ripping triangular backing for crown moldings

[wdreamsmaycome]

any suggestions about which would be the safest (both for me and for my bt3100) and most efficient (read: least wasted wood) way to do this?

I am still a reasonably green behind the ears woodworker, so my first idea was to get a 2x4 and cut triangular slices off it to make four 1x1 triangular lengths out of it, however I am wondering if it's really feasible to cut a 2x2 in half.

I see everywhere I look (books, dvds, ...) that experienced people do use backing when installing crown, but I can't seem to find anywhere that actually explains how they make said backing.

Thanks in advance for any tips you might have.

[siliconbauhaus]

Do you have a mitre saw mate? Seems like it would be the safest way to cut what your after

[wdreamsmaycome]

I do have a compound miter saw, but wouldn't this limit me severely in terms of length of these triangular pieces? although it should still be ok even if they are only 12" long I guess.

Still, how would you do this on the miter? just have a long piece square to the saw and chop it first at 45 for 12" and then put it parallel to cut the two 12" sections off?

[LCHIEN]

I don't think you can make the backings you seek with a miter saw. SBH must have misunderstood your problem.

[Jan]

For small crown I just run 2x4 through the table saw. Set the blade to the correct angle. mark your 2x4 and run it through. Then set the blade upright and rip off the next length of blocking. That way every pass produces a length of blocking. I drill the blocking and attach it to the ceiling plate with screws.

Put some blocking at all the corners so that you'll have something convenient to nail to when you get there.

Jan

[siliconbauhaus]

I guess I did mis-understand, I thought you were after peices to attach to a cabinet.

[Stormbringer]

dreamsmay come,

I don't know what size crown your using, just make sure you cut the backer to allow at least a 1/4" - 1/2" space behind the center of the crown to allow for deviateions in the wall and ceiling. The first piece I ever cut filled the entire void behind the crown and did not allow the edges to sit flush with the ceiling and wall .

How are you cutting your crown? Jig? On the flat? Vertically nested?
And how are you doing your inside corners? Coping? Mitering?

Good Luck,
Greg

[wdreamsmaycome]

For small crown I just run 2x4 through the table saw. Set the blade to the correct angle. mark your 2x4 and run it through. Then set the blade upright and rip off the next length of blocking.

I can definitely understand the first pass, where you end up with two long triangular blocks and a square 2x2, but how do you rip the remaining 2x2 in a safe way (for yourself and for the saw)? Do you have the blade tilted towards the fence or away? What kind of push stick are you using?

[wdreamsmaycome]

How are you cutting your crown? Jig? On the flat? Vertically nested?And how are you doing your inside corners? Coping? Mitering?

given that I have a compound saw I was planning to cut it flat and either measure the actual inside angles and cut accordingly (likely not 90) or pre-make a few pieces at different angles as shown in this video and cut the ones that fit best. I really would want to avoid coping personally.

http://video.google.com/videoplay?do...31152727602693

oops, this video used to be free on google until a few weeks ago, bah! Anyways basically the host advocated pre-cutting a few inside left/right corner pieces at 43-45-47 degrees and try and fit them on the corner(s) to see which one(s) work best, so you never have to measure the angles (could be left 44 and right 46 for example).

Personally I think it's no biggie to use the protractor and one of the online calculators (like this one) to get the exact angles without having to pre-make things.

http://www.issi1.com/corwin/crown.html

still this particular calculator is a bit confusing, so I guess I'll see once I start which method works best...

[Rand]

It cost me about 30 dollars worth of crown moulding to learn how to cut it properly. My advice is to forget about the compound cuts and use the upside down and backwards method.
There is a decent description with picture here:
http://www.josephfusco.org/Articles/...ngcrownpg3.htm
There has been articles on crown moulding in several recent wood working magazines as well.
To answer your question. I'm not sure this is the safest but it worked for me. Set the angle of the blade on the table saw to the spring angle of your moulding towards the fence. For a clean cut clamp a piece of scrap plywood or something against the fence and raise the blade so it just touchs the sacrificial fence. Push the last 6 inches through with a scrap of 2x2.

[JimD]

I also like the upside down and backwards method.

I would not use a backer on the walls where you have both a floor joist and a wall stud to nail to. I only use a backer when I am missing a floor joist to nail to. I like to take a bit of extra time to locate the wall studs and the joists with a stud finder and then mark how far down on the wall and out from the corner on the ceiling I want the crown moulding to fall. I put these marks at the studs and joists so they serve both purposes. Then when I am nailing the crown in place I push it to the marks and nail.

I rip backer on the table saw. Blade away from the rip fence.

Jim

[sbd1]

In my opinion the only way to cut crown molding is the upside down and backwards method. Inside corners are always coped and outside corners I use a starrett protracter to determine angle. If this is newer consruction and a smaller crown I don't use the corner block. Mark your studs and nail at every stud. If you cut the crown correctly about an 1/8" longer than the run you should be able to "snap" the piece in place tack the center and work towards both ends.

