I am making a cabinet door approx. 6ft x 2ft with a central rail. I have cut all the mortise and tenon joints and assembled it to check on how it fits together before grooving the frame for the ply infill panels. Unfortunately I find I have a slight twist in the frame and wondered if you have any tips as to how I rectify this before I get to the gluing up stage.
This can happen from time to time and especially if you are unaware of certain critical factors. Here is my punch list for procedure in making doors. They are steps if you will, because door making is a lot of work and especially so by hand. Of course the problems telegraph through the work whether you use hand or machine methods. To end up with a twisted door is frustrating. It’s not always too late to adjust things but it can be.
1) The material itself must be dry and dried to try to match its estimated moisture content in the environment it will live in when done. Not so easy. The reason for this is that moisture exchanges can cause wood to absorb moisture at differing rates and cause twist after construction. Drying to around 10% is a good maxim. Working in an environment that’s dry is ideal.
2) Planing stock dead flat and out of twist (even minute twist) is imperative. The reason for this is that you will cut mortises parallel to the outside faces of the stock and so the mortise holes will be conformed to the twist of the door stile. So too the rails with the tenons. If just one rail is twisted it will fight the others and the stiles and can cause slight twist.
3) Tenons out of alignment with the run of the rail. This causes twist. Check that tenon face is parallel to the surface of the rail on both sides. I use a router set to the shallowest point for this. Press the hand router down on the rail face and move across the tenon face checking the cutter against the face of the tenon. If you don’t have a router, drive a nail through a board until it touches the high point and check it with that.
4) Check the shoulder alignment; that the shoulders are dead square from side to side. if there is a variance in the shoulders and you clamp them tight, this too can cause twist, even if it is just one shoulder that’s out.
5) And this one is less easy. Check the mortise holes for parallel to the outside face. The easiest way is to cut a piece of wood the thickness of the mortise, insert it in the hole and use a straightedge on the outside face of the stile to see if in fact your mortise hole does align parallel to the outside face of the stile.
6) And my last consideration. Sometimes the surface you clamp on is twisted or the clamps are not properly aligned. This can clamp a frame in twist.
Some of these issues are fixable and some not. Sometimes you can glue up the door and then plane the twist out, but this always has a compromise somewhere as something has to give. Alignment issues on the tenons or mortise holes means that when you pare them into alignment you have lost some wood somewhere, which must be replaced somewhere else by cutting shims to suit the flaw.