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stevega_gw

Making tenons

stevega
14 years ago

I'm doing well making mortises with a plunge router and home made sliding jig. I am struggling with tenons using a store bought tenoning jig. The thickness is critical and I get that using a spacer that precisely fits the mortise rather than "flipping" the board. Should I cut the cheeks first or shoulders first? The cut depths are hard to measure/judge. It seems that cutting the shoulders first may have less chance of damaging the cosmetic shoulders.

The tenons are 4 and 5" long so I can't make all the cheek cuts on the jig because it can't accommodate that width. I can do those with a bandsaw or crosscut sled. Recommendations?

Thank you in advance

Comments (17)

  • sombreuil_mongrel
    14 years ago

    Call me old fashioned, but I use a mortise marking gauge to lay out the mortises and tenons and then cut the tenons roughly on the tablesaw, with the shoulder first, then the bulk removed with a vertical pass. The rough tenons then get planed to the gauge line with a rabbet plane, only then do I make a final cut for tenon breadth, ticking the size directly from the mortise with a marking knife. Then I start test-fitting. If you plane just to the gauge line it will still be too tight and you can fine-tune the alignment by planing.
    I chop out the mortises with a hollow-chisel machine, and rough out tenons with the tablesaw, but from there on out it's all by hand. The rabbet plane is also used to correct the shoulder fit. If you hd the $$ you can buy a special shoulder plane, but the old 78-type plane is really okay.
    A standard tablesaw accessory is the tenoning jig; delta and craftsman each sell their versions.
    Casey

  • stevega
    Original Author
    14 years ago

    Thanks Casey, shoulders first. I am a fan of the microplanes for shaping and removal. They do a great job and are very controllable but lack the "satisfaction" feel of a well tuned plane. I may have spent more time jointing/adjusting/taping the 1/2" spacer for tenon width than I would have fine tuning each your way. Hopefully, it will pay off as I have 44 to do with the tenoning jig.

  • sombreuil_mongrel
    14 years ago

    I have yet to try a microplane on anything other than Parmesan.
    I should have mentioned, if you have a tablesaw and a stacked dado blade, you can easily do the rough tenons without repositioning them to a vertical cut. Just set set up the dado blade to the maximum width and make 3 or more passes. There's a litle tearout at the end of the cut, and unless you have one of those $300 dado blades, you'll still want to do the shoulder cut first with a fine crosscut blade.
    Casey

  • Jon1270
    14 years ago

    I always crosscut the shoulders first, on the table saw. Set the rip fence to the right of the blade, and put the crosscut guide to the left of the blade. Square the stock against the crosscut guide, butt it against the rip fence, and cut the shoulders.

    I prefer to cut the cheeks free with my tablesaw -- primarily because it leaves a smooth surface, but also because my bandsaw isn't always perfectly tweaked for such fine work. If I take the time to set it up, the bandsaw does fine.

    One thing I've learned is that the TS blade deflects away just a tad when its full width isn't buried in the wood. When setting up my jig, I typically make several fine adjustments while cutting a tenon on a piece of scrap. Since this incremental creeping up on the correct arrangement means that the last cuts I take on my scrap tenon are very light, the blade is deflected away from the tenon, which ends up misleadingly fat. Before cutting the wood that really counts, it's best to cut ANOTHER practice tenon on new scrap, with the blade taking a full cut on each side.

    The commercially made tenoning jigs I've used haven't been anything to write home about. A good shop-made jig could easily perform better.

    Like Casey, I'd prefer the rabbet plane over the cheese grater. Microplanes are fine for sculpting, especially in softer material, but they don't do a good job of keeping the cut surfaces flat and the don't get into tight inside corners well.

  • stevega
    Original Author
    14 years ago

    I only recently noticed that microplanes can be used as a food grater. Not too many of my tools are diswasher safe! I'll try it on parmesan (we keep it frozen).
    I used to have a dado set, haven't seen it in several years. Mostly use the router table. Every once in a while I use the wobble dado blade.

  • brickeyee
    14 years ago

    " Every once in a while I use the wobble dado blade. "

    Wobble dado setups leave curved bottoms in the dado.
    Not usually a desirable thing.

    I use a large sled and stack dado blade.
    Cut the shoulder with an 80 tooth crosscut blade, than set up the sled and dado so that you can make a pass, flip the board over and make another pass at the same setup.

    The tenon is perfectly centered and the crosscut blade leave perfect shoulders.

    Micro-plane tools do not leave as smooth a surface as a real plane, and thus make for a poorer glue joint.

    Mine live in the kitchen for zesting and Parmesan.

    The dishwasher will quickly kill the cutting edges of a micro-plane.

