How to you test the Thrust Bearing on the BScrew of an older Haas?

From my other post on Backlash below w/ a Q on testing the thrust bearin assy: I simply do not know how to test one. So, starting a new thread. Reason: Seems for BL issues. many/most posts quickly send the thread owner to check the thrust bearings as the usual suspect... But I cannot find out how we actually go about to do that. I searched and searched.

The Kid is bidding jobs now... so I want to get his X axis diagnosed correctly before I dig into parts and my time. Haas wants like $600 for the kit (w/ core).

Y is a solid 2tens. we also measure the BL in various positions. Way left, right, and center etc. X is always 7-8 tens.

If you cannot eliminate the backlash or it is inconsistent the thrust bearing is likely bad. I think that may be the only indicators without pulling it out and looking.
My '91 used a needle thrust bearing. The cage disintegrated and started cutting a groove in the ball screw shaft. I replaced it along with its mount with the later double angular thrust ball bearing.

I have a video that I'll be posting in a while showing the rebuild process for an axis on my Fadal, it shows how to test this, but I can explain the process in the meantime!

The process is basically the same for any CNC axis. Get access to the end of the ballscrew opposite the servo, it is usually center-drilled from when they made the screw. Put a small wipe of grease in the center-drilled hole, then use the grease to stick a single ball bearing in there, 1/4" is usually a good size but it will depend on the size of the screw and center-drill.

The bearing will give you a place to take readings using a dial indicator that will be consistent even if the end of the screw was not cut perfectly clean & square.

Mount a tenths or half thou indicator on the frame of the machine with the needle resting on the bearing as close to the center as you can get. It shouldn't matter if it's a little off but get it close as you can.

Now fire up the machine and move the axis back and forth in decent sized increments, say 0.1" or 0.01" at the least...

The reading on the dial indicator will not change if the thrust bearing is good because the screw will not be able to move axially.

If the reading on the dial indicator changes then it's a sign that the screw is moving axially which is usually because the thrust bearings are shot.

Sometimes the end of the screw or the way the bearing was mounted will cause the reading to change cyclically as the screw rotates, ie: it will go up and then down as you continue rotating the screw in one direction. This does not indicate a problem.

The immediate indicator of a problem is if the reading suddenly jumps when you change the direction the axis is moving.

Thanks aa. . I 've seen your posts before. Good stuff from you. Appreciate the help! We did check the end w/ the way cover off but did not really know the bb trick. :-) Solid idea!
I'll check in w/ the Haas guys on a kit and such and may as well just put it on order and do over a break.

All; We've done about everything else on this thing... so why not tackle this too. Getting it out does not scare me... putting it all back in and getting everyting back and correctly adjusted does. The manual just has some crude steps on the thrust-bearing replacement.... Maybe it's just that easy?

reminds me of my favorite quote in the house of Haas;
Experience is a tough teacher... you get the test first and the lesson after!

aa- Looking very much forward to your Video. We'll subscribe if you have a channel running.

countryguy said:

Thanks aa. . I 've seen your posts before. Good stuff from you. Appreciate the help! We did check the end w/ the way cover off but did not really know the bb trick. :-) Solid idea!
I'll check in w/ the Haas guys on a kit and such and may as well just put it on order and do over a break.

All; We've done about everything else on this thing... so why not tackle this too. Getting it out does not scare me... putting it all back in and getting everyting back and correctly adjusted does. The manual just has some crude steps on the thrust-bearing replacement.... Maybe it's just that easy?

reminds me of my favorite quote in the house of Haas;
Experience is a tough teacher... you get the test first and the lesson after!

aa- Looking very much forward to your Video. We'll subscribe if you have a channel running.

Click to expand...

Glad to be able to help mate! Let me know if you have any issues... I am no not a HAAS guy but there is a lot similar between most VMCs!

My channel is on YouTube under the name Gough Custom: YouTube

It's mostly been knife stuff and some CNC stuff so far, will be branching out a bit with some machinery design/build content soon!

In theory, put a dial indicator on the end of the ballscrew and push pull the axis by by hand. In reality, this doesn't necessarily indicate like you would think. I just replaced the Y on my vf2, the symptoms were growl noise and bump sounds, as well as close to .001 backlash.

