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A new PAIR of improved AR XA or XB pivot screws for tonearm. Like all of the parts Vinyl Nirvana has undertaken to provide for vintage AR and Thorens turntables, these are an improvement upon the original design in terms of the materials used. These PAIRS are made with 17-4 PH (UNS S17400) stainless steel heat treated to H-900 condition.
Alloy 17-4 is a chromium-copper precipitation hardening stainless steel that is used for applications requiring high strength and a moderate level of corrosion resistance. It is one of the most widely used precipitation hardening grades, as it has high strength hardness while demonstrating good corrosion resistance. It is commonly used in Aerospace applications.
Replacement tonearm pivot screws have been something XA and XB owners have sought for decades. Not only are these now available, but also the material and machining process likely ensure you will never need another pair. Before I had these manufactured people were left to re-thread the existing part to allow a more widely available thread pattern and fashion a pivot point from whatever material was available.
Third photos shows original pivot screw on left.
Installation instructions provided, but the attached Youtube video link below goes into better detail.
Why are pivot screws important?
(Points below summarized from Pasquale Robustini.)
- The pointed tips of the pivot screws rest inside delicate bearing cups or races. This minimal contact point allows the tonearm to swing horizontally across the record and float vertically over warped records with almost zero resistance
- If a pivot screw is too loose, the tonearm will exhibit "slop" or mechanical play, leading to rattling, misbehaviour on imperfect vinyl, and severe mistracking.
- If a pivot screw is adjusted too tightly, it pinches the bearings. This causes binding—restricting the arm's natural free motion.
PAIRS manufactured here in the USby a highly regarded local machining company.
NOTE: Not for use with the later XB-77 turntable tonearm
Install video:
I advise watching this BEFORE purchase.
