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## Pekka Huhta (30 May 2007)

Just as a side note: I do the initial flattening of the chisel/iron backs with the side of a Tormek grindstone. I'll get the back flat on the 10-20 mm area I usually flatten in a few minutes and then it's just a matter of minutes to polish the back with "fine", "finer" and "ridiculously smooth" oilstones. It wasn't easy at first, but nowdays I get them very nice without any grind marks. 

Flattening the back seems to be a cultural thing as well. Over here all the old woodworking books instruct that the back should be touched as little as possible to avoid wearing the thin cast steel on a laminated iron. It goes so far that when a very old relative looked at my tools he was astounded that although I have such a pile of tools, I have not learned myself to sharpen properly "without ruining the edges that way" - pointing at the flattened backs.

Looking at the chisels and plane irons I have got from eBay someone definitely has misunderstood "flattening the back". 

Pekka


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## woden (31 May 2007)

I've been flattening the backs of some blades recently and it really is a chore. I've went for coarse sandpaper glued to a piece of plate glass to grind the steel. One of the things that annoys me is that if you decide that enough's enough for now and move on to polishing the blade up through the sandpaper grits you've then got to undo all that careful polishing if you go back to flattening it some more with coarse paper again. Not to mention that it seems like a waste of finer paper when you're only going to be undoing it all when you go back to flattening again.

Derek, are you still using the disc sander for doing the donkey work when flattening backs as you demonstrated over at the ubeaut forums? In the end I decided to go for an intermediate speed (1425 rpm) grinder for doing the bevels but would seriously consider getting a disc sander and dial magnet to do the backs.


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## Derek Cohen (Perth Oz) (31 May 2007)

Hi Woden

No, I prefer to use sandpaper over the disk sander for the backs of blades. It is just more reliable, that is, less error prone. 

The key to using sandpaper is that you:

1. must use a long glass plate. Mine is 1 metre long. This reduces effort quite significantly.

2. Stay with a coarse grit (80 - 120) until the surface is flat. Do not get impatient and attempt to move on until this is so. This is the most important stage. Get this one right and all the rest combined take a fraction of the time to do as this one.

3. Do not skip grits as you remove scratches. Go 80-120-180-240-360-600-1200-rouge. Note that the back of the blade only needs to be flat (you can stop at 180-240 grit), not polished and it is just the 1" behind the bevel that goes up the grits.

Do it once and do it right. This method really takes little time.

Regards from Perth

Derek


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## woden (31 May 2007)

Thanks for getting back, Derek.



Derek Cohen":21oy9k2x said:


> No, I prefer to use sandpaper over the disk sander for the backs of blades. It is just more reliable, that is, less error prone.


Awww, schucks.  I was hoping you wouldn't say that as the disc sander seemed like a dream system in terms of ease of doing the job. Did you find out it was error prone the hard way, ie. a few blades got irretrievably gouged or something?



> 1. must use a long glass plate. Mine is 1 metre long. This reduces effort quite significantly.


Yeah, the piece of float glass I managed to get my hands on for nothing is 900mm long and 15mm thick so it does the job well. But when you say use a long plate are you saying that you need to run a strip of 80 grit (or whatever you're using for the initial flattening) all the way along it? If so, I take it you use 80 off a roll?

How long would you say is too long to flatten a blade this way? What I mean is after how much time rubbing on the 80 grit would call it quits if the blade still wasn't flat and opt for a micro bevel using the ruler trick?



> Note that the back of the blade only needs to be flat (you can stop at 180-240 grit), not polished and it is just the 1" behind the bevel that goes up the grits.


But surely it involves little extra effort or sandpaper to polish the full 2/3 inches (obviously no further back than the slot) or so that you've been flattening on the 80 grit all the way up to a fine polish. It's just that I fear if I reduce the distance I'm polishing down to only 1" or so the blade is more likely to lift by accident and dub the edge. Maybe it works for others but that's just my own worry.

Finally, would you ever go below 80 grit to 60 or even 40 in an attempt to flatten a particularly stubborn surface?


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