Cutting Compound Angled Mortises

[John TenEyck]

A few days ago a question was asked on how I cut compound angle mortises with my horizontal router mortiser. Why might you want to do that? Well, if you make chairs the rail between the front and back legs is often at a compound angle where it meets the legs. Typically the rail angles out and up where it meets the back leg, for example. Here's how I would handle that.

The end of the rail is cut to whatever compound angle is needed. Let's say the rail angles out at 5° and up 2° where it meets the back leg. OK, first I cut off the end of the rail at those angles.

https://lh3.googleusercontent.com/DJr25vmT4DhBAUEdtAd5WPy-m20xYzvRKeR-G4o6olo6Vu1ylrElfko21RmFty3fJyyryvVuazFIkIMkmSuUzp scb-1Tb64tvlctU6mic8iHlsBOy7G3kxwgXStI6Bw9PcI0Jk-2nUIuRaLcbO1HkQBM9u2YT7-OsMBACcPNxWHJOjseY_GfbGNaS8AtwXpKJYK-FBZlENgexvvpqJHeoxHUcX-QQFFQY2Jd7r4IuwqNUq_vZieOYMq1LVhEZcbqhII4emgvyhcyb Pe9BNbuwJ9f76Nn8GqhhjWkA4lBkvP4X85OAyhMnW7sgYgIJR5 Ll9r5I7qlusxEZZfks5Hk26asKdqERwHVEsFoQBvppjeW_ulc9 kFNFIuKI23Ht1DmVA4-SZ4umajRJrdTirkxmyIFIenQfjDDJ3ehgoiBzEQQuCPIYMl6qz 3RCnjFzBehtiCiZUByZ1PkKtBNgYJr6_-Glwa1AopQGfRfqCFR-j2Q3hXjYgvA1whhUqSey974TygJCKESu8yjWqgrR9ANwPj1q8-ILSE5inYd9ABHsHlb5XESPM9np-gNeSVtsr7QUXXp1ulguJbNgaw50FgSNPJBcZceRGO66rbe9Gal WbAInHw0Bi5PCw73buq8Zi4aalL4k0zt6jIcc94KDkRj8lsw22 l8sknmAKaC8Hlg8PDv9EW6hGt13tYyuKzOAdLp0WKyjt_EdRHU dKe5kWZpcRpwew=w470-h626-no

https://lh3.googleusercontent.com/4cYYoy8j17HHV4X9EeH8KHLwmxjTH0eNAHlAasbhJGQppdrkZ7 Q0ycctyaDy0Z0GQGTcNw5e7mzcjYIXUDv1SWMuTu2rjSsuerqP vO6lwQm3vEy-CNTwDH-NSU9GLLG0KcdtZqfjWpFmPfbEtbtyHK6xrarr1oBdSJqtYdxnU XzHfVxuWWZMngKSepB4wY5QlAsSVYBefJYaJC3712IyC8rmQCQ 5dHHim6V-CTFVnbpePg-M5WbYR7cH_gfVO2Fqq7VlaHS_rgyw_RIPXclYtgjwlodHtwEGo BIuyfw2PzTb_rDjfPjGaTm-6yZQ4F5bWEVP0eAeYPT9oyEWfwOVwpzjYSDkE8C3qC4HEdkaQw Su3cm3-ZqOUnkDjDUN0BzHTUWb2x1yn2luCy1QtIMxehciMWWa75fYl3T DAMvOwlBJCuqUg-_kOODJN9P_brTTE_oqMmuqihXCSkkX3VLp7nyEstF8h1DhuCEI TJECKit_ekIdDiwaE4pUYu2OIWn40vU-rcMFfA9i3GYFRsmJQrQMjq1z86vlV9pPtvVFPDYL3dLuNHeVaL rJWvL65rYYAjaqgF4ilmQmcAf73dQa-mWk2HWXIdu0groEGODcaud33xZYM6GpVGntP_k2XADkYfTUQ6H Mpv_bzNzr1l-VzP23xokNWUhJgMZ2Y5rrOcvzazdDxO2x2dx4Fik6XDlDRyww9 092sV8GEosepOHwAgrv5A=w835-h626-no

The table on my HRM is set to 5° and the workrest angled to 2°.

