Thread Cutting Attachment Modification

Thread Cutting Attachment Modification


New & Old Support Arms

The Sherline Thread Cutting Attachment is a great accessory for the lathe but, when mounted to the front of the lathe (for use with the motor in place), the clamp screw points down toward the lathe mounting board, a position that makes it really hard reach with an allen wrench. This new primary support arm rotates the clamp screw by 60 degrees and makes it easily accessible with the Sherline T-handle wrench when the attachment is mounted to the front.

Begin by drilling and boring the hole for the "gear B" shaft. The hole should be a snug rotating fit on the "gear B" shaft. The hole for the lead screw support is 1.950" from the first hole. This hole needs to be bored for a snug slide fit to the lead screw support. Getting these two holes right is the critical part of this project. The rest of the machining is relatively straight forward.

Convenient Clamp Screw
  1. Mill away the excess side material on the support arm and set the angles.
  2. Fly cut the thin portion.
  3. Slit the clamp slot.
  4. Drill and tap the mounting screw hole.
  5. Drill out the clamp screw hole with a 10-32 tap drill, then relieve the outer side only with a #9 drill.
  6. Tap the other side 10-32 and you're done.

The photo (above right) compares the new support arm with the old one.

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