The Paul Sellers Knifewall Technique

[Music] I love telling people about the knife wall I've used the knife wall for decades now and I love it it's so improved my woodworking when I realized what I was really trying to do was establish a wall made with a knife that cross fibers in preparation for joinery where I would cut the shoulders cut the dovetails down to the shoulder line I wanted the most perfect crisp clean edge that I could ever get and when people previously described the mark that I make with the with the knife as a marking knife or a marking I didn't feel like it was enough I saw more often than not that it bruised the wood what I wanted to emphasize the importance of severing the fiber so for me the cross grain cut that goes into the shoulder of a tenon is so critically important that I always use a knife because it's cross grain that means that the the strands are going along the wood this way along the long axis so if this is a tree growing the strands these cells are growing upwards they've got to be cut because they're a bit like rope if you imagine like rope so if I was making a tenon onto this piece of wood like this let's say I'm just gonna rough out a tenon this will give you an example of where I'm running my knife walls too there's one side shoulder lines all the way around I don't have to go all the way around in this case but just to give you an example I would be taking off these two sides they would be the cheek so in this case this is where my knife wall comes in I go right onto my cut line there and I make a wall that goes across the grain like this with a super sharp knife this is a Stanley folding pocket knife it's one of the best knives I've ever used if not the best it's got a double-sided bevel so when I'm pulling my knife across here instead of going vertically I slightly lean it to one side and that gives me a vertical cut because I'm compensating for the bevel that's so important so two or three passes however many you want go into this corner here go down to this one here flip over and do the same from this face here and what we've got is something that separated the surface fibers so that's the knife wall we go all the way around I'd go on this face to so what do I do now I go into my vise and this is where I'll make a very deliberate pass with the chisel here so I'm going into that knife wall now you start seeing why it's called a knife wall now because when I take away those fibers I've got a very definitive step down and in that step down is where I place the saw and just rub that soft tight up against the knife wall and I get the crispness that I want not only on the surface corner here so I've got no tear up zero tear out here but I get no tear I got the chair out on the waste wood but none on the good wood on this side so that's perfect for me that's the knife wall that's what the knife wall gives me so shoulder lines for Tenon's shoulder lines for dovetails it's the same thing what I'm going to do now is take this piece of wood and if I was making a dado so this would be the bookcase joint I place my piece of wood I'll mark it with a pencil to get my rough lines so let's go ahead and put a couple of lines on here put your second piece of wood on here that's going to give you a rough mark for where this is going to go so I've got my housing dado going here however deep I want to go let's say in this case we're going maybe quarter of an inch deep something like that so we make a line make a line and then we've got these pencil lines pencil lines are not very definitive so we start off with the knife right on the first cut line not the second one at this stage we'll do that later this goes here a light pass enough pull I've established a very shallow knife wall once I've got that I go all the heavier and now I can go as heavy as I like again I've established the knife war very important for me because what does that mean it gives me the accuracy I want it gives me the precision I want to cut a perfect joint and to get the Christmas between the two components so now again I can go down with my saw like this right up against that knife off and cut or I can go on the bench top with my chisel hammer and I can chisel down in the knife wall right up against that knife wall and I get a really crisp clean sharp corner back in the vise for safety and then I come in this way when muscle that's in or use your chisel hammer chisel out that waste wood and what I have is a beautiful crisp clean line if it's not crisp if I've moved off with my chisel I can go back onto the knife wall pop it with the hammer and I've got the Christmas that I want once I've done that I go back in here bring my knife right into the corner almost as though I'm reaching underneath the corner there's my exact position flip this so I can put the bevel on the waste wood so my bevel from my knife is now on the waste wood pull the knife wall across here again I've got that knife wall chisel into the surface fiber like this angling matches or and I've got the exact position I want whether I saw or sharp I've now got my second knife wall in position and I've got the exactness that I want so that's my knife wall for those procedures there but what about I've got this long piece of wood it's 7 feet long and I only want three foot six split it in two what I'm going to do is go directly with a knife wall this time so I go in here and watch this this is a trick that I've used throughout my working life I pull the knife wall across compensating for the bevel so I have a perpendicular cut in the wood and then watch what happens here I'm going to move over what I think is close to the saw kerf the thickness of my saw with the teeth protruding each side pull the second wall so I've got two walls there I pull the second wall like that over right onto that far corner go into this side like this and I'm going to put that wall onto this eye or those walls both of the walls this is my crosscut method I don't have a chop saw I don't use one actually but you could use one but this is the hand tool method for cross cutting your piece of wood getting the kind of Christmas that you need so these knife walls are not just guidelines for the saw and the chisel they're the guideline also for other perfecting of the cut that you might want so you can cut in between there I'm just pulling a shooting board in because I use it as a as a bench hook to cross cut with now I take my saw and I'm right in between those two sections of wood now I've got my knife wall on either side and these fibers just clear themselves out because that opening cut is removing the sawdust right in between dropped my hand here I'm following in the knife wall on the edge and that now is guiding my knife cut my saw foot on the other side as well so now my six foot piece of wood is now two three foot pieces of wood let's take a look at what we got what we have is I've got a knife wall here I've got a crisp clean line and I have a fraction of wood on the other side I've got the same on this side can you see but what I don't have I have no torn fibers and that's important no torn fibers and no torn fibers on this side what's the next step this is where I start to use those two knife holes that I can see on either side I'm going to plane this end grain free the free hand like this so I take my plane and I'm looking for the sole of the plane registering against the knife wall on this side see if I can show you what I have is perfect this is perfect alignment here it's still inclined up to this side so I have a little step down let me put this here now that this is out of the way I come in from this side in a circular motion and elongated elliptical movement like this and I'm again I'm looking for my knife wall a little bit smaller there and what the knife wall has told me is that I'm dead square across so I have no step down anymore I take my square I can check myself here I've got dead square so that's one way and the other way is to bring in the shooting board again if you want to use one of these they're fine they do help I've got my knife wall on here there and I can cut to that I can use my plane to trim this up but I'm not actually using the shooting board to guide me so much as the knife wall just let me put a little bit more set on here so I check myself to see how I'm doing I'm right on my knife wall here a little bit more maybe let me just set this a little bit deeper but this is a wonderful way to make sure the ends of your cells are nice and straight and square so there you have it this is the term that I coined years ago knife will keep it with you it's yours for the rest of your life use it for the accuracy use it because people will understand what you're talking about it's a perfect term knife wall did yours though [Music] you

Channel: Paul Sellers

Views: 68,790

Rating: 4.9602737 out of 5

Keywords: Knifewall, knife wall, hand tools, paul sellers, woodworking, DIY, workshop, joiner, carpenter, craftsman, crafts, furniture, joinery, hand tool woodworking, hand plane, dovetail joint, Paul Sellers (person), woodworking tips, woodworking tools, woodworking techniques, woodworking techniques and tips, woodworking knife

Id: 9iQ1-kuQ1qY

Length: 12min 26sec (746 seconds)

Published: Tue Jun 11 2019