Reply 1 (by OkumaVet_Southeast):
Running with growing Z-axis backlash on an Okuma MB-46VAE is something you can manage for a while depending on what you're making, but you need to be honest with yourself about what the machine is actually producing versus what you think it's producing. Okuma's OSP-P300 control does have backlash compensation built in and the service technician can update the compensation value to mask the mechanical wear temporarily, but compensation only corrects for a consistent, repeatable backlash value — if your screw has irregular wear along its length, compensation helps in one zone and hurts in another. The way to know your real situation is to run a ballbar test, not just a manual dial indicator check, because ballbar data will show you whether the backlash is consistent or variable and give you a proper diagnosis rather than a guess.

Reply 2 (by BallscrewRebuilder_WI):
From a repair standpoint, the Okuma MB-46VAE Z-axis uses a 40mm diameter x 20mm pitch ballscrew that is readily available from both NSK and THK as a replacement, and if you get to a regrind or replace decision the current lead time from most North American distributors is running 6-8 weeks for a new screw versus 3-4 weeks for a professionally reground unit from a shop like Rockford Ball Screw or Steinmeyer. One thing worth noting — when Z-axis ballscrew wear is significant, always inspect the Z-axis linear guide rails and carriages at the same time because the wear patterns between ball screw and linear guide degradation are usually related and fixing one without the other often means doing the job twice within 18 months. On the Okuma MB series the Z-axis guideways are Fanuc-compatible roller types and they're not complicated to replace if you're doing a proper rebuild.

Reply 3 (by QualityMgr_Aerospace):
If you're doing any tolerance-critical work — aerospace, medical, automotive precision components — you really should put a go/no-go decision on this sooner rather than later because Z-axis backlash creep affects every operation involving plunge moves, drilling depth, peck cycles, and any tool path that reverses Z direction mid-feature. I've seen shops run with "compensated" ballscrew wear on Okuma vertical machining centers for months thinking parts were fine, then get a customer audit that pulls SPC data showing their Z-depth feature variation has been slowly trending out for weeks. Okuma's Thermal Friendly Concept on the MB-46VAE does a good job managing thermal growth but it cannot compensate for mechanical backlash, and the two error sources compound each other in a way that's hard to catch without real process monitoring data. Run a capability study on a Z-direction feature before you decide to defer the repair.

Reply 4 (by ShopOwner_Ontario):
Practical reality check for anyone in this situation — get a quote for the ballscrew repair now, even if you're not ready to pull the trigger, because machine downtime planning is way easier when you've already done the vendor conversations and know your lead times. We deferred a Z-axis screw on our Okuma MU-500VA for about four months longer than we should have and when it finally got bad enough to park the machine we were scrambling to find a replacement screw, schedule the downtime around customer commitments, and find a technician all at the same time, and that chaos cost us more in overtime and expedite fees than the repair itself. In 2026 Okuma's OSP control also supports remote diagnostics through their Okuma App suite if you've set up the network connection, and their factory service team can actually monitor your axis servo data trends remotely and give you a data-driven timeline estimate for how long you realistically have before it becomes a hard problem.