Chatter milling in X direction only

[waltpermenter]

It sound like the endmill to me too. I think I would start bumping down the rpm during the cut until it goes away, or try a new endmill.

who is this directed at, the op with the tormach or the threadjacker with the novakon?
walt

[SWATH]

who is this directed at, the op with the tormach or the threadjacker with the novakon?
walt

The op with the tormach.

Also one thing to triple check would be that everything about Y axis ballscrew and table are tight. I had similar problem when cutting in the Y axis. Turns out it was a loose coupler in the X axis ballscrew that was allowing the part to sort of deflect away and bounce off the endmill. That was with a different machine with linear bearing ways so the problem may have been magnified by the low friction. That might also explain why it only happens on one side and not the other.

[SCzEngrgGroup]

I think that this is not the end mill problem as in the -X to +X there is no chatter and only gets ugly in +X going to -X. As I mentioned that I didn't take on video the first attempt when at first chatter was gone after tightening gibs, up until endmill reached -X of the vise corner and then like someone had turned on "switch" that controls CHATER. And the second attempt was captured on the video I was expecting the same behavior as before but it started right from the beginning (as you can see in the video I even stopped for couple of seconds because I was expecting that there will be no chatter like the attempt before and chatter will start only latter). For backlash I did this using recommended procedure in manual with TDI. OK now for the slop please explane more on this, because I don't know how to check it.

I've seen, more than once, and on more than one machine, one endmill will work poorly, and another brand with identical specs will work perfectly on the exact same cut. There are specific brands I avoid for just this reason. Trying a different endmill would not be a waste of time. If that is a carbide endmill, it would also be worthwhile to try a HSS one. On smaller machines HSS will often work as well, if not better.

Regards,
Ray L.

[Hirudin]

who is this directed at, the op with the tormach or the threadjacker with the novakon?
walt

Hi,

my comment was related to the OP's issue. That isn't thread-jacking. If you'd like to see what thread-jacking is, consult this list: http://www.cnczone.com/forums/search...st&showposts=1

[BAMCNC.COM]

HSS *can* work better due to it being sharper.

I don't think Hirudin was thread jacking, I only seen helping.... and Hirudin's list is HILARIOUS!

[philbur]

Sounds like either resonance in the end-mill or resonance in the part, there's a lot of overhang on the part. If you think it,s not the end-mill try a shorter piece of aluminium or clamp your part to the table, at least for a test?

Phil

[Mantas]

Hi there again,
I have to do more testing but I think that overhang in this particular case is not the issue as dimensions of the peace is something like 13,8"x4"x2" and I even did some support on the ends with bolt and nut to give it just a little tension, in the video it is hard to see this. I tried different end mill 10mm also carbide Precitool (same brand as 3flutes) with 2 flutes and it is not chattering, but I don't like this endmill because it has I think 30 degrees flute angle and gives a lot of vibration on the mill. I always wanted to try that high helix 45 degrees endmills and I think it would be good solution to this chatter problem as Hirudin showed in his video. So for now I did that part with 2 flutes, but there was also some sections in the part that this endmill was almost starting to chatter. For now I really don't know is it only the endmill problem or machine or maybe both. I will check the Y axis stepper motor coupling to make sure it is OK, but for now I have a lot of work and even can't find time for this.

[philbur]

Have you tried another part geometry?

Phil

[BAMCNC.COM]

Have you tried a veriable helix endmill?

[Steve Seebold]

HSS *can* work better due to it being sharper.

I don't think Hirudin was thread jacking, I only seen helping.... and Hirudin's list is HILARIOUS!

Sometimes a HSS end mill can actually be TOO SHARP in which case, they could squeal like a hurt puppy.

[Mantas]

Phil I don't know what exactly you mean different geometry, but if you are asking have I milled other parts with this endmill then yes i did and there seems very similar problems with it. Because of this chatter I prefer using smaller endmill 6mm in diameter that gives no chatter, but for large parts you can't get that removal rate. That part is now half made and waiting for its time to be flipped over for other side to complete.

[philbur]

I guess my point is that the degree of chatter seems, in part at least, to depend on where the cutter is on the part.

