The Ultimate Guide To South Bend Crossfeed Lock Screws

The South Bend Lathe is a machine tool that has been in use for several decades. While it is a durable piece of equipment, some of its components may need replacement or repair over time due to wear and tear. One such component is the crossfeed lock screw, which plays a crucial role in the machine's functionality. This screw is responsible for securing the crossfeed mechanism, ensuring smooth and precise operations. However, issues with the crossfeed lock screw can arise, such as stripped threads or wear and tear, which can impact the overall performance of the machine. In such cases, users often seek advice and solutions from online forums, sharing their experiences and expertise to troubleshoot and repair this vital component.

Crossfeed screw dimensions

The crossfeed screw dimensions for a South Bend lathe vary depending on the model. For example, the crossfeed screw for a 14 1/2" South Bend lathe manufactured around 1945 had an original screw outer diameter (O.D.) of 11/16" with a left-hand turn.

For a 9" South Bend lathe, the crank 12-24 nut and stud are integral parts of the crossfeed screw assembly. The crank 12-24 nut can be replaced by cutting off the thread stud, boring, and tapping it for a 12-24 threaded rod.

The crossfeed screw for a South Bend 10K lathe has #12-24 or 7/32-24 threads, which are considered fine and challenging to repair without access to another lathe. A possible solution is to cut off the threaded portion and drill and tap a hole for a retaining screw, such as a #6 32 counter-sunk socket head screw.

It is worth noting that crossfeed screws may be interchangeable between certain models. For instance, a user reported that they had used the same crossfeed screw for both the 9" and 10K South Bend lathes.

Replacement crossfeed screw/nut

The crossfeed screw and nut are essential components of a South Bend lathe, ensuring smooth and accurate movement of the cross slide. Over time, these parts may wear out or become damaged, requiring replacement. Here is a comprehensive guide to replacing the crossfeed screw and nut on your South Bend lathe.

Identifying the Issue:

It's important to regularly inspect your South Bend lathe for any signs of wear or damage, especially if it's an older machine. Common issues with the crossfeed screw and nut include wear, stripping, or breakage. These issues can lead to improper functioning of the lathe, affecting the precision of your work.

Sourcing Replacement Parts:

When it comes to replacing the crossfeed screw and nut, you have a few options:

• Original Equipment Manufacturer (OEM) Parts: You can source OEM replacement parts from authorised South Bend dealers or online marketplaces. This ensures an exact fit and maintains the original specifications of your lathe. However, OEM parts can be more expensive.
• Aftermarket Parts: Aftermarket parts are produced by third-party manufacturers and can be more affordable. Ensure that you purchase from reputable suppliers to guarantee compatibility and quality.
• Custom Fabrication: If you have the necessary skills and equipment, you can fabricate your own replacement parts. This allows for customisation and can be a cost-effective solution.

Installation Process:

Replacing the crossfeed screw and nut on a South Bend lathe can vary depending on the model and specific design. Here are some general steps to guide you through the process:

• Disassembly: Start by securely locking the cross slide in position and removing the handle. This will expose the crossfeed screw and nut assembly.
• Removal of Old Parts: Carefully remove the old screw and nut, taking note of their orientation and any retaining mechanisms. Clean the area and inspect for any additional damage.
• Preparing New Parts: If necessary, cut, weld, or modify the new screw and/or nut to match the required dimensions. Ensure that the new parts are clean and free of any burrs or imperfections.
• Installation: Install the new screw and nut, following the reverse of the removal process. Ensure that all components are securely fastened and aligned correctly.
• Testing and Adjustment: Once the new parts are installed, test the cross slide for smooth and accurate movement. Make any necessary adjustments to the gibs or other components to ensure optimal performance.

Additional Considerations:

• Lubrication: Proper lubrication is crucial for the longevity of your crossfeed screw and nut. Use recommended lubricants and maintain a regular lubrication schedule.
• Preventative Maintenance: Regularly inspect and clean your South Bend lathe to identify potential issues early on. This can help extend the lifespan of your machine and reduce the need for frequent repairs.
• Documentation: Keep a record of any repairs, modifications, or adjustments made to your lathe. This can be helpful for future maintenance and troubleshooting.

By following these guidelines, you can successfully replace the crossfeed screw and nut on your South Bend lathe, ensuring its continued accuracy and reliability for years to come.

Crossfeed screw wear

The crossfeed screw is an important component of the South Bend lathe, a machine tool used for various manufacturing and development tasks, including gunsmith work and the production of miniature military items. Over time, the crossfeed screw can experience wear and tear, leading to reduced performance and functionality.

One common issue with the crossfeed screw is axial play, which refers to the in-and-out play of the screw shaft in the collar. This can occur when the thrust surfaces on the screw, collar, and dial wear down, causing a gap to develop between the graduated dial and the 'bushing'. The wear can also affect the flange on the inside of the crossfeed screw and the underside of the bushing. To address this issue, it is recommended to dismantle the setup, inspect all wear surfaces, and make the necessary adjustments to tighten the system.

In some cases, the wear on the crossfeed screw may be severe, with pointed threads and significant degradation. This can impact the performance of the lathe and may require fabrication or replacement of the screw. One option is to fabricate a new screw and nut using materials such as W-1 drill rod and brass. The fabrication process involves cutting the acme threads and bearing portion of the lead screw, as well as machining the nut to ensure a precise fit.