Thanks! Was there anything difficult in the procedure? Any tips or high level 1,2,3 items we can read up on. Water looks cold to jump in. . Rather have a transistor or two instead to replace.

countryguy said:

Thanks! Was there anything difficult in the procedure? Any tips or high level 1,2,3 items we can read up on. Water looks cold to jump in. ��. Rather have a transistor or two instead to replace.

Click to expand...

My Z drive just fried itself yesterday, can I send the card(s) to you to fix them??

[I do NOT love the smell of burning G10/FR4 in the morning...]

the newer Silver or the Gold type? I did buy several of the parts that I thought could save me some $$$ IGBT's and I think a few other things. :-) weird but I just brought that envelope in from my electronics box yesterday to put w/ the now large collection of Haas parts bits and bobs...
I've been inside the drive but not repaired anything as yet. My first one was about 3 weeks into learning 'haas'.... You doing them too?

Milland said:

My Z drive just fried itself yesterday, can I send the card(s) to you to fix them??

[I do NOT love the smell of burning G10/FR4 in the morning...]

Click to expand...

countryguy said:

the newer Silver or the Gold type? I did buy several of the parts that I thought could save me some $$$ IGBT's and I think a few other things. :-) weird but I just brought that envelope in from my electronics box yesterday to put w/ the now large collection of Haas parts bits and bobs...
I've been inside the drive but not repaired anything as yet. My first one was about 3 weeks into learning 'haas'.... You doing them too?

Click to expand...

Heh - It's so old that I haven't got a "color" (at least, I don't know if I do yet). It's a '97 VF-2, and given that it made a bit of a stink when the alarm code came up (163 Z Axis Drive Fault), it gives me hope that it's a just a failed component than then burned a trace (the "G10" smell), and that at worst I can replace a discrete bit or two and jump the trace if need be.

I have a 2001 VF-5, and I might luck out that cards are similar enough that I can do some swapping, but given my horrible 2020 I'm almost certain to wreck the working mill if I try.

I need to become a Utube influencer so I can have lots of money to buy some new equipment...

Here is what Haas quoted me. Mine never seems to use 'thrust bearing' but I get the term.
motor housing bearing, the pt.# is 93-2901, $345.00. The radial bearing opposite that is pt.# 51-2025, $9.95. So we're going to go pick them up later or tomorrow and play over the 4th weekend if we/he can.

friesen said:

In theory, put a dial indicator on the end of the ballscrew and push pull the axis by by hand. In reality, this doesn't necessarily indicate like you would think. I just replaced the Y on my vf2, the symptoms were growl noise and bump sounds, as well as close to .001 backlash.

Click to expand...

countryguy said:

Here is what Haas quoted me. Mine never seems to use 'thrust bearing' but I get the term.
motor housing bearing, the pt.# is 93-2901, $345.00. The radial bearing opposite that is pt.# 51-2025, $9.95. So we're going to go pick them up later or tomorrow and play over the 4th weekend if we/he can.

Click to expand...

I think you'll do just fine, just take your time and make sure to remember where everything goes Quick photos with a smartphone during disassembly can be a life saver!

Also: pulling the dead thrust bearings off with a gear puller or similar is fine, but I have to caution about using a press/force/hammer blows during assembly with the new bearings. The bearings and possibly other parts of the housing are usually a heat shrink in these machines. Though I can't speak specifically to HAAS so I might be off base here...

On my machine, after pulling everything apart and cleaning it well, I then: heat up the outside of the thrust bearing retainer assembly to about 350ºF using a propane torch until the bearing is an easy slip fit into the housing. I then let everything cool to room temperature and bolt on the thrust bearing retainer collar. After that's in place I gently heat the entire assembly (including bearings) until it's a gentle slip fit onto the ballscrew and then tighten up the large nut that retains the ballscrew inside the the thrust bearing.

