Loud tool change thud

Luke-AO · Jul 30, 2020

I was setting up a job this morning on my 2008 Haas VF2 and it started making a 'loud thud' when removing a tool from the spindle. I did a few changes to see if I could tell where the noise was coming from and it sounds like it's coming from inside the spindle.

It's not the 'tool change pop' I see people talk about (mine does that when it's cold) this is a loud deep-throat-ed sound.

Any ideas?

machineit2 · Jul 31, 2020

There is a "pre-charge" circuit in the tool release. It puts a small amount (lower pressure) of air in the cylinder before the the full pressure is sent to the release side. This keeps the piston from slamming into the top of the release shaft. Before the piston hits the tools release shaft, that air needs to be pushed out and that cushions the initial contact. Bad explanation, but that circuit is probably not working.

Mike

ChipSplitter · Jul 31, 2020

It's coolant residue on the tapers. If you get them good and clean using degreaser and Scotchbrite you'll be fine again.

Luke-AO · Aug 6, 2020

machineit2 said:
There is a "pre-charge" circuit in the tool release. It puts a small amount (lower pressure) of air in the cylinder before the the full pressure is sent to the release side. This keeps the piston from slamming into the top of the release shaft. Before the piston hits the tools release shaft, that air needs to be pushed out and that cushions the initial contact. Bad explanation, but that circuit is probably not working.

Mike

I do have the spindle cover off, I checked and cleaned the solenoid, no debris or gunk, solenoid seems to release without sticking.

How would I test the piston and or inspect it?

I didn't mention that the noise comes at the very end of the cycle, it's the last thing you hear.

I've done a few test cycles with the spindle cover off, and I haven't heard it again, but it happened on about 6 tool changes or so before I posted.

Luke-AO · Aug 6, 2020

ChipSplitter said:
It's coolant residue on the tapers. If you get them good and clean using degreaser and Scotchbrite you'll be fine again.

I'll definitely clean that. Thanks.

Luke-AO · Aug 6, 2020

Should I be greasing my tool holder pull studs with grease? I'm 100% self-taught and I think I may have been screwing up in that regard(?)

Sendit · Aug 7, 2020

Luke-AO said:
Should I be greasing my tool holder pull studs with grease? I'm 100% self-taught and I think I may have been screwing up in that regard(?)

yes with Mobilgrease™ XHP 222

Luke-AO · Aug 13, 2020

Ordered that grease last night, thanks

Luke-AO · Aug 17, 2020

machineit2 said:
There is a "pre-charge" circuit in the tool release. It puts a small amount (lower pressure) of air in the cylinder before the the full pressure is sent to the release side. This keeps the piston from slamming into the top of the release shaft. Before the piston hits the tools release shaft, that air needs to be pushed out and that cushions the initial contact. Bad explanation, but that circuit is probably not working.

Mike

Which part of the circuit would it be, or how would I go about checking it?

toolsteel · Aug 17, 2020

Looks like you may have it under control.
If not resolved......I would do a couple of tool changes with empty pockets. Might help isolate whether it is a machine issue or a holder / gripper issue.

Luke-AO · Aug 17, 2020

I've been out of town so I haven't done anything yet, that said I did a few tool changes after I removed the spindle cover to inspect the solenoid and it wasn't making any noise. Just wondering if there's anything I can inspect before I reassemble to go back to work. The cover is kind of a hassle to remove so if there's anything else to check I'd like to.

Luke-AO · Aug 18, 2020

Luke-AO said:
Should I be greasing my tool holder pull studs with grease? I'm 100% self-taught and I think I may have been screwing up in that regard(?)

Sendit said:
yes with Mobilgrease™ XHP 222

Besides the pull stud, should the tool taper also be greased or oiled? I would think grease on the taper would be a bad idea, just checking.
Besides cleaning the spindle taper should it also be oiled, if so what kind?

Luke-AO · Aug 19, 2020

Okay, so I cleaned and lightly oiled my spindle taper, then did 25+ tool changes to apply a little grease to the tool studs and to get a better idea of exactly what the tool change issue was.

What I found was a varying air release noises, varying volumes of air released, varying spring rate return speeds of the tool change spring. (Shown in the picture)

When malfunctioning there seems to be a very large volume of air released that is loud, along with a varying stalled release of the spring as if it were sticking in the middle of the cycle.

When the cycle appears correct, there's a low volume air release, definitely not loud, and a faster return spring rate without hesitation at the spring.

Out of the 25 plus tool changes, there were only 3 or 4 that were correct.

friesen · Aug 19, 2020

Perhaps a video? I'm guessing either the preharge or release solenoid isn't doing right.

Luke-AO · Aug 21, 2020

I believe we have it narrowed down to the QUICK EXHAUST VALVE, the replacement should be here Monday.

metal-ica · Aug 21, 2020

I believe inside that housing you circled is a rubber flapper thingy. You can open it and see if it's repairable .... or just wait till monday

Luke-AO · Aug 21, 2020

I took it apart and cleaned it, it was better but was still malfunctioning. When I opened it up there was a black sticky goo in the housing, even after cleaning everything it was still sticky. I think the rubber diaphragm was degraded.

Spruewell · Aug 21, 2020

That is called a Humphrey valve. It is a type of proportioning valve to regulate the pressure and flow of air. It is used to control the tool release, and I suspect it is the source of many complaints about the violent tool release people experience with a HAAS. I had the tool release solenoids and Humphrey valve on my VF2 replaced recently. Now it practically shoots the tools out of the spindle.

Luke-AO · Aug 22, 2020

I had the occasional 'tool change pop' (seemed to be worse in the winter) hopefully the new Humphrey QEV fixes this too.

Luke-AO · Aug 25, 2020

It looks like the QEV valve was the problem. I just installed it and did about 20 tool changes and didn't have any hiccups. Just have to finish buttoning up the machine and I can get back to work.

Loud tool change thud

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