https://lh3.googleusercontent.com/ddJyHguaUSrTPcIUh68cABVMmMGiF1dW7UDCYq2O-aFvqzx3do_UiCfE2X61pDaxmif53SO--4oIXeNMIaVeV3isqyAcIR9zHiIWKoQZ_IXM-5vibq4W6CV2Cl_Yw8_B0YRLzYM6CF6r4lUyqMIYF6IaldNee_1 I3q4eb8jc3ZXKAAOizpd-joXr0sfwPAjnI7MhBDKHkEtzGfn2MsCCRLI1T8JRoMJPs0-yJwaFRmIQD5PS4Y8WboHxP0DMlfGCD1Xt7qGOvQ6p7veJ0Inx-pLfbGqC5faAsF8He6dinaTKAUgpxRiuaObdEu-hOdJX6ZKXmnKcwNyIYflzbp-RIFoX9y82H5STLx0IjZqhHez8yUfr35pS1OvBld2R8crgjztwt 0JBwxdnliYTiAZpwzJfO8UNf8lWPyYcvDt4CXbbn5eGHUy307n K_QV0_SD5YkZa0I_TtHqS2epYloPKOfWpS6zHl3vr5kn4h8ars PWY0c_kD7DiXb7DD4TTrKK-qf06Nx_VatG2raIedIR2S6Qq2JXb56udtIkRNxhY2Tp0HRnyy-b8y2f3j8Zq7ds4bprWWDDu8M1Ake-1Og5y2-eklQ_14gY8ddyGrJho5VQsQczM9LYTc4DgciWCZC0cJONZSTaD 6JO6TTLF9NTwaqjwgCul99C9RMAOVQDkxzDtVn-oYUAafYE2F0EKFbBi64AxzGFhafptcqS6I7jDtLNltQ=w835-h626-no

https://lh3.googleusercontent.com/hmxocMQAi2vK_e7raU0GTjk6UKzhbQH5rdWSIZIVgpq3AkZUCw zqEWgZDCEbvSul_Xgn5qqrxRdF6CfyFlcIM6UwIv1p6ehB-SQD3AwzNeitHIaejjyvpzGpLC0CHOTn5Xeu1hhvlHeSWxwp1LB 1oIaDHhjfN3yvcHG7QEjdOecbxQkkI4OVV8ruJBz1NTNM_L2yD rYwYxsWY6BgXbEQDFmlchCxZd-kQk8xoaO0a63yaOeMW4aXR1NJrReVL5hUFDlu_4EM5CISmvZ9u ZZ65rUPsI4Z8ER0y5r3Y8gED9x3xsSuQjNUShKpjMxxxuCB3oL Sr7EqGv_pTJg0lr1ySfSZmb5tPIyNHYYPFksYjYQEahIuM82EF 0Sh5QsLKt3DK70YG-sXnHyG82GH1ZJ3PCHarmG4v2u3XYtbpkG5gKaKx3-9p443OZYGNW7v9lf4PhRw702371W0vWOGj_yZP8c18EObLAbn_ P-XAdx0K7HFnwN2bLHcwBAmWpqa2n2MLa3_UyeDhbTpTCb-KDFEAqb-cmHavb8lAKg_UQqLlNvwtu4hje81_qqifLED6n2u2lraO0z7yC EIdXP5ZtNkk7jrCmlt4hEHjGySul6LbWk9u-ZsOOqxYo0WJxXb2m-j5INXSueBruetpyP1MNTXQJcrOvOo0NjZj-RfsTT7pdbo1STys--fNvxAxKYZct00_tQBTfoHDJ5sVl_45WbDvubNXQ=w835-h626-no

And now the mortise is cut.

https://lh3.googleusercontent.com/hjf4FfkBdLeJlvAlHjrILmqSgKdV1LV8BclhhtAFkfA734kLOI 4cEHexUJSSg8A9hmXTzQdthyELceu_x_M41KSTUnkEz3zCtKMz wL9W2Ngaj0g8zAFpiblmsunISb9LC6NCYaSRsFsx3WBatDrEmj 9pBhkS6AyfxIOSKMnA-qIlR9LfOKSuTGJ5WqGhH6v459sOUm_bGj0loNTGi8z-D4Tw1QAP7su5-sLzBCFVJxlxEWnycdA40v-QYCwLUsDk-OlCqXGS7ayBd2zUVUWzG0lL4loELYSRSZj2tgy5yzd-OOoHC0O3XTg5_pZS_gI3ay5HoMqpzQuXBhQ8tMkcSv0YuXKW-yTFHFz-1neqZYsKwxx11isZo2FPZ34ejHQXh7fpQ08sjIhrVvxVXu-gurxJMEKYlzugXKbJNtUcG3f1HMvzpRM9d4329lrut8Eaj2lya f7Ust9IR5hH4qipN-k91jIiTY6XbN6OuryxnY_PEVtvRqXAdc3j-wLGAW7a1trmJJ3Z0-L8NZrDyo9u0qhtBV2APxJlrIsvHoKdDqqtJclnpZeJvcWak3ta JMxcwxZGjAw3qbiR27D5T-_pAuC7fG3Ph0HShCs5RaPmGw671eiYnjXfWZjbJKdKZ-RA2y7y1dNlznQ9_VjVmebvNRGqIJGjysszg8o8UQSJdSYB-voMjx5rizM-j-xF8l6ii9cIc-CAYraUojf_78pFvAPiNg=w835-h626-no

