Chopping a Mortise by Hand

let me give you some tips on chopping immortus this is one of those procedures that being done by hand can be so superior to being done with the power tool now if you have a Hall which is a mortiser which is essentially a machine that drills a square hole there fantastic and I use mine a lot however you're limited and how far in from the edge you can get they have a very shallow depth of throat if I'm having to chop a mortise in the middle of a 24 inch whiteboard I can't use a hollow chisel mortiser and the process of setting up a router to do it is more than I want to go through I could chop that in minutes with a chisel let me give you a few tips I'm gonna do one on the edge of this board so I'm putting together a frame so the first thing we want to do is know the dimensions well if you're gonna chop a hole or a mortise in this it's no good to leave sixteenth inch walls that's gonna be your weak link nor do you want a little 8 inch mortise because the tenon would only be very small and that would be a weak link so we'd go in thirds so if this is 3/4 of an inch then we want to chop a quarter inch mortise use a quarter inch mortise chisel so I'm just gonna throw some lines on here and this is the this will be the outside edges of the mortise now what I would do with my mortise gage is adjust it to the width of the mortise chisel set that in there just tighten that second cut er up until it squeezes the mortise chisel between the two then tighten this brass knob and now that dimension is the exact width of the mortise chisel so we'd come over here and we want to Center this so I'm gonna eyeball it first and try to get it close and then push it down now I've seen my mark so I'm gonna flip it over and see if they line up and they don't quite so I gotta come over just a little bit more much try it again in a different spot that looks good now you can come in there and use that to leave yourself a mark and what I don't like about this is the fact that the bevel is on the keeper side so I actually prefer to use one line and this is where I would use my marking gauge I'm going to set it down in that groove on the far side that way I'm keeping my nice square edge on the outside piece or in this case the cheek so there's my line now I find it helps if you go in here and just draw some perpendicular pencil marks off of that and this will help you orient your chisel in the chopping process now you want that on something nice and solid and this is a softwood so I could probably do this in the vise but it would actually be better off if it was up on the bench squeezed between the two bench dogs now I want to stay away from this outside line and this outside line until I'm almost finished so I'd start here at about the eighth inch mark and instead of trying to guide my chisel between two lines which I find very difficult to do I'm gonna stay tight to that line on my right and I'm going to I'm using I'm using this line to line up the chisel edge so that I know I'm not twisted one way or the other I'm also looking at it this way so that I can see plumb because if you're doing this entirely by hand you you have to make that hole go in so that the side wall is going to be perpendicular to the face so when your tenant slides down there it's not off on an angle and what you would do is chop and then you're gonna step back a little bit depending on the wood will determine how much you can take each time try to go a little bit deeper each time and what happens is the chisel the bevel of the chisel will ride and it'll push the fibers toward you and in doing that they easily sever now when you push this don't hold on like this I do it just like I would operate the bolt on a on a rifle and just push like that and that means that side walls will guide the chisel you're not pushing it one side to the other and scraping and it'll just break up these fibers and then you just keep going each time trying to get a little bit deeper now what I neglected to mention was the depth what I normally would do is take a sharpie measure off of my opposite piece how far down I want and put a line across there and usually going to be a little bit deeper because I don't like going in and trying to clean out the bottom of that mortise it's difficult it's of no value from a gluing perspective so I'm going to go a little bit deeper than what I need and you can tell at what point you you can pound a little bit harder I'm about 3/16 of an inch away from that line and this is Aspen so it's really soft nice wood to practice on and the fibers come up in little chunks it's really cool the way they break off but it's very easy to do this is not a difficult procedure holding it plum is a bit tough now once I got to this end actually I go a little bit farther but I don't want to go right to that line until my very last step that way I'm free to pry this way and not worry about going beyond where my shoulder is going to protect our cover turn that around and now we got to come back just break some of those fibers I'm down to depth just watching my gauge line on the face of my chisel which you can't see but now when I finally get close to that line what I would do is now stand this way because I want to see plum in this direction the hole or the mortise will guide my chisel now I've turned it the other way so that the bevel is now facing out and I'll just start chopping down watching my line back here push that over slightly just to break those fibers free at the bottom and then I would just eventually work my way to that back line wanting to make sure that the outside edges are nice and plumb and don't worry too much about what it looks like in there the whole idea is to try to keep that chisel from twisting if it twists and you're going to end up making this opening a little wider than you want as long as you keep that chisel so that the sides are parallel to the line then that mortise is going to be the exact width of the mortise chisel and you'll take that reference when you cut your tenon and it'll be the sacked width and you may get lucky enough so it'll fit the first time good luck

Channel: RobCosman.com

Views: 37,849

Keywords: mortise, rob cosman, woodworking, wood, hand tools, cabinetmaking, furnituremaking, tenon

Id: ipG50d_ZvBY

Length: 7min 50sec (470 seconds)

Published: Mon Mar 09 2020