Page 1 of 4 1234 LastLast
Results 1 to 15 of 58

Thread: Only one mortise chisel?

  1. #1

    Only one mortise chisel?

    Iíve seen it suggested by several woodworkers that you can get by with a single mortise chisel, e.g., 1/4 or 5/16. Iím interested in building shaker style furniture, and there are many 1/2 mortises. Many tables have a 1 1/2 leg, so that would be a 1/2 mortise using the rule of one third. That seems so common to me that Iím confused why some suggest that you only need one chisel? Are they going over the mortise twice, as in one side with the 1/4 and then the other side? Or do you just cut an undersized mortise bc 1/4 is strong enough?
    Last edited by Jason Sellers; 05-26-2022 at 9:28 AM. Reason: Add info

  2. #2
    Join Date
    Sep 2007
    Location
    Longview WA
    Posts
    25,011
    Blog Entries
    1
    There are a lot of different theories proposed in woodworking as in other endeavors.

    In some circles folks suggested instead of the 1/3 rule for M&T sizing using the 1/2 rule. The M&T would be half the width of the pieces used.

    Some suggest all planing work from scrubbing to jointing and smoothing could be done with a single plane. For some it is a #4, some like a #5 or a #7.

    For me one vehicle, a pick-up truck, is all that is needed. Others like to have multiple vehicles from sports car to SUV.

    Cutting a 1/2" mortise with a 1/2" chisel will be easier than cutting it with a 1/4" chisel.

    IMO, the 5/16" mortise chisel is so common because 4/4 lumber probably measured in the 15/16" range when surfaced.

    Narex mortise chisels are economical when they are not "Out of Stock."

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  3. #3
    Quote Originally Posted by Jim Koepke View Post
    IMO, the 5/16" mortise chisel is so common because 4/4 lumber probably measured in the 15/16" range when surfaced.
    Thanks, Jim. But I guess why Iím confused is that some, e.g. Chris Schwarz, say that a 1/4 or 5/16 chisel is all you need. I understand that 4/4 is a common size, but arenít legs sized 1 1/2 and up also a very common size? Particularly for mortises, arenít those typically seen in table legs which are thicker than 4/4? So then why the 5/16 suggestion?
    Last edited by Jason Sellers; 05-26-2022 at 10:26 AM. Reason: Add info

  4. #4
    Join Date
    Apr 2015
    Location
    New England area
    Posts
    489
    Quote Originally Posted by Jason Sellers View Post
    I’ve seen it suggested by several woodworkers that you can get by with a single mortise chisel, e.g., 1/4 or 5/16. I’m interested in building shaker style furniture, and there are many 1/2 mortises. Many tables have a 1 1/2 leg, so that would be a 1/2 mortise using the rule of one third. That seems so common to me that I’m confused why some suggest that you only need one chisel? Are they going over the mortise twice, as in one side with the 1/4 and then the other side? Or do you just cut an undersized mortise bc 1/4 is strong enough?
    I generally think of the famous "1/3 Rule" as applying to the rail and not the leg in the example you've cited (there are exceptions!). If you chop a half inch mortise, you're going to be cutting a whole lot of barefaced tenons on your rail stock, or have shoulders lacking in enough depth to do their job. You really do need four shoulders for rack resistance, and cosmetically to cover any bruising of mortise arrises. If you're rail stock is to be almost always 7/8" thick, then you'd want a 5/16" mortise chisel, a 1/4" chisel for 3/4" thick rail stock. When people drag a piece of furniture across the floor when they move it, and they will, the shoulders at the top and bottom of your rail tenons become crucial as the legs are frankly being put through hell. Happily, these shoulders don't depend on rail thickness per se.

    If you plan to make large tables you're probably going with through mortises which will be bored out and pared so the selection of a mortise chisel is moot -- they are not made that large. You use regular bench chisels to clean up after the mortise waste is drilled out by power or hand, whichever you prefer. These are more an exercise in timber framing than they are cabinetmaking.
    Last edited by Charles Guest; 05-26-2022 at 10:48 AM.

  5. #5
    Join Date
    Feb 2020
    Location
    Camarillo, CA
    Posts
    204
    I only have a 1/4” mortise chisel. If you mostly make cabinet/side table-sized things, that is usually the right size. When I make larger mortises, I just use a bench chisel that is the right size.

    I would always use a chisel sized to the mortise. If you are just making a few, a bench chisel works fine. If you are going to be doing a bunch of pieces that require bigger mortises, then it may be worth getting a mortise chisel specifically for that size.

  6. #6
    Thatís also been confusing me. In some places, I see itís 1/3 of the mortised piece, and in other places, 1/3 of the rail! I guess it makes most sense for mortised piece though, bc you wouldnít want thin wallsÖ

  7. #7
    Join Date
    Jun 2005
    Location
    Shorewood, WI
    Posts
    884
    Think of it this way: if a mortise is much more than 1/3 the thickness of the thing you're putting it in, the walls begin to get thin enough to be weaker than the tenon and might compromise the strength. If the tenon gets much less than 1/3 the stock thickness, it gets weak enough that it may compromise strength. So I'd think of a tenon 1/3 the stock thickness as a rough minimum, and mortise 1/3 the stock thickness as a rough maximum. Very rough, as 1/2 seems close enough. You are fine as long as both tenon and walls are large enough for the strength you need.

