Devloping My Mortise Alignment Jig

Back in the dim and distant past I found myself struggling with an issue. I’d learned to chop mortise holes parallel to the outer face by rote repetition. With non-through mortises this can be difficult to get perfection in. In my teens I pretty much mastered the technique but most people don’t have what I had in an apprenticeship. Cutting hundreds of them was part of my ordinary work. No one would do that today. Decades later I watched each batch of students struggle to cut good mortise holes if they were not through-mortise holes and even then they were somewhat higgledy piggledy.  It was a battle and disappointing for them and for me.

My early mortise alignment jig. How this changed my ability to teach students successfully.

Through mortise holes are simple because of course there are gauge lines both sides to work to. Chopping through from both faces and meeting in the middle meant that any bending could be straightened by paring the inner walls. The difficulty arose when the mortise stopped or mitred internally, forming an intersecting point governed by the size of the leg or the length of the tenon. In table joinery what often governs the length of the tenon is the distance from the inside face of the leg; putting the mortise holes too close to the inside edge shortens the tenons because the corresponding tenon is cut short as it were by the adjacent positioning of the mortise cut 90-degrees to the other. See photo’s. Short tenons can be far from ideal for some work so it’s more a question of trying to find the balance. What to do? Many of my projects, the ones I’d designed for classes to develop and reinforce skill, relied on mortise holes cut dead parallel to the outside faces. Even one degree off could render alignment to be out by 1/2″ by the time the tenon 18″ away was introduced to the opposite leg mortise. I needed something to help my students.

These doors were made using my most up to date system. Fast and very efficient for hand work.

I’m talking of something back in the dark ages when hand tool work was generally being more abandoned than sought out. That’s changed. It’s been a slow, uphill slog, but now hundreds of thousands are doing what I do to make their pieces. Back in the 1990s a new generation of woodworker began to emerge and my classes were always full. They sought the hand tool tradition but with a view to mastery of skilled work rather than a speedy outcome. What I teach today resulted from my early days teaching them. I found what they struggled with and sought answers. One thing I knew I had to do was find a way they could mortise with guaranteed results. On a personal level I had mastered the art and could do that task every time. New woodworkers and then those used to machine methods only struggled to get the accuracy they sought. Another major issue I faced with their misaligned holes was that because the tenon followed the angle of the hole, the shoulders would be presented at the wrong angle too and so would not meet correspondingly. This resultant gaps would sometimes lead to hours of awkward fettling. The thing I knew from those early days teaching was that I had to be a solution.

I added metal plates to the ones i used more frequently.

My classes were constrained by time. No student had unlimited time to spare. It was distressing if students just couldn’t get it and we couldn’t spare half a day to put things right. As with most teachers, seeking a solution to a teaching problem often means agonising for an answer. YouTube was yet to be born and even then, when it was, it was as much the primary source of misinformation then as it often is today. My agonising over two weeks led to an idea for a mortise guide and one I have more fully developed today. How did it happen?

Walking across an open field on my way to a class of 20 students, I contemplated my dilemma.  They would be arriving in an hour’s time but before I arrived at the workshop I came up with what became a perfect solution. The 20 students gathering in the workshop would become my unknowing guinea pigs. Waiting there with bated breath they wanted to learn as much as they could. I set to to make 20 hitherto unseen alignment jigs from oak. They were basic but they came together quickly and they worked.

The overall result of my mortise alignment guide combined with my hand routing system is amazing!

Since those early prototypes I have revised different elements to give them longevity and have even resolved issues to adapt them to other tasks. Combining this with my hand router techniques for surface-planing tenon cheeks I won the cause. Students since then, over 5,000 in my classes, and now many multiples of thousands online, have developed their techniques and gone on to master their cutting of mortise and tenon joinery. My attempts to give you all of the systems I have developed since my apprenticing days has become my success. Here is a video showing you the early system and the methods I used in my earlier classes. Making this quick guide for mortise hole cutting gets you in the zone immediately. Here is my current version showing how effectively this works.


  1. The mortice guide really helps with accurate work.

    However, as a relative beginner, I didn’t see myself chopping same-sized mortices regularly so figured that I’d like something more flexible, so I improvised a guide using adjustable wedges.

    I can’t seem to post a link or picture here, but look under New Old bench stool in WW Masterclasses forum and you’ll see.

