tool_scrounge
Well-known member
The stock lathe key that came with my 3 jaw chuck is great for tightening. But is is a pain the wrist when making large lathe jaw adjustments. Turning it 1/2 a turn at a time is also pretty slow. So my goal was to make a key that could be operated with one hand quickly while my other hand was supporting the round stock.
I had a spinner handle with way too many stripped set screw holes in the junk pile. I had been debating on recycling it. But I figured sooner or later I would find a use for it. The lathe key was a 0.44" square drive, so a 1/2" socket extension would be good starting material. I ended up using an old Craftsman 6" extension as the shaft was 0.52" in diameter and the spinner handle had a 0.50" bore.
Milling the extension flats down to 0.44" square was pretty easy with sharp tooling and a machinist square. Lathing that shaft diameter down 0.02" was harder than I expected. It turns out the Craftsman extension is not very straight. It is bad enough that you cannot turn it with carbide tooling as the interrupted cut breaks the carbide tip. But high speed steel lathe bits work just OK. Not great finish but good enough for this application.
I press fit the modified extension into the handle with added Loctite 648 retaining compound. It holds very well. I will use the stock handle for the final clamping on metal, but the speed key good enough for for final clamping on plastics.
Originally I left the spring loaded ball in the extension, but it made inserting the key into the chuck a bit too difficult. So I milled out the back are removed the spring. The key is sized close enough that it stays put in the lathe chuck even without the spring loaded ball.
Overall it works very well.
As with any lathe key, you do need to remove it before turning on the lathe for safety sake.
I had a spinner handle with way too many stripped set screw holes in the junk pile. I had been debating on recycling it. But I figured sooner or later I would find a use for it. The lathe key was a 0.44" square drive, so a 1/2" socket extension would be good starting material. I ended up using an old Craftsman 6" extension as the shaft was 0.52" in diameter and the spinner handle had a 0.50" bore.
Milling the extension flats down to 0.44" square was pretty easy with sharp tooling and a machinist square. Lathing that shaft diameter down 0.02" was harder than I expected. It turns out the Craftsman extension is not very straight. It is bad enough that you cannot turn it with carbide tooling as the interrupted cut breaks the carbide tip. But high speed steel lathe bits work just OK. Not great finish but good enough for this application.
I press fit the modified extension into the handle with added Loctite 648 retaining compound. It holds very well. I will use the stock handle for the final clamping on metal, but the speed key good enough for for final clamping on plastics.
Originally I left the spring loaded ball in the extension, but it made inserting the key into the chuck a bit too difficult. So I milled out the back are removed the spring. The key is sized close enough that it stays put in the lathe chuck even without the spring loaded ball.
Overall it works very well.
As with any lathe key, you do need to remove it before turning on the lathe for safety sake.
