View Full Version : Question about couplings...
JW1977
22-04-2021, 02:24 PM
Hi!
I’m unsure of what couplings to use. As it seems I will go with alu couplings with a slit in them. Any thoughts about that?
I’ve noticed that the ball screws are round at the end. Is there any reason that they don’t have a flat surface as the motors has?
I’m thinking that maybe if something goes wrong they will come loose and prevent further damage.
Thanks, JW
29827
JAZZCNC
22-04-2021, 05:16 PM
No, they are the worst coupling to use. you are better using an Oldham-type coupling like this.
http://www.fbtmotion.com/html/16.html
Or better still a disc type coupling like this
http://www.fbtmotion.com/html/17.html
Regards the ball screw then just file a small flat onto the shaft, the machined portion is soft enough to file.
JW1977
25-04-2021, 11:22 AM
Thanks!
I guess the coupling is flexible above a certain amount of torque right?
dazp1976
25-04-2021, 01:07 PM
Thanks!
I guess the coupling is flexible above a certain amount of torque right?
I've snapped 3 of those metal 'flexible' couplings so far.
I now use the spider type with no problem at all.
https://ae01.alicdn.com/kf/HTB1MDweX5LxK1Rjy0Ffq6zYdVXag/D20L25-jaw-flexible-motor-coupling-aluminium-CNC-spider-flexible-jaw-coupler-5x8mm-3mm-4mm-5mm-6mm.jpg_Q90.jpg_.webp
JAZZCNC
25-04-2021, 03:26 PM
Thanks!
I guess the coupling is flexible above a certain amount of torque right?
It's all to do with parallel and Angular misalignments and to a lesser degree axial growth or misalignment.
Read this it will explain the different types and Torque ratings etc.
https://www.thomasnet.com/articles/hardware/coupling-types/
JW1977
07-06-2021, 08:43 AM
*JAZZCNC*
Do you have any idea or an example of how much runout that can be accepted in a ballscrew?
Offcourse its hard to answer and its related to length but i was thinking that maybe you have a general idea?
Im asking because i had some of mine modified in the ends for different reasons. The guy who did it is an experienced machinist used to high precison machines so i guess that in his world my screws are pretty bent. I dont remember exactly but i think that my 900 mm screw where off by 0,4 mm. Im gonna check for myself when i get it back but i think the measure he referred to was when the screw was laying flat and you measure from the flat surface up to nearest point of the screw...
Cheers
Powered by vBulletin® Version 4.2.5 Copyright © 2025 vBulletin Solutions Inc. All rights reserved.