  2. I watched the Mortise Guide at Masterclass, real genius. My only thing I might do is make a few of them with different sizes to make my beginners work better and much more accurate. Thanks again Paul

  3. I couldn’t find metal stock where I live so I got a brass door hinge and cut off the barrel. It already came with the holes counter sunk and made a perfect templet. I use sheets of printing paper to adjust the thickness. Works perfect.

  4. This is a blessing for me Mr Sellers. As you may recall during my invitation to attend your 2 day course last year I struggled with hand shake. Thankfully I was misdiagnosed and although my condition is no longer life threatening the tremors will continue with no chance of improving in the future. I am absolutely determined to produce a standard of work that I can be proud of and little jigs such as this has given me the boost that I needed when I had thought that repetitive joint making would be assigned to a machine. Thank you for everything you do. Al.

    1. Hello Al – I read your post and thought I needed to respond as I myself suffer severely from intentional tremor. I obviously do not know what kind of tremor you are suffering from but if it is intentional tremor, I thought I had to tell you there is help to be had for curing it. If your tremor is of another kind I do apologize for interfering.

  5. Several years ago I stumbled upon the first video and fell down the rabbit hole. Thanks for sharing all of your thoughts and experience, Paul!

  6. As always you go out of your way to share your knowledge of the Craft. I for one as I am sure so many folks appreciate all you do. I was sad to hear that you had returned to England as I had hoped to be able to get to one of your classes. I am now glad as you have give me something to look forward to on my bucket list to get back to England and take a class with you. Sir you a true teacher and we all thank you for the knowledge you have presented. I hope you have a Great 2018 and the business goes better then you expect. You have reached so many of us through the digital media and he helps a great deal. Thank you for all you do and may your Higher Power Bless You..

    1. I’m not altogether sure that I have finished my work in the USA at all. It was my coming to live in the USA that brought me to teaching and helped me slough off cultural constraints I struggled against here in the UK. It was totally freeing!

      1. Hello Paul. Happy New Year. Thank you for all you do. Your woodworking methods, knowledge, and skill have helped me become a woodworker. I have built a number of your projects and really enjoy the process. Sometimes I’m able to spend 4 straight hours in my shop and always feel complete later in the evening when I reflect upon my day’s work. Following your designs have helped me design and build my own shop dresser. I’ll post pics in the gallery when it’s completed. It got a lot beefier than I wanted but when I make the 2nd one I’ll downsize. It’s horribly out of square which lead to a lot of problems with shelves and drawers but I look forward to correcting those issues when I make the 2nd one. Plus, I’m making a design change to help with overall squareness. I really challenged myself with design. It’s basically a big hope chest with an open front to accommodate drawer space? I remember you saying “And this is how we grow.” in woodworking masterclass videos, and now I truly understand this meaning at a deeper level.

  7. Hi Paul,
    Your jig is a god send. With my impaired vision, it’s probably the only way I could cut a decent mortice. As a structural engineer, I do have a question. Why do you cut the step on both sides for the jig? You have the same offset on both sides. Cutting the second step weakens the jig and allows it to bent more. You used the jig to test the mortice fit, but wouldn’t you have cute the tenons in the rails before you started cutting the mortices and would use the actual tenon to test the fit.
    I wish you and your team a most bountiful and happy new year.
    My Best Regards,

    1. It really doesn’t bend negatively enough to affect the mortise and I have two faces to register should one wear before conclusion of all mortise work. But of course people can do as they wish and do one side if they have the added material.
      I’m glad the guide helps. What I like about it the most is that it doesn’t substitute for doing the mortise and that’s important. Otherwise why not stop being a woodworker and become a wood machinist?
      Happy New Year to you too!

      1. Paul,
        Good point. In your video, you cut a 1/2″ tenon. That size tenon would not deflect very much. My question was based on my current experience. Every mortice I’ve cut is in 3/4″ or slightly thinner material and is only 1’4″ wide. These thinner tenons are not as sturdy.

  8. I made one awhile ago. I used it a couple of times but enjoy chopping mortices without it. How long should tenons be? Half the thickness of the wood it’s fitted into?

