Service Home How To Procedures 50 Taper - TSC - Compensating Union and Threadless Transfer Tube - Replacement - Mill - AD0412
Last updated: 09/10/2019

50 Taper - TSC - Compensating Union and Threadless Transfer Tube - Replacement - Mill - AD0412

AD0412

Applies to machines built from August 2018

Prerequisites

This procedure explains how to replace the compensating coolant union and the threadless transfer tube  on the vertical 50 taper mill built after August 2018. This procedure can also be applied to the horizontal 50 taper mill built after August 2018. Skip the "50 Taper Mill - TSC - Threadless Transfer Tube - Replacement" if you only replacing the compensating coolant union.

Compensating Coolant Union - Removal

1

Note: You must remove the spindle head cover to gain access to the compensating coolant union [1]. The compensating coolant union is located on top of the tool release piston (TRP).

[ Power the machine OFF ]

Disconnect all hoses that connected to the compensating coolant union.

2

Remove four bolts [1] that secure the compensating coolant union to the TRP.

Remove the compensating coolant union [2].

Threadless Transfer Tube - Replacement

1

Remove the snap ring [1] that keeps the transfer tube [2] bearings in place.

Pull the transfer tube assembly [2] out of the TRP.

Important: Do not use the pliers to pull the transfer tube out. This will damage the transfer tube. If the transfer tube is stuck, insert Ø0.25"X 24.0" rod through the bottom of the spindle and gently tap the transfer tube out.

2

Inspect and clean the bore [1] of the transfer tube bearing retainer.

Make sure that the hex and the o-rings [2] on the bottom of the transfer tube are free of defects.

Apply Red-I grease to the o-rings and the hex [2].

Insert the transfer tube into the TRP until you feel that it contact the drawbar.

While gently pressing down, slowly rotate the transfer tube to align the hex on the transfer tube with the reciving hex on the drawbar and then firmly press the transfer tube down into the drawbar.

Important: Never use a mallet or any other excessive force to drive the transfer tube down. If the hand force is not enough to seat the transfer tube, remove the TRP and inspect the bore on top of the drawbar.

Install the replacement snap ring [3] over the transfer tube bearing. Make sure that the snap ring is fully seated in the groove on the bearing retainer.

Compensating Coolant Union - Installation

1

Inspect the top of the transfer tube for any debris or damage.

Apply Red-I grease to the rubber seal and the bore on the bottom of the coolant union [1].

Install the compensating coolant union over the transfer tube with the fittings pointed to the right.

Tighten the four mounting bolts [2] and back them off 1/4 turn.

While rotating the spindle by hand, gradually tighten and then torque the mounting bolts in the criss-cross pattern.

Note: Refer to the Haas Fastener Torque Specifications for the correct torque value.

Insert a screw driver [3] into the top JIC fitting [4] until you feel it contact the piston [5].

Note: The top cover has been removed in this image to illustrate the piston. Do not disassemble the coolant union.

Lightly press downwards until you feel the piston [5] contact the shaft [6] to eliminate the gap [7].

Reattach the hoses to the coolant union.

Run the spindle motor at 100 RPM and verify the union is not rubbing on the shaft. Gradually increase the spindle speed from 100 to the max RPM and check the coolant union for abnormal noise and vibration.

Compensating Coolant Union - Troubleshooting

Symptom Possible Cause Corrective Action
A large flow of coolant comes out of the drain tube when TSC is turned on. The union piston is not seated. Put a high-pressure (small orifice) tool in the spindle and run TSC. The pressure should push the piston down. Or, disconnect the hose and use a screwdriver to gently seat the piston.
The amount of coolant flow from the drain tube is more than a few drops. Runout on the carbide tip or damage to the piston cup seal The 50T compensating union will bypass slightly more coolant than the 40T union, especially with tools with large orifices. This is normal. If the amount of coolant seems excessive, check the flatness of the carbide seals or check the piston for damaged rubber seals.
The union is leaking coolant. Leaky drain tube or no air supply to the union. The drain tube connection is not watertight and requires glue to seal it during union assembly, make sure the hose clamp is tight. Check the solenoid and hose for air supply problems.
The union makes a high pitch ringing noise when running TSC that does not go away after a few minutes of running. TSC union alignment, or transfer tube runout. Check the transfer tube for runout. Inspect the piston cup seal. Re-align the union with no hoses connected.
The union makes a high pitch ringing noise when running TAB that does not go away after a few minutes of running. Excessive back pressure. Try using a tool with larger orifices to reduce back pressure or try turning on TSC briefly to lubricate the seals. When running TAB with a small orifice tool, a high pitched noise is normal.

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