1) The first pass along the from face of the part, with climb milling, is bad but seems to change frequency as the cutter approaches the left hand end of the vice jaw, how parallel is the part/jaws, are they gripping over there entire length.

2) The second pass along the back face, also with climb milling, doesn't sound like it has any chatter, or at least not the same sound.

This suggests to me that the chatter is position dependant and therefore more likely something to do with the part.

Just a thought

Phil

[mr_ping]

Did you fix this ? Got same in my linear rail brother cnc.

Hi there, I have noticed a problem with chatter when machine moves only in X direction doing climb milling. And that I can't rid off changing feed or RPM. At first I thought that this is only bad RPM or feed, but then toolpath went on Y direction and the chatter was gone and that kept doing all the time as tool was cutting in X axis... I am using iMachining for this part, but I can tell you that in the straight line feed is about 50ipm and spindle tested range from 3500 to 5000 no effect on chatter. WOC varying but max set to 0,051" and DOC constant to 0.32". I am using carbide 3 flute 10mm end mill for this. Can this chatter be from loose gibs or this is related to something else? Waiting for some thoughts as I am now away from machine and thinking what can I check to fix this.
Best regards.

[Steve Seebold]

Phil I don't know what exactly you mean different geometry, but if you are asking have I milled other parts with this endmill then yes i did and there seems very similar problems with it. Because of this chatter I prefer using smaller endmill 6mm in diameter that gives no chatter, but for large parts you can't get that removal rate. That part is now half made and waiting for its time to be flipped over for other side to complete.

What size cutter are you using? I seldom use larger than a 3/8 end mill. And I never get chatter.

[mr_ping]

6, 8, 10, 12, 16mm. They all chatter if I slot mill 3mm deep or take like 10mm deep in steel with 2mm woc.

Only in X direction climb mill.

What size cutter are you using? I seldom use larger than a 3/8 end mill. And I never get chatter.

[philbur]

You don't provide a great deal of information to go on.

How old is the machine?
How mach use has the machine had?
Which model machine is it?
Can you post a photo of the chatter marks?
Is the chatter in both directions of the x axis?
Have you check for chatter when climb milling at both extremes of table x axis position as well as a central position?
Have you checked for chatter when climb milling in the x axis with the table positioned at both extremes of the y axis as well as a central y position?
Have you checked for backlash/lost motion at different x and y axis locations?

You may want to search for a forum that deals with your specific type of machine.

Often people will put as much effort into answering a question as is put into asking it.

Phil

[mr_ping]

Its a brother tc225 with retrofitted control.Had it for 6months, always been like this in my possession.
Servos on all axis, 1kw and 1.2kw.

It happens on Y axis climb mill, not on conventional.
Happens on X too but with three times WoC.

Ive exchanged spindle bearings but that didnt help.
Runout is 0.015mm

I think it is the carriages but im not sure. Its the exact sound as in his video (threadstarter).

You don't provide a great deal of information to go on.

How old is the machine?
How mach use has the machine had?
Which model machine is it?
Can you post a photo of the chatter marks?
Is the chatter in both directions of the x axis?
Have you check for chatter when climb milling at both extremes of table x axis position as well as a central position?
Have you checked for chatter when climb milling in the x axis with the table positioned at both extremes of the y axis as well as a central y position?
Have you checked for backlash/lost motion at different x and y axis locations?

You may want to search for a forum that deals with your specific type of machine.

Often people will put as much effort into answering a question as is put into asking it.

Phil

[philbur]

You didn't answer all the questions.

How did you set the bearing preload when you replaced the spindle bearings?

0.015mm runout on a spindle is a lot.

Phil

[mr_ping]

It was 0.015 before I changed bearings too.


Ive tested extremes, same result. You see that the table moves out 0.05mm when I climb mill and goes back if I stop the cut. When doing light passes it doesnt happen, and finish is good.

You didn't answer all the questions.

How did you set the bearing preload when you replaced the spindle bearings?

0.015mm runout on a spindle is a lot.

Phil

[mr_ping]

https://youtu.be/F49kW8TLPBY

theres a movie. I walk in and stop etc.

It was 0.015 before I changed bearings too.


Ive tested extremes, same result. You see that the table moves out 0.05mm when I climb mill and goes back if I stop the cut. When doing light passes it doesnt happen, and finish is good.