Ball Screw and Nut issue, just started making a ticking noise when rotating and rough

laminar-flow · Nov 25, 2019

My Haas HPCL, discontinued about 7 years ago, has been working just fine. Today, we suddenly noticed a tick-tick-tick-tick when rotating mainly in the X+ direction. With careful examination, we have concluded that it is the X Nut / Screw. We wiped off the grease on the screw and it seemed to change sound a bit. When turning the axis by hand it is rough and feels bumpy. The screw looks fine and shows no marks at all.

My assumption is that a ball has fractured. My question is, would it be possible to replace the balls in the nut and give it a try? I have never opened up a ball screw before but it can't be that bad.

I have contacted Haas but I don't think they support this machine any more.

Larry Dickman · Nov 25, 2019

Replacing the balls isn't too hard, but if you've never done it before you can make a mess of things in a hurry. Check out some UTube videos. I would suggest checking the thrust bearings first, they are way more likely to be the culprit.

Delw · Nov 25, 2019

I'd check your thrust bearings on the end of the screw before anything else. pull your motor off and turn it by hand also to eliminate the motor.
if you show no marks or unusual wear on the ball screw I highly doubt its the ball screw.

plastikdreams · Nov 25, 2019

Delw said:
I'd check your thrust bearings on the end of the screw before anything else. pull your motor off and turn it by hand also to eliminate the motor.
if you show no marks or unusual wear on the ball screw I highly doubt its the ball screw.

I agree, a cracked or damaged ball would leave plenty of carnage in it's wake.

laminar-flow · Nov 25, 2019

Well thanks. The noise just started so would that be enough to damage the screw? What is harder, the screw, nut, or balls?

DavidScott · Nov 25, 2019

Balls wear the most, then nut, then screw. Replacing the balls isn't hard, just tedious. It takes time to figure out exactly what ball to use, but does depend on the type of nut and how it is preloaded.

Delw · Nov 25, 2019

laminar-flow said:
Well thanks. The noise just started so would that be enough to damage the screw? What is harder, the screw, nut, or balls?

doesn't make any difference what it is or when it started, until its taken apart completely you will not know if its motor bearings screw nut balls etc.
take the motor loose try moving the screw and check motor, if the motor is good then take the thrust bearings out and spin the screw.
also the clicking noise and rough turning can be from a coupler. you wont know until everything is checked.

laminar-flow · Nov 26, 2019

OK, will do. It will be next week. Video's on YT are helpful.

laminar-flow · Nov 27, 2019

Had some time and investigated the problem. It is the balls and the nut. The screw looks fine, so far, but the nut has pitting and scoring. The balls measure 2mm Ø. I'm just left a message with the HFO and let us see if they have that part and how much. Who makes the Haas Ball Screws?

garyhlucas · Nov 27, 2019

Depending on the type of nut the preload to eliminate backlash may have been accomplished by loading with oversized balls. So you don't just buy stock size balls you get ones made to the right size. I had Whitney punch that the ballscrew looked good but there was too much wobble in the punch. I measured the slop and bought some oversized balls to compensate the wear. That's not a precision job though, I just wanted to reduce the slop so you may want to send it out to be done by a pro.

G00 Proto · Nov 27, 2019

I'm just going to be a ray of optimism... some of the Haas machines have a plastic sleeve that rides on the ball screws. It is a loose slip fit, and it's only function is to be a sacrificial hard stop if the limit switches fail. Periodically those develop a noise that is very similar to what you are describing... I have spent the money to have a Haas tech come out and tell me the good news. Not saying that this is your issue, but thinking happy thoughts may help you enjoy the holiday.

Milland · Nov 27, 2019

laminar-flow said:
Had some time and investigated the problem. It is the balls and the nut. The screw looks fine, so far, but the nut has pitting and scoring. The balls measure 2mm Ø. I'm just left a message with the HFO and let us see if they have that part and how much. Who makes the Haas Ball Screws?

