Turn on the Power for Rapid Tenons
Thursday 06 May 2010
Marc Fish says tenons can be quickly cut using bandsaw, milling machine, router table, spindle moulder and of course the mighty Domino
In a professional workshop efficiency cannot be over-emphasised. One has to be commercial to survive so areas where techniques can be substituted or improved to save time are welcomed, and this includes making tenons.
If you really want to speed up joint making then one word speaks volumes. Domino. The introduction by Festool of the Domino machine a few years back has revolutionised furniture making and for many makers made mortice and tenons completely redundant. I am sure there are many purists out there who take great exception to this but there were many objections to the first automated weaving loom and I hope we have come a long way since then.
The downside to Dominos is their cost and if you are not lucky enough to own one then these machining tips should help to speed up your tenon cutting.
Using a bandsaw for cutting joints is nothing new, but a couple of set-up tips will help with any technique requiring the use of one.
I have changed over to a tungsten carbide-tipped blade very similar to that on a circular saw blade. These are a lot more expensive but the finish is quite unbelievable. Check the tension on your bandsaw. If you are reading the scale on a machine fitted with a carbide-tipped blade it will be under-tensioned so have it checked properly. Mine was only one-tenth of the tension required. Set up the guides accurately. They need to be very close to the side of the blade but not quite touching.
When machining your timber make a spare component and when setting up your bandsaw for cutting your tenons use it to check the fit in the mortice and the position of the tenon.
Cut one side of your tenon and then flip over, cutting the other. Remove the waste and check the fit. When this is satisfactory cut all the tenons on these settings. The key to success here is that the spare piece is identical to the other components and that this is checked carefully for fit before cutting the real thing.
Now I know most makers will not have access to engineering tools but I would like to enlighten those who do and maybe inspire those who do not that it might be worth investing in them.
I use the milling machine half and half between wood and metal, tenons being the ideal process that a milling machine will undertake.
You will need to make a jig to hold the workpiece to the bed. My jig is multipurpose as it is also used for router tables.
I mark up my spare tenon as per normal but can dial in any number of joints after the spare one has been machined and readings taken from the dials.
If you wish you can machine up to your scalpel lines on each joint as it is easy to see what you are doing and micro adjustment is available, an ability that makes use of a milling machine preferable to a spindle moulder or router. It is slower than the spindle moulder but far less scary, and it achieves a better result.
Woodworking router cutters or milling cutters both work OK, but router cutters do operate better at a faster speed.
Router table and spindle moulder
These two machines are very similar in their application and techniques. I have used both for making tenons but must admit that the spindle moulder only gets set up if I have a few to do, otherwise the router table or milling machine does the job.
The spindle moulder is a much more powerful machine. If the tenon is large, requiring lots of waste removal, then it will be your best choice. Various cutters are available for both machines although a better range is available for the spindle moulder. Twin-headed blocks allow both sides to be cut at once, and these work with either a spacer in between the two blocks, or an adjustable gap.
As for the bandsaw, always make a spare component to use as a set-up piece. On the router table you will need to make a jig to hold the workpiece firmly, with an extra piece of wood protecting the exit edge on your work.
This jig needs to be very accurate. Ensure the fence for the workpiece is truly square to the fence of your router table. A cutout is made by hand to allow the cutter to protrude up to the work and the whole jig is moved along the fence.
The spindle moulder does not require a jig but will need either a mitre slot or sliding carriage to ensure square shoulders. I have the latter and again use a sacrificial piece at the exit point.