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constant surface speed

An Intro to Constant Surface Speed on a LeBlond RKL Manual Lathe

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Want CNC functionality at manual prices? Check out Constant Surface Speed (CSS) for your LeBlond RKL manual lathe.

We are doing a series of posts on CSS, a feature on a Newall or AccuRite Digital Readout (DRO) that gives consistent finish to workpieces with different diameters. CSS is available for precision high speed variable speed lathes (RKL-1300V, RKL-1500V, RKL-1700V and RKL-1900V models) and heavy-duty models (RKL-2100, RKL-2500 and RKL-2900).

How Does Constant Surface Speed Work?

This feature automatically determines appropriate spindle speed in revolutions per minute (RPM). CSS does this based on the speed specified in surface feet per minute (SFM) in inch mode or meters per minute (MPM) in metric mode. A manual lathe operator inputs the cutting tool’s current diameter position and the DRO calculates the spindle speed in RPM accordingly, based on the following formula:

RPM = SFM x 3.82/Cutting Diameter

An operator can refer to specifications provided by tool manufacturers for recommended surface speed for different combinations of tools and production materials. When CSS on your DRO is activated, the spindle speed automatically changes the position of the cross slide. For example, with facing operations, when the tool bit moves toward the center of the workpiece, the spindle speed accelerates, maintaining constant surface speed during cutting as the diameter of the workpiece decreases.

CSS Installation

Regarding gear selection, many LeBlond RKL manual lathes have one, two or three different gear settings. When installing your DRO equipped with CSS, you must install switches on the machine to detect gear changes.

When you turn off CSS on your DRO, you set the spindle speed via the lathe potentiometer.

Summary of CSS Benefits

CSS is beneficial in providing longer tool life and improved surface finish. It also improves productivity as you have reduced machine shutdowns and shorter machining time.

You really want to employ CSS when cutting workpieces with varying diameters. When cutting parts with minimal diameter changes, CSS is not that helpful.

If you’re interested in new LeBlond or K.O. Lee machines or require OEM parts for your LeBlond, K.O. Lee, Standard Modern, Johnson Press, Deka Drill or W.F. & John Barnes equipment, call LeBlond at +1 (888) 532-5663 or fill out a form here.

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