Ballscrew machining problem ?

Hi,
I bought two HIWIN balscrews and asked seller to machine ends. I've put the long ballscrew (1,3m / 4 feet) into bearing blocks (BF12) and it is stable only in one position (which I guess, means that it is either bent or machining is not concentric).


Here what's happens when I hand tighten the bearings (2x 7001A - DF cinfiguration). Bearing Block is moving in a circular fashion. When I press it down so that it cant move, ballscrew becomes hard to rotate


http://www.mycncuk.com/attachment.ph...id=15511&stc=1


https://www.youtube.com/watch?v=bfo-9KJfJu0


I know that it's not on a perfectly flat surface - is this the reason for it or it is the ballscrew?


I've also measured concentricity as shown on the picture below and TIR is around 0,1mm / 0.004" which, I guess, could also mean that bearings are not concentric.


http://www.mycncuk.com/attachment.ph...id=15512&stc=1


Any ideas whats wrong?
And, no I cant put it into gantry yet as I still don't have it :/


Best regards
Bart

It appears like the either machining is not concentric or bearing block isn't but to be honest untill you get the end bearings fully fastened down and everything tightened correctly you won't be able to tell.
I've seen screws look much worse than this on bench turned by hand or drill and be perfectly fine when on the machine.!

I'd suggets you mount it and setup correctly attach a stepper then do some measureing.!

Thx for reply. I hope you're right.

regards
Bart

Nice frame end supports. Where, how much ? :unconscious:

Hi Silyavski,
I got it directly from SYK http://www.syk.tw/eng_index.asp (access to full price list after logging in) - very nice people and very good customer service. I was mailing with Mendy - one of the sales rep that you can also chat online with.

As to quality I'll tell you once I assembly everything. Just by looks and how all parts fit each other it seems to be very good.

Delivery time - around 10 days since payment.
On delivery, I had to pay 22% VAT when it came to Poland. It was still tiny bit cheaper then buying in Poland and of higher quality ( I got BF12 C3 grade and FK C5 grade whereas in Poland I'd get C7)


Best regards
Bart