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1998 VF3 z height issue

Dennisprototype

Plastic
Joined
Oct 27, 2018
Location
Tulsa
Hey guys, i need some help. I have always had a hard time maintaining a consistent z height on my parts on this old mill. Ive blamed junk vises, junk tooling, etc. But tonight i ran parts fixtured directly down to the table, and went way above and beyond making sure they were flat. I started off by measuring my haimer probe height and i always write that height to the offsets page. I ran my parts for around 3 hours and constantly had to raise my z height to stay close to my dimension. So at the end of the night i rechecked my haimer probe height and it had shrunk by .0125”!!!! That seems insane??? Does anyone have any insight, that is out of control. Any help is appreciated. Thanks.
 

MikeAZ

Plastic
Joined
Oct 4, 2021
If you have a nitrogen counter balance, check to see if the cylinder pressure is correct. If the pressure is good, then I would take a look at the Z-Axis motor coupling or possibly it could be a faulty encoder.

Try running rapids at 25% throughout the day, and check the height the same as you did before.

Does the Z-Axis line up properly for the tool change? Check to see if that is high or low also.
 

friesen

Cast Iron
Joined
Jul 13, 2016
What does the haimer show if you push on the head with it indicating on the bed? What about if you push on the spindle area?

Don't get too excited if the haimer shows a thousandth movement or so pushing on the head.
 

Dennisprototype

Plastic
Joined
Oct 27, 2018
Location
Tulsa
I actually added charge to the counterbalance not too long ago, head was drooping under alarm or estop. Its within spec now. Tool change doesn’t seem to be an issue either. I checked the z axis coupling, everything was tight and seemed great. I ran a program that raised and lowered the z axis onto a test indicator, over the course of 10 minutes i didnt see any deviation on the indicator. Someone mentioned to ditch the haimer and see how that works out, so we shall see?
 

countryguy

Hot Rolled
Joined
Jul 29, 2014
Location
Mich, USA
A bit outside my wheelhouse but I called the Son as I remember him noting something similar upon a time. He did note some tool pull-down when using cheap(er) collets and tool-holders. Plus w/ Weldon and Flats in toolholders could be reviewed?
 

countryguy

Hot Rolled
Joined
Jul 29, 2014
Location
Mich, USA
Good point- we did both a spindle regrind, and replaced the drawbar on our 98 when the Z was being stupid erratic. There must have been 15 broken washers on that. I know you can pressure test them etc... it's a beat up 98 was my take. It was $430 if I recall and no core (on the drawbar). the instructions are well laid out in the manual for this procedure too. Hope you get it licked.
Maybe check your drawbar?
 

D Farms

Aluminum
Joined
Dec 11, 2018
Haas service manual pretty much says its related to the leaking counter balance. move the z axis to the top of travel, then look at the gauge on the hydraulic tank, better yet take a picture as straight on as you can. check it periodically. if the system is leaking, this would cause the problem. its not a complicated system, so having it serviced shouldn't be exceedingly expensive. I built up my own rig to recharge the system on my hs-1 after disassembling it to get it in the garage, its the same setup you would use to charge large shocks for off-road vehicles, granted it needs about double the pressure.
 

plastikdreams

Diamond
Joined
May 31, 2011
Location
upstate nj
I worked at a place with one of the nitrogen counterbalances, there was a tank of nitrogen right next to the machine. Only had to pump it up once I think.
 








 
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