I’m thinking of expanding my product line to include passage doors. For now, let’s assume we’re talking about eight foot high by three foot wide by 2 1/4” thick interior doors in paint grade.
Is using a laminated core warranted for the above example? If so, is regular yellow glue sufficient for the laminations?
I’d like to use loose tenons for the doors. What thickness and length should they be? Should a better glue (i.e. polyurethane glue or West System) be used?
If the panels are going to be made of MDF, is it advisable to glue the panels into the frames for extra stability?
Eight foot high, three feet wide and 2 1/4" thick? Whose castle are they going in?
Also, for a door that size, if the sticking is not hardwood, I recommend using a paintable veneer over a hardwood stave core on the edge of the outer rails, and at least three 4-1/2" butt hinges with 1-1/4"screws into hardwood. Tenons, top of door 2-1/2" by 5" if the cross rail is 4 to 6"wide. Bottom of door, two on each side if crossrail is 10" wide. One each side for each cross rail under 6" wide. I make my tenons at least 1" thick for 2-1/4" doors.
Yellow glue should be fine for interior doors. Urethane glue is awful hard to control/clean. I have used the Hi-pur hot glue on some of my newer projects and it grabs really good, but that can be a real bugger if you're not quick. It's also urethane and can be messy. I haven't had a failure with the yellow glue, and my doors are still swinging and looking great 6 years now in an office building on State Street, Boston. They are the same dimensions you are working with, only in solid oak with solid wood panels (extremely heavy doors).
I would use yellow glue on a 3/4" thick by 3" long tenon with copes. Try to destroy a sample - you will be surprised at how strong it is.
If you do panels of MDF, use the type that machines well. I would not glue in the panels, but machine for a tight fit thickness-wise. A rimmed panel of MDF with an added raise of solid may be the right panel type for the job, if the budget allows it.
If this is your first venture into the world of large doors, make a good sample or two, go slowly and take into account many things you might not consider important with other types of woodwork. Poplar does like to move around, so let it relax at each stage of machining, and keep your humidity and temperature the same as in the finished building.
Is poplar the norm, or would another species be more stable?
Is it necessary to face joint the core pieces before laminating them together?
What kind of clamping schemes do you use for the cores?
Contributor D, can an integral tenon be machined without flipping the piece over for a second pass? I’d like to avoid doing that, as it would seem to require that the stock all be dead nuts equal in thickness in order to have identically sized tenons. How do you handle the situation?
Poplar is the norm, but is not real stable in my opinion. Hoadley's book lists it as a big mover. Pine (sugar or Ponderosa is wonderful) or maple are better. Look for some 12/4 pine and forget the laminating.
We use an old single end tenoner to cut square shoulder tenons in one pass. We also have a 9 hp shaper set up to do the copes and tenoning in one pass.
Our planer is off by up to .025 side to side, depending on its mood. We mark all the final thicknessed parts with a face mark, and then run it all face down - plows, tenons, mortises, copes, sticking and assembly. Any unevenness comes up on the "back" and gets leveled in the wide belt on the first pass. This overcomes the variability, since all parts are referenced and machined from the same side.
Don't forget to eat your Wheaties - these things get real heavy.
I ran the mating sides through the planer, then glued and clamped. The clamps were an idea I saw from somebody's website pictures - 2 pieces of 4" channel cut to however wide you need (I made mine 12" figuring that would be the widest piece I'd need), then drilled near the ends and joined with all thread rod. Stick your wood in between, run the nuts down with an air impact wrench. I put one "clamp" deal about every 15" or so of length of board. I got the channel from a welding shop's scrap pile for scrap metal price (about nothing). I later needed some more, and stopped by an electrical supply house and picked up a 10' length of conduit support bar. It's U shaped fairly thick stuff with holes every couple inches. Just chopsawed it into the lengths I needed and all threaded again.
Another idea for cores is 1 1/4" thick Timberstrand OSB with 3/4" edgeband and 1/4" skins for 1 3/4" doors or 1 3/4" thick banded microlams with 1/4" skins for 2 1/4" doors. This is fast and very flat. Really fast if you have a heavy lumber bander.
Contributor D, tell me if I understand your technique correctly. All horizontal rails have an integral 3” tenon, which is made in one pass. (8” diameter cutter?). All mid stiles have a shorter stub tenon (5/8”?). Everything gets patterned with the same cutter, leaving a 5/8” groove. Side stiles get slot mortised to accept the integral tenon.
Finally, do you guys use stacked shaper cutters or is insert tooling the preferred choice?
You have the process right. One of our sticking/cope profiles is made with stacked carbide heads, and makes a 3/4" wide plow, 11/16" deep. This mates nicely with a 3/4" thick mortise/tenon and also creates a haunch as well as the panel plow.
PS - I'm wondering about the moisture content of those things in contributor J's post. Isn't framing lumber up around 12% MC?
A lot of this stave technique depends on your equipment. A larger shop in my area face glues 1X material into beams and resaws staves out of these with a large resaw.
Using OSB for the core of a high-end interior door stile sticks in your throat a little... I have to say they stay very straight.
You are right about the sticky throat thing. We try to do it as right as practical, and have stayed the course with solids. This builds value to the customer and is still stronger. I like nothing more than to see an MDF door or two on a site with broken stiles at the latch bore or mortise. This just doesn't happen with solid stiles.
What happens if the Timberstrand is a bit warped to start off with? Being a manmade product, I imagine it can’t be face jointed with HHS knives, so would you just make the skins thicker and face joint after the skins are glued on?
Secondly, how are the hardwood edges applied to the Timberstrand (again, the issue of running the glued up assembly through the planer using HHS knives)? Are they applied leaving a lip and trimmed flush with a lipping planer?
Bowed edge strips and skins can also cause a little bow. If your skins are bowed you can oppose the bows.
Our technique for Timberstrand cores is to glue the 13/16" X 1 5/16" edgebands on with a Maranaka thick wood edgebander. Similar to the Hess. Flush trim with a lipping planer, then wide belt sand a little. Lately we are getting close with the bander and just sanding. This method is way faster than solid staves if you are using a jointer and planer. We now have a S4S machine and are going to try a batch of solid staves just to check out times.
Comment from contributor A:
Here's a little trick I sometimes use. When laying doors flat to clamp them, all the edges recieve different amounts of pressure, causing some joints not to compress the glue (when stacking two or more doors on top of each other). I put dense styrofoam or something similar between the clamps and door edge so that they all recieve almost equadl pressure.