It is important to note that the brass nut is typically the first component to wear, followed by the screw itself. Replacing the nut can be a viable option, but it is essential to also inspect the screw for any signs of wear. In some cases, custom nuts made from materials like Delrin or Eartalyte can provide tighter clearances, even on a worn screw.

Overall, addressing crossfeed screw wear on a South Bend lathe requires a combination of inspection, adjustment, and, in some cases, fabrication or replacement of the screw and associated components. By taking the time to maintain and repair the crossfeed screw, users can ensure the continued accuracy and functionality of their South Bend lathe.

Crossfeed screw repair

Step 1: Assess the Issue

Before beginning any repair work, it is important to identify the problem with your crossfeed screw. Common issues include wear and backlash in the screw and nut, which can affect the accuracy and performance of your lathe.

Step 2: Disassemble and Measure

Remove the crossfeed screw from your lathe, taking note of its orientation and any relevant measurements. Measure the total length of the acme screw to the gear face and record this measurement.

Step 3: Cut and Prepare the Old Screw

Cut off the old acme crossfeed screw just in front of the power feed drive gear. Clean up the end by facing it off and spot-drilling the center. Drill and ream to the specified dimensions, creating a snug sliding fit for the new screw blank.

Step 4: Prepare the New Crossfeed Screw Blank

Turn down a length of the new crossfeed screw blank to match the dimensions of the old screw. This step ensures a proper fit between the two parts. Finish off the length of the new screw blank to match the recorded measurement from Step 2.

Step 5: Test Fit and Mark Alignment

Test the fit of the new screw blank and the old lead screw shaft. Use a dial indicator to measure run-out and achieve the lowest run-out possible. Mark the parts for alignment during the final assembly.

Step 6: Adhere and Cure

Apply Loctite 680 or a similar adhesive to the tang of the new screw blank. Reassemble the screw assembly, aligning the marked parts with the low side run-out down. Allow the adhesive to cure for the specified time, typically around 24 hours.

Step 7: Install a Dowel Pin (Optional)

After curing, check the run-out again and straighten as needed. You may optionally install a dowel pin to secure the connection further. Drill and ream the assembly to press fit an appropriate-sized dowel pin. The position of the dowel pin is typically at the end of the gear teeth.

Step 8: Final Assembly and Adjustment

Finish off any remaining areas, such as the front of the insert tang. Follow the provided instructions, such as South Bend drawing No. ATT. 208 or ATT. 212, for guidance on refitting and adjusting the crossfeed screw assembly. This may include adding thrust bearings and making adjustments to eliminate any unwanted backlash or endplay.

Step 9: Reinstall and Lubricate

Once the assembly is complete and any necessary adjustments have been made, reinstall the crossfeed screw into your lathe. Apply lubricant to ensure smooth operation and reduce friction.

It is important to note that these steps may vary depending on the specific model of your lathe and the nature of the issue you are addressing. Always refer to the appropriate manuals and resources for your machine before attempting any repairs.

Crossfeed screw alternatives

When it comes to the South Bend 9" Lathe, there are a few alternatives to the crossfeed lock screw that you can consider.

One option is to replace the entire cross slide screw assembly with a new one. This can be a costly option, with quotes of over $2400 for a new screw and nut from Leblond. Another user suggests contacting Brain at Miller Machine and Fabrication, who make a number of screws and parts for the 10ee, which may be compatible.

If you're feeling adventurous, you could attempt to fabricate a new crossfeed screw yourself. This involves machining a new screw and nut, or sourcing an off-the-shelf Acme threaded rod, welding it to the end of the old shaft, and finish machining to the original shape. This method requires careful execution to ensure the shaft remains straight and centered.

Another approach is to repair the existing screw by cutting out the worn segments and silver soldering or pinning new sections. This can be done with an interference fit and Loctite, or by taper pinning the new section. One user mentions using off-the-shelf Acme screw and nut from McMaster-Carr, cutting off the old threaded section, and drilling and reaming the mating section for the driver, before taper pinning them together.

Additionally, you could explore other fastening solutions as alternatives to the crossfeed lock screw. These include:

• Rivets: Permanent and strong, ideal for joining metal sheets.
• Bolts: Suitable for heavy applications like furniture legs or mounting shelves.
• Adhesives: Seamless and versatile, but require research to match the right type to the material.
• Wood joinery techniques: Tongue-and-groove and dovetail joints create strong and elegant connections.
• Velcro and hook-and-loop fasteners: Reusable and easy to use for lightweight applications.
• Cable ties and zip ties: Colorful and easy to use for lightweight items like cables or fabric.
• Welding and soldering: Industrial techniques that can be applied to custom metal furniture or sculptures.
• Clamps and brackets: Provide a secure hold and clean finish for wood pieces, especially at right angles.
• Joinery techniques: Dovetail, mortise and tenon, dowel, miter, pocket-hole, and biscuit joints offer strong and seamless connections.
• Hot glue and epoxies: Quick-drying solutions for small-scale projects or heavy-duty bonding.
• Industrial tape: Gaffer's tape, foam mounting tape, and high-strength bonding tapes offer residue-free adhesion for various surfaces.
• Magnetic fasteners: Versatile and easy to use, perfect for custom curtains or decorative elements.
• Suction and vacuum holders: Ideal for shower caddies or spice racks, providing a secure grip without damaging walls.
• Binding clips and pins: Affordable and versatile for organizing cords, sewing projects, or hanging lightweight items.

These alternatives offer a range of options to explore, depending on your specific needs and applications.

Frequently asked questions