After lurking a while, I have begun to wonder if there's a right and wrong way to rip. If you need a 1" wide piece, and have a 4" board, do you set the fence 3" from the blade so the "waste" is the desired cut, or do you set the fence 1" from the blade and let the 3" be waste. (Assume that I'm taking kerf into consideration and setting the fence based on the proper cutting teeth.)
Also, when you need to "extend" a board, for example, to put up chair rail, and you scarf cut, is there any magic to the scarf compound angle? I usually set up a 22.5° in miter and bevel and whack away. Is there a preferred, professional angle set for scarf cut?
Your keeper piece should fall between the fence and the blade 99% of the time. This way, you can cut the same width over and over to exactly the same width. If you cut very narrow pieces, in the 1/8" an narrower range, it would be safer to have the keeper on the normal waste side.
I'm in agreement with Leon. If I can safely get my push stick between the fence and the blade, my keeper piece is there. Otherwise it's on the outside of the blade.
Can't help with the scarf question. Sorry.
djb (who's out of the shop for a while with a broken 5th metatarsal in my left foot. Damn kids and their footballs...)
As for the scarf joint, in general, the longer the scarf joint the better. However, for chair rail or base, a 45 works well for painted molding. A simple butt with biscuits, splines or dowels will serve better. IMHO
I use a long push BLOCK (NOT stick) for narrow rips, all the way down to 1/8", between the fence and blade. The blade gets set to slightly higher than the work, and it will cut a groove in the push block.
The push block is simply 3/4" MDF, with an MDF "handle" edge glued to it, and mouse pad material glued to the bottom. It's about 4" wide x
Technically, for safety reasons, the proper way is to have the wide side=20 of the cut between the fence and the blade. Gives you more room around=20 the blade as you feed the stock.=20
However I don't know of many, including myself, that strictly adhere to=20 that principle. Especially if you are cutting repetitive sized strips=20 off of the stock and want them all to be exactly the same width. Say=20 three one inch strips from your four inch stock for example.
So, in short, there is a right way. However there is usually more=20 reasons to not do it that way then there is too. =20
If you want to cut a bunch of thin strips, make a guide block so you can be consistent. Cut a piece of wood about 2 or 3" wide by about 6" long. Put a
3/8 x 3/4 strip on the bottom that will fit into the miter slot. On the blade side of the block, put in a round head screw. Set it up so that the distance from the screw head to the blade is the same as the desired width of piece you want to cut. Clamp it in place well ahead of the blade. Now you can use it a guide to set your fence for each cut. Just move the board to the screw head, bring the fence into position and cut. repeat as needed.
On a boat, long scarfs are a structrual thing, so they have to be done correctly or you end up with "hard" spots.
Whether you make a short scarf or a long scarf doesn't really matter as far as time is concerned, but it does impact the amount of material needed.
Maybe I'm just prejudiced, but I've seen a lot of short scarfs on trim work that tend to open up after a few years.
To me, that reflects back on the craftsman who did the job, demonstrating for the world to see, a lack of pride, or maybe a supervisor who just didn't give a hoot as long as they got paid.
You can't get there from here with a chop saw IMHO.
Might work for a base board molding, but those aren't real scarfs, IMHO.
Guess it just depends on how you look at it.
I look at my scarfing jig the same way I look at my sled.
Basic tools that are required before you open the shop door and turn on the lights.
SFWIW, my first attempt at making scarfs were 16:1 made using a hand power planer and a scarfing jig clamped in a B&D Workmate.
The whole thing was done outdoors.
The strips were Doug Fir, 5/8"x1-1/2"x24ft cut from 2x12x24 construction timbers.
Cutting those was an interesting exercise.
Estimate that I made over a mile of cuts that day, filling a dumpster with saw dust.
When I was finished, had 24 ft long strips, but needed 65-70 ft long strips.
Only had 30, 3" C-Clamps.
A few days and a gallon of TiteBondII later, had about 400, 72 ft long strips.
Filled up a another dumpster with planer chips.
Add about 5,000 deck screws and you get a mold that eventually turned into weenie roast fuel, once the fiberglass hull was complete.
My sympathies on your foot. I, too, am out of the shop for a few months, due to rotator cuff surgery. Picked up three planes (a Stanley #4, an adjustable throat block plane and an old woodie) and I can't work on them to tune them up. Believe me, I feel your pain. I wish you the best for a speedy recovery.
I suspect that the scarf joint was invented before the biscuit. The first time I tried this it was on a 1x4 piece of exterior trim (a pretty tough environment). It held up perfectly for about 5 years. The structure was them demolished so it saw no further testing. If you can, us some kind of spline (biscuit dowel, whatever). The pieces become essentialy one piece of wood.
I find this works well for a coped molding as the difficult end can fiddled with and then the butt end is just cut for and exact fit, them the spline slot is cut.
I'm curious if others have found a problem with the spline approach as scarf joints appear to continue to be conventional wisdom.
I like to have the waste piece be the one that is on the side of the blade that is farthest from the fence. I use an ice pick on the skinny ones.
Most trim carpenters use a forty five but I don't think they hold up well over time. I believe the reason for this to be that the gluing surface has too much end grain in it for a good bond over time.
What I've usually done is to clamp a temporary fence onto the SCMS, that is basically a square piece of MDF, with some blocks glued on, so that I can clamp the trim to it (I also glue on a piece of sandpaper to the edge that the trim gets clamped to, so it doesn't want to slip around so much). This gives me a fence that is at ninety degrees to the regular fence.
On the SCMS I can get a long scarf that gives more of a face grain gluing surface and joints cut this way seem to hold up quite well.
Regards, Tom.
Thomas J.Watson - Cabinetmaker (ret.) tjwatson1ATcomcastDOTnet (real email)
| > Also, when you need to "extend" a board, for example, to put up chair | > rail, and you scarf cut, is there any magic to the scarf compound | > angle? I usually set up a 22.5° in miter and bevel and whack away. Is | > there a preferred, professional angle set for scarf cut? | >
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