I am making several parts with a simple part with a hex. I know I am an anything like expert. I know at least two shortcuts by me but they don’t explain why I get good finish in one axis and chatter in an other. Can you folks help me explain some improvements. I did several with differing speeds and feeds and I used a 12mm 4 flute endmill with flood coolant. Kind of a big endmill for the small mill.
I am attempting to add a photo. Can’t figure it out (photos).
Hard to say for sure without seeing the setup but a couple things come to mind.
First, when is the last time you checked your gibs and AC bearings for proper adjustment? X and Y axis components will wear differently based on how the machine is used so it’s possible one axis has a bit more slop than the other which could be contributing to your issue.
Second, what does your workholding look like? Is it possible the part is held in such a way that it’s less rigid in one axis than the other?
Third, and this is more of a bandaid than a root cause, can you run a smaller tool? I have often found that a smaller diameter tool, run at higher rpm, relieves a lot of chatter issues. At least to a point. Too small a tool and you loose rigidity and then you’re right back to chatter.
Gosh, that wasn’t hard. I could not find the button. Ian, thank you for your patience and help. I made these parts in a small batch of 12.. I know I am short cutting steps and I was sure my work holding is and issue. I won’t describe the worst offensive thing but I made it better improving it with a 3 jaw chuck mounted to the table. Soft jaws in the vice would be good but the time and yet another set of odd jaws hanging around in the shop made me not do it. The work holding is at least half decent I think. I used this 12mm coated 4-flute because I have them and they seem to work okay. I am using flood coolant. The one axis confuses me as it is side milling and g-code generated hex. I also know that I did it wrong because I milled in conventional direction. I didn’t go crazy but a changed rpm from 4000 to 6500 rpm and 18-35 inches. It really didn’t change much at all. No, I have not checked the gibbs or the lead screws but haven’t put much time on it. I did measure the spindle tram which is abysmal but I can adjust it besides leveling it. On my Bridgeport is set to very close. On the Tormach 440 measuring about a 3” circle there is more than 0.003”. I like this little machine and I am blaming problems on me. I know I don’t know much.
