Hi all-
I’m a ‘closet’ carpenter with big ambitions :-)… I’ve got about 30 windows that I’m trimming out and 12 or so doors. This was a delead project on my house and we decided to rip and replace. I’m having custom molding cut to match the original 100 yr old molding including stool and aprons. I’ve been reading various procedures on how to get that 45 deg miter done and there seems 2 approaches.
1) cut piece by piece, test fit, cut, repeat, nail.
a. seems like this will take forever, and I fear gapping on those miters once winter cold sets in.
2) assemble on a bench as a unit using biscuts to hold the miters.
a. This old molding is pretty thin… I worry that my biscut cutter will be to thick and will not leave enough meat on the molding. Do they make thinner blades and biscuits?
b. What happens when the preassembled unit lines up on the window and the lower legs don’t run parallel to the window/door sides? Or is this not really a concern?
And finally, I’m getting tripped up on the terms used when nail sizes are recommended… for example in a FineWood working article, they recommend 6d or 7d finish nails, which I understand to be 2″ and 2.5″ nails. My nail gun can hold those lengths but they are 18 gauge nails… am I good to use 2 or 2.5, 18 gauge nails?
Sorry for what are probably really basic questions! But I love challenging myself with this stuff and learning.
Replies
How long will the returned portion be? For the short one's, say <1" or so, I've had no issue using just glue and spring clamps 'til the glue sets up. Anything longer for a built up gothic looking head casing I'd nail. Any nailing in the return I use brad nailer.
Use whatever gauge nail that won't split your wood. Different woods act... differently. Softer woods you can use a larger gauge nail. Most everything I shoot is 15g. For flex trim use the smallest gauge for the required length you can find. (15g has always gotten me call backs for splits on the flex.) If you're shooting through plaster I've had better luck with the 15g.
For length, long enough to engage the solid material beyond.
1/2" DW (or whatever your wall board thickness is)
+ 1/2" to 1" into the framing (studs/headers) (longer nails & you risk penetrating wiring /plumbing) (my idela is somewhere between 5/8" & 3/4")
+ the thickness of the trim material.
= ~Nail Length
As for bench (#2) Vs build up (#1) do whatever is quickest for you. I prefer #1 to avoid confusion & errors incurred on the trip between bench & trim loc.
This old molding is pretty thin...
What species are you using, and could you supply some more information about the cross section? How thick, how wide, what profile? All this will factor in to determine the "best way" to do your work.
Since you're working in an old house, I would definitely suggest cutting each piece to fit as opposed to pre-assembly on a table. You can almost guarantee that lots of your windows and doors will be somewhat out of square; cutting each piece one at a time is the only way to really compensate for that.
What I usually do is make a number of "try" pieces, each about 24" long. (It's critical to use a piece that's long enough to get a true read on the window or door -- short pieces just don't work.) Cut natural 45-degree miters on one pair, and hold them up to the window or door corner you're working on. With a little practice, you'll be able to eyeball the true miter angle needed. Until you get good at the estimating, I'd suggest making some additional "try" miter pairs at, say, 46 degrees, 44 degrees, etc.
When doing softwood miters, I'll typically glue and cross nail them in the fat, outboard portion of the miter, using an 18ga gun with maybe 1-1/4" nails.
When nailing the casing into the framing, I like to use 15ga x 2-1/2" nails. When nailing the casing into the edge of the door jamb, I might use 15 ga x 2" nails, or maybe a 16ga or even 18ga -- it depends on the inboard edge of the casing. If the inboard edge is very delicate, the heavier nails are more likely to blow it out or cause excessive dimpling which will just make for more filling work when it comes to finishing. On the other hand, the thinner gauge nails are more prone to "shine".
To answer your question about biscuit joining the miters, I've tried it and it didn't work for me personally. Other people like it, however. I've found that I don't get good, consistent alignment between the two pieces and I just have to end up fighting the biscuit. I'm sure lots of this is operator error. But for me, I've found that gluing and cross nailing the corners works well and allows me more wiggle room to get the joint just right.
Each window, even new windows, will be a slightly different size. If you want the fast method, build them all the same on the bench. If you want better results, build each frame to match the window, which won't necessarily be square or with equal sides.
