So I got this iterated again, thanks to tips from @Thomas_Sanladerer and @Ryan_Carlyle . It should do the job now. Swaped LM8UU for LM10LUU and rigidized the lead.
I have a spanner I’d like to throw in the works. If that’s going to be a 200x200 max build plate you’re going to probably be ok. Bigger may be a problem, I know this because this is how I used to build my Z on mine I ended up with 2 Z motors and this on both sides to keep it level.
It will be 300x200x200mm (WDH) but maybe I should cut the coupling. Thanks for your recommendation!
I also thought about a setup like yours but ditched it. I will give my design a try. Adding or changing axes can be easily done here.
That looks great. Nice design.
Cantilever length (distance from edge of bed to the screw) is really the only parameter that matters very much. 200mm is about the most I would recommend. The springboard effect gets worse and worse.
What you have here will work, you’ll just need to be gentle with the Z motion settings. Low jerk and acceleration, no aggressive Z-hopping, etc.
Is there any data available on how much torque a lmxxluu and similar can handle? I can do the math on torque myself
It’ll vary by bearing manufacturer, but sure, you can find the moment load ratings for the bearing and do the torque math. I wouldn’t worry too much about the bearing load capacity though, it’s flex of the rod and cantilever that kill you.
A bearing+rod at its max rated capacity will be flexed far too much to be acceptable for 3d printing. That’s why we use vastly-over-spec’d parts and lightly load them.
Ah okay. So it would be appreciable to use stronger rods than 10mm depending on the height of the z axis/length of the table and the resulting torque/load on the bearing and the rod to get lower vibration on the parts. I don’t have the English word at hand now but what you call springboard effect is “aufschwingen” in German. Rising amplitude over time. Right?
Yes. The more weight you have being supported with a cantilever, the more likely it will want to bounce up and down when making quick movements. A good alternative to linear rods and bearings would be to use linear rails with one long carriage or two smaller ones. For my bigger printers I will use a linear carriage with an integrated ball screw just to make things easier.
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I would suggest at least 16mm rods. Lead screw behind the rods will also add unnecessary stress to the cantilever action. I would suggest moving the rod mounts on the outside of the extrusion. Looks good, 3d printed parts or milled aluminum?
had issues with a cantilever so went for a 3 point bed lifting …
Okay, got it then, @Blake_Dunham .
@Kyle1 it’s going to be milled.
Umm… rethink the mount of the linear bearings! You put an angle on the surface of the screws, screws don’t like that 