What is the maximum size of a frame and panel door to join it with cope and stick?

[Daniel Bejarano]

Hi everyone,

I am building two set of doors, each door is 29" x 95" x 1-3/4" thick. So they are big doors. I will be using poplar. They are paint grade. The styles are 5" and starting from the top the rails are 5", 6" and 8", so they carry two panels (mdf 1/2") each. And they also carry a molding hence the idea of using just a set of male and female shaper knives that give me a cope and stick joint. But being these doors so big I am almost convinced they need a big tenon, so I am having trouble deciding how to build them strongly.

One way would be to groove the pieces first for the panel, run the pieces on the shaper to get the profile with only one knife, (so flip the pieces to get the same profile on both sides. And enlarge the groove with a mortising machine ( that I don't have but that mmmaybe could borrow) where the rails go for a big tenon that I can indeed do at the table saw. Or maybe do this step first so the mortising machine doesn't deflect when enlarging the groove for the tenons.

They are closet doors so they won't get the same traffic that normal doors get. Would it be enough using the small tenon the cope and stick knives give me, knowing that I could perhaps glue the mdf panel to the doors?

Any advice would be really appreciated

Daniel

[Jamie Buxton]

Is the panel solid lumber, or plywood? If is it plywood, glue it in. Glued in, it acts as a big gusset holding the corner joinery together.

[Kevin Jenness]

Would it be enough using the small tenon the cope and stick knives give me, knowing that I could perhaps glue the mdf panel to the doors?


I wouldn't. You can probably get away with it but using a substantial tenon will assure that the doors will hold up long term. Gluing the panels certainly will add to the cope joints' strength, but you should consider that those are large panels, mdf moves, and there will be seasonal stress on those joints.

I have built many man doors with cope/stick joints plus spline tenons using a shaper and stationary slot mortiser and I am not worried about their longevity. You can cut mortises with a plunge router and simple jig. The spline thickness can be the same as the groove or greater. 1/2" is fine on a 1 3/4" door.

Coping the rails on either face of an integral tenoned rail will require either very large shaper tooling, a stub spindle on the shaper or a custom router bit. Another way to do integral tenons is with jack miters, relieving the molding at the joints, but that is quite laborious.

[Jim Becker]

I built a door for the basement stairs at our old property using the same materials...I did laminated stiles using poplar so I could essentially do full bridle joints for the rails and stiles with huge glue area. The panels were 1/2" maple ply and I also did an applied molding for a simple profile to match other doors in the house. No shaper needed or required. That thing is rock-solid.

[John TenEyck]

Add spline tenons as Kevin said and glue in the panels. They will last as long as the house. You can easily make a jig to cut the mortises with a plug router. If you can get at least 2-1/2" deep with a 1/2" bit it will be fine.

John

[Greg Funk]

We built our house about 20 yrs ago and it includes a mix of 1 3/4 poplar w/mdf or cherry doors with a similar style. The MDF panels are 1 1/4" thick so the doors are quite heavy. I was concerned that they should have a mortice and tenon in addition to the cope and stick but the door manufacturer assured me they had built many doors this way without any issues so I agreed. 20 years later we've had no issues. The profile for the cutter knives is shown below (on the right) and you can see there is a significant amount of glue surface.

The same company also made our very heavy oak front door 44 x 100 x 2 1/8" but I don't recall whether they used an additional tenon. Because it's exposed to the outdoors that door moves a fair amount between the seasons and it also has had no issues.

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[mreza Salav]

I built 30+ doors (hard maple) for our house, 3/4" plywood panels glued in the grooves and I used mostly 1/2" dowels. Super strong and absolutely no issue after 7 years.

[Jared Sankovich]

I'd dowel the joints (as well as gluing in the panels)

[Greg Quenneville]

If you have ever hankered for a Domino XL this is your chance. I made 25 big doors and machined right through the profile for the loose tenons.

[Mark Hennebury]

Glue the panels and your good!