[jwatte]

I was slotting some stainless, and the machine started squealing like a pig.
Turns out, the chatter led to some pull-out ...

Attachment 462080

This was at 4000 rpm, 8ipm, 4 flute carbide end mill.
My guess is it sticks out way too much; I didn't have a stubby available.
Also, it's probably cutting too little per tooth, so I'll reduce speed for now until I can get a stubby in the mail.

[shred]

I was slotting some stainless, and the machine started squealing like a pig.
Turns out, the chatter led to some pull-out ...

I can't say if it's the cause or effect, but lots of chatter always meant tool pullout in my old 1100.

Every now and then a really heavy cut could cause it, but far less than the chattery ones.

[upnorth]

I don't have a Tormach mill but I do use the TTS. I have seen the tool pull out when profiling steel . I don't know if the chatter causes the pullout or the pullout starts the chatter. Minimizing the length of the tool reduces the chances of it happening.

[Tigster]

What is the stick out on that? An inch? It really doesn't seem over the top. No way your collet is worn? Dirty/oily? I am NO EXPERT on the subject, just blown away that a tool of the length could lead to this. All I really cut is stainless, sometime too aggressively, sometimes way to conservative. I never really consider tool length (I'll be more cognizant now) but no chance it's in your collet? A chip somewhere in the relief cuts? Related/unrelated question, what is the correct drawbar torque for the 440? I want to say it's pretty low...25ft/lbs?

[jwatte]

Yes, the stick-out is a hair over 1". As you might see from the (slightly blurry) picture, the shaft is not rusted or dirty. (I try to keep these in order.)
I think it was caused by the chatter. Lowering spindle speed removed the chatter and didn't repeat the pullout.
I have no idea what the drawbar torque is supposed to be -- I use a power draw bar (with the belleville washers) and adjust by tightening until it doesn't let go, and then back off a quarter turn.
In general, I haven't had pullout problems, other than when trying to take too deep cuts with 1/2" tools. I tend to not go over 3/8" these days.

[popspipes]

I can't say if it's the cause or effect, but lots of chatter always meant tool pullout in my old 1100.

Every now and then a really heavy cut could cause it, but far less than the chattery ones.

this has been my experience too, if I hear any chatter I stop and adjust the cut.

[CL_MotoTech]

Pull the collet and clean and lubricate all the bits. I think Tormach has a pdf on the process, or at least they did when I was setting up my TTS drawbar. Either way, if the the moving parts find themselves a bit sticky then you don't end up with enough drawbar pressure and chatter seems to be the result. Either that or it doesn't like to release the tool, sometimes a combination of both. That's my experience with my homemade drawbar anyways.

I run fairly large stick out all the time with my G0704, my favorite end mill has 1.25 of flute. For steel however I try to use smaller tools with less stick out. A 4 flute .25" end mill is my go to, though I do have a 5 flute .375" that works quite nicely too. Less stick out does seem to help, though when drawbar pressure is correct chatter is rarely an issue. I started my thread in the bench top section when I experienced loads of chatter and pull out, it mostly came down to getting the PDB to exert full pressure. I also will run slight light on the chip load, but not extremely so. Maybe 15% under.

[toyshop]

Had the same issue milling stainless on my tormach. Even on a Bridgeport at work I use a solid r8 holder with a set screw when pushing hard. Yeah, I have to set the z every tool change but it won't pull out. I usually pull the end mill down to the set screw also.

Dave

[maker of things]

I also have had similar issues with chatter. TTS or any other collet system a tool can pull out with chatter. However, if the chatter is being caused by slippage, as CL_MotoTech pointed out, clean. If you get even the tiniest bit of that copper anti-seize on the tool holder and inside of the tts collet, you are doomed if trying to take a decent cut. Acetone was my 1st choice, isopropyl alcohol as second. Q-tips work decent for cleaning the tts collet (installed in spindle) while not washing away the antisieze from the outside. And you do want a tiny bit of anti-seize the OD of the tts collet to make sure the drawbar is getting it's full effect.

[mountaindew]

There is a recent video made by haas machine tools that does a good job of explaining some of the issues.
While the subject of TTS pullout is not the problem in the video. The issues and results are very much the same. Just the taper tool holder does not pull out, the cutter itself pulls out of holder.
They do show an eye opening example of a cutter pulling in a holder.

[lens42]

The TTS pullout causes the chatter. I know because I’ve had cuts sound fine, and then start that screech. Stop immediately when it screeches and I bet you can slide a paper between the TTS flange and spindle nose. When the TTS pulls outs even a few thou and the flange is no longer tightly seated on the spindle nose, THAT’s when the chatter starts.


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