Anyone out there ever have issues with lead screws for Z axis automatically moving downward due to the weight of the gantry/carriage? How have you resolved it?
I had that issue with my Anet E10. I just tried not to touch it because if I pushed on it, usually 1 motor would spin more than the other and it would throw my calibration off. The remedy to fix this is to attach a belt to both lead screws to make sure they spin at the same time. This way if the z axis does move down, both sides move together. I ended up just buying an Ender 3 which only has 1 lead screw so I don’t have that issue anymore.
I solved it in my i3 clone that didn’t have a good route for a belt by switching to single-start (8mm diameter, 2mm pitch, 2mm lead) lead screws instead of the more typical 4-start 8mm lead screws.
@mcdanlj Sounds like the best solution. I always wondered why are these 8 mm lead screws used instead of the 2 mm ones - why reduce the Z resolution?
@Petr_Sedlacek maybe it’s because the Z axis is accurate enough and 2mm would make the Z Axis take forever to go up and down?
@Kevin_Danger_Powers I really like the Ender 3, thinking about getting one to have better print quality for my (seemingly endless) large delta build. But this single Z screw makes me nervous - I imagine the X gantry must be sloping since it’s only supported on one side But I suppose it’s not a problem if the X-Z interface is stiff enough.
@Kevin_Danger_Powers The only upside I could think of was the speed - but I was thinking who needs to go fast in Z? Also, I’m used to an M8 threaded rod for Z with 1.25 mm pitch
@Petr_Sedlacek It’s VERY stiff actually. I was worried about that as well but it’s so solid I bet that I could remove the vertical support on the right side and it would still print decent. This is the 3rd printer I’ve owned and it’s by far the nicest.
@Kevin_Danger_Powers Good to hear that. It’s really amazing what they can sell at $180 and still make a profit!
@Petr_Sedlacek I was blown away at the price to performance ratio of the Ender 3. It’s far better than expected.
Even on my custom corexy build I’m doing, where I have one motor and synchronous belt driving two lead screws, I’m using single start 2mm lead screws. I see no reason for fast start screws. Z speed is just not important, resolution and stability are…
Yup. I was hoping to find a simple firmware setting to keep the Z stepper from de-engergizing, but turns out you have to recompile the firmware from source. Not quite that brave yet.
I ended up putting a second nut on the rod, separated with a spring and held close with a zip-tie. That increased the friction enough to almost eliminate the sagging.
See the comments for a picture:
zyltech carries single-start T8 lead screw with anti-backlash nuts in the US: http://www.zyltech.com/8mm-t8x2-lead-screw-trapezoidal-acme-w-brass-anti-backlash-nut-kit-pre-cut-lengths-150mm-2000mm/
I haven’t purchased from them only because I learned about them about a week after I bought my most recent T8*2 from china after giving up on finding it in the US…
My ball screw does the same when my big router is mounted. Fixed by using some long rubber bands as anti gravity lifts. I can lift over 20 lbs but if the motor goes idle 3lbs would make it drop. This does not add any mad like a counter balance would but I’d very effective. May take a little trial to get it correct, but very chest and easy.