Tenon Guide
I designed this guide about 4 or 5 years ago and offered it to Lee Valley, who looked into producing it. In the end, however, LV decided that they could not find a way to manufacture it cheaply enough as a commercial proposition. So finally I now have the design back and I am passing to the public to build for private use (there are dimensions later on). I just hate to see a great design not get used.
Who is likely to use the guide? I think just about anyone, expert and beginner alike. I do most of my joinery without any guides or jigs, and I have used this one enough to recognize that it will help those wanting to develop hand memory. It replicates hand methods and is purely hand power rather than introducing any machinery. It is also possible to do production sawing.
So what do we have?
There is a fence with embedded rare earth magnets to hold a handsaw tightly against it.
The fence is adjustable and permits a very wide range of tenon shoulder and cheek widths and lengths.
It can guide a saw on both the shoulders and the cheeks.
Undo the knob and remove the fence, leaving the base …
The top of the base has a tenon that guides the fence. The front of the base has non-slid.
The fence is attached to the base by the tenon, which runs in a dado. The fence is has a through slot. This locks the fence at different projections.
Re-assemble the parts and lock down the knob ….
For use with this guide I recommend two saws such as those below. This is not critical – I have successfully used a wide range of saws, old and new, Western and Eastern.
The 14” tenon saw is by Gramercy. This will be used for sawing the cheeks. The flush cut saw is by Lee Valley. This will saw the shoulders.
Now before we use the guide it is relevant to go through the process of marking out a tenon, since sawing a tenon on this guide is no different from using a traditional handsaw method.
Below is a tenon that will end up with a cheek ¾” long and a shoulder 2” wide. The stretcher is ¾” thick.
The choice is to score the shoulder line with a square and knife, working from a reference edge. This method is preferred by some.
Others prefer a cutting gauge from the end. This method depends on the end being square to the reference edge, which benefits from using a shooting board.
Whichever method you use, ensure that the line knife is sharp and the line is shallow and fine. More later.
Whichever method you use, evidence of how parallel the opposing sides are is when the line is continuous.
Some prefer to score the cheek lines with two single-cutter gauges. I prefer a double cutter gauge – here a Kinshiro – since once the distance from the reference side has been decided, this is transferred to every other stretcher to maintain coplanar. The tenon width is decided by the width of the mortice chisel. In this case it is ¼”. This follows the 1/3 Rule (1/3 shoulder + 1/3 tenon + 1/3 shoulder).
Do not forget to score the sides as well …
The last marking is the cosmetic shoulder. I have set this at 1/8”.
OK, we are all set!
First thing to do is loosen the knob and sliding the fence forward about ½” over the front face, as below ...
Now take the stretcher and butt it against both the underside of the fence and the tab at the side …
Once this is done, you can clamp them together and lock them upright in a face vise …
I find it preferable to saw in this position since the stretcher will not move. However, you may prefer to saw parallel with the bench. In which case you could conceivably forgo the clamp as the non-slip (sandpaper) does a good job at holding the work securely …
Once the work piece is clamped, slide and position the fence against the further cheek line …
(Note that I always saw to the line. I choose not to leave waste to remove. Your preference may differ. Choose accordingly).
Now place the saw against the magnetic fence ...
… and saw to the shoulder line …
Once this is done, remove the saw, loosen the fence knob and pull the fence back …
Now reposition the fence for the second cut. What I do is attach the saw so that I may include the saw’s set as well …
Saw this out as before …
The cheek cuts are done. Now is the time for the shoulder cuts …
Remove the fence from the base and turn it over.
The base has two fences, one on each side, along with non-slip. These will become a guide for sawing the shoulders …
It is possible to simply hold the guide in place. A clamp is not necessary, but does improve accuracy.
Slide the fence right up to the line. This is why the shoulder line needs to be a scored lightly, not deeply. A fine line is easier to set up with the guide …
The flush cut saw has no set and will cut exactly where the guide is positioned. It leaves a smooth, clean shoulder …
When sawing the other shoulder, do not forget to work from the reference edge. This requires that the guide be reversed (which is why there are two inner fences) …
Below – the basic tenon is done …
There is more set of saw cuts to make – the cosmetic shoulder. You can use the guide here again if you choose …
The saw cuts are made …
The final task left to complete the tenon is to “destroy” all the fine, careful work done to reach this stage – undercut the shoulder with a chisel, and chamfer the tenon ends with a block plane …
Done!
Commentary
A few points to note following on from responses on forums.
The first is that the learning to saw straight is definitely preferred. Some cannot do so, for a number of reasons, one simply being limited coordination and/or hand strength. Another may be confidence - and I would hope that they would obtain the muscle memory and confidence from a guide such as this (in the same way that many have done so using the LV dovetail guide).
The second is that this guide was designed as a way to replicate handsawing of simple items. Nevertheless it is also capable of production sawing. All one has to do is saw one cut at a time, removing and inserting successive stretchers. In production, all pieces will be sized the same, and therefore all settings will be held the same by the guide.
Below are the dimensions for the Tenon Guide if you would like to make one for yourself. They do not need to be these dimensions. Enjoy.
Regards from Perth
Derek
November 2014