Also, the way in which the trim mates with the wall will vary all around each window so it's actually much easier to get the best results by piecing the trim on.
The time it takes to piece on trim depends more on how good you get at dealing with trim-wall and trim-window fitting.
I've seen many guys prebuild casing and spend any time savings trying to get it to fit correctly. The end result is poor fit and zero time savings.
If you don't have the experience to know, you should piece it on.
Beer was created so carpenters wouldn't rule the world.
What Don said is good advice.
To take it one step further, get a low angle block plane(like a Stanley O6O,12 degree). This will allow you to make fine adjustments to the miter at the window.
The perfect fit is usually a combination of adjusting the miter angle and the bevel without changing the over all length.
The plane can also help prepare the jamb.
DAVE
I have biscuited 2.5" colonial casing before on stain grade work and it made installation very easy.
That said:
I use cam clamps: http://miterclamp.com/Orders.html that close the miter tight. I also use Porter Cables Biscuit joiner with the special (small) blade and biscuits.
If you try it, make sure your casing is all the exact same thickness, as the registration surface (flat) is the back side of the casing. So the back side will be prefectly coplaner, but any variation in thickness will show up at the front miter as a ridge.
You will need to dial in the depth, making a few trial/error cuts, until the groove is centered on the thinnest part of the casing (2.5" is the narrowest molding I would try this on.).
Using biscuits does not preclude cutting the correct miter. I check all windows/doors for square prior to cutting, noting piece sizes on a cut list. (I usually use the buscuit and clamps technique when I have a lot of windows/doors, because the time spent on just one or two isn't justified, IMO.) If the miters are relatively close, and the lengths are long (say, 36" and longer) you can adjust the legs for out of square conditions. Make sure to tack the miter in place before doing so to minimize the stress on the biscuit. I have yet to have one fail, but I don't push them too far, either.
Good luck.
"I am the master of my fate, I am the captain of my soul." Invictus, by Henley.
Be careful bisquiting small pieces without clamping.
The cutter can grab the piece and throw it, pulling your hand towards the blade.
I still have my fingers, but I had a close one.
I don't know exactly how wide the 1/4"-thick "belly" section is, but that casing doesn't sound like an ideal candidate for biscuit joining.
Since you're not using MDF, cross nailing will be no problem.
I would cut each piece independently, and glue and cross nail the miters.
We just did around 50 window and door openings in my house (both sides) with 3 3/4" wide poplar casing a lot like you are describing and using clam clamps. #20 biscuits and Gorilla Glue. At the biscuit joint the casing is about 3/8" thick. No problems.
Jeff
Edited 8/17/2007 8:36 pm ET by Jeff_Clarke
In the best of all possible worlds every casing miter joint would be biscuited. In that world all the trim carpenters are masters of their domain, all the trim has been in a climate controlled house for a month and its primmed and ready on a trim rack, all the carpenters have nice compound slide saws, the homeowner is playing with Monopoly money and the contractor provides a table saw with a biesemeyer fence, a jointer and a table mounted biscuit joiner. And even in that world biscuit joining casing miters has some issues, as described above.
Forget about 18 gauge brads as your main workhorse. Wimpy nailers use wimpy fasteners because they take less energy to drive... they also take less energy to pull. The industry standard is 15 gauge, and there’s a big difference. Also note that trim gun nails have a chisel point. To avoid splitting fine pieces you need to orient the chisel to cut across and thru the grain and not split it like a wedge.
One good thing about biscuit miters is that the glue helps to seal the end grain. So just go ahead and glue and pin or trim nail the outside corner. A hand driven 1 ½ trim nail, cut from a rack, will drive it tighter than the gun can.
Cut the side legs a bit long. If the bottom fit to the window stool or floor needs correction do that, then mark the side legs at the top reveal and cut the mark on a 45 degree miter and nail both pieces all around. Cut the head piece maybe 1/4 inch long and hold it parallel with your reveal marks on the head jamb to see how to adjust the miters. Your casing changes thickness across it width, so you may need to adjust for bevel as well.
In any case, take it easy and have some fun. That’s why they invented caulk and paint.
Edited 8/17/2007 11:18 pm ET by Huplescat