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Haas ST-15 vibration

Josh@OTTP

Plastic
Joined
Sep 5, 2018
Location
Dryden, Michigan
I have a 6 month old Haas ST-15 on the floor. Honestly it has a lot of problems, some have been fixed but this one is bad and I'm reaching my limit. Since new it has had a vibration. With nothing in the chuck at 4000 rpm it is slight, put a 1" 6061 bar in and it is very noticeable, put a 2" 303 bar in and at 2100 rpm the machine vibrates so bad it seems like it will start walking or maybe explode. Put a 2" 6061 bar in it and at 2900 rpm it starts to vibrate bad. All bar lengths are about 47-48" long. I have the spindle liner kit and these bars do not hang out of the liner. I am only at about half of the max bar weight per Haas bar feeder spec too.


So far the tech has done the following with no change.

Checked level.

Tightened the belts.

Cleaned the actuator and balanced/set runout. (it was packed full of Loctite and had .007" of runout)

Replaced the actuator and balanced/set runout.

Ordered a trusty cook spindle liner to see if the liners were causing it.


My question that Haas hasn't been able to answer is this. With a test indicator on a piece of stock hanging 5" out of the chuck, how much movement should I see on the stock and on the backside of the spindle in a push pull test? With very little force say 20lbs pushing on the stock I see about .003" of movement off of center.
 
How much movement of bar at tail of Spindle?
Have you checked the spindle bearings for play?
I would run Max pressure on collett.
At 3000 RPM It takes very little run out of the Bar to create a very unbalanced situation
and the spindle liners are usually a sloppy fit.
 
I have tried different bars, even some stainless bars that were ground and had very little run out. When the machine vibrates you can visually see the bar moving at both ends. I think the spindle is bad, how do you check it for play?
 
The run out is important.
I had the hydraulic union replaced on my SL-10 lathe...the original did vibrate a good amount in the 5-6ooo rpm range.
I forgot what the tech brought the union on my SL-10 down to, but it ran much better.
On my Emco I had that to under a thousandth when I did a spindle repair.

Aside from that its important to keep in mind bar stock does not come in true.
A 2" bar of 303 is about 50lbs, a little whip in the bar is going to have that bar rocking and rolling.

Spindle liners like the plastic Haas ones are great...but they are not perfectly true, they are sloppy on the ID and the little fins that hold them in place flex. So a bar whipping a little pushes on the liner allowing it to flex allowing more whip, worse vibration...pushes on liner harder...more whip, more imbalance etc etc.

When I have to hold tighter, I'll add some tape or an o-ring at back to help center.

The other options are to turn slower OR cut stock shorter, 36" or 24"...yes more remnants if cut shorter, more time if turned slower.


Pushing on the end of a piece of stock extended out past the jaws or collet imparts a whole lot of force...

Increasing drawbar pressure helps a bit at times...but only to a point, assuming you have tried at maximum recommended.
 
Actuator is .0003" run out now. We have tried max pressure with no change. With shorter bars it gets better but still bad. A 2" 303 stainless bar that's 24" long sounds like it will explode at about 3000 rpm. We've also tried a better fitting trusty cook liner with no change in vibration. Current stainless bar has .003" run out.
 
Actuator is .0003" run out now. We have tried max pressure with no change. With shorter bars it gets better but still bad. A 2" 303 stainless bar that's 24" long sounds like it will explode at about 3000 rpm. We've also tried a better fitting trusty cook liner with no change in vibration. Current stainless bar has .003" run out.

I HAVE A ST20 RUNNING 10' BARS OF 1018 crs 3/8"-1 1/4" Dia and I limit my RPM to 2000
because of the vibration from some bars also it would push back when using a 3/8" drill.I took some long pointed soft jaws and bored left about 1/4" on width x 3" long serrated and had case hardened .The longer contact patch of the jaws helps to steady the bar a little and cured the push back.
I don't think that you will be able to run bar stock at 3000 rpm. Just a little run out creates an unbalanced condition and then will run out even more.
Push on the bar at the end of the spindle with an indicator on it and I think that you will see the bar move some.The Collet chuck may be accurate up close but probably has a short contact patch and IMHO I don't think that you can get as much gripping power of a 3 jaw chuck with narrow long serrated jaws.
To check the bearings place an indicator on the top of the chuck and with a pry bar or 2 by 4 pry up on the chuck .It should be less than .001 movement

I had a machine that only ran 1500 rpm max and had a 2" bar of aluminum with spindle liner sticking out about 2' past the spindle and when i started the spindle it seems like it immediately bent that 2" bar 90 deg and destroyed all the sheet metal on the end of the machine and moved it about 6" off the pads.I was lucky it didn't bend the Spindle or Actuary.
 
The collet pads have 2" of grip length. I haven't experienced any push back with it. What is a reasonable speed and amount of vibration? I just had a 2" piece of 6061 in it, 20" total length, sticking 5" out of the collet. At 3100 rpm the vibration gauge is maxed out, at 2000rpm its still vibrating but only about half as bad.

Haas says it has a problem and isn't normal but can't seem to isolate it. That's why I'm here and asking questions.
 
With a test indicator on a piece of stock hanging 5" out of the chuck, how much movement should I see on the stock and on the backside of the spindle in a push pull test? With very little force say 20lbs pushing on the stock I see about .003" of movement off of center.

