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Chatter is the enemy of all machinists. Encountering chatter is inevitable, so it’s vital that you know how to stop chatter on a lathe once it pops up. In this article, we’ll tell you what chatter is, why it matters, and two approaches to stopping it.
What is Lathe Chatter?
Chatter happens when the lathe used to reshape the workpiece does not or cannot retain contact with the surface. Instead, the lathe skips over the surface of the metal, breaking and regaining contact. This generates a vibrating, oscillating hum known as chatter.
Why Does Lathe Chatter Matter?
Chatter is an indication that something is going wrong. When you hear chatter, there’s a reason, and it’s never good news. Finding and eliminating the cause of the chatter is a routine and recurring task for any machinist.
Whatever the cause, chatter can cause significant damage to your workpiece.
- Chatter can make it impossible to get a smooth surface finish for either wood or metal.
- If you’re using a lathe to machine metal to a high degree of accuracy, chatter makes it difficult to hit those exact dimensions needed for detailed lathe work.
- If chatter goes unchecked, it can even make your part or workpiece unusable, turning it into scrap metal.
What Causes Chatter?
When the tool pressure is too high, and the setup of your workpiece is not rigid enough, chatter is the inevitable result. Changing one of these two variables is necessary to stop chatter from happening.
Chatter is more likely when machining certain metals; aluminum is known to be particularly chatter-prone.
Make sure you’re using the best lathe, even if it’s just a beginner one. A high-quality tool will be made with high-quality parts and reduce the chances of chatter.
Stop Chatter on a Lathe By Increasing Rigidity
A setup that is as rigid and locked down as possible is the first step to eliminating chatter from your lathe. Here are some steps you can take to lock down your lathe setup.
- Use tail support. If you’re not using the tailstock to help support your workpiece, this is by far the easiest solution to try. The tailstock holds the workpiece firm and steady, increasing rigidity and making the skipping that causes chatter much less likely.
- Reduce exposed material. If possible, insert more of your workpiece into the clamp, chuck, or collet holding your work, or put more of the workpiece into the bore in the headstock. Shortening up the amount of exposed material makes the material less likely to move back and forth.
- Use locking slides. Another issue that can be a factor during machining is loose slides. Locking your slides in place while you’re working reduces that source of vibration, thereby helping to minimize chatter.
- Check your compound and tool post. If your tool post is overhanging your compound, consider readjusting so that the two parts are in line. Or, if you’re not using your compound for this particular project, you can remove it completely to minimize vibration and increase the rigidity of your lathe setup.
- Tighten spindle bearings. This isn’t usually an issue on newer machines, but an older machine may have loose bearings in the spindle or a loose part in the chuck. If you’ve tried everything else and are still getting chatter, it’s wise to check on your spindle and tighten the bearings to see if that quiets your machine.
Stop Chatter on a Lathe by Decreasing Tool Pressure
Once you’ve determined that your setup is sufficiently rigid, attack the problem from the other direction by decreasing your tool pressure.
- Reduce the overhang of your tool. Expose as little of the tool as possible — just enough to do the work you need to do.
- Check for dullness. Tool pressure is increased when using a dull tool bit. Make sure to sharpen your tools before use.
- Consider another tool. Tools with rounded noses tend to give a nicer, smoother finish, but they are also the culprit for a fair degree of chatter. You might want to think about whether you can get the same results with a less rounded tool.
- Take smaller cuts. If you’re removing a lot of material with each pass, this increases your tool pressure. Back off, and remove less material, taking smaller bites out of the metal.
Chatter on a lathe interferes with getting the best results when machining metal. One cause of lathe chatter is insufficient rigidity in your lathe setup. Another is tool pressure that is too high. To stop chatter on a lathe, decrease the tool pressure or increase your setup rigidity.