Key, 4x18 mm

Finally found the right replacement for part 166 on my SC4 parts diagram—this flat key fits the shaft perfectly. The 4x18 mm size is a precise match, and it locked into the intermediate slot without any fuss. My bench lathe is back up and running smoothly.

Popped this flat key into my SC4 lathe's intermediate shaft and it seated perfectly with zero modification needed. The 4x18 mm dimensions match the original part exactly, saving me the hassle of filing or grinding like I've had to with other replacements.

Barely had to file it down to fit the SC4's shaft slot, which tells me the machining was spot-on for the spec. Saved me from having to cut a new key from scratch.