This is from the web…
Closed-loop stepper motors combine the benefits of both worlds. They achieve the highest maximum torque, the best efficiency and optimum dynamics, but also feature the lowest torque ripple and exceptionally quiet running .
However Im not aware of the complexity it involves to make it work with the actual boards used with the LR.
The cheaper end of closed loop steppers, at least, only really give you a bit of protection against missed steps. That’s not a bad thing to have, as such, but it’s a relatively big change for something that shouldn’t be a huge issue.
It doesn’t really give you any more performance in the ranges we’re talking about because ultimately that’s limited by the performance of the stepper itself. You can get a bit more by running it closer to where it’d skip steps with any pulsating torque loads, I suspect, but that’s probably not transformational.
The closed loop servos with stepper inputs would be a bigger/better step but then you’d need more rigidity in the motion platform to take advantage of that. More rigidity means bigger, heavier, more expensive and so on. Ultimately more dangerous, as well.
Edit: I suspect the closed loop steppers have the biggest advantage where missed steps could cause machine damage or where there’s a huge advantage to having the steppers run cooler/quieter when lightly loaded.
Agreed, they are great but do not actually add much. A skipped step has almost never been my issue and when it was I am very thankful the step was skipped and the machine did not tear itself apart.
What is a temporary fix that us LR3 people can do to mitigate this? Some shimming or new printed parts to fix the issue? I can do cad pretty good so can make updates to the parts if time is an issue for you.
As long as you don’t have the M3 screws that hold the lead screw nut bound in tight, and you keep the lead screw lubed up that has worked for everyone on the LR3.
The CAD is good. If your printer were 100% accurate, there would be no problems. The problems start because the physical reality if the parts is not the exact same as the digital. Also, plastic drifts over time, a little.
I had to shim one z stub a little, the other was fine. The shimmed stub was fine for quite a while, then… it wasn’t.
Fortunately it was really easy to shim, I just had to go and do it.
Anytime I saw an issue it was actually a hair too tall so a tiny bit of sanding made it perfect. Watch the tip of the leadscrew when you move up and down and see if it goes in or out.
Did I leave my keys in he…. oh hey guys, how’s it goin?
Seems to be going ok 
Excellent.
That reminds me - Ryan please please PLEASE make the zip tie slots in the design wider than the current one. Thanks.
3x6mm currently
How wide? I use a bunch of reusable zipties that are 7.5mm wide, I end up making 8.5mm slots in my mods.
I get that regular tiny one time use zipties are super cheap.
EDIT: Found some 5mm reusable zipties a while back, have been using those in recent builds… https://www.amazon.com/gp/product/B07R2JKWXV
The more and larger the holes we put in the parts the larger the parts need to be. Regular/small zip ties can hold like 60lbs we do not need to go bigger. Reusable are nice but they are large. When I want to go reusable I use bailing wire.
so toddler and pre teen only, got it.
Just kidding btw!!
3.6mm are far more common where I am than 3mm if you can make them 3.6x6 that’d be lovely.
stainless safety wire FTW!
What is the size under that?
Ours are 2.4 and 2.5mm. Then it goes to 3.3-3.5
Yeah same, 2.4, 3.6, 4.8/5.0, 10
Perfect, just go down a size. A 3.6mm tie needs a 4.5mm slot.
Im just curious if any of the beta testers have a 4’x8’ machine that they are testing the LR4 on? Specifically in terms of increased rigidity, just because that’s my main issue that I am dealing with on my 4x8 LR3.