Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: NormB on February 12, 2010, 06:09:14 PM
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I have looked at so many I am confused now, seems they are all the BEST if you read all the Bull.....I need someone with experience with these to advise the best to use.
I am currently using a split coupler but it keep loosening up I am not sure why. Maybe That is the best and I have a bad one something.
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Not sure what you are meaning by split couplings but the likely cause of them slackening is misalignment.
Hood
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Norm, if you have the type in the pic I'm showing (top pic), those are too stiff unless you have PERFECT alignment of your leadscrew and motor shaft, which is pretty rare. When using rigid couplers, if they do not line up, the screws will just loosen more and more and create problems. This is why you need flexible couplings (lower pic) that allow for some mis-alignment of the shafts.
Hope this helps-
Dave
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The first pic is the coupling I have. all three axis. I have not seen one like the one you show in pic two Helicalbeam. I have to try an find those.
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My own view is that a flexible coupling takes the shock out of fast back & forth movements rather than misalignment.
So with low power and acceleration hard coupling would be OK
Some people have reported that the coupling in the lower picture can UNRAVEL, that shows the forces these this things have to put up with
Phil
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I use Oldham couplings on my router & Mill 4th axis, they allow for a small amount of mis-alignment and you can also remove the motor without having to undo the coupling. You can also get different centres for them.
Steve
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Just to add a little more info here, Phil is correct, if you don't get the proper helical couplers for YOUR specific needs, it will not hold up, but that really should go without saying as you must choose any coupler for your specific application. It's not a "one size fits all" kind of thing.
I do also like Bowbers idea of "oldham" type couplers as well as those are great too. Again, though, you have to figure out what your specific needs are.
When ordering any coupler, they give you the specs of the particular coupler that you need, such as torque rating and misalignment data as well.
Hope that helps a bit more.
Dave