I received a call today from my customer, John, who needs a stop to locate in his drawtube of his lathe to position a 16” long part on his z-axis. John informed me that this is the first operation of this part and he has a 16C Pullback Style collet chuck. I recommended the following:

This Spindle Work Stop (Also known as a Drawbar Stop) is a tool that is used as a parts stop in a lathe spindle or draw tube for quick setups, enabling accuracy or consistency of linear dimensions. Place the workpiece in a chuck or collet and set the proper length. Insert the work stop into the rear of the spindle or draw tube. Expand the fingers using the supplied T-handle wrench until they touch the spindle, then back off the screw a quarter turn. Using the T-wrench, slide the work stop into the spindle until it contacts with the workpiece. Tighten the work stop and remove the wrench.

Spindle Draw Bar Work StopI explained to John that he needs to be aware that when using a Pullback Style collet chuck, linear dimension can change if the OD diameter of the part varies. For every .001” on the diameter, the linear position will move .003”. Being that he is doing the first operation, he will simply program the machine to face the part to establish his overall length of the part.  If John was doing a second operation and the OD of the part varied (Lets say +/- .003”) and he also had to hold the linear within .002”, this style stop would not work. This is because the stop moves with the draw tube and he would be unable to hold the linear dimension of .002”.  For that situation I would recommend that John make a fixed stop to fit his machine that is independent of moving with the draw tube.  For more information on this product click here: Spindle Work Stop. As always, feel free to contact us for more info: 800-423-5145