  • mike_kaiser_gw
    14 years ago

    Have you thought about using loose tenons instead? Essentially you cut the mortises on the mating pieces and then mill a tenon to fit. Picture a big biscuit.

  • stevega
    Original Author
    14 years ago

    Brickeyee-thanks for the input. Confirm wobble dado curve, shoulders first, microplane surface rougher than real plane (but better than the rasps I have) and centered tenon when "flipping" board. It takes trial and error to get "perfect" tenon width on each setup. I imagine that I will have a series of spacers for each typical tenon width and only have to get close to center and use the same working face for each cheek cut.
    I was actually thinking that a slightly rougher surface may be a stronger joint because it would prevent glue starved areas. That's just me thinking, I don't have experience to canfirm.
    Mike-thanks also. I have thought of loose tenons and will try them on another project. It just seems like integral tenons would be better for the bed headboard and footboard. I will also have vertical slats that might be a good candidate for loose tenons.
    Thanks again all.

  • brickeyee
    14 years ago

    A rougher surface creates a thicker glue line and weakens the joint.

    Maximum strength glue lines are in the thousandths of an inch range.

  • sombreuil_mongrel
    14 years ago

    Just thought I'd mention, you don't necessarily want a tenon centered, especially if the mortise is not centered. A marking gauge is used by first selecting the face side of all your stock, and x-ing that side so that you reliably gauge only from the faces. The end result is perfectly-matched face exposures with the bulk of corrective flush sanding done on the backs. You should be selecting faces for purposes of grain- and color-matching anyhow.
    Casey

  • brickeyee
    14 years ago

    I use a Muttico hollow mortiser for cutting all mortises.
    They are centered and accurate.

    The tenons are the same, centered and accurate.

    Accurate setups make sure even large projects with multiple joints allow for the same setup throughout the job.

    A set of gauge block for setting up the tools allows the setup to be recreated exactly.

    I will make up gauge blocks for a particular job if I do not already have what is needed.

  • stevega
    Original Author
    14 years ago

    Thanks again all for tips. Joinery went very well. Only cheese grater rounding of tenons was required. One problem was my stopblock slipped while making shoulder cuts on the 18 slats. Somewhere after 50 times sliding the slats against the block it started to move. I had angled the EZ clamps (I used two) as I tightened and the repeated tapping moved the block. It took a while to discover the problem and correct. Fortunately I can make them all 1/4" shorter.

  • brickeyee
    14 years ago

    If you back up stop blocks with the rip fence there is a lot less chance of them moving.

    You need to make sure the block is large enough to create the needed clearance between the blade and the fence, especially if the cut produces any type of cut off.

    A cut off that can wedge between the blade and fence WILL be ejected very rapidly towards you.

  • stevega
    Original Author
    14 years ago

    Brickeyee good points. I use a crosscut sled approx the size of the saw table (like David Marks has)and clamp the stop block to the rail closest to me. I use it whenever it is possible. There have been a few times when I put a cut in a bind and the rail stopped the missile.

  • someone2010
    14 years ago

    On table saw with tenoning jig. Start on the tip of the board, about 1/2" up, and make the four shoulder cuts first but about 1/8" thicker than the tenon. Raise the saw blade to the height of the shoulder (1/2"). Next put in jig (waste should be on the outside of the blade, not next to the fence) and cut the cheeks on one side about 1/8" wider, flip the board and cut the other cheek about 1/8" wider. Take out the board and check it against your mortise. Put board back in the jig and cut off a small amount, about 1/32", flip the board and cut the other cheek. Keep doing this until the width of the tenon is correct(slides in with some friction but fits with hand pressure). Next cut the top and bottom on your tenon. Using your miter gauge on the table saw make the top and bottom cuts but again about 1/8" thicker than the mortise. Measure it against your mortise and make thin cuts again and measure against your mortise. Keep doing this until it just slides into the mortise with some friction. Now the tip of your board has a good tenon that can be used to set the blade to make the full length tenon. Set your blade height and make your finish shoulder cuts. Raise the blade, put your board back in the jig and adjust to make the cheek cut. Flip the board and make the other cheek cut. Finally, use the table saw miter gauge to cut the top and bottom cheeks. I always get a perfect fit, no plane.

  • someone2010
    14 years ago

    Didn't notice the tenons were 5" long the first time around. Looks like you guys got it covered.

  • stevega
    Original Author
    14 years ago

    Someone, you give a good clear description for cutting mortises. One advantage with your way over using a cross cut sled is that the blade height for all shoulder cuts does not change. The disadvantage is that the piece is 4' long and 6" wide and the miter gauge wouldn't hold it on end very well. I may have misstated the "length" of the tenon. The tenons are 1/2" "thick", 3/4" "deep" and 5" "long". Thanks again for the clear description-shoulders first-everyone (not just someone) agrees.