Side Mill Surface Wavey

[zerodegreec]

Squaring up my first blocks (6061 Alum). 1/2" 2 flute end mill. Running at 2200rpm and 1.2ft/min (thats as fast as I can crank the wheel. Also tried really really slow and I get the same result)

I have tried climb and conventional and the same results

I can feel the ridges with my nail. It just seems like I am doing something wrong

[holbieone]

there could be a lot of causes for you problem

the greatest thing is, how rigid is your machine ?

causes :free play in your ways
free play in your axis screws and or thrust bearings
flex in your spindle or lose bearings
machine not rigid enough for the cut

put an indicator on your ways and see if there is any side play
do the same for the screws

put a tool in your spindle with an indicator on the spindle , push on the tool
put the indicator on the tip of the tool , push on the tool

you shouldn't have any play on the spindle , at the tool you should very little , depends on how stiff the tool is

you can also put an indicator on different parts of your machine and see if there is any flex when making the cut

other causes can be : cutting dry , the material is galling on the tool
the tool could be re cutting the chips

tool not rigid enough for the cut

try coolant and make sure the chips are clearing the cutter

try liter cuts with the side of the cutter and cutting in multi. depths

[knudsen]

How is the work being held? (i.e. how rigid is it?)

Squaring up my first blocks

IMHO: side milling is not the best for squaring, if you need them to be accurate.

[Robin Hewitt]

I get that sometimes, usually on a corner, it's called "chatter". The tool is vibrating.

Awkward thing is you have to change tool to get rid of it because it will 'echo' on to the next cut if you go fine and recreate itself if you go deep.

My usual reaction is, "Maybe that tool wasn't the bargain I thought it was"

High helix for aluminium but remember it will pull down harder so be sure to lock the quill if you have any slackness in the vertical direction. It gives you more of a slicing action.

A nice solution for chatter is unequal helix, but you don't want to go that way if you are still experimenting. Get the feel of the machine before you feed it anything expensive.

[zerodegreec]

Did some tests after work today and found: (My machine is a BF20)

With the gibs tight 0.05mm play in the head when I push on it (both side pressure and front/back pressure).

The spindle has 0.1mm of play front to back and 0.05 side to side.

The cuts in the pic were made with a Sowa HSS 2flute end mill (so not bargain bin)

[zerodegreec]

My Machine is a BF20

I got some measurements today after work:

Spindle has 0.1mm play front to back but only 0.05 side to side

Head has .05mm side to side and front to back play with gibs tight.

anyone with a BF20 that knows how much play they have? This seems excessive.

(To be honest I dont know what a good side mill face should look like, all I know is what i am making seems poor)

[mwood3]

I have heard that the BF20 mills have a lot of slop in the quill...i have not measured mine yet because my indicator holders have not come in...

My guess is that Hoss could tell you, maybe he will chime in soon

[photomankc]

How are you measureing the spindle slop? 0.1mm would be mammoth I would think, that's around 0.004" and most would find that unacceptable. I measured my PM25-Mv and with the DTI clamped to the mill head I can only shove the spindle around by maybe a hair over 0.00025" with the quill locked.

The spindle shows a good 0.0005" of movement between the quill locked and unlocked, and that is angular, it gets worse the longer the tool is. With the quill retracted I can move the spindle by 0.0005" by pushing it.

I can move the spindle around by 0.0015" by the time the quill is lowered an inch.

Make sure your DTI is mounted to the head to measure the spindle play so you aren't measureing flex in other parts of the system. If you really have 0.1mm of play in the bearings that's pretty bad.

[zerodegreec]

More testing. as suggested I put my indicator on my head and set the dial on the spindle. The spindle is NOT moving.....

But when I put the indicator on the spindle and measure the table I get movement when I push or pull on the head. (yes the column bolts are VERY tight and the ways are tight and locked down.

So I tightened the heck out of the z axis, tightened the ways on X and Y. I ran fast and slow and the surface has very slightly improved...kinda.

[mwood3]

this really looks to me like you are recutting chips, try a constant airblow while cutting and see if it improves further...

[jvangelder]

Im with MWood3, looks exactly like climb milling without air/coolent. Try an air blow while a climb milling finish cut, i always use 0.005 for a finish but thats just me.

Also, any way you can get more rpm's?, 2200 is rather low for alu with a half inch mill

[zerodegreec]

I ran a pass both conv and climb with LOTS of air, It did improve (not as deep) but still I have the same pattern left on the surface.