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Is there not a flat turned bearing journal for the AC bearings? I am possibly not understanding what you are saying but is the whole area threaded? Peace
Pete
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I purchased some new ballscrews from roton and had them machined locally. When I place the AC Bearings the ballscrew threading, it causes the bearing to tilt because of the lack of surface in a spot where the groove in the ballscrew is located. Is there a trick to getting the bearing to sit in a manner so that the ballscrew will not make the elliptical spin? I have searched but have found nothing explicitly like this.
Is there not a flat turned bearing journal for the AC bearings? I am possibly not understanding what you are saying but is the whole area threaded? Peace
Pete
The ends have been machined to put the bearings on the end to but up against the "threads" of the ballscrew
You are saying that the angular contact bearing gets pushed up against the start of the ballnut threads and the odd shape is causing a misalignment of the bearing. If that is the case I would say that perhaps you are using a too large bearing and the journal of the bearing does not have a solid even at the center to ride up against. My ballscrews have the bearings up against a shoulder that lies slightly below the meat of the ballscrew threads. That way it is solid. Really tho unless your having some interference there as long as the journal they machined is a snug fit the bearing should be forced to ride straight as the journal is machined. How snug is the bearing fitment? Either that or I still do not understand you....peace
Pete
What size Roton ball screw and what AC bearing do you have? Part number of the bearing is fine if you don't have the size.
The 5/8" Roton barely cleans up at 0.472" (12mm) ID which is the standard bearing size for that ball screw.
The 3/4" Roton barely cleans up for the standard 0.590" (15mm) ID bearing.
I know what your talking about however if the journal is turned correctly and the bearing is a snug fit on the shaft there isn't much chance it can cock on you. It would require clearance from the OD of the shaft and the ID of the bearing in order to cock.
Richard
Rev
SX-3 Mill, 10x22 Lathe, RF-45 Mill, GH-1340 Enco Lathe
LLDesigns
You need a spacer in front of the bearing, I show in this build how to do it, from start to finish, also the ER16 spindle build shows a spacer in front of the bearing also
http://www.cnczone.com/forums/cnc_wo..._friend-9.html
Mactec54
The ID of the bearing is .39 and the OD of the shaft of the turned down ballscrew is .393
So how the heck do you get the bearing on? haha Maybe you got that backwards or I misread the hell out of it. Anyways, Even if it is backwards .003 slop is not gonna cut it for the bearings... Did you give them the specs or is that what they just did to make the bearing fit. It needs to be a nice snug fit really... Are they already cut to length? Can you remachine them back again or will they be too short. If they are too short you are only out the longest screw probably. You really should not need a spacer on the shaft either I do not have any on my screws. They just butt up against the shoulder and I machined back a bit to make sure the meat of the ballscrew did not damage my outer bearing race or interfere for the movement. Do I have this all wrong in my understanding of what you are experiencing? Peace
Pete
The bearing is actually on there pretty tight. We dont have a lot of machine chops around where I live. I took the work that was done and "assumed" that it was correct. I am guessing I will have to having the work done and shipped to me from elsewhere next time.
Are you saying you pressed on a hardened bearing on a hardened ballscrew shaft that was .003 undersize? How the hell did you get it on? If it is .003 oversize then it must have a real bad high spot somewhere in there that you did not measure or it could not possibly be tight right? Are all of the screws this way? You can do as I said remachine the screws to the next shorter one in length and that will only force you to buy another single screw. Are you sure they machined them pretty concentric? That is another issue if the guys who did the turning of the screws for you were not real good or up on the way to machine a ballscrew> Sorry you are having issues. Maybe you could post a picture to show what you are talking about so it can be a little clearer for us to try to help you. Peace
Pete
The shaft is actually .003 larger than the inside diameter of the the bearing. I took off the bearing and noticed that where the screw was turned down was not flat but more of a taper the last 1/32. Mind you that I am not a machinist so some machining things will escape me.
pete from TN
There should be a spacer before the bearing that's the correct way to do it, In a case like this there is almost no shoulder on the shaft/screw so the bearings need a shoulder the same dia as what the inner of the bearing is
LLDesigns
If you have 10mm bearings .393 for the shaft the bearing would be loose, for that bearing to be tight your shaft must be bigger than .3937 which would be size for size for 10mm bearing
Mactec54
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