Chatter while cutting...

[saturnnights]

I think I already know the answer to this (mill's too small), but I'm gonna ask and verify...

I have an X2 mill that works well when I'm doing small cuts with small endmills, but whenever I try to work with a ball endmill larger than around 0.25", the cutter starts to chatter violently. Plunging is hard enough, but if I then start to feed in X or Y, the endmill jumps around and the whole machine shakes and makes a horrible amount of noise. I'd really like to use even larger endmills, but that's completely out of the question.
This is why I've been thinking about upgrading to a larger mill like the RF25 clones or the small knee mills.
Is the size of my mill likely the problem here?

Thanks,
Mark

[HuFlungDung]

How does the tool look when you stop it, is it plugged up (gummed up) with aluminum? Ball mills cannot successfully plunge very far, you would have to ramp into the cut and should never go deeper than the radius of the ball. Even that is pushing things if the cut is full width of the ball, most likely the tool will plug solid.

Try a bit of WD40 on the surface next time. This will usually prevent the tool from plugging up, but a Trico microdrop lube unit works wonders for milling aluminum and clearing the chips from the cut zone on a continuous basis. Trouble is, the Trico thingy might cost as much as the X2 mill

[dertsap]

i agree about the ramping it in , the cutter isn t meant to be plunged so your cutter is probably starting bad and it just carries through the whole cut

[ViperTX]

saturnnights.....I would agree with your last assessment.....larger machine.....Hu & dertsap have great information.....but lacking that information a larger machine helps us overcome that lack of infor.....

[brownandsharp]

whats the highest rpm your machine can go?

[rhino]

wd40 will work but i have found if you use kerosene on the tool it works alot better. (that is if its building up on the cutter)

[Yiros]

I use ballnose cutters a fair bit for engraving, I have also been known to use a small ballnose cutter to cut right through 5mm aluminum and then proceed to cut out lettering. I use a $250 AUD
coolant tank and pump setup and flood the job with a good water soluable coolant with no problems. (keep those chips out the way mate.)

[saturnnights]

Originally Posted by HuFlungDung How does the tool look when you stop it, is it plugged up (gummed up) with aluminum? Ball mills cannot successfully plunge very far, you would have to ramp into the cut and should never go deeper than the radius of the ball. Even that is pushing things if the cut is full width of the ball, most likely the tool will plug solid. Try a bit of WD40 on the surface next time. This will usually prevent the tool from plugging up, but a Trico microdrop lube unit works wonders for milling aluminum and clearing the chips from the cut zone on a continuous basis. Trouble is, the Trico thingy might cost as much as the X2 mill

Hi,
The cutter never clogs - but I'm cutting brass, so maybe that's the difference? I have tried taking small passes as well without much success. In the past, I've tried coming in from the side and taking very small cuts but it seems that the larger cutters just grab the brass and start to chatter back and forth - I can actually see the cutter moving laterally rather than just remaining still. I've come to assume (right or wrong) that the X2 isn't heavy enough to keep larger cutters from moving and that I probably need a bigger mill :frown:

Mark

[saturnnights]

Originally Posted by brownandsharp whats the highest rpm your machine can go?

It can do 2500rpm... When the chatter starts at higher speeds, it's downright frightening!

[saturnnights]

Originally Posted by dertsap i agree about the ramping it in , the cutter isn t meant to be plunged so your cutter is probably starting bad and it just carries through the whole cut

Unfortunately, this is a manual mill so ramping is not very easy (at least, for me)

[CrazyRonny]

Do you feed always in the opposition to the cutting force? For manual mill it's the only way to go because manual machine have to much backlash in it. And it's more important with brass and copper, this material pull the cutter in the piece really hard. If you feed the same way of the cutting force, each time a tooth of the cutter is engage in the material, the tool is pull in from the backlash amount.

CrazyRonny

[mxpro32]

Crazy Ronnie just said what I was about to say. Make sure you are conventional cutting. When climb cutting, the cutter will try to "walk" up the piece because their is backlash. When this happens chatter is terrible.