That sounds like a fixable problem, especially if you don't mind doing some work yourself. If the nut pitting is minor, and the current balls in reasonable shape, try measuring some and confirming if they're all the same size or of the "hi-lo" variety. And once you have that and a good ball diameter starting point, you could order a hundred or two (whatever's needed plus some extras) from a good stocking house like Boca Bearing. 2mm should be cheap, so get them in nominal and a few steps in +.0002 from what you think you need.

Balls - Steel, Ceramic, Plastic & Glass by Boca Bearings :: Ceramic Bearing Specialists

Clean everything carefully (especially the nut and its bypass tubes/guides), and using a light oil install the balls (how tos on the web and Youtube), being sure not to overfill. You'll also want to ensure the nut seals are still good (perhaps what failed that started the wear) - they should be available from ballscrew rebuild co's.

Most of what I've read suggest the preload of the ballscrew should be measured with a string wrapped around the OD of the screw and a fish scale used to pull the end, with a force value set by the size of screw or manufacturers suggestion. If installing new nut seals, leave them off until the measurements are done, and have the screw supported so you're not cocking/binding it during the pull.

DavidScott · Nov 27, 2019

Been there done that. .00005" is a big jump in ball diameter if the balls do the preload. New ball screws use balls that are round to within 5 millionths or so, balls you buy off the internet, or the company in Cali, are 25 millionths. Doing the reball may cost $500-$600 when done if you do it yourself, that is what it cost me when I did it, and will not be even close to a new screw in quality of finished product. And it will take several weeks of screwing with it. Being a Hass try to get a new screw, they are probably near the cost of a competent reball.

laminar-flow · Nov 29, 2019

Here are the specifications on the ball screw. 11.4mm diameter, 5mm pitch. The nut is internal recirculating, and 22mm Ø and 38mm long, a cylinder with no protruding features.

If Haas no longer supports this machine I will have to find a replacement.

Does anyone know who makes the ball screws for Haas?

DavidScott · Nov 29, 2019

If Haas no longer sells them then ask them who they got them from, they should tell you if they are not going to sell one to you. Start with Haas then go from there.

And get a part # from Haas if they won't sell one to you. When I was reballing the screws in my Enshu I found out the screws were made by NSK, or so. I call them up to find out what preload the screw originally had and from the info I gave them they pulled up the print on the screw. They would have sold me a new screw if I could get Enshu to OK it.

While at it is your nut preloaded by ball size or a spacer in the middle?

Mud · Nov 29, 2019

DavidScott said:
Been there done that. .00005" is a big jump in ball diameter if the balls do the preload. New ball screws use balls that are round to within 5 millionths or so, balls you buy off the internet, or the company in Cali, are 25 millionths. .

You mean Bal tech? i didn't know that. :eek:

DavidScott · Nov 29, 2019

Mud said:
You mean Bal tech? i didn't know that.

Yes, Bal-tec. My balls were 1/4" so the 2mm balls would have even smaller size differences to deal with.

Mud · Nov 29, 2019

DavidScott said:
Yes, Bal-tec. My balls were 1/4" so the 2mm balls would have even smaller size differences to deal with.

Mine were ~.250, and some lots varied measurably from ball to ball. I sorted out the flyers and attributed that to bad handling of inventory, but I had no way to measure roundness. Where would one go to get better balls?

DavidScott · Nov 29, 2019

Mud said:
Mine were ~.250, and some lots varied measurably from ball to ball. I sorted out the flyers and attributed that to bad handling of inventory, but I had no way to measure roundness. Where would one go to get better balls?

I don't know, never seen better for sale.

laminar-flow · Dec 13, 2019

The new screw and nut arrived from Haas. The nut has on it Steinmeyer 31/13-3 M. In looking on the Steinmeyer web site, these pages were found about lubrication.

Grease Lubrication - August Steinmeyer GmbH & Co. KG

Recommended Grease - August Steinmeyer GmbH & Co. KG

The Haas HPCL has no provision for lubrication of the nuts and screws. We have been wiping the screws with Lubriplate 1242 HP, which is what we use on the slide trucks and on the TM1 mill. But now we plan on modifying the blocks that hold the ball nuts with a grease fitting and forcing grease from the inside of the nut out.

Ball Screw and Nut issue, just started making a ticking noise when rotating and rough

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