With both the table tilted and workrest angled the mortise ends up exactly perpendicular to the face of the compound angle cut. But if you'd rather the mortise be parallel with the length of the rail, you don't tilt the table, you just angle the workrest. Now the mortise looks like this.

https://lh3.googleusercontent.com/njksyPrqgM3FPXtSC6qNTqcSli5zswXkbkcChRjbuQlWUBmveD exHozanmdvWgzVBtHBGHF6U6megX1ogVYrfrUMGlTgwW1kwXXN XEzMs6GqoveEiRPRSZaHs_u1p3-BHGrGzw8UWiTL9OiIlUI6JKDMezR6N8vAu3UW4ky6bEn18FoTO R8RpxdBoatezFUAfndX7pAYSl2Sc0LMNhUpL8hLw4DZ6cv_ffl E4ULAUf-WKTjKMm8vixHsAsenL46VxVPq0uYdtT96fQ3MG0GiJ3q_tz6jY cYlBHu4O0zI-jVSI5FWAHt7YiL6MOpR9N0zwgzt-yzy_9zapE3UtYJ45DIHTbAdg2phiPWXraGNk7X64_hZRZeJg_Z xag2ZvOnr9_mt5u-ZHWGdUp7NCTwAWUTyfYq2cdv3Ekm_-z9Mvef655aWotJLgJcWCojfbw_hzf3IHhQVFKM92KjsIWqPwGM 9uhJoSAMkpDO3v0zD_ZJTn_34oHvsryQUvzr6YtzJe2L2typd-d11ThUDX7wfAVZPhFmnqiQsa4VhMDF8xVm9RLZ7BhoPZfPPbD_ mA2q5BUtYmkHsXkB81q0VLPkvhzANQCm--AoIXPrQx3Ipxaopo1Ne3iORqP4z7gHkxB4FprI7kNKJj5LtLrj uBUVdoy5kAEzHe9m-vMb_v_06MN38uguA3uAdWYG1dX_R30ECs16VFdgGSr2Jo6fWhC 3WOj0mnA=w835-h626-no

If you'd rather have an integral tenon you cut those in the same way, only you start with longer parts, obviously, and you cut away material to leave the tenon rather than into the rail to create a mortise. But the principles are the same.

There are other ways to do this but I don't know of any that are easier or faster within the budget of a hobbiest woodworker.

John

[Jim Andrew]

Thanks for posting that. Way cool.

[Rick Potter]

Pretty slick, John.

A video would be even nicer. :o

[Jason Mikits]

Thanks for showing this. I don't often reply, but am very glad to see this. I know you've posted this before, but can you show the link for this horizontal router table build again?

[Brian Holcombe]

For maximum strength of the joint the ‘tenon’ side (skirt) should be straight and the mortise side (leg) should be angled. This is for two reasons, it minimizes short grain, increases the long grain in the mortise and maintains the dovetail effect created by splaying parts.

[John TenEyck]

Thanks for showing this. I don't often reply, but am very glad to see this. I know you've posted this before, but can you show the link for this horizontal router table build again?


Happy to: https://sites.google.com/site/jteneyckwoodworker/current-projects/horizontal-router-mortiser

John

[John TenEyck]

Pretty slick, John.

A video would be even nicer. :o

There is a video on my webpage for the HRM: https://sites.google.com/site/jteneyckwoodworker/current-projects/horizontal-router-mortiser It is shown with the original, non-tilting, X-table, but the operation is the same.

John

[John TenEyck]

For maximum strength of the joint the ‘tenon’ side (skirt) should be straight and the mortise side (leg) should be angled. This is for two reasons, it minimizes short grain, increases the long grain in the mortise and maintains the dovetail effect created by splaying parts.

Thanks Brian. As I showed above, you can cut the mortise (or integral tenon) in the rail either way. And the same goes for the leg mortise, so you can orient the tenon any way you like. I've seen them cut both ways but your explanation makes complete sense for integral tenons, though maybe less critical for loose tenons.

John