Reduce any Overhangs

One key parameter with regards to any tools is to reduce the overhang and so reduce the chance of chatter or even worse parts and tools breaking.

The image shows a simple change in the length of cutter tool that is protruding from the collet chuck, but this small change in length will have a significant impact on the stiffness of the cutting tool.

If the cutting tool is not stiff enough it will chatter and you will have to reduce cutting depth and feed rate.

You can also change the way in which the cutter is held:

The difference in tool overhang when changing from a drill chuck to direct 3MT collets is huge.

This image shows two different setups in my old Amadeal Milling Machine.

All of these changes reduce the distance between the point at which the cutter is making the cut and the bearing in the shaft. If you reduce the distance between the point at which the force acts and the point at which the material is anchored you will increase the stiffness.

 

The basic principle of reducing overhangs and keeping all distances as short as possible applies to all forms of machine tools. Chatter in the lathe can create a nice effect, but only if you want it.

Chatter marks on the workpiece are the result of vibration of the lathe, saddle, toolpost, tool or workpiece itself.

Sometimes it can be very difficult to stop this from happening and I often find this is because I′m using the lathe at it′s limit of capacity or capability. Normally because of a clash with the saddle.

Tool overhang can result in vibration, the upper image shows the tool has been located a long way out from the toolpost, shortening the overhang will increase the stiffness and so increase the frequency of any mode of vibration associated with the tool in cantilever.

More information around Noise and Vibration can be found within our pages.

About Nigel 187 Articles
Have been making models since I was around 7 years old and using a lathe from the age of 11, a self taught engineer with a passion for making model engines.

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