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PTE Service Tips

Power Tool Lock & Ejector (PTE) Service Tips

A customer should attempt only simple, basic service operations on a Lucas PTE system. I do not recommend that ANY customer attempt to perform an 'in field' rebuild of the PTE. There are too many different designs, and too many 'shop tricks'. Since a tool that is released from the Spindle while the machine is running presents a considerable personnel hazard, even telephone assistance beyond the most basic items is not provided.

Be aware that there is a tremendous amount of spring pressure 'trapped' inside the Spindle when the PTE mechanism is fully assembled. DO NOT attempt to disassemble the mechanism without a thorough understanding of how to either release or contain the spring pressure. If the spring pressure is released in an uncontrolled manner by removing parts in incorrect sequence IT CAN BE LETHAL! Be certain to examine cross-section drawings before attempting disassembly. If the mechanism does not look EXACTLY like the drawing, you are looking at the wrong drawing. STOP and get the correct drawing. The safe disassembly process of one model may be deadly on a different model!

NEVER STAND BEHIND THE SPINDLE OR ALLOW YOUR HANDS TO GET BEHIND THE SPINDLE UNLESS ALL SPRING PRESSURE IS VERIFIED TO BE RELEASED!

You should be aware that the maintenance manuals describe a procedure called "Assembly and Facing In Instructions". It appears to be a simple 'cookbook' that could be used by a customer to perform a complete rebuild of the PTE mechanism. Please be aware that this procedure contains several flaws and that while it 'might' successfully rebuild your PTE, it is just as likely to result in your irretrievably scrapping all of the repair parts that you are installing. The procedure described is too 'simplistic'. It might work if ALL of the parts being used are manufactured exactly to blueprint dimensions (including the Spindle itself), however, it makes no provisions for what to do if several parts (or even one part) are not exactly perfect.

 

As stated, there are several different designs of PTE, the most common are:

Design 1: Die Spring operation with 6-finger, wedge lock collet
Design 2: Spring Washer operation with 6-finger, wedge lock collet
Design 3: Spring washer operation with 8-finger, non-wedge lock collet.

These tips only apply to the 6-finger, wedge lock collet system with Spring Washers, which is the type used on most machines.

 

Things a customer CAN do:

  1. Collet replacement: Generally, collets may be replaced by a customer without problems. You need to perform the 'pry test' and possibly to recalibrate your setting gauge. After the bolt holding the collet has been tightened, strike the wrench handle sharply to 'seat' the bolt. Failing to strike the wrench handle will almost certainly result in the bolt loosening up. NEVER use thread-locking compounds on the bolt threads
     
  2. Setting Gauge Calibration: Instructions are containing in a separate document.
     
  3. Ejection Cylinder O-Ring Replacement. Get the O-Rings from Lucas. Some of the assembly drawings specified incorrect commercial part numbers. NEVER use gasketing material or cement between the cylinder sections. If you must replace minor hardware parts, MEASURE the old parts to assure the new parts are the same. Proper O-Rings sizes will not 'feel' right. Piston & Cylinder machining dimensions are non-standard.
     
  4. Spring Washer Replacement. Get the Spring Washers from Lucas. Only one brand will function properly. Certain 'Original Equipment' Spring Washers are obsolete. We have proper replacements. Lubricate the washers during assembly with grease. Do NOT use 'anti-seize'. 'Anti-seize' will dry out; grease will not.
     
  5. Be extremely cautious if you use 'injected coolant' tooling. If the tooling arbor is 'open to the rear', you will fill the headstock with coolant and damage the PTE.
     
  6. Releasing a Milling Machine tooling arbor that has become locked in the Spindle Taper: Raise the Eject system pressure slightly - approximately 20 to 30% Remove the cutter blades from the tooling arbor. Strike the tooling arbor INWARD as though trying to 'seat' the arbor into the Spindle. Use approximately a 4-pound Copper Hammer (or pad thing heavily with Oak). If the arbor is not released within 3 blows - stop and call Lucas. Clean and inspect the Spindle Taper and the Tooling Arbor for proper 'fit' and burrs. A Milling Machine taper will occasionally seize if it or the Spindle get hot.
     
  7. Releasing a Drawback Collet Adapter (Drawstud) that has become locked into the collet. This is caused by a loose Collet mounting bolt. The tooling arbor is NOT seized to the Spindle Taper. The bolt has 'backed out' far enough to strike the rear of the Drawback Collet Adapter BEFORE the collet has 'passed through' the Collet Retainer (the ring). The arbor may be tight or loose in the Clamped position - that doesn't matter! The arbor will get tight in the Eject position - proving that the Collet Mounting bolt is striking the Drawback Collet Adapter.
     
  8. Here's how to fix it: Remove the Tooling Drive Keys. Unscrew the Tooling Arbor from the Drawback Collet Adapter. Remove the pipe plug from the end of the Drawback Collet Adapter. Get an 18-inch long piece of black iron pipe of the proper size to enter the Drawback Collet Adapter. Put the system into Eject. Screw the pipe into the Drawback collet adapter. Put the system into CLAMP. Either start the Spindle rotating at its SLOWEST RPM in the clockwise direction OR use a 'slow speed' drill motor to spin the piece of pipe. 'Bump' the end of the pipe (or the back end of the drill motor) with a piece of wood. Each time you 'bump' the pipe, it will 'bump' into the bolt head. Each time it 'bumps' the bolt head, it will cause the bolt to screw in a little. Continue 'bumping' until the bolt is screwed in far enough to allow the collet to eject.
     
  9. After the Drawback Collet Ejector is removed, everyone wants to simply tighten the collet bolt and go back to work - DON'T DO IT. Remove the Collet Bolt. Remove the collet. Re-install the Collet being absolutely certain that the pin inside the rear of the Collet is Properly aligned with the 'notch' on the end of the pushrod. Install the collet-retaining bolt. After the bolt holding the collet has been tightened, strike the wrench handle sharply to 'seat' the bolt. Failing to strike the wrench handle will almost certainly result in the bolt loosening up again. NEVER use thread-locking compounds on the bolt threads