I prefer to size stretcher tenons with a Turner’s Gate (Sorby calls it a Sizing Tool). It’s major advantage over dowel plates and tenon cutters is that the tenon shoulder can be easily removed using a skew, plus the tenons are always in line with each other.
A turner’s gate fits over a parting tool or bedan and can be adjusted through trial and error to cut whatever size tenon is required. Or if you want to get fancy, Tim Manney has come up with a way to add a micro adjust. If the tenon can be twisted 1/3 to 1/2 the way into the mortice without hurting your arm, the tenon is a good fit. You only drive the tenon in once, since you’ll never get it back out without breaking the stretcher.
Most of my stretcher tenons are 5/8″ diameter, except walnut tenons (11/16″) and child chairs (9/16″). I leave my gate set at 5/8″ all the time and sharpen the bedan without removing the gate.
The basics of using a parting tool or bedan fitted with a turner’s gate are similar to using either tool without a turner’s gate. Since these techniques are covered in many good spindle turning books (I recommend Turning Wood with Richard Raffan), I’ll focus on the techniques specific to using a turner’s gate:
Most tenons take several overlapping cuts to complete (my bedan is 3/8″ wide so I make three cuts to complete a 1″ long tenon). If you are getting a stair-step surface on your tenon, there are three possible causes: the tool is not perpendicular with the axis of the turning, the tool is not flat on the tool rest, or the end of the bedan isn’t ground square. Make sure you aren’t swinging the handle to the right or left as you raise it during the cut. Pull back against the gate when cutting (really it’s a scraping action). Otherwise the gate is useless.
Since engaging the turner’s gate drops the edge of the tool into a scraping cut, vibration is a major problem. Some anti-vibration tips:
Remove the majority of the wood with a shearing cut, then drop the tool down (lift the tool’s handle) to engage the gate.
Turn lathe speed up as high as it will go (4000 rmp in my case). As a general rule, vibration decreases with higher lathe speeds when using a scraping cutting action. Vibration increases with higher lathe speeds when using a shearing cutting action.
The closer the cutting action is to the lathe head/tail centers, the less vibration you’ll get. If it’s more than a couple inches, I cut the stretcher shorter.
Continuous cutting can exacerbate vibration, so I often take a cut for a second, pause, take a cut, pause, until the tenon is sized.
Impatient to get started building chairs? You are in luck! I’ve had a few cancellations, including one in my class at Roy Underhill’s next week. Here’s my current class openings:
Continuous Arm Rocker at The Woodwright’s School in Pittsboro, NC from October 16th to 22nd, 2017.
In my shop:
LOOP BACK SIDE CHAIR, January 22nd to 27th, 2018 – $1200 – One spot left
COMB BACK ROCKER, May 14th to 19th, 2018 – $1400 – One spot left (returning students only)
CONTINUOUS ARM CHAIR, June 11th to 16th, 2018 – $1200 Two spots open
I’ll be adding more classes later in 2018 soon.