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Haas DT1 Barking noise on spindle accelleration


Mar 11, 2014

I have a 2018 Haas DT1 and it's making a noise during spindle acceleration. The sound is like a seal barking and it's only after a tool change as the spindle is accelerating. If I run TSC (I have the 300 PSI version), the noise goes away for about 5 tool changes, then comes back.

My first thought was that the TSC rotary union may not bein alignment or something. I had a look and checked the runout per the Haas install documentation. The radial runout was right at the 0.0005" (this is at the limit according to the Haas documents) but the axial was 0.000 or at the limit of my indicator. The rotary union shaft face looks fine to me, but then I don't have anything to compare it with.

It's strange to me that the TSC works fine and the noise goes away after running it even for a few seconds. Maybe the TSC is lubricating whatever is causing the sound? I have a link to the audio file with the sound below.

I see that Haas now sells an upgrade kit to a self compensating rotary union for this machine. Does anyone have experience with this upgrade or know if they had an issue with the bearing less model like the one on my DT1?

Any help is greatly appreciated.

DT1 spindle acceleration noise

Last edited:


May 11, 2017
Minneapolis, MN, USA
Yeah, it sounds like your rotary union is doing that. I had one that would squeal continuously at a really annoying high pitch if the TSC hadn't been running recently.


Hot Rolled
Dec 1, 2009
I have a 2013 mazak vmc that does this randomly a couple time a year and has for like the last 5 or 6 years. I also assume it to be the rotary union. It's not broken yet so I haven't fixed it yet to so I can't be sure what it is.