Just as a FYI, those with Xcontrollers, the auto torque reduction is the main source of machine movement during bit changes. You can disable it by turning off DIP switch #4 on each axis driver. It may even be worth doing with a screw drive as well.
Auto torque is a great feature to control temps of steppers and the Xcontroller but can cause step issues as well, even potentially during carves.
Just FYI they come that way be default. Almost nobody should need to touch it
The torque reduction? Mine was enabled when I received it and the Inventables instructions say to enable it.
I didnāt claim that screws slip. Still doesnāt change the fact that having 30% of torque available is not necessarily a good thing, independent of belts or screws.
The reason for my comment was due to what was previously discussed by both Casey and Rob was that switching to screws fixed or will fix their axis slipping during bit changes with belts. Thatās fixable with an adjustment to the machine controller. Thatās like buying a new car instead of just replacing the battery when it dies.
Just trying to be helpful.
I am with you man I am not sure how they where making the machine loose steps when doing a bit change?
I am thinking that there belts might have been loose
not enough current going to the motors
or they are over tightening there tools it does not take much to lock a tool down tight
No. The Xcontroller has an auto torque reduction feature that, when an axis is idle, it reduces the reference voltage to 30% of ānominalā, this has a direct effect on holding torque since the current is reduced as well (V=I*R) so the carriage can move.
That feature is enabled by default (or at least on my Xcontroller and others that have posted pics of DIP switches) and also is shown as the desired setup in the instructions.
For the record, Iām not saying anything negative about @Phantommās system. I think itās a great idea as it reduces a lot of possibility for user tolerance and has numerous other benefits discussed earlier. Iām also not saying anybody only bought the upgrade only to stop the carriage moving, just an added bonus that comes with the upgrade.
I have a Z-axis with ACME direct drive and Delrin block.
With stepper idle=10 the weight of my router would make the carriage drop under its own weight, the friction was almost zero.
This was with undersized motors btw and stepper idle = 10.
My point is, a smooth screw drive should have very little friction indeed and not inherently ābetterā against position shift due to excessive man-handling 
I use 50% current reduction on my drivers now (and bigger motors) and they have been behaving perfect 
Interesting. Without the motor attached my vfd spindle would also fall but once I attach the motor without power it takes a finger to push it down. But with power nothing moves without rotating the couplers.
Consider this. Z slipping during bit change is not a concern for most since it will require rezeroing after the bit change. The biggest concern was xy slippage during bit changes. I have experienced that a few times with belts but Charlie kinda saved my work more than once. Iām not sure what allows it to slip but I do remember back then being able to move the carriage during bit changes but not as much during operation. What setting/dipswitches should I check?
And what do the settings do? (In laymenās terms)
And define undersize vs underpowered.
On the list and canāt wait!!!
Update. So I am almost done negotiating prices with my supplier. Iāll be emailing everyone with due dates prices and payment methods for the batch.
For anyone who has not sent me their email yet please do.
I am just looking at cnc machines at the moment. This looks upgrade looks like it makes a huge difference to the machine. I like it. I am looking to use a cnc to inlay designs on cutting boards. The designs can be quite complex. I worried about repeatablilty and cutting a mirrored design to fit into the original and not have gaps. I will keep an eye on this thread. thanks
Can I still get on the list?
I donāt believe this is accurate. If you modify designs that were licensed by Inventables, you create adapted material. If you sell that material, it must include a derived license.
So for example, heās welcome to sell these modifications, but must publish the plans with them ā at least for his customers. Otherwise itās a violation of the license from Inventables that you accept by using their CADās.
Didnāt use their cads. 
But Iām still gonna avoid the issue.
I understand thatās one interpretation but having reviewed the license, I donāt believe itās correct. While Iām not a lawyer, I work a lot with open source licenses in my job, and am familiar with the CC license that Inventables is using.
Itās pretty clear that derived works have to be distributed with a Creative Commons license. Thatās explicitly called out in the āShareAlikeā clause.
I donāt really have a horse in this race since I neither have this product, nor am I part of Inventables. That said, if @Phantomm didnāt even use the source CAD files from Inventables, this is all a moot point since his work is not adapted material 
Really? Iām not sure why you would resort to a personal attack like that?
I donāt want the screw drive and I donāt want the plans for the screw drive. I even explicitly said that if Inventableās CAD files werenāt used, this license doesnāt apply.
This is the way open source licenses work though ā if you use and adapt open source material like Inventableās CAD files, then it must be distributed with a compatible license. You can read more about this at copyleft.org.
Either way, both @JustinBusby and I pointed out that weāre not lawyers. If I were to build a business on possibly licensed work, I would definitely consult with one to make sure everything is in the clear.
Iām pretty confused about the way this thread is going.
It appears that everybody (for the most part) agrees and are discussing the same side of the issue.
Yes, there is a license.
Doesnāt seem to be any infringement.
The discussion continues.
What am I missing?
Not sure. I was originally under the impression that open source CADās were used, but @Phantomm cleared that up.
Project looks great! One thing Iām curious aboutā with the screw drive, would it be feasible to upgrade to a beefier (and heavier) spindle? Iād love to start being able to use 1/2" shank toolsā¦