I think people get stuck pressing or hammering things together sometimes when a little heat goes a long way! Just make sure to not overheat the grease in the bearing, and don't melt your bearing seals! An adjustable heat-gun can make a useful ally here too... I like to like dangerously with my MAPP/Propane torch

Best of luck!
-Aaron

I'll document the journey here a bit on the Thrust bearing (bearing cartridge kit) replacement for a Haas VF/4 vintage 98.
1) The kit to order I am told is: 93-2901, $345.00 BEARING CARTRIDGE RETROFIT KIT Note: This bearing is a replacement from 93-30-0154 which is unobtainium.
2) The radial bearing opposite that is pt.# 51-2025, $9.95. (Which I think is the bearing at the other end of the screw? )

The instruction I have for the new bearing Cartridge retrofit kit is:
32mm Ballscrew Bearing Pack Retrofit Kit Installation AD0461

Sooooo... The parts were picked up and we'll probably attempt to put it in over the next week or so. I now get to run a Jr. back to College for dorm life prep. yep- going to be a very interesting school year .. heck year.(period) for everyone.
I just hope the PN's are all the right stuff.... and that a Bearing cartridge kit is actually a 'Thrust bearing' as everyone seems to note to swap. ;-)

Some related DIY haas goodies: ref goodies :
Ballscrew - Spacer - Installation - AD0250

32mm Ballscrew Bearing Pack Retrofit Kit Installation AD0461

Talked to a buddy in OR told it's easy to do these thrust bearing R&R.. (ok.... putting it in writing LOL). Now I'm probably screwed....
Notes to self more than anyting:

Told to use Kluner NBU #15 grease for the bearing. 1/3 pack . (amazone has a tube for $41) here Thurs.

Told to check the Screw & saddle mount to table for any looseness.

Told to check the 'saddle nut' and ensure it's a tight as possible. Not sure what that is.

Only issue- There is simply no - way we see to possibly get into the Saddle and Ball Nut directly under the table... yet there must be some trick we're not seeing yet. Someone must have a bit of wee magic insight?
Whoot.. just noticed, I made cast iron... :-) hehe..

If you are using the HAAS pack, I'm pretty sure you shouldn't be greasing it, I'd say its together and shouldn't come apart, at least according to HAAS.

I replaced the bearings in the thrust pack myself, its difficulty is overrated. As near as I can tell, the bearing faces are precision machined for the correct preload. They weren't pressed in, or at least they basically fell out of the housing once the retainer was removed.

If you pull off the side panels, you should be able to see the saddle assembly.

Yesyes! We have the part in hand now... I get it. My pal did this on a lathe and bought his own! Thanks for the detail.
TY for some help w/ the comlexity... Mucho' appreciated.

friesen said:

If you are using the HAAS pack, I'm pretty sure you shouldn't be greasing it, I'd say its together and shouldn't come apart, at least according to HAAS.

I replaced the bearings in the thrust pack myself, its difficulty is overrated. As near as I can tell, the bearing faces are precision machined for the correct preload. They weren't pressed in, or at least they basically fell out of the housing once the retainer was removed.

If you pull off the side panels, you should be able to see the saddle assembly.

Click to expand...

For the kid...
tip: Guides for removal of motor and Motor bearing assy. (and with re-assy instructions;
https://www.haascnc.com/content/dam...english---vf-series-service-manual---2003.pdf


Tip: Review of ballscrew & bearing combination ID ref. doc
Ballscrew Bearing Combination Guide


tip: Ballscrew space installation;
Ballscrew Bearing Combination Guide

covers are off.... lights on...shields up... We're going in :-)

Completed! Bearing Sleeve (thrust bearing) & Lead Screw Support bearing.

All done. success. No a bad job to do at all. Son and I only had 1 issue on a bearing locknut on the bearing support side. So stubborn we had to drill the center out of SHCS cap to pop it out.
As noted we did the bearing on both sides. Just seemed appropriate for age of the unit. We also had the 5 X axis oil metering restrictors on hand so put them in as well.

The Kid is glowing with accomplishment.... No backlash measured in X on our initial tests and it sounds 'beautiful' .. I assume over a break on period we'll see a ten or two? Dunno but this was rather fun.

We will get it run-in over the next few weeks. The guides used were all listed in the prior posts on this thread.

Thanks everyone for the support and encouragement.
CG & Son