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Bolt Base Surface Rust — Prevention and Treatment

Summary

The Bolt base top surface is mild steel, precisely toleranced and machined flat. It is intentionally left bare (uncoated) silver with only a thin film of oil applied from the factory. As that oil rubs off in use, the steel becomes exposed and will rust — especially in humid environments, coastal locations, or anywhere with significant temperature swings that cause condensation.

Do not paint the working surface. The top is a precision-machined surface; any paint layer changes the tolerances and can affect how the arm sits on the base.

The correct fix is: clean off the rust, then re-apply a film of oil.

Symptoms

  • Orange-brown rust spots appearing on the top surface of the Bolt base plate.
  • Surface may feel rough or gritty rather than smooth silver.
  • Accelerated in studios near the sea, in humid warehouses, or in high-humidity climates.

Fix

[CONFIRMED] Clean and re-oil

  1. Clean off the rust using a rust remover or fine abrasive (e.g. fine steel wool or rust eraser).
  2. Wipe the surface clean and dry.
  3. Apply a thin film of light machine oil or corrosion inhibitor spray to the entire top surface.
  4. Place the arm back onto the base.
  5. Apply a finishing coat of oil or paint to any exposed (non-working) perimeter surfaces if desired.

"The base is mild steel and the top is precisely toleranced and exactly level. That is why it's left in bare silver and only a film of oil applied to it. As the oil rubs off, the steel then becomes subject to corrosion and rust. The recommended way would be to clean off the rust and re-apply a film of oil to keep it clean and stop it from rusting." — gordon_admin (MRMC), 2023-11-01

Recommended products: - CRC SP-350 corrosion inhibitor — leaves a slightly oily film, prevents flash rusting. Recommended by field operators. - Any light machine oil applied regularly. - Anti-rust primer on non-working perimeter areas only (not the flat arm-mount surface).

Ongoing prevention

  • Re-apply oil to the top surface periodically, especially after setups in humid or coastal environments.
  • Keep the arm in place on the base when possible — reduces exposure of the top surface.
  • Consider a cover or case insert for transport in high-humidity conditions.

Source

Timestamp User Evidence
2023-11-01 GTakagi "I have found that our BOLT base got rust on its top side. Our studio is located in a warehouse near the sea."
2023-11-01 gordon_admin (MRMC) "The base is mild steel and the top is precisely toleranced and exactly level... The recommended way would be to clean off the rust and re-apply a film of oil to keep it clean and stop it from rusting."
2023-11-04 StrobeGeek "I use some CRC SP-350 corrosion inhibitor on my mill/lathe, leaves a slightly oily film but keeps it from flash rusting."