[wdreamsmaycome]

If you cut the crown correctly about an 1/8" longer than the run you should be able to "snap" the piece in place tack the center and work towards both ends.

meaning that you always cut the crown 1/8" longer than what you measure? I also wonder, if the LOML is not around to assist, is it even possible to measure long runs alone?

[JimD]

You are right to think long distances are not readily accurately measured alone. If the piece goes from an inside miter or cope to an outside miter, sometimes you can put a nail in the wall to hold the cope end and then put the piece in place and mark it at the wall - always better to just mark the piece in place than to measure when you can. Really long walls get done in 2 pieces anyway since you can only get 16 foot lengths, at least around here. When joining two pieces, I like to put a backer of 1/4 or 1/2 plywood or wafer behind the joint and staple and glue it on (with staples that don't come through to the face). Takes more time but the joints stay shut and show a lot less.

Jim

[bmuir]

Note: Posted this as an answer to another post on crown mouldings. Thought it was worth repeating here.

About 18 months ago, I installed 300 feet of crown moulding in my house. Here is what I learned:

1. Use a backer board all around the room. Overkill maybe, but it just makes things way easier. A backer board is a triangular shaped piece of wood cut from a 2x4 that matches the spring angle of the crown moulding and ends up about a 1/4 inch from the backside of the crown moulding. Screw it to the top plate at the ceiling all around the room with drywall screws. Now you can nail any place you need to. More work? Yes. But it makes the job easier.
2. Make a gauge block of wood that equals the distance from the ceiling to the bottom of the crown moulding where it meets the wall. This represents where the bottom of the crown moulding should be on the wall. Now, place a strip of blue painter's tape every 16 inches all around the room. Next, place your gauge block on the ceiling and mark each piece of tape at the bottom of the gauge block. This give you a reference point for the bottom of the crown moulding all around the room.
3. Use a homemade or purchased jig like the Bulldog or the one sold by Rockler. I used the Rockler jig and it worked great. Crown moulding goes in the jig upside down and backwards and this eliminates the compound cut. Just cut at the angle you need.
4. Because I was doing so many rooms and outside corners, I bought a Starrett Angle Finder (http://www.amazon.com/Starrett-505A-.../dp/B0000DCBLW) They also make a new 7-inch model. This tool gives you the exact outside angle or inside angle. It divides the angle in half and tells you to cut the outside miter at say 47 degrees. No guessing or calculating angles ever again!
5. Cope inside corners. I cut at 45 degrees and coped the ends.
6. Cut pieces of moulding long and cope the correct end first and check the cope. It if is a bad job (it happens), trim that end again and cope again. To check copes without going to the wall, I build a test box out of MDF. This box had an 8" piece of crown moulding installed in one corner. The box had a 1/2 top and no end. This way I could slide the box up to the coped end and check the fit. It it was bad, I cut the end again until it was close to perfect.
7. One coped end with a straight opposite end on each piece is the best and easiest to install. Try not to cope two ends. Here is how to avoid two coped ends in a self-contained, four-corner room (no outside corners). Take a scrap piece of crown moulding about three feet long and straight cut each end and place one end in a corner of the room and screw (don't nail) to the backer board (make sure the bottom is at the correct distance by using the gauge and tape in the corner). Now, cope the end of the piece that will fit into that corner on the wall at 90 degrees to where the three-foot piece is and make it fit by measuring the wall and trimming the square end until the piece fits snuggly (note: do not nail within about three feet of the coped end of this piece, more on that later). Then the second piece is coped, square cut and installed on the next wall; and the third piece is coped, square cut and installed. Now, remove the three foot piece. Measure for the fourth piece. Cope the end. Square cut to fit and sneak it in behind the coped end of the first piece. No double coped pieces! Remember to go back and nail the first piece into the backer boards over the last three feet into this corner. Works great.
8. Use an air nailer. I used a finish nailer. Saved lots of time!
9. I did this job by my self so I used a tool called a Third Hand to hold the crown moulding piece in the middle. Google it.
10. I used 16 foot pieces but some of my runs were over 16 feet. In this case, figure out where the scarf (30 to 45 degrees) will be and do not install backer board within about 16 inches of that area. Now scarf cut both pieces and glue the joint together with a piece of backer board glued to the back (use clamps to hold it until the glue dries). The backer board piece is about 12 inches long or so. Once dry, install the piece as normal. If one end needs to be coped, I would do that before doing the scarf joint.
11. Because no walls or ceilings are straight, I caulked top and bottom of the crown moulding with painter's caulk (this worked because my crown mouldings were painted white before I put them up).
12. Filled the nail holes with spackle and painted over.
13. Because some of my copes were not perfect (imagine that), I used some caulk on the corners. Worked great and only I know!
14. Note, if you have a room that leads to hallways with outside corners, plan the room out carefully because most likely you can find a wall that you can start with two straight ends. This eliminates at least one cope.
My wife loved the job. And I got a 12-inch miter saw out of the deal!
Works for me! Good luck.