What's new
What's new

Is there a way to "tighten up" an old haas?

Motorsports-X

Hot Rolled
Joined
Nov 22, 2014
Location
Texas
(besides placing it tightly in the dumpster)

I can set the indicator at table 0 and push it 2 thou in either direction (4tir) on both axes.. the spindle also has an issue with movement, but im not sure if in the spindle or ways. I think its probably some of both. it seems like y- moves "lift" the spindle a hair.


its just old and worn out. the ball screws have backlash as well, and I know you can have those worked, but what about the ways? is there gibbs that can be tightened or replaced? its like a 96 model vf2.
 
I don't think Haas ever made a box way machine so no gibs to tighten up. Everything considered I would say the cheapest way to tighten it up is to move on. I reballed 2 screws and replaced all the ways on a drill/tap machine I have for about $3000 and am pretty sure it was all a big mistake 2 years on. The screws seemed good for the first year after I reballed them but then went south just after I replaced the ways, thinking not having to replace the screws made it worth it. Screws are over 2k per axis plus the bearings.

Does it come back to center when you let go?
 
no it does not come back to center. which is my main concern. as far as it goes for machining, its not stacking up tolerances or cutting to far off.. you just have to work up to everything, and you cant really do any serious work with it.
 
Your machine is a little older than my VF2, which had a broken oil line to the Y axis. It was not a heavily used machine and has not got a lot of wear even with improper lubing. If you have the time you could remove the way covers and do a quick analysis of the ball screws and thrust bearings, and check the lube lines.

The linear bearings are pretty robust, my guess in order of wear would be thrust bearings first, then ball screws, and last the bearing trucks.
 
When you have a day to play with your mill take the way covers off and see where the movement is coming from, only then can you decide what to do. It does sound like the thrust bearings are the main suspect since it doesn't come back to center, which is the easiest to fix. Taking a day to go through the lube lines making sure they are all working, cleaning up things, and inspecting/tweaking your way covers is good to do once in awhile.
 
(besides placing it tightly in the dumpster)

I can set the indicator at table 0 and push it 2 thou in either direction (4tir) on both axes.. the spindle also has an issue with movement, but im not sure if in the spindle or ways. I think its probably some of both. it seems like y- moves "lift" the spindle a hair.


its just old and worn out. the ball screws have backlash as well, and I know you can have those worked, but what about the ways? is there gibbs that can be tightened or replaced? its like a 96 model vf2.
.
.
most cnc use a backlash compensation. you setup indicator and program a move and return move and adjust backlash compensation til indicator agrees with programmed distances. it moves turns extra when ball screw reversed direction
.
often a parameter adjustment yearly done. i have seen ball screws turned by timing belt have .005" backlash adjustment, direct drive usually less. this is one reason why when indicating if you reverse direction you can get distorted readings measuring a part. basically what it cuts and what you measure in handle mode often is different.
.
programming i have often seen extra moves to always come from one direction to lower backlash effects. or a move to overshoot and then come back to takeup backlash. basically programming the way you would use a manual machine
.
spindle loose often see if you bore a hole and replace boring bar with same length .0001 indicator and if it shows hole just bored offcenter its not uncommon to see .0005" shift especially with horizontal mill. vertical mill harder to predict which direction it will shift too
.
the worst if machine section flipping like 4 legged chair with one leg short. not unusual to change direction on one axis and machine balance weight shifts and a different axis measures a position change. for example on a horizontal mill a Y change cause Z to change. only way to describe is the 4 legged chair and one leg short. when balance point reached the short leg goes down to floor and a different leg comes up. we joke about putting 500 lbs of sand bags on machine to keep parts on the same 3 "chair" legs. you often will never see it in 50 years with a .001" indicator but you can often see it if using a .0001 or .00005" indicator
 
not a lot one can do to fix it unless you want to spend a lot ,, even haas thinks there machines are only good for 10 years ,,, I like linear way machines but haas uses the smallest and lightest ways and screws they can get away with ,,, I have tried reballed screws in the past and it did not work out ,, so if you need a better machine buy a better machine and let someone else have it .
 
