Signs your lathe is too small or low power for negative rake tooling

Negative rake toolholders are among the most popular choices in industry due to their ability to tolerate high cutting forces and high feeds and speeds without breaking inserts. However, negative rake tooling is not suitable for smaller lathes due to the greater strain this puts on the lathe and lathe motor. Here's a brief guide to working out whether your lathe is not suitable for negative rake tooling, although experience remains the greatest teacher:

The lathe is small enough to lift by yourself

If your lathe is light enough that 1 man can physically pick it up it is extremely unlikely for it to have a strong enough motor or rigid enough bed for it to handle negative rake tooling well. Lathes rigid and powerful enough to take advantage of negative rake tooling will not be mountable on a bench top but will be large floor standing lathes that need to be wheeled or craned into place.

Squealing, chattering, juddering on normal turning operations.

These are all signs that your machine is not rigid enough to absorb the cutting forces being produced, and is instead transferring them into harmonic resonances via rhythmic deflection of the toolholder away from the workpiece..

Motor slow down

There should not be any noticeable slow down of the lathe spindle motor when the cutter engages the workpiece . On a manual lathe, this will be most noticeable when threading using the lead screw/half-nut, which advances the cutter at a set rate per spindle revolution . Since the lead screw is driven off a gear chain attached to the spindle motor, any slow down in the speed of the motor will be noticeable in a reduction in the speed the carriage advances.