襯套，同步皮帶輪

Finally got around to swapping this sleeve onto my SC4 and the machining on the bore is noticeably smoother than the old part. It slid right into place with zero binding, which saved a lot of adjustment hassle.

After replacing the original sleeve on my SC4 bench lathe, the new one fits exactly as the part diagram indicated—no filing or adjustment needed. The machining on the pulley surface is clean and precise, which made installation surprisingly quick.

The fit on my SC4 lathe is spot-on, so the timing marks line up without any fiddling. It’s clearly machined to the same spec as the original part, and I didn’t have to modify a thing to get it seated right.