from http://diy3dprinting.blogspot.ca/2014/12/sli3dr-3d-printer-by-richrap.html
Ah cool.
I think the idea is getting the (large) motor mass off the gantry, which could significantly improve the dynamic performance of the system. Of course, that’s balanced with the increase in pully mass and complexity.
What’s more interesting is the use of a cable (vs timing belts). This is/was common on large format plotters and printers.
Corexy also unloads the motor weight. What new to me is putting the motors on opposite sides of the frame. I hope you like long wires!
This design also appears to avoid the two planes required in a corexy design. The belt in a corexy must change planes twice, which places lateral stress on the belt (not designed for that) This lateral stress may weaken the belt over time and make it more elastic or stretch it.
P.S. you can put the motors anywhere you like along the path, if you prefer you can put the motors on the same side of the frame. In fact, you could place the motors at the location of any of the pulleys and reduce the bearing/axle count.
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I think the point with the placement is also that this model completely evens out the tension on the lines, because they aren’t directly connected to any of the connectors and are placed so that they have a relative normalized pressure distribution.
EDIT: CoreXY is pulling directly on the platform for instance.
I like the slider model… It’s very elegant.
I’ve seen this on 3D printers as well. But apparently has some problems and I havn’t seen a good working example that is as good as an x , y setup.
Problems with precise movement control.
Lots of issues for precise movement control. And bad position holding characteristics. But probably great for high speed non-precise movement control with a spring tensioned cable.
It would depend on the elasticity of the wire used, no?
As far as I can tell, this setup was originally used for plotters, so less weight and less tension variance.
Okay yeah I think that’s what I was told. Makes sense. The belt is so long that the flex adds up and creates too much. Especially when you compare that to having 4 shorter belts instead
The problem with this design is stretch along the full length of the wire and all the pulley bearing tolerances and all the pulley roundness tolerances adding up.
The challenge is sufficient slack to accommodate tolerances without causing that slack to translate into movement. This design results in slack required to accommodate tolerances resulting in movement.
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