  8. #8
    Join Date
    Apr 2015
    Location
    New England area
    Posts
    489
    The chance that a mortise wall is going to blow out is remote as long as you're not mortising where the grain is running wildly off the edge. Stock selection is always key. The chance that the system of rails will be subjected to racking is almost assured. You need shoulders. I'd rather have a rail fail than a leg. A leg might have all sorts of things running into it: aprons, drawer blades/drawer rails, lower rails. A leg could carry six or eight tenons (of course with corresponding mortises) of varying sizes, easily, depending on the piece of furniture. If you'd rather have that fail than one of the rails you'd be completely bonkers. The fatter the tenon, the bigger the chance you induce failure in the leg if something catastrophic happens.
    Last edited by Charles Guest; 05-26-2022 at 11:41 AM.

  9. #9
    Many people prefer to use one tool for everything and this is their choice but as Jim pointed out there are different approaches.
    IMO it really depends on what type of work you do. You can get by with a 1/4", or 5/16" chisel but when you move away from standard 3/4 stock into heavier timber or larger M&T joinery, you really need the start using larger chisels. When your mortises are 1/2", 3/4" or more, you will appreciate a larger chisel for many reasons.

  10. #10
    Join Date
    Apr 2015
    Location
    New England area
    Posts
    489
    Once you're past 1/2", you're looking at 'registered' or basically straight-sided firmers and not mortise chisels that are thicker than they are wide. A mortise over 1/2" wide is really a candidate for drill-and-pare.

  11. #11
    Quote Originally Posted by Jason Sellers View Post
    I’ve seen it suggested by several woodworkers that you can get by with a single mortise chisel, e.g., 1/4 or 5/16.
    Well, in theory, a skilled woodworker could build the USS Constitution with nothing but their grandfather's jack-knife, but that doesn't mean it would be enjoyable or smart

    You could get by with only one size mortice chisel if you only make one size mortice or only make a few mortices here and there. If you make a lot of mortices and in a lot of different sizes, you probably would want more than one size of mortice chisel.

  12. #12
    Quote Originally Posted by Jason Sellers View Post
    I’ve seen it suggested by several woodworkers that you can get by with a single mortise chisel, e.g., 1/4 or 5/16. I’m interested in building shaker style furniture, and there are many 1/2 mortises. Many tables have a 1 1/2 leg, so that would be a 1/2 mortise using the rule of one third. That seems so common to me that I’m confused why some suggest that you only need one chisel? Are they going over the mortise twice, as in one side with the 1/4 and then the other side? Or do you just cut an undersized mortise bc 1/4 is strong enough?
    A Shaker table would have legs about 1 3/4 square and have mortises that are about 5/16 wide and 1 1/2 inches deep.

    A Shaker cupboard door would have stiles and rails that are about 7/8 thick and have usually through mortises that are about 5/16 inches thick.

    Paneled doors that have mouldings on the frame members often do not have the mortise centered in the stile.

    I have six mortise chisels, 1/8 to 7/16 by sixteenths, but I would encourage you to buy a single mortise chisel and learn to use it well before buying more.
    Last edited by Warren Mickley; 05-26-2022 at 12:11 PM.

  13. #13
    Join Date
    Jan 2007
    Location
    Michiana
    Posts
    2,436
    Quote Originally Posted by Jason Sellers View Post
    I’ve seen it suggested by several woodworkers that you can get by with a single mortise chisel, e.g., 1/4 or 5/16. I’m interested in building shaker style furniture, and there are many 1/2 mortises. Many tables have a 1 1/2 leg, so that would be a 1/2 mortise using the rule of one third. That seems so common to me that I’m confused why some suggest that you only need one chisel? Are they going over the mortise twice, as in one side with the 1/4 and then the other side? Or do you just cut an undersized mortise bc 1/4 is strong enough?

    I have two, a 1/4" and a 3/8". I'll usually focus on what size the tenon stock is and use the 1/2 rule. A 1/2 inch thick table apron gets a 1/4" mortise and tenon. If it's a 3/4" thick apron, I use a 3/8" mortise and tenon. 5/16" would work for both I suppose.
    Sharp solves all manner of problems.

  14. #14
    Join Date
    Feb 2004
    Location
    Perth, Australia
    Posts
    8,434
    I mostly use 1/8" or 3mm, 1/4' or 6mm, and 3/8" or 9mm.



    Regards from Perth

    Derek

  15. #15
    Thanks for replies, everyone. There are lots of other threads answering “what mortise chisels do you use” so I want to be clear that I’m asking something slightly different.

    I’ll try and rephrase it: Why do woodworkers like Chris Schwarz say that all you need is a 5/16 mortise chisel when table legs 1 1/2 inch are common, and you should size to 1/3 the width of the leg, I.e., 1/2?

    One person said that the mortise should be sized to the TENON stock, so in that case, it would make sense that you could get by with 5/16.

    Another person said that in Shaker furniture, they would use a 5/16 in a 1 1/2 leg. So that makes sense too.

    If both of those people are correct, then I understand why Chris Schwarz would say that all you need is a 5/16, but please correct me if I’m wrong…
    Last edited by Jason Sellers; 05-26-2022 at 2:22 PM.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •