X3 conversion - ballscrew mounting question

[Neil_J]

Originally Posted by LazyMan Guys, First off, the new rex nut is preloaded using the lead offset method and includes a flange, The preloaded nook XPR nut cost $60 not $30 and there optional flange cost $30 or $35 bucks. THe rex nut is not anymore expensive. The price for the screw is cheaper too although it is less accurate rated at .0018"/foot. Even so, I am still dissappointed and would have preferece those nook screws partially because I have never even heard of REX. I am on a quest to find those XPR screws for the same price homeshopcnc provided with no such luck. I requested a quote for a 40 in .631 XPR screw with a PRN preloaded nut and they told me $460! Thats around double the cost of what homeshopcnc offered!

I had planned to buy the Nooks from Mcmaster at $24.65 per nut (double on X,Z, preloaded single on Y).. I found flange nuts on Ebay for $7.00 each. That would have totaled to $146.00, plus $1.27 per inch of ballscrew needed. The Rex system OTOH would be $285 + $1.89 per inch of ballscrew needed.

Obviously if you have the extra cash, the Rex system is the winner here. Only $150 more, but better accuracy and more X/Z travel (compared to double-nuts). Hmmm C7 quality versus T8??? I'll find somewhere else on my machine to save $150. Yep I know where my money's going

[Neil_J]

Originally Posted by ataxy rex is the mother company of homeshopcnc http://homeshopcnc.com/page2.html

So for that price, are they 'Made in the USA' by Rex Industries, or imported from a foriegn vendor?

[lgalla]

Neil,I agree the homeshop Rex is the best accuracy for the money,but you must determine that the ballnut is not to large.Next choice would be McMaster carr.At Reid thompson nuts are$124.00??THK's at MSC are to reduculous to bother.
Here is some Roton info I got from searching the CNC Zone.
Lead accuracy anywhere from .003 to .010.Apparently you can request .003.Rolled screws can vary a lot and manufactures select and grade what they rolled.
Many Zoners used Roton and are quite happy.Perhaps they got lucky.A call to Roton may be in order to confirm the .003 request.If they can supply they would be the best bang for the buck.Sorry I know nothing about mills.I researched screws for a 5X10 wood router and have to go R&P.Even 10'Rotons are $700.

Larry

[Neil_J]

Originally Posted by lgalla Neil,I agree the homeshop Rex is the best accuracy for the money,but you must determine that the ballnut is not to large.

I believe they will fit my X3 mill. They are a bit bigger than the Nook square nuts, but not by much.

Many Zoners used Roton and are quite happy.Perhaps they got lucky.

They're probably happy they got a ballscrew setup for <$100. I can relate, I bought a new laptop for $300 the other day, which isn't a great performer by laptop standards, but hey it was only $300.

[cadmonkey]

Dredging up an old thread but my clearance model for the X3 indicated that without milling/grinding the nut flange on the new Homeshop nuts they would not fit.

The reason you got a sticker shock with a quoted price on the Nook nuts is because the nuts that should go with the XPR screws are not what Homeshop (and CNCFusion) were/are offering at ~$30 a piece. The nuts they were offering are the cut nuts not ground nuts which are intended to be paired with the SRT screws. I opted to drop to the cut nuts and save the $$. I threaded one on when my 6' of screw and 3 nuts showed up (2 for X and 1 for Y which will get preloaded with some oversized balls) and the fit was beautiful. Rolled all the way down to where I rolled the sheath back on the screw with no effort whatsoever, shaft was barely elevated from horizontal, and there was no perceptible lash, but under load I'm sure that'll change. Once I get my X and Y machined, turned and installed I'll design the Z around the same screw (got a 6' standard length which is enough for all 3) and should be up and running by the end of March.