  9. Economical – Basically a person can get a free one for each project by allowing for a few extra inches of material from which to cut the gauge from. The cost of the tools to perform handmade tenons are much cheaper than the machine options and safer. And if you don’t like making your own gauge there is sure to be a resin infused option at some point to go along with a resin infused dovetail marker 😉

    Accurate – By leaving material at the end of a board, there is support for the router plane insuring flat tenons of the same thickness; a benefit of using a single tool to layout gauge lines.

    Efficient – By cutting several rails out of a single board, a person can take advantage of a single setup.

    Learned a lot from this and one of the best techniques learned to date.

  10. For those living in townhouses with neighbours using hammer could be a problem. It’s fun to use it, but this is where we are. What you propose in this case? Boring and chiseling? What is a no noise method to cut mortises and dovetails?

  11. I have read and watched your ingenious gauge many times. Fantastic!
    I am new to Woodworking and originally watched you tube videos from various woodworkers that relied on machines. I was fascinated and thought that I needed all of those various machines to begin. A bit overwhelming and expensive. Then I stumbled across your videos and I literally fell in love with your approach, skill and humor. Hand tools are how I will proceed and I know I will enjoy every minute. The smell of freshly cut pine is magical.
    Thank you for sharing your skill and time…a true mentor.
    By the way, the individual that films your YouTube and masterclass workshops is also a true master.
    Boulder Colorado

    1. That’s Phil and Eloise. They are great to work with and they make me look better than I am really.

  12. If the initial stock is slightly longer, than all the shaping of the “tenon” could be made with the router plane supported on both sides. The extra bit would then be sawed off as the final step. No need to work with the router cantilevered.

    1. Yes, and we have shown that too, but it is not difficult to cantilever either so I just don’t want people thinking it is difficult when it’s not.

      1. Joe/Paul- lightbulb moment, cheers! If you do it this way and form the tenon first, and if you get your extra bit of cutoff measured appropriately, your cutoff is then your ready-made mortise guide! 😀

  13. Smoothness of Mortise walls and Tenon faces
    I am a novice woodworker , I’ve made a few mortise and tenon joints. I’ve cut them several ways:

    totally by hand via chopping ( Mr P Sellers way, Japanese way)

    Every time chopping mortises by hand, I always get ragged cheeks. Pine seems to be the worst. By “ragged” I mean divots in the side walls due to grain tearing out or non-perfect movements of the chisel, or crushed grain, or, who knows what.

    I’ll trim faces or edges with a chisel, small plane or file if the fit is too tight.

    How can I avoid the ragged surface?

    Best regards

    1. If you want to follow this system I put together for YouTubers here, it will train your muscle memory and reduce the ‘divots’ whilst perfect tenons with mortises of equal parity is the result.

      1. Thank you for your reply Mr Sellers.
        I am currently chopping mortises for my workbench legs. Is rhis system usable for larger mortises? It’s 90 mm deep. I am not sure if chisels will be long enough.

        1. You can use anything to align the chisel as long as it’s square edged to the wide face. Clamp it to the face, tap to align and pare down. If the chisel is not long enough because the bolster of the chisel catches you can taker a plane blade oiut and use that if it is wide enough to fit the width of the mortise.

  14. Dear Paul,
    I have both your books and i have watched your newest video making the guide using the router plane. In your book(which happens to be the photo above), two pieces of wood are used and the front one, the grain is aligned horizontally in order for the guide to be longer lasting. In your newer version(with the router), the grain is vertical. My question is this: If i make my guide using the newer version, can i make the whole guide with the grain hotizontally or is there a reason that the grain, is now is vertical?
    Thanks Paul

    1. The issue becomes bend and strength. Horizontally the part in the vise will bend and flex and could even distort with atmospheric moisture content. That said it might not too. You could make it from thicker material to resist bend. I would just go ahead and try it for a season.

  15. I am a 78 year old, very very basic woodworker, always had trouble cutting a decent mortice, until i tried your method, bingo!!!, now quite proud of the results. As said, at my age i don’t have enough time left to be skilled, but i do enjoy woodwork in my little shed, many thanks. Keith Tindell

Comments are closed.

Privacy Notice

You must enter certain information to submit the form on this page. We take the handling of personal information seriously and appreciate your trust in us. Our Privacy Policy sets out important information about us and how we use and protect your personal data and it also explains your legal rights in respect of it. Please click here to read it before you provide any information on this form.