Haas VF-4 drawbar issues

[SilentMatt]

We're having issues with the drawbar sticking on our oldest('90's) Haas. Most everything I find on the web has to do with the taper sticking due to being worn,
but this also happens after it has been sitting overnight with no tool holder in the spindle. It's kind of annoying when the tool change times out before it pops tool out.
Just wondering if anyone has experienced anything similar?

[Rescue912]

Do you have a spindle taper master? If so,  blue it up, clamp it and look at the contact area. My guess is you have contact at the base but not at the mouth of the taper.

That will affect accuracy also allowing the tool point to move a bit in cut. If you don't have a master try bluing up a tool and see what you get.

Could also be your tool holders are worn but most sticking tools I've worked with seem to be caused by the bottom of the tool to spindle not fitting properly.

[SilentMatt]

It sticks regardless if a tool holder is in the spindle. It seems like it's somewhere in the drawbar bore.

[Rescue912]

You may have a broken belleville or two in your drawbar. Do you have a clamp force gage? I bet your clamping force is low.

[SilentMatt]

Don't have a gauge. It's funny, this morning it worked first push of the tool release but after that, the button has to be pushed a few times for it to pop free. It works fine if you don't let it sit with no tool changes for 5 minutes or more.

[LeE]

This happened to an old Fadal I use to run parts on. I learned a trick from an old crusty machinist. Take a piece of scotchbrite on the spindle taper where is sticks and then clean out any remaining debris with a spindle taper wipe. 

[SilentMatt]

We've cleaned and used scotchbrite to no avail. I think the problem is it the drawbar bore, but I'll keep digging.