The Ruler Trick

welcome now I believe that the ruler trick which I've advocated for many years is pretty well known however I'm very disheartened by the number of times that I see it miss described or shown badly so I want to go and cover it today the traditionalists tend not to like it they have a habit of coming up with all sorts of spurious reasons for not doing it or for why it's a bad thing or why it doesn't work the more adventurous like the Neilson Rob Cosman Tom Fijian and Chris Schwarz to name a few enjoy using it and benefit from it I'm going to do a practical example and I'm going to take the blade out of this little rebate block plane to demonstrate whether now taking the blade out of rebate and shoulder planes is a little tricky because we particularly don't want to knock the corners of the blade so there's usually some twisting very careful lifting involved and there we have it sharpening on the bench is not considered to be good practice so I shall I shall move to my sharpening page right I'll just take my 800 stone here the tick tells me that it's flat and this is one of my lovely stones where I've glued them all together so as I can use up the last bit I'm just going to create a little paste on the stone so I keep saying this is not flat name this is just to create the paste that you see here now I'm going to pop the blade into three Neilson honing guide and I really like this because it's always the same projection for the same angle the other great thing about it is that finger pressure here is sufficient to clamp you firmly now here I'm trying to get a wire edge very near that is a small wire edge or hook or burr whatever you want to call it all the way across the blade now I shorten the projection by about two to three mil and I don't really have to measure that except that I've messed it up perhaps though well a little shorter than that clean the wheel clean the tool so as not to contaminate the polishing stone now what I have here is an oh he she polishing stone these are interesting stones because they don't need to be soaked like my old king stones here these will work just with a spray of water and this 10,000 grit polishing stone is very nice in my opinion now because I have tipped up 2 or 3 degrees it will literally only take me 3 strokes to polish the tip of this blade and they're quite gentle strokes that's the advantage of changing angle I don't have to polish the whole of the 800 bevel now I'm going to take the Ngurah and create a little bit of paste on the stone you see how it cleans away the previous metal deposits from the sharpening now for the ruler trick you don't want this paste to be too wet I don't like to find water on top of my roller that almost certainly ensures that it's going to move around so if you're very lucky you may persuade the ruler to stick in the mud but it's probably much safer to hold on to it now I use a particular kind of ruler it's a narrow ruler as you can see and it's half a millimeter thick 0.5 of a millimeter and I've done some trigonometry and when a blade is sitting propped up on the half mil ruler the angle that we impose on the back of the blade is two thirds of one degree which is really very little a lot of people want to tell me that this is a bank bevel and the back bevel is going to cause problems problems with the chip break of fit for instance and it's not so it's a negligible black back bevel and when I prepare my chip breakers I have one and a half degrees of clearance angle on the underside of the lip so I get a perfect fit no matter what position chip brake is in now here we go there is a wire edge I probably want to draw that onto the stone two or three times I don't like to trap a wire edge underneath the blade now two fingers there perhaps 20 strokes for a normal sharpening unless your blades been very abused and you notice that I go off the edge of the stone and I don't come on to the edge of the stone more than ten millimeters because if I did come very close to the ruler the angle would get steeper and steeper which I don't want so this is really quite simple quick and very effective now almost always if I have a big wire edge I will see it come off on the sponge cloth or possibly on the towel which I try the blade with if I were to see a new are edge left I would know that something had gone astray now many people like to strop but what I keep pointing out is that the grit size of the particles in these polishing stones is probably finer than most people's stropping paste I don't need to strop the wire edge is perfectly polished away and those are some of the reasons why I think the river tricks wonderful we'll try and get a close-up to show you exactly what's happening here now you've seen the little one millimeter band of high polish which stretches across the cutting edge of this blade I can really see no point in trying to polish the whole of this area as we were told in the past I'm not trying to make a mirror I'm trying to get a sharp edge now you may also have seen in the close-up but some of the manufacturers surface grinding scratches are still present just at the edge of the polished band but because the polished band is at a slight angle they've been removed by the time we get to the edge now that's very difficult to show I think you can imagine it I can see it quite clearly with my little 40-times microscope so the Polish is where we want it we avoid we avoid stiction you notice I remember when I first started using Japanese water stones and I was polishing backs they used to stick in the mud frequently and in an irritating manner and that may be one of the reasons why I started to use this technique however there is a much more compelling argument if we think of a traditional sharpening it requires the stone to be perfectly flat and the back of the tools be perfectly flat for the wire edge to be honed away and it's quite clear from the number of people who enjoy stropping as a final stage that this doesn't really happen very often the probability of honing away the wire edge is massively increased by tipping this up at little two-thirds of a degree on the ruler because the contact area is so much smaller and I find that it's very rare for me to get a sharpening failure now I think it's possible that I've come to the end but what I want to say is if you do the ruler trick correctly if you do it on a fine polishing stone such as an eight thousand or ten thousand grit Japanese water stone you will get the most stunning results you you

Channel: David Charlesworth

Views: 77,575

Rating: 4.8275862 out of 5

Keywords: Tool sharpening, Woodworking Tools, Hand Tools, Woodworking, Furniture Making

Id: nykVPKbUGTo

Length: 16min 28sec (988 seconds)

Published: Wed Nov 16 2016