Making flat cabinet doors

[John Gregory]

Over the years, some of our cabinet doors have come out flat and others not so much. We are at the point of making the doors for our kitchen remodel. The raised panel will be MDF, the stiles and rails hard Maple. Some doors are pretty tall, up to 72". What is the best way to glue and clamp our doors to insure flatness?

Thanks,

[Mel Fulks]

If you are using bar clamps use a hammer and block to tap them flat in the clamps before applying the final pressure .
Avoid using bent clamps.

[Andrew Hughes]

Take the time to make sure your stock is milled with edges square to the faces before you cut the jointery. Use a good reliable square and don't over clamp. If you have one come out of the clamps with a twist set it aside and make a new one.

[Brian Holcombe]

Cut long tenons, as long as possible with a haunch.

I check mine with winding sticks along the rails during glue up, makes it easy to check for a clamped in twist.

[James Pallas]

Kitchen cabinet doors are the most abused in the house except for bath vanities. You usually have cabinets on outside walls. Those are subjected to cool in one side and hot moist on the other. The dish cabinet gets damp dishes from the dishwasher on the inside and than closed up. I won't talk about under the sink or the one with the heat register in front of it. Pick the best material for the rails and stiles, quartered is nice. Clamp straight with good size tenons. Hope for the best and you may get minimal movement. It's just like hoping your concrete patio will not crack. Maybe and maybe not.
Jim

[Lee Schierer]

Make sure your materials are all acclimated and at a low moisture content. As others have stated, milling correctly can eliminate many problems. Make sure your doors are flat in the clamps and they should turn out flat. Then apply equal amounts of finish to both sides of the doors.

[Tom Norton]

When I have built kitchens I tried to steer clear of doors that tall. I would split them in to 2 doors to avoid the problem.

[Robert Engel]

John,

Even with the best of preparation and wood selection, you never know what a piece of lumber is going to do in 6 mos or a year. You may want to consider doing something in a preemptive way to avoid the problem.

There is a technique I learned it from watching a Charles Neil video he calls "splining" (think its the Pie Safe series)

Basically, you make the groove for the panel very deep, to within about 1/4" of the edge, and then glue in a spline & clamp it flat. Then you make replow the groove.

The key is to use a stiff drying glue like TB3, plastic resin or epoxy.

Give it a try.

[Mark Blum]

Since you are using an MDF center panel you can actually glue it in instead of leaving it floating, since wood movement isn't an issue with the MDF. That creates a much more cohesive and stable door, as everything tends to lock in place. I built all of the cabinets for my kitchen remodel several years ago and glued in all the panels (my panels were veneer ply). Even the largest doors on my pantry (60" height) have remained dead straight with no twist or warp.

[John Gregory]

Thanks all!!!

[Warren Lake]

John people put posts and we all answer but often there is not enough info. YOu post your doors are not always flat? what does that mean flat accross the width? ir on the length you did not say later on so it sounds like the issue is there after clamping

If you are talking width then clamping on bar clamps and some are flat and some arent then its to do with your clamps or more likely the height of the wood in the clamps as you will get a different door pressure on the styles at the bottom of the clamps so you need to adjust the material height on the clamp, use the winding stick as Brian has said. I dont use cope and stick but you should still be able to get a straight door with that, that is you dont need to have a full size tennon for a straight door, sure it would help a bit its what i was taught. You dont need six months on a door if you have style issues, you can machine your material once or twice over a few days taking tension out to make it more stable but that doesnt sound like what you are saying when I hear some come out straight some dont need more info. when doors get to a certain height id like to see thicker doors. ive opened high end kitchens with a long door in 13/16 and they bend from a magnet on one end trying to hold it tight,

[Rick Alexander]

I like to use 7/8 or 13/16 R&S and that seems to help some. If I've got really big or tall doors for sure I use 7/8. Absolutely make sure you start with perfectly prepared 4 square wood - this usually requires purchasing 5/4 stock to have room to square the R&S. When I'm putting the doors together I use a solid core door I have to make an assembly table and make sure it's perfectly flat and level by shimming on some sawhorses in my shop (I don't have room for a separate assembly table all the time). I use Bessey clamps and make sure they are sitting on the clamp bars at all 4 corners laying flat on that door. Once they are clamped I can then stand them up on the door to dry while I work on the next one. I also have a drum sander to flatten after assembly which helps a lot. Still - sometimes the wood will relieve stress at some point after install - it happens.

[Scott Buehler]

The truth is that there will be doors, no matter how square and well prepared on a perfectly square and flat clamping table, that they will just warp, especially at that length. But there are some great tips given in this post. Good luck

[Don Jarvie]

I just recently made some similar size doors and can offer you a few tips. I made shaker style doors and use 1/2 plywood for the panel and had the back of the panel flush with the rails and stiles. The groove was around 1/4 inch thick and 1/2 deep. The plywood should be stable enough to keep the door in line.

I would use rough maple maple for the rails and stiles and let it sit overnight after each run through the jointer and planer. While this adds extra time it allows the wood to release. Nibble away on each pass and you should get flat rails and stiles. Also add a mid rail.

The key is flat rails and stiles. If their bowed or twisted it’s just going to make it harder for the doors to stay flat.

[Jim Andrew]

I use 7/8 material for the frames, and after gluing up the doors, let them dry and run them through my thickness sander. Helps very much in flattening doors, as well as panels.