I am building 13 eight foot tall doors out of 7/4 bubinga. 11 of them will be french doors with double-paned glass in the middle. Two of them will be paneled in the center with 3/4″ bubinga pieces, 5″ wide T & G in a herring-bone pattern. I am going to dowel the stiles and rails with 4 inch long, 7/8″ diameter dowels and use West Systems 2-part epoxy glue. (These are all exterior doors).
What do some of you veteran door makers think of my plan?
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sobriety is the root cause of dementia.
Gonna need a crane, that stuff is HEAVY. Beautiful too, but heavy. Good luck.
I assume dowels because it's easier? Or to minimize materials used? Obviously traditional mortise and tenon joinery (possibly pinned or pegged) would be stronger, IMO, but you have the plans.
BTW, just for grins and giggles, what's the final material cost gonna be, just for the wood? Thanks.
I like using epoxy for door glue up, but I would not use dowels. They are just not a good substitute for a MT joint. Bubinga is a beautiful dense wood that has a high extractive content which will not permit very good penetration from the epoxy., so the joinery becomes more important than on lighter easier to glue woods.
Also be sure to use a filler in the epoxy, it is too brittle without it, and it will improve the capacity to bridge gaps.
What is "filler"? Do you mean putting bubinga sawdust in with the epoxy?
The filler that I use is Colloidal silica which is a very light weight powder. For using most epoxies for glue, you should mix in at least enough to be as thick as latex paint or even up to mayonnaise if more bridging capacity is desired.If you have been sanding any of the wood of choice, you can also add some of the dust to the mix for color, or universal tints can be added.If you are buying small amounts, West Marine will have lots of good stuff. I usually buy in 5 gallon pails from http://www.fgci.com/
I like their price much better.
Okay, thanks, now here's another problem, guys:
I am drilling the holes for the dowels using a 7/8" forstner bit. 2 1/8" deep. I have made a bunch of dowels from 7/8" dowel stock. I cut them to 4", beveled the ends and cut a groove down the side. They are a tight line-to line press fit in the holes. In the past, I have used pre-made dowels for cabinets, either 3/8" or 1/2". They don't fit so tightly in their 3/8" or 1/2" holes. Maybe I should have turned down these dowels or looked for pre-made 7/8" dowels. I am thinking such a tight fit will not leave any room for glue. Plus, there is no way to "dry fit" the door pieces. I'd never get them apart.
IMHO, the joints are gonna open up on you, since these are exterior doors. Mortise and loose tenon should be used on the rails and stiles. This will give you much more glue area. You can easily mortise 2"+ deep with a router using an edge guide and a good carbide spiral bit.
I've heard of microwaving the dowels just prior to use which will shrink them just enough.Although for a project this size, no reason not to spend $175 on a mortiser.JT
I tried microwaving a dowel. (1 minute) I heard a pop in the oven. When I opened the door, I could see some moisture on the dowel. It had exploded in the middle. Now, the dowel was bigger than 7/8"
I tried baking some in the oven at 250 degrees for 2 hours. They all shrunk so they slip in the holes! Now, I'll put some grooves in them and I'm ready to go. I'll have to wait on the baking of the dowels till just before assembly. Otherwise they'll all absorb ambient humidity back to their 7/8" diameter.
I used a drill press and a forstner bit for the holes, so I think they'll be perpendicular enough. I center-punched the hole centers and made sure that the bit's center tang was right there before drilling.
I have always had trouble when doweling in getting the dowel holes perpendicular to BOTH pieces of wood that are to be joined with the dowels, AND in getting the dowel holes spaced accurately. There is no way that I would try to do a glue-up with a dowel-connected joint unless I had a successful dry-fit. I think that I would be VERY likely to end up with a bunch of half-assembled parts, and no way to either force them together without splitting one of the pieces, and no way to get them apart (the dowels by now having swollen up with the glue and jammed the joint)!
As for the dowel fit problem, you problaby have the solution in your shop... find another bit than will give you the right clearance...
When using dowels, I usually try several bits to see which one will work...and sometimes it's a speed bit...in a pinch, grind a 15/16 speed bit to the size you need. Dowels are notorious for not being to size.
That said, you are getting excellent advise from the other posters; however there is an option to M &T that I have used for several doors and a very large oak door ;It is a loose tenon joint...easy to make with a router and a 1/2" x 4" straight bit; rails and stiles are milled the same and loose tenons are made to fit...with epoxy, IMHO this joint would be very strong.
good luck... give the m & t or loose tenon some serious consideration...
silver
As others have said, I would not use dowels, go with the mortice and tenon. If you don't want the M&T to show, it is more work but you could go with a hunched tenon.
I wanted to use M & T too. I couldn't find anyone to do the mortices. I dont have a morticer. I looked into doing them with a router but the depth was not very much.
If you can afford that much Bubinga I'd think you could afford a mortiser, neh?
I had a similar job about 15 yrs ago.spent $850 on powermatic HC mortiser, kept it for 10 yrs or so & sold it for more, only because I needed the floor space-- I still miss it! Listen to Bob & Tom, they know what they are talking about.
One more thought---buy the tools, save $1000 on labor--save $ 10,000 on warranty work
I can support your use of dowels to pin the joints, because many doormakers doing big volume (Simpson, Morgan, JeldWen, etc.) have been doing this for years.