There are several ways to improve the surface finish of a steel part. Here are some suggestions:

1. Use the right tooling: The tooling you use can have a significant impact on the surface finish. Make sure you use sharp cutting tools that are designed for the specific material you are working with. Dull tools can leave marks and imperfections on the surface of the steel.

2. Optimize machining parameters: Adjusting the machining parameters can also help improve the surface finish. You may need to adjust the spindle speed, feed rate, and depth of cut to find the optimal settings for your particular part.

3. Use a coolant or lubricant: Using a coolant or lubricant during machining can help reduce friction and heat, which can lead to a smoother surface finish. Make sure you use a coolant or lubricant that is appropriate for the material and machining process you are using.

4. Consider post-processing: Post-processing techniques such as grinding, polishing, and buffing can help improve the surface finish of a steel part. These techniques can remove any surface imperfections and produce a smooth, polished surface.

5. Use a different steel grade: If you are still having trouble achieving the desired surface finish, you may need to consider using a different steel grade that is more conducive to achieving a smooth surface. Some steel grades are more difficult to machine than others, so choosing the right grade for your application is important.

It's worth noting that achieving a high-quality surface finish requires patience and attention to detail. Experiment with different techniques and settings until you find what works best for your specific part and application.