What causes X axis chatter?

Getting quite a bit of chatter going while carving with .25" straight bit on my x axis… any suggestions on what to look at to fix the chatter?

What are your speeds and depth of cut, what are you cutting. Have you checked all the v wheels on the X axis carriage? On the Z?

Was at around 45 in/min at .05 depth.

Some really dry edge glued spruce panels from big box store.

V wheels seemed fine on the carriage

It can be from the orientation of the grain. The bit wants to try and follow the grain. You might try a spiral bit.

Chatter is a function of several things, based on mainly flex/give and harmonic frequencies.
Chatter can even occur without actually carving.

Xcarve have two belts on Y (each side) but only one on X. That might be part of it. What happen if you try a feedrate at 50% of current speed?

What do you go by when setting your vwheels - should the wheel move just slightly without the gantry moving, or should it be tight enough that the vwheel only moves when the gantry is moving?

Check your tramming. If the bit is not as close to perpendicular to the material as possible then it will want to walk around on you, chatter.


Bringing up my old topic to ask quick question.

I upgraded my X axis, checked V Wheels, Checked square, Checked belts and everything seems good.

If I start a project and it is doing the first pass through the wood, so 100% step over I wont get chatter, but when it moves onto the 40% step over I get chatter on my x axis.

Currently doing .25" bit at .1" depth at 50ipm into black walnut.

I had a pretty harsh chatter issues at relatively low speeds. I ended up doing this…

Another encouragement to start with stiffening the Y axis. An unsupported Y axis rail will quickly introduce chatter causing flex.

Probably a stupid question but how does flex in the Y axis cause chatter in the X axis.

I always figured Y flex would cause chatter when traveling in the Y direction not the X direction.

Not stupid at all. If your router is moving to the left or right (x- or x+) the structural piece that resists the movement are the y axis rails. For instance, if you were to lock the motors up so it resists all movement, and then you were push the router in line with the x axis, the y axis rails will tend to bow with force in whichever direction you were to push.

This bending also happens in its practical application as a bit is cutting in the X axis direction. Mix that with the resonance you generate by cutting and you have a recipe for chatter.

This can be eliminated or reduced by installing simple stiffening brackets on the y axis rails to tie it to the wasteboarf or frame structure under the wasteboard.

I hope this helps and doesn’t just confuse the matter even further.

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@MitchWillard did you find anything to help your chatter?

My plan is to support my Y axis and see how that helps. I have the lead screw upgrade ordered though so I will be waiting until that gets here so I don’t add some supports then find they don’t work with the new upgrade.

Ideally one would attach a bracket with tnuts in the extrusion so that the brackets on both sides resist movement in both directions. I did, however, find that a good temporary step is to just screw down wood blocks to the wasteboard that are tall enough to butt snugly against the Y axis rails. If you do one on each side, the left block will resist movement to the right and the right block will resist left movement. This is quick, temporary and effective. If this stops or reduces your chatter, you will know that this was at least one of your issues.

The other common cause is the stock z axis assembly. It is terribly prone to movement/flex that can also contribute to chatter in the x direction.