Tool Holding

Unlike larger CNC milling machines which use conical taper systems like 30 taper, 40 taper, 50 taper, etc., Tormach uses their own custom tool holding scheme called the Tormach Tooling System (TTS).  The spindle of the machine actually accepts a standard R8 collet, which is the same type used in most Bridgeport mills as well as many smaller mills like our small red X2 mills.  However, standard R8 collets have a problem in that they do not offer repeatable tool heights.  Generally speaking, when you loosen an R8 collet and remove it from the machine, the tool it is holding also loosens.  Furthermore, the exact height of the tool depends on how tight the drawbar is closed.  This causes a problem in a CNC situation, where you want to be able to change tools for different operations within a job, and have a known and repeatable tool offset (distance from the spindle nose to the tip of the tool).

TTS improves this situation by using a modified R8 collet which holds a 3/4" shank.  The tip of the collet is ground flatter than a normal R8 collet, so that it does not protrude from the nose of the spindle when drawn in by the drawbar.  Custom tool holders that feature a 3/4" shank are then inserted into this R8 collet, and the drawbar is tightened, clamping the tool into the spindle.  TTS tools have an additional feature which rests squarely on the nose of the spindle when the tool holder is drawn in, and this is what allows TTS tools to have a repeatable height.

More information on the Tormach Tooling System here.

This scheme also allows tool heights to be measured "offline" - that is to say, using a height gauge and a granite surface plate - before G Code is executed on the PathPilot CNC controller.  The height of each tool is measured, with the height being entered into the tool table on the PathPilot controller either manually or via a USB connection to the height gauge.

Our Tormach machine has a pneumatically actuated power drawbar system, which allows rapid manual tool changes in only a few seconds.    With TTS, the special TTS-R8 collet normally stays in the spindle at all times (except for maintenance), and the power drawbar system pushes the collet out of the taper only enough to allow the TTS holder to drop out.  

Always make sure to hold onto the tool with one hand when releasing the power drawbar, as the current tool WILL fall out of the spindle when the drawbar is released, causing damage to the tool or injury to the operator.  For efficiency, our power drawbar system features a foot pedal actuator, so you can hold on to the currently mounted tool with one hand, and the next tool in the other.  By using the foot pedal, you can remove the current tool and swap in a new one in about 5 seconds.

Because of the way the power drawbar system works, you MUST always leave a tool holder in the spindle, even when the machine is not in use.  The power drawbar uses a series of springs, which will pull the R8 collet deep inside the spindle if no tool holder is inserted into the spindle, and this will cause fatigue and eventual failure of the collet.  Chris E. has made a special "dummy tool" to leave in the spindle when the machine is not in use.

We have the following tool holders and accessories available for use with the Tormach mill: