(248,’2006-09-22 12:00:00′,’figNoggle’,’2006-12-20 08:02:36′,’david’,’Ground Ball Screws From eBay A Good Deal?’,”,’For many of us, eBay is a great source of many things that cost lower (sometimes way lower) than retail.
It only makes sense that when shopping around for expensive components like ground ballscrews and zero backlash (or anti-backlash) nuts, eBay is a great place to start looking for these treasures.
Buyer beware! With things like ball screws where axial accuracy is important, it’s sometimes difficult to catch with the naked eye. Here’s how we found out:
We landed an OK deal on a ground ballscrew from THK with a C1 grade, angular contact bearings and end bearing, and the zero-backlash preloaded ball nut. Nice!
Upon opening up the package, it looked great – minus the pits and two spots where the “thread” was mangled a bit, but it appeared operational. We probably should have asked more detailed questions prior to bidding, but it just slipped our collective minds..
All was going according to plan until we mounted the ballscrew in the Y-axis of our home-brewed CNC vertical mill… Something was off and wobbly.
So, we chuck the shaft end into the 8×12 mini-lathe, swap the belt ratios to yield 125 rpm and turn it on. Guess what we found? Click the picture to see the video:
Runout! Major runout! So bad in fact, that once it was assembled for testing, it caused stalls all over the place.
Stay tuned for how this was fixed.’
‘,’
For many of us, eBay is a great source of many things that cost lower (sometimes way lower) than retail.
It only makes sense that when shopping around for expensive components like ground ballscrews and zero backlash (or anti-backlash) nuts, eBay is a great place to start looking for these treasures.
Buyer beware! With things like ball screws where axial accuracy is important, it’s sometimes difficult to catch with the naked eye. Here’s how we found out:
We landed an OK deal on a ground ballscrew from THK with a C1 grade, angular contact bearings and end bearing, and the zero-backlash preloaded ball nut. Nice!
Upon opening up the package, it looked great – minus the pits and two spots where the “thread” was mangled a bit, but it appeared operational. We probably should have asked more detailed questions prior to bidding, but it just slipped our collective minds..
All was going according to plan until we mounted the ballscrew in the Y-axis of our home-brewed CNC vertical mill… Something was off and wobbly.
So, we chuck the shaft end into the 8×12 mini-lathe, swap the belt ratios to yield 125 rpm and turn it on. Guess what we found? Click the picture to see the video:
Runout! Major runout! So bad in fact, that once it was assembled for testing, it caused stalls all over the place.
Stay tuned for how this was fixed.’
‘,”,”,”,’Home-Brewed-CNC-Vertical-Mill’,”,0,”,0,4,1,1,’article’,”,”,’ground-ball-screws-from-ebay-a-good-deal’,”,”,”,”,”,”,”,”,”,”,’29f81aca7900ba2fb551779f91626181′,’2006-09-22′);