Hi All,
I have noticed my aluminium z coupling with the anti-backlash flex is also very flexible in the Z direction. It’s like a coil spring suspension!
Does this cause anyone else any concern? Would you recommend a Z coupling without the anti-backlash feature?
Cheers
There should not be any springiness in the coupling. The leadscrew should be setting hard against the stepper shaft. The coupler should only need to accommodate a small lateral / angular misalignment.
An aluminium coupling is basically a spring (cut in spiral shape)
Is your threaded rod that hard to turn so it flexes the coupling ?
I had an anti-backlash nut and spring on mine but I did not install them. I only installed the lower screw and added a drop of lube to make it turn smooth.
More importantly, the weight of the router is large, and always down. So as long as you have closed the gap. The weight should remove any backlash.
Hi guys! Thanks for responding!
@Paradox_Pete Even like that, it will still lift when plunging.
@jeffeb3 , yes, a heavy router helps.
@UndCon , correct. My T8 screw is lubed and easy to turn.
I was just wondering if there was a better style of coupling. Perhaps the pineapple printed coupling is actually better?
I am using this one:
It is not flexible or springy like the aluminium ones.
So far works very well.
Excellent, thanks for letting me know.
I have a Lowrider not an MPCNC, so perhaps my thought here are incorrect, but lifting while plunging implies something is resisting the Z axis motion. This begs a slew of questions.
First, does it stretch the Z coupling while just jogging the Z axis down in the air or only while milling? If the former, something is binding the Z axis and this should be chased down first.
If it only stretches while actually cutting, then the bit is unable to mill as quickly as it is plunging, which leads to a different set of questions.
What type of bit are you using? Is it end cutting? up cut or down cut?
Are you ramping into the material, or doing a straight plunge? Ramping should help with this.
What kind of material are you cutting?
How fast are you plunging?
I’m sure there may be other things to consider, but I think the stretching is a symptom, not a root cause…
It’s just an opportunity to eliminate some undesirable movement, regardless of plunge rate or anything else.
I had the same issue but changing to a solid coupler fixed the issue, something like this. https://aliexpress.com/item/10000391089957.html
Yep, I’ve installed a solid coupler too. There’s no need for a spring here - you wouldn’t put a spring on your x or y axes would you? I’m eliminating all the room for error that I can. Seems to be working.
I also installed a second custom tool mount to hold the top of my spindle.