Setting up a small lathe on a bench that moves
The lathe arrived in two boxes and the bench it was going on was the one I built fifteen years ago for hand planing: a softwood top on four legs, 80 cm high, sturdy enough for planing but, as it turned out, not for a spinning 2 kg blank that is not quite balanced. The first time I turned a rough bowl blank at 1000 rpm the whole bench walked 5 cm across the garage floor in under a minute.
The first fix was mass. The bench had an open shelf underneath, and I filled it with four bags of dry sand, each about 20 kg, in heavy plastic bags inside cardboard boxes so they would not split. That added 80 kg low down. Walking stopped; vibration did not. The top still hummed at certain speeds and a pencil set on it would roll off.
The second fix was the floor. The garage slab is not level, falling about 12 mm over the length of the bench toward the door, and one leg was effectively in the air with the other three taking the load. I cut shims from hardwood scrap, 3 mm, 6 mm and 9 mm, and packed under the legs until a spirit level on the bench top read true in both directions and all four legs were tight to the floor. Then I screwed a diagonal brace of 50 by 25 mm softwood between the back legs, since the original bench only had stretchers on the sides. The hum went.
The third fix was height. A planing bench at 80 cm puts the lathe centers at about 100 cm from the floor once the lathe bed is on it. The rule of thumb is that the spindle axis should be at about elbow height, which for me is 108 cm. I added a 70 mm riser under the lathe feet, two lengths of laminated plywood bolted through the bench top, and the difference in my back after an hour of turning was immediate. The lathe is bolted down through the riser with four 10 mm bolts and fender washers, not just set on rubber feet as the instructions suggested.
Final test: a deliberately unbalanced blank, a 15 cm half-log with the bark still on, at 600 rpm and then 1000. The bench did not move, the level did not shift, and a pencil set on the top stayed put. The fixes took sand, scrap and an afternoon, and the lathe has not walked since. The next job is light; a single bulb above a lathe throws the shadow of your own hands onto the work, and I have been turning half blind for a week.