This procedure shows how to replace current spindle front caps with solid front caps. 

 Note: Only replace non-solid caps with a front solid cap if you are experiencing high runout and poor surface finish problems. 

This document applies to the following service kits :

• 93-5172 - RIGID FRONT CAP CONVERSION KIT A2-6 SVC

Required Tools:

• Feeler gauge
• 0.0001" Dial Indicator with Mag Base
• Air line with quick disconnect
• T-0151 A2-8/A2-6 SPINDLE DEFLECTION TOOL KIT 
• T-0156 A2-5 SPINDLE DEFLECTION TOOL KIT 

 Note: Only one of the above kits needs to be ordered. Choose the one that fits your spindle size. Refer to the Lath Chuck Diameter Chart if needed. 

Note: This procedure uses a ST-35 for illustrative purposes. The same applies to all machines listed above unless otherwise specified. 

Remove chuck from spindle [1].

Remove bulkhead ring [2].

Remove the existing front cap [1] and clean up any sealant on the spindle head face [2], near the bearings [3], or where the bulkhead ring was seated [4].

Install the solid front cap [1] with half of the bolts. Snug bolts hand tight.

If the cap has 6 holes, use 3 bolts skipping every other hole. 

If the cap has 8 holes, use 4 bolts skipping every other hole [2]. 

If the cap has 10 holes, use 5 bolts skipping every other hole [3]. 

Place a feeler gauge [1] under the empty bolt holes [2] to measure the gap between the solid front cap and the spindle head face [3].

The desired “crush” for a solid front cap is .002” - .005”.

Based on the previous feeler gauge measurement, there are 3 possible scenarios:

1.  No feeler gauge will fit underneath the empty screw hole position.  This means there is no crush on the bearings.  Add 1x inner shim [1] and re-do step 4 with feeler gauge until desired “crush” is achieved.
2. A feeler gauge more than .005” fits underneath empty screw hole. This is more than the desired “crush”.  Add 1x outer shim [2] then re-do step 4 with feeler gauge until desired “crush” is achieved.
3. A feeler gauge between .002” and .005” fits underneath empty screw hole. This is the desired “crush” amount, so no extra shim is needed.  Proceed to step 6.

 Note: The inner shim will sit on top of the bearings and the outer shim will sit on the spindle head face.

 Note: A majority of machines should need either 1x inner shim or 1x outer shim. Rare cases may need 2x inner or 2x outer. If more than 2x of the same shim are needed contact Haas service.

Once the desired “crush” is achieved, install any remaining bolts [1] into the front cap.

Install the drain screw [3]. 

• Snug the spindle cap srews [3]
• Use a .001" shim [4] between the cartridge [1] and the spindle retainer [2]
• Tap the spindle retainer with a plastic mallet until the shim clears every section of the cartridge
• Torque the retainer screws [3] in a star pattern. HAAS TORQUE CHART
  • Note:You may need to start at a 1/3 of the torque value and torque them down 3 times. Torqueing down all the way the first time may displace the retainer cap and require it to be reset. 
    
• Sweep between the cartridge and the retainer cap one last time to verify the .001" shim has clearance all the way around [4]

Follow the Spindle Deflection Test procedure to confirm bearings are properly loaded.

Re-seal and install bulkhead ring [1]. 

Install chuck onto spindle [2].