View Full Version : Plastic ball nuts - any thoughts ?
22-03-2014, 07:45 PM
Came across this from Igus, looks interesting, no lubrication plus other benefits, could be an alternative to China ball screws etc. but is it any good ?
23-03-2014, 09:25 AM
That should be good in a perfectly clean, dry environment.
23-03-2014, 09:50 AM
Maybe it's better than that, here are some applications
igus® Applications with DryLin® linear plain bearings (http://www.igus.co.uk/wpck/2870/app_overview_dry)
Also linear guides
igus® DryLin® N low profile linear guide system - Program overview (http://www.igus.co.uk/wpck/1969/drylin_n)
23-03-2014, 11:12 AM
Our work uses the plain linear bearings, they require a bore to the correct tolerance to ensure the internal bore of the bush is to correct size after it is squeezed in.
I would still use a ball bearing type on a round rail having used both.
23-03-2014, 12:28 PM
You'd want to use the anti backlash version.
igus® drylin® - Anti Backlash nuts (http://www.igus.co.uk/wpck/7000/DryLin_Anti_Backlash_Muttern)
They should work fine, as there are hundreds of builders at CNC Zone using plastic nuts on acme screws, including myself.
3 things to be aware of.
1) They typically aren't rated nearly as high for loading as a ballscrew. With an anti-backlash plastic nut, if you exceed the load rating, then you may see some backlash.
2) Even though they claim no lubrication is needed, they will work better with lubrication. I use pneumatic tool oil on mine.
3) Depending on the screw, they are probably somewhere between 50%-80% efficient. Compared to a ballscrew that is about 95% efficient. SO you typically lose~30% of your motor power to frictional losses.
**EDIT** I hadn't watched the video prior to posting. It appears that their special thread profile increases the efficiency But I still doubt that it's better than 80%, but I'll have to look into it. I wouldn't be surprised if these are more expensive than ballscrews from China. ** End EDIT**
Having said that, I'll be using plastic nuts and acme screws on the Z axis of the new machine I'm building. Mainly, because they are far more compact than a ballscrew and nut. And The homemade plastic nut on my current machine's Z axis has been working fine for over 5 years.
26-03-2014, 10:30 PM
As ger21 says, these work fine on acme. Jump over to cnc zone and look up the "evanut". It's a cool easy way to make nuts. Just made 2 for my xy table and they lowered my torque an eliminated backlash for bout 2 bucks. There is conjecture on how they would work on a ball screw screw, why don't you try it and let us all know
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