How to Make Bridle Joints
Step1: Start by marking out the tenon by drawing a line around the entire piece of wood to create the tenon length. The length of the tenon will be the same depth as the width of your other piece of timber which has the mortise.
You must now mark your tenon width which should be around 1/3rd the thickness of the timber. Check to see if the tenon matches the closest size chisel or mortising drill bit and if it doesn’t modify the lines to match the chisel or mortising drill bit.
Step2: Now you cut the tenon and there are two methods of doing this the first being with a tenon saw. Put the piece of timber in a vice on a slight angle to create a neat and straight cut and then carefully cut along the lines.
Next put the timber back upright in the vice and mark 5 millimetres in from each end although it can be slightly more with larger tenons.
Now cut straight down where you marked to create small cut outs on both sides of the tenon, the reason you do this is to create a neat and flush joint but it also hides any gaps you may have from your mortises if they are cut slightly to wide.
The second method of cutting tenons is with a band saw and all you have to do is cut along the lines like you do with the saw.
This method is usually better because the band saw has a guide rail making the cuts quicker and more accurate. Remember to cut the tenon shoulders before cutting the rest of your tenon.
Step3: For this step you need to mark out the mortise and decide where you want to position the joint.
Next you can use your recently cut tenon as a guide for the width of your mortise and you do this by resting it across the timber that will have the mortise and drawing lines along the two edges of the tenon.
After you have the width sorted you must put two more lines in between the ones you have already drawn to create the thickness of your mortise.