Tracking down some shudder

Milled some 6061 Aluminum this morning and noticed that the XC was shuddering a bit when making very rapid, small changes in the X axis. It seems like it might come from the motor, but I’m not entirely certain. It could also be flexing of the Z-axis, just not sure. What’s certain though is that it happens on short jerks back towards the left. All other movements while machining are nice and smooth.

I observed this while using a feedrate of 600mm/min and a DoC of .2mm with a 3mm single flute end mill.

I’d appreciate your thoughts about likely suspects to check out and eliminate.

Spent some more time on this today. Ran the carraiage back and forth on the gantry by hand with the machine off and felt some bumpiness. Noted that there were a few chips of aluminum embedded in the carriage v-wheels and carefully scraped them out with a fine screwdriver and then readjusted the eccentric nut to make sure the wheel was tracking properly. Also upped the X-Axis current pot to the 2 o-clock position.

Still am seeing, and feeling, a sort of grumbling sound when the X-Axis is cycles back and forth. Will do further testing to isolate where it’s coming from.

[SOLVED] Turned out this was due to a combination of factors. In addition to the AL chips embedded in the wheels, the tightness of the v-wheels for the carriage was all over the place. One of them was very tight, which made it difficult to move the carriage at all. 2 others were very loose, which allowed the carriage to shift around when force was applied to it.

Figured this out by disconnecting the X-Axis belt entirely and trying to move the carriage by hand. Didn’t feel smooth. Loosened the V-Wheels, propped the spindle on a 1/4" bit and adjusted the Z-Axis by hand until the carriage was sitting on the top wheels with the front square to the wasteboard. Slowly adjusted the v-wheels until they could be barely turned by hand and then backed off 1/4 turn. Retracted the bit by hand until the carriage was only supported by the rails and tested by hand. Moved nice and smooth with no up and down slop.

Put the belt back on and slid carriage back and forth on X-Axis while tightening the belt. Stopped when belt tightness seemed to make the carriage hard to move and backed off the tension one full turn.

Seems to work like a champ now.