Cutting Tenons on a Shaper

Advice on making end tenons on a shaper. March 3, 2009

Does anyone use a shaper to cut face frame tenons? We have been using the table saw and the dado blades to cut face frame tenons and have been thinking about changing over to the shaper. Using the shaper would give a uniform thickness to the tenon and the variation in lumber thickness would not matter. We would have to change the way we cut mortises and only haunch the top and bottom rails so that there is no blow out of the stiles. We would also have to be accurate on the stop and start point of the mortise so that the mortise hole would barely show, because the tenon would be the same width as the mortise. It should be the same thing as cutting the cope on doors, only on a larger scale using straight cutters. Any experience in this matter would be helpful.

Forum Responses
(Cabinetmaking Forum)
From contributor K:
I thought about it about 15 years ago and tried it with cutters from a shaker door set. The problem I found immediately was making the extra cut on the two edges of the tenon. Then I still needed to buy a mortiser. I finally decided to go with a Multi-Router and cut slot mortises and make my own loose tenons. This way, you can make easy mortises of any needed size on the end grain as well as the edges. I cut 1/4" x 1" slots for everything. My standard face frame is 1 1/2", so a 1" tenon gives me a 1/4" shoulder on all sides. If I have a face frame, say 2 1/2" wide, I lay out for 2 tenons spaced 1/4" in from the edge of the frame, which would leave a 1/4" space between them. I make my own loose tenons to match them in bulk. I use poplar for the tenon stock and run about 50 ft. of 1/4" x 1". I bullnose both edges, then cross cut on the tablesaw sled to just under 1.5" long. This makes about 350 loose tenons which will go a long way. I cut 1/4" x 1" x 3/4" deep mortises. I have made setup jigs and milling fixtures for the Multi-Router to make the slotting process fast. I have even set up a fixture for making the haunches for beaded face frames using a 45 degree flat bottom chamfer bit without a bearing. The thing I like most about this process is that I cut the face frame parts to finished length and I have no worries of openings changing size when cutting a tenon too long or too short. I also purchased a glue system from Colonial Saw which allows me to insert a shaped glue tip into the mortise and inject a registered amount of glue with no hassle and very fast. Multi-routers aren't cheap but I found it well worth the investment.

From contributor J:
I use a shaper to crosscut tenons all the time. It depends on the depth of cut. 1/2" is the limit. A tenoning gauge of some sort is what you will need. I made a cross-cutting jig for mine that I set up on a separate shaper. The sample below is one that I made for a router table. As long as you have a backing piece (opposing cut) on the piece you are cutting, you shouldn't have any tearout. (Note: the bearings I used are Igus bearings, which don't allow play, so your cut is consistent all the time.)

From contributor R:
Anytime you make a big change like this, there are other things that pop up that you've never heard of! Tenons on the shaper are a breeze, but that's only the main shoulders. Now you have to cut the narrow shoulders. Yes, you do get a consistent thickness to your tenon, but no guarantee it will be centered! Each thickness of wood will need to be adjusted for. Or, you set it up once and cut all your mortises using the same dimension off the same face. Now you need to be able to cut very consistent mortises as well. As I work through this little exercise, I too am deciding that cutting two mortises and using a floating tenon makes sense. Seems to me you should be looking at a dedicated slot mortiser of a Festool Domino.

From contributor P:
I cut lots of tenons on my shaper up to 3 inches deep in one pass. One setup on the shaper and two detachable jigs will do both tenon shoulders if required. I have a sliding table which makes things easier. I stack a pair of deep groover heads and get them spaced properly. Get everything set so the tenon is centered. The next jig raised the stock higher off the table to cut the short tenon shoulders. Thus, it is done in three passes. One to do the main tenon and shoulders centered. Two to do one short shoulder. Three, flip stock and do the other short shoulder. Once set up, I can fly. With a tilting arbor, I can do angled tenons, curved work, etc. For short runs and smaller pieces, I use the Domino.

From contributor T:
Have done this numerous times. You can use a single cutter to cut the shoulders one at a time by passing the wood over the cutter. This will result in a constant shoulder depth. Any variance in stock thickness will result in varying tenon thickness. This way you can make the shoulder and haunches on the same cutter at the same time by rotating the stock. Another method is to pass the stock under the cutter and cut the tenons in two passes. With this method you will get a constant tenon thickness even with varying stock thickness, but the haunch has to be cut with a separate setup. The haunch can be cut on a bandsaw, with dadoes, etc. I prefer the second method. Poor fitting tenons are a plague I avoid at all cost. I check my stock with dial calipers when machining to final thickness. A 0.010 variance in mortise stock (centered mortise) will leave a 0.005 offset at each shoulder. That's about the thickness of a sheet of typing paper.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor A:
Why use a shaper when a table saw is perfectly fine? A quick and accurate way to make tenons on the table saw is to use your dado end blades with a spacer in the middle sized for your tenon (would be oversized to account for width of teeth). Run your pieces through upright with a tenoning jig (either shop made or after market). Register your face off the jig and the tenons come out perfectly aligned. Cut the shoulders with a miter sled setting the tenon against a block of wood clamped to fence behind the blade to ensure same depth on both sides. Cut the top shoulder at the same time and hand saw your tenon to width. Make a haunch as you usually do.