Planing a Straight Edge with a Cambered Blade

now in our edge exercise you saw that the amount of blade showing was wide enough to cover the whole edge of the piece of timber now clearly when I come to a surface here this is not going to be wide enough and I take what I call a set of shavings I want to be able to travel across the piece of wood or in from each edge in such a way but I don't upset the accuracy which should be there from your machine planer I have quite often seen people planing at random and I get very worried about what's happening to the accuracy of their surface this diagram is to show roughly what happens I'll put in a pencil line about 10 millimetres in from each edge and the first shaving I take I'll put the centre of the blade which is the centre of the plane I will put it on that pencil line and go right through and it will cut a scallop from the edge clearly this is an exaggeration now I will also have scribbled with pencil all over the surface and this first shaving will remove all the pencil up to this point it tells me where the edge of the shaving is I don't have to measure this just the disappearance of the soft pencil this is my favorite soft pencil will tell me where that place is and that is the position for the center of the plane for the next shaving now you'll just see from the numbers I'm working in from each edge and if I were to see a narrow band of pencil in the centre I would take two shavings one to the left and one to the right even though all the pencil may have disappeared on the first shaving now I then may take a third shaving and I would hope to show you that the third one cuts no timber this exercise and many of my exercises depend on the fact that we're working on a component size piece of timber with a plane of roughly this length the size of the plane is roughly of the same order of magnitude of the size of the piece of wood now if I had a bench component like piece for this top which was six foot long five foot long and if I planed it hollow till the plane stopped cutting I probably have a hollow of a quarter of an inch or more and similarly you can't use the same technique for going across white board or white tops or line panels when you get on to working with these large components you must have a decent straight edge and quite a long straight edge and just to give you an example when I made benches like this with students I would get them to plane the leg hollow by a sheet of paper about four thousand Asst over about well thirty six inches maybe I've scribbled here this is an extra little point this is where I believe the Snipe to be from the thickness of my machine thickness err and I'm hoping that if I take a delicate set of shavings we may see where that small depression is you'll notice also perhaps um I don't need an advice to do this your bench top shouldn't be too slippery and at the most if I had to I might put a very thin piece of plywood here and clamp it over there out of the range of the plane just to stop things from pivoting I think squeezing timber thin timber in its length is a very bad idea so my first shaving I'm moving about 10 mil about 3/8 in towards the center and I'm going to take a shaving now unfortunately the pencils disappeared but I did feel a funny little kick happening about here and about there and I think that was something to do with the snipe now I'm going to put a few little tail tails on this edge just to show you that my second shaving doesn't take an extra amount of the long edge so my center of plane it goes onto this line here and we take that through over now I come in from the other edge Center a plane 10 mil in take that shaving take the next shaving and look mostly there's a small bit of pencil left here that I would give that to shavings one cent of there and one cent of that let's take a third virtually nothing happens now I am pleased with my experiment because this low area is caused by the fitness immersion and it's what we refer to as snipe now before I can do accurate planning to create my datum surface I would like this whole surface to be clean so I'm just going to take another set of shavings of it and I'm pretty confident but it will clean up this time ten million ten million again I will take two shavings there not much with a second and nothing at all over the third so we're now in a position to think about doing the accurate work and in a similar manner to the way which we approach the edge I'm going to just look at this and see what the straightness of length is and lo and behold there is a bump in the length now in order to do that I'm going to take a set of stop shavings [Music]

Channel: David Charlesworth

Views: 1,389

Rating: 5 out of 5

Keywords: hand planes

Id: lXvUnU-Ep7o

Length: 7min 46sec (466 seconds)

Published: Tue Jan 29 2019