I used my SCMS to cut bookcase dados today. A router might have been faster, but I just had my Bosch Colt along and didn’t want to burn that up. The joinery did not have to be perfect, as the faceframes cover the joint. Still I wanted them to be tight glue joints, so I cleaned up the saw cuts with a chisel.
This brings up an important point, the depth of the dado cut can be such that you are chiseling with the grain of a ply layer (plow just a little different depth and you will be fighting to clean the dado out across the grain). In a pic here you can see the grain and the curved shavings that easily peeled out.
These cases were just a bit too deep (13″) for my saw to plow all the way…after I plowed out all I could, I flipped the board and just finished the two outside cuts on each dado. The remainder was easily chiseled out. It took 2 hours to cut and clean-up 24 dados this way.
One more note, I start all my SCMS cuts in plywood with a shallow scoring “pull stroke,” then drop the blade down and push back through to finish the cut. I get a very crisp edge this way…no splintering or tearout.
Tomorrow I install the cases and then apply face frames in place.
Replies
Basswood,
Looks like you got very nice results.
One question, though. You mentioned having to flip the boards to complete the cuts due to the limit of the saw carriage travel.
If you made the cheek cuts of the dado by flipping the workpiece around, why didn't you just finish up the middle of the dado with the saw, too?
The remainder popped out with one light chisel blow, so I figured it was an easy way to finish it off.
Fair enough. I guess you had the old chisel out anyway! For a minute there, reading your post, I thought you had roughed out the entire length of the dado with your chisel.
Looks good! One question - how did you control the depth of your cut? I've tried to plow dadoes with a SCMS before by setting the stop so I'd only cut a certain depth, but met with problems anyway.
And what make/model saw are you using? I did my experiments with a Bosch 3915, but after I killed that in a kickback incident, I've now got a new Hitachi 10" slider, which maybe would be a better candidate for dadoing.
Jason
I have an old Hitachi 10" slider. You can lock the depth of cut on my saw with consistant results. I think the key is to have both the "doubled nuts" and the wing nut tight.
Basswood,
Are you actually using a dado set up on that saw or just making repeated cuts with the standard blade?"Poor is not the person who has too little, but the person who craves more."...Seneca
Dovetail,
He's just using a standard blade to cut the dado cheeks. Look at the first two photos and you'll see.
Ragnar,
That is what I thought. I was just confused by some of the posts. I have never heard or seen anyone use a dado blade on a SCMS. So thought I would ask ."Poor is not the person who has too little, but the person who craves more."...Seneca
What Ragnar said.I am using a 72 tooth Tenryu Silencer blade, full 1/8" kerf. Definately not a good job for a thin kerf blade <g> With some careful practice, I was able to make the two cheek cuts, then finish all the repeated cuts with the blade running (cutting on both pull and push strokes) while I fed the material in with my left hand a safe distance away.Works well with my roller-style work-support stand, and may not be a good method for some.I should get some video of this.
One more note, on my Hitchi, the carriage travel stops at the fence too soon, so the curve of the blade results in the fence edge of the dado cut being ramped up to a shallow end, rather than full depth. This just occurs in the last 1/2" of the cut.The remedy is a 1x1 spacer against the fence. Then the ramp effect occurs in the spacer and the dado is full depth all the way. The spacer does reduce cut capacity, but still allows dados in a 11-1/4" board (the depth of most bookcase stock), without flipping boards to finish the cuts.
It looks like your results turned out better than mine with a new dewalt slider. There was just too much up and down movement to be anything approaching consistant, even with considerable effort spent on consistant hand pressure.
While not traditional, I must admit to cutting fewer dados since pocket screws came along.
Beer was created so carpenters wouldn't rule the world.