Thread Cutting Attachment, P/N 3100

(Click on photo for larger image.)

3100 Thread-cutting Attachment 3 lb. $131.25

About the Thread-cutting Attachment...

One of the big advantages of having a lathe is being able to machine threads. Many threads can be cut using taps and dies, but having a tap and die set that will enable you to cut all the non-standard thread sizes would be very expensive.

The thread-cutting attachment uses a set of metal gears to coordinate the movement of the spindle and leadscrew. Hand-cranking the drive gives you the ultimate in control where the small size and short lengths normally encountered on a lathe this size make a motor-driven engagement unnecessary. It also allows the control to cut threads right up to a shoulder.

Sherline offers a unique and versatile thread-cutting attachment for its lathe. This low cost attachment enables you to machine 36 different unified thread pitches (Pitch range from 80 to 5 threads per inch) and 28 different metric thread pitches (Pitch range from .25 to 2.0mm). What’s more, it allows you to cut them as either left-hand or right-hand threads. The lathe tool can be ground to cut any of the various thread forms, and any of these various pitches or thread forms can be cut on any pitch diameter you desire. This versatility enables you to machine any standard or nonstandard thread you need as long as it is within the size limitations of the lathe.

A typical threading project—1/2-20 male thread being cut. This is a radiator tank cap for a small IC engine. The top of the tank with the threaded hole for the cap is shown sitting on the lathe table in the first photo. (Click on either photo to view a larger image.)

The attachment consists of 15 accurately hobbed metal gears*, mounting brackets, engagement mechanism and a 4" (102mm) handwheel to drive the spindle. Threads are generated on the Sherline lathe by gearing the spindle to the leadscrew. As the spindle is rotated with the handwheel, the tool will advance an amount determined by the ratio of the gears. When the tool has completed its movement, you simply stop cranking, back up the tool and turn the spindle in the opposite direction until the tool is past its starting point. Then reset the tool and you’re ready for the next pass. It’s as simple as tapping! By using a 127-tooth gear (supplied), true metric threads can be cut on an inch (model 4000, 4500, or 4400) or true inch threads on a metric (model 4100, 4530, or 4410) lathe.

A complete gear ratio chart and detailed instructions are included.

*NOTE: We have done a special short run of gears with tooth counts in between the ones included in the set. If you need special gears to do a thread count different from the ones mentioned in the table, these gears might help you achieve it. The gears have tooth counts of 21, 23, 25, 27, 29, 31, 33, 35, 37 and 39 teeth. Call Sherline for price and availability. These gears are not listed on the regular Replacement Parts Price List. (11/06)

Customer, Cary Millsap, has given us a tip on how to install a Removable Tach Sensor for easier installation of the spindle gear. See Tip #75 for his step-by-step instructions and photos.


.html Version (Web site version)

.pdf Version (The same as our printed instructions. Requires Adobe Acrobat program to view.)


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