When you say "back side of spindle", which part of the machine are you specifically referring to?

absolutely not normal, sounds like a mechanical misalignment more than anything.
 
When you say "back side of spindle", which part of the machine are you specifically referring to?

absolutely not normal, sounds like a mechanical misalignment more than anything.

With the sheet metal off on the backside of the spindle where it leaves the casting. There's an adapter there that bolts to the actuator, I measure off of that.
 
With the sheet metal off on the backside of the spindle where it leaves the casting. There's an adapter there that bolts to the actuator, I measure off of that.

Yes...I'd expect to see that at 3' from the chucking point.

Hell , clamp the end of a 4' rod in the best of the best vises on the most rigid table and with 20 lbs I bet I'll move it that much...rods flex.

Trick is to keep rod centered and true as best as possible. Rod not true and supported it will whip and it only goes downhill from that point on.

You said rod is out .003, Okay not horrible...but over what length? Did you put on a set of rollers set at each end and indicate it? Or V-blocks...or just hung out of chuck and placed indicator on it.

If Haas says something is wrong..then fine, I can accept that, let them fix it.

But it also sounds like your spinning a long, not well supported rod pretty fast.

We run 1-5/8" dia SS in 4' lengths I have RPM locked at around 2400rpm...I say around as sometimes it needs to be dialed down some till Rod gets a bit shorter.
In my SL-20 we run a few rods 1-3/4 and 2" that I made snug fitting plastic doughnuts that keep rod running true. Snug to Rod and "just slides" in the spindle. Even with that you know something is in the spindle at speed which is 2500 - 3000rpm max.
 
Yes...I'd expect to see that at 3' from the chucking point.

Hell , clamp the end of a 4' rod in the best of the best vises on the most rigid table and with 20 lbs I bet I'll move it that much...rods flex.

Trick is to keep rod centered and true as best as possible. Rod not true and supported it will whip and it only goes downhill from that point on.

You said rod is out .003, Okay not horrible...but over what length? Did you put on a set of rollers set at each end and indicate it? Or V-blocks...or just hung out of chuck and placed indicator on it.

If Haas says something is wrong..then fine, I can accept that, let them fix it.

But it also sounds like your spinning a long, not well supported rod pretty fast.

We run 1-5/8" dia SS in 4' lengths I have RPM locked at around 2400rpm...I say around as sometimes it needs to be dialed down some till Rod gets a bit shorter.
In my SL-20 we run a few rods 1-3/4 and 2" that I made snug fitting plastic doughnuts that keep rod running true. Snug to Rod and "just slides" in the spindle. Even with that you know something is in the spindle at speed which is 2500 - 3000rpm max.

On the backside I wasn't measuring stock, I was measuring the actual OD of the spindle adapter. It's the first part that bolts to the backside of the spindle. Its about 3" from the rear spindle bearing.
 
Update on this. The spindle bearings were found to have some runout, they were reseated with no change. A new spindle was ordered and installed with no change. A brand new ST-15 was tested at another facility by my HFO and it also vibrates the same way. My HFO is taking back this machine.
 
That's great news. I have been following this because we have a pretty new ST20. Who is your HMO?
I'm assuming you're being sarcastic, since I can't see an upside to Haas finding, and admitting to, two brand new lathes with bad "something" that they can't even diagnose!
 
I HAVE THE SAME PROBLEM, yes my lathes are brand new, ST15 with all the features you can imagine, and I can't go beyond 2800 rpm my runout goes to.005 in 1.0 length , 1 inch round bar, precision special made liners , and cant get those damn lathes to the job, not to mention all the problems that I have being dealing with since they hit the floor, oil leaks everywhere, coolant leaks all over the floor, lots of loose screws, i can go on and on.
 
I have a 6 month old Haas ST-15 on the floor. Honestly it has a lot of problems, some have been fixed but this one is bad and I'm reaching my limit. Since new it has had a vibration. With nothing in the chuck at 4000 rpm it is slight, put a 1" 6061 bar in and it is very noticeable, put a 2" 303 bar in and at 2100 rpm the machine vibrates so bad it seems like it will start walking or maybe explode. Put a 2" 6061 bar in it and at 2900 rpm it starts to vibrate bad. All bar lengths are about 47-48" long. I have the spindle liner kit and these bars do not hang out of the liner. I am only at about half of the max bar weight per Haas bar feeder spec too.


So far the tech has done the following with no change.

Checked level.

Tightened the belts.

Cleaned the actuator and balanced/set runout. (it was packed full of Loctite and had .007" of runout)

Replaced the actuator and balanced/set runout.

Ordered a trusty cook spindle liner to see if the liners were causing it.


My question that Haas hasn't been able to answer is this. With a test indicator on a piece of stock hanging 5" out of the chuck, how much movement should I see on the stock and on the backside of the spindle in a push pull test? With very little force say 20lbs pushing on the stock I see about .003" of movement off of center.
Hello I have brand 2023 ST15 subspindle lathes bought 2 for a long period job, nothing but trouble on those machines since new, every week there’s something wrong, the worst is runout, all I can say is that we fix that our self, puting a new collet chuck, no vibration no runout to worry about at 4,000 rpm, put a new collet chuck, and wow what a difference, they are using junk jaw chucks, and they don’t want to pay for the change, this are under guarantee, and they have no chance to get out off this, or else
 








 
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