Poor-man's lathe — Boatworks

It’s been a while since I’m thinking about building or buying a lathe for my workshop, to turn wood.

Recently I stumbled upon a problem which this tool can solve:
wooden plugs, for closing screw or rivet opening in boat’s planks are 13mm on Meritaten.
Plugs which I have are 15mm diameter.

I could widen openings on planks from 13 to 15mm, with modified spade drill, but I don’t feel good about it: that inevitably weakens the structure. Instead I want to turn the plugs into a proper size.

Since it does not take much time I tried to build my own lathe. The most important part is a chuck. to position accurately the part to be turned. I wanted to use my drill as an engine so I needed something which can be held in drill’s chuck.

Thick block of wood with 3 nuts glued on perimeter, aligned to meet in the centre, is all I needed. Thickened epoxy would hold them good enough for such light turning.

Big nut in the centre is for aligning three peripheral nuts. It is placed in routed cutout which will be used for drilling the axis later.

After careful alignment I removed the big nut and added more thickened epoxy to anchor three nuts to the wood.

The thing solidified overnight so I could give it a try.

First thing was to cut screw heads as they were too high. I should have used plungers here but had none at hand so that was a quick fix. Then I could calibrate it - to find a position for all three screws to meet exactly in the middle.

By counting turns on each screw I opened the chuck enough to place my wooden plug. Then the whole setup was mounted on a drill. Metal file was used as a grinding platform.

The result was, well - not satisfactory. The whole setup is flimsy and takes a lot of time to setup each plug to sit exactly on the axis. Even then the slight off-set makes the final result oval-shaped instead of required circle. In my test 15mm plug was turned into ellipse 13 and 14mm diameter.

So now it is clear why most DIY-selfers, who build the lathe, buy the self-centring chuck on eBay.

I’ll need to re-work my plugs on a proper lathe.