Ball Screw Bearing replacement.

countryguy

countryguy

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I have a situation that required me to remove the Ball Screws on two of my units axis. (Y and Z ) X later if/when I tear that down.

The Thomson BallScrew unit I have listed balls as .125 nominal. The Mill Co. owner of my unit noted that while he liked the Thomson's they often had balls in the .123 range. He noted to get into a better .125 precision ball to help w/ backlash (since I had the unit opened up under the saddle anyway).

The Thomson BS site had all my info in PDF form. I pulled the specs. Confirmed my ball sizes. Ordered from Grainger as 4RJH5 .125 to .0001 tolerance.... (not that I can measure beyond +/- .0005 anyway on my scale).

Balls came in , and I found this great Thomson Vid on how to repack the balls into the unit. https://www.youtube.com/watch?v=CoTboHFy3eY

I have 69 to replace in each unit and it seems very easy thus far. Cool tip and great vid by the OEM.

Onward ho!
CG
 
ok.... 26 inside . Getting there... :) using the Thomson vid method. Need to PUSH them down in and then down into the screw a bit... they seem to 'pop' down a good 1/8" each time. I think I'm pushing the whole BB train back? having fun yet? Yep! (I think I can I think I can.... LOL) .
 
48...49...50! 50 inside. My method: Put 3 in.... Push down (small piece of 12Ga copper) Hold down tight and gently turn the screw (w/ as many in as I have) Take them down to bottom of screw.... While still holding down w/ the wire, now gently spin opposite way (maybe 3/4") to rotate the end balls back into each other (keep a constant chain... My hope?). Remove gaps... I hope. Getting there.

OK.... 51 - 60 now.... Stand by. (oh- there are 9 in the external return tube). Will grease em' up as in the Thomson Vid). so last 9 to go in! Sweet! That only took 8 seconds.... And now I have balls to the top of each return hole. The zillion dollar moment. Return tube insertion. Will he fold to the pressure? The newb takes a Steely (pun intended) stare at the grease..... a smoky Obi Wan lingers near; "Use the Force Newb". :)

Sound from the kitchen lair like the crackle of the phasers! A whiff of smoke that smells of grease & flesh.- BAM! Flipping up the blast shield & oddly enough- It's together and working fine! Total time- About 45mins. Off to the Z axis later. No big deal. Just takes a big bowl of Ice Cream to get them installed! (hence the suger buzz SW commentary!) :) Uggggg

CGout!
 
Let us know what the finial backlash is. I have my .125" ball bearings and I plan to install them on Saturday.
 
I can tell you already it's significantly smoother and BL is much better. I have the Jensen glass scale DRO's and I tell ya.... I was doing controlled increments of .0002 positions on this thing. freakish good. But- Just something quick. I iwll be under power tonight sometime. I have Mach3 for Y w/ a BL of .006 if I recall and I'm going to be in the .001 range for sure. Looking forward to re-calibrating and doing the Hoss video BL check runs again. PS- My bag only came w/ 97 in one. 100 in the other. Doing Z axis next as it's a sore spot w/ me.
 
countryguy said:
I can tell you already it's significantly smoother and BL is much better. I have the Jensen glass scale DRO's and I tell ya.... I was doing controlled increments of .0002 positions on this thing. freakish good. But- Just something quick. I iwll be under power tonight sometime. I have Mach3 for Y w/ a BL of .006 if I recall and I'm going to be in the .001 range for sure. Looking forward to re-calibrating and doing the Hoss video BL check runs again. PS- My bag only came w/ 97 in one. 100 in the other. Doing Z axis next as it's a sore spot w/ me.
Click to expand...

Thanks for the update, sounds good and I will let you know how I make out.
 
The backlash is about .0008 to .001. So I have set mach3 to .001 on Y. At these digits on an Asian 3:1 setup I am really happy! I honestly did not expect that large an improvement! I completed the z axis ball replacement in 20mins end to end. Very simple now that I have my process. This is nothing to worry about as a newb project and the gains tremendous!
 
countryguy said:
The backlash is about .0008 to .001. So I have set mach3 to .001 on Y. At these digits on an Asian 3:1 setup I am really happy! I honestly did not expect that large an improvement! I completed the z axis ball replacement in 20mins end to end. Very simple now that I have my process. This is nothing to worry about as a newb project and the gains tremendous!
Click to expand...
Wow! That's great, better than I expected.
Bob
 
My BL was set to .007 in Mach before this. I used the method as shown by Hoss in his famous X2 vids.... So I had Mach 3 in step mode and .0005 a step to .001 and went thru numerous checks. It was a real .007 as I could tell. X is .006 and I'll pull that one out when the next set of bearings come in from Grainger. I am short 10.
 
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