not a lot one can do to fix it unless you want to spend a lot ,, even haas thinks there machines are only good for 10 years ,,, I like linear way machines but haas uses the smallest and lightest ways and screws they can get away with ,,, I have tried reballed screws in the past and it did not work out ,, so if you need a better machine buy a better machine and let someone else have it .
.
.
never saw a big boss yet who didnt seems surprised his maintenance people and machine operators are having more and more problems holding tolerances and even keeping a machine operating
.
any normal person realizes especially machines over 20 years old whether a cnc or a car is going to have more and more maintenance issues and more rattling and looseness. big boss often stop buying replacement equipment so it looks like company is making more money. eventually it catches up. might take 20 years. maybe they figure they dont have to worry as they will be retired by then.
.
what upsets most is when boss acts like machine not running or holding tolerances is his employees fault. rather than admit the problem is coming from upper management. i have seen many a engineer think the laws of the universe do not apply to them somehow. machines wearing out is one of those laws that cannot be ignored forever
 
ballscrew nut itself can have looseness but also
.
what holds the end of the ball screw often is a bearing too and that can get worn and loose too. it you can get indicator on the end of ball screw see if the whole ballscrew is shifting position when direction reversed
 
Until you know what is wrong you can't figure out if it is worth repairing. Barring a lubrication or contamination problem I will hazard a guess that most of the slop is thrust bearings, which are probably worth replacing. If it were ways the table would come back to center.
 
10k worth of parts gets quite a way vs a new machine. To a certain degree perhaps it's like Tom and ray said about the cheapest car is the one you already own. For cars I think it becomes more of of a desire to have new than cost, and perhaps it's the same for new machines as well. Ballscrews run around 800 and linears 1200.
 
Mount you mag base on the headstock near the spindle and .0001" indicator on the bottom side of the spindle and measure the spindle that way, that will eliminate a chance your moving the Z axis ways. If you push / pull it and indicator moves and release pressure, pull it. Your checking for lost motion. Then put the indicator on the bottom and use a 2 x 4 to lift the spindle, not a lot of pressure. It should not move more then a few tenths. When new they say .00005" to .0001" when cold and zero when hot. You may want to call Haas before attempting to adjust the linear ways, most screw them up if they don't know what they are doing.
 
The ones I have worked on one side is stationary and the other side is adjustable with screws or shims. I worked on Hi-Win and NSK. http://www.nskamericas.com/cps/rde/...d_Precision_Machine_components_bookmarked.pdf

look at page A-72 -77. Everyone assumes the rails are straight but the are bent and need to be installed straight. One side needs to be installed using a granite straight-edge as show in the documents. Then the other side is installed and adjusted.

Like I said this is something a professional should do as I have seen service techs from distributor try to adjust them and screw them up. The loosend the positive side.
 
as bad as linear rail might get..... turcite wear often can get much worse. in theory turcite can be replaced relatively easy. in practice many wait too long and you can get .005 to .010" wear on turcite cause nobody wants to take a machine apart to replace it and remachine or scrape it. it needs to be machined or scraped as the epoxy used to glue it on will always vary a bit in thickness so turcite would be wavy and uneven just glued on
 
The ones I have worked on one side is stationary and the other side is adjustable with screws or shims. I worked on Hi-Win and NSK. http://www.nskamericas.com/cps/rde/...d_Precision_Machine_components_bookmarked.pdf

look at page A-72 -77. Everyone assumes the rails are straight but the are bent and need to be installed straight. One side needs to be installed using a granite straight-edge as show in the documents. Then the other side is installed and adjusted.

Like I said this is something a professional should do as I have seen service techs from distributor try to adjust them and screw them up. The loosend the positive side.
I didn't see anything about adjusting them for wear. What page is that on?
 
There is no adjustment I am aware of. If you are the experimental type you can order oversize balls from baltec and do it yourself. It takes about 15 minutes per truck. Shoot for .0002+ larger balls unless it's real loose.
 
Any ideas why I get a 502 bad gateway cloud fare page when I try to view this on my desktop?
 
If you haven't actually taken off the covers then you have no real knowledge of the problem.

Think simple first! I bet your problem is in thrust bearings.

#1 With Haas is the thrust bearings with your era machine - they are small and not constantly lubricated. A reasonably mechanically talented person can remove, clean, lube and or replace and adjust in a full day?

Everything you need to know is in the Manual.

Invest in a pair of hook spanner wrenches - I don't recall the size, once you have the cover off you can check.. DON'T USE PLYERS!
Clean, clean, clean! Use a fresh container of high quality grease.

Thrust bearings are available from any bearing supply something like $20 ea. They are captured needle type [pair of washers and one bearing].

Once they are back together adjust for free spin but no axial movement with indicator on coupling - you want the bearing only measured.

Follow procedure for setting compensation parameter.. if needed. Use a 0.0001" indicator or don't bother.

You may not get back to OEM spec's but I did my '92 VFO and fixed exactly what you describe, labor only, I bought and replaced bearings but after cleaning and very close inspection decided they were fine and could have reused them. I haven't done a ballbar test but am very happy with results - good enough for such an old girl!

Good Luck!
 








 
Back
Top