Whoo boy! Okay, there is a lot to unpack here so let’s get started.
When I finished making gnomes and walking sticks for the year, I disassembled my bench top lathe and stowed it under the workbench. The biggest part of the lathe is roughly eighty pounds so I have officially given up trying to lift it up to the bench myself. Gone are the days when I could carry three, fifty pound feed sacks on my shoulder (I really could, honest). So I decided to build a permanent lathe stand. So much for growing older.
The design is from an old Popular Woodworking article called, “The Ultimate Lathe Stand”. I’m not sure what makes it ‘ultimate’, other than the fact that it is likely to be the last lathe stand that I ever make. The two distinct and defining features of this design are that it is made of Baltic Birch multi-ply plywood and it uses a unique bolt together fastening system.
Multi-ply has thirteen plies, while regular plywood has only seven. The effect of this difference is staggering, particularly when you try to pick up a sheet of 3/4″ multi-ply; it is incredibly heavy compared with regular 3/4″ plywood. Regular plywood is heavy enough at 3/4″ to require most people to request help or employ some device for transport. Multi-ply is over twice as heavy. The weight is necessary for the stand in order to overcome the vibrations caused by out of balance turning pieces, before they are trued up and balanced for turning to shape.
I went to my local lumber yard to order the plywood and requested delivery, partly because of the weight and partly because I can’t fit a whole 4’x8′ sheet of plywood in my car, let alone three sheets. I was reminded at the store that Baltic Birch sheets are roughly 5’x5′ (they’re metric). As my longest component was 63″, the Baltic Birch would not be large enough. The guy at the counter suggested a domestic birch plywood that was 4’x8′. The domestic product is known as Apple-Ply and is also a multi-ply, so I asked if it was Apple-Ply. He said, “Yeah”, so I said, “Sure go ahead and substitute with the domestic stuff”. Well, when it arrived it was something called, “shop birch” and was seven plies, not thirteen. Apparently the counter clerk didn’t know what Apple-Ply was and was embarrassed to admit it. As I had to call in a favor to get the delivery, I didn’t feel like I could send it back and told myself that the weight wouldn’t be missed, as my lathe was a smaller bench model. So much for mistaken assumptions.
The second feature, the unique fastening system, uses through bolts to connect the end legs to the ends of the connecting beams. The bolts are secured with nuts in cross bored holes lined with copper pipe for strength. Because the tension on the bolts can be spread over half the circumference of the pipe, they can be tightened down extremely tight. This is expected to make the joint secure against vibrations and wracking loads. The thing is, I’ve never been comfortable with fastener joinery, that is joinery that relies on the fastener to act in shear as well as tension. My training suggests that joints should rely on mortice and tenon or other such classic joinery to hold pieces in shear; fasteners (screws, bolts, etc.) should only be expected to provide tension. However, expediency, laziness and the description in the article worked to convince me to give it a try. So much for the dismissal of principles.
Only time will tell if the joinery will withstand the vibrations and if the plywood is heavy enough for the project to be a success. In any case, I think that this will be my ultimate lathe stand.
One thought on “On growing older, mistaken assumptions and dismissing principles”
I’m enjoying your thoughts on aging & woodworking!