Anyone built one of these CoreXZ variants?

o_lampe

@fcwilt
Nope
It's just a hint, how I'd do it. Zig-zacking a single Aramid line over three planes and then tighten it to #C´´´´

deckingman

That picture looks to me like an exercise in how to take the worst features of every kinematics type and put them all together in one machine.

fcwilt

@deckingman said in Anyone built one of these CoreXZ variants?:

That picture looks to me like an exercise in how to take the worst features of every kinematics type and put them all together in one machine.

I know little about it. I was searching to find what a Core XZ was and ran across that. The person who posted it seems quite pleased with the design - maybe it is his - I don't know.

I won't be building one, was just curious as I had not seen that design before.

JoergS5

A similar robot, which is usable for endless pick and place, is this: https://www.youtube.com/watch?v=Omd90UfgGv0 with homepage https://www.bell-everman.com/products/linear-positioning/kaos-oem , if a Y bed movement is added.

o_lampe

For a Delta the rods needs to be parallel (in top view), but not here.
It would be interesting to try a trapezoidal rod distance in this case. Wider distance at the effector vs. narrow distance at the towers.
It would be stiffer around vertical loads, like a 45° tilt. That would also give more room above the effector for direct drive and such.

Even a triangle would be tempting, Two rods on top (as trapezoid) and one rod below the effector.
Hmmm, I have a spare set of mag rods laying around...

o_lampe

This post is deleted!

dc42

@o_lampe said in Anyone built one of these CoreXZ variants?:

@o_lampe
just some food for thought:
the XZ motion could be done by two Rotary arm steppers. Like the real servo driven deltas do...

A problem with rotary deltas is that you need very fine resolution of the rotation of the rotor arm. This means that you need to use a gearbox, which introduced backlash.

Would that kinematic be easier to implement or does it even exist already?

It isn't implemented in RRF and it would be more difficult to support than the linear tower arrangement. The linear tower arrangement (i.e. delta with just two towers) needs to do only basic maths and square roots to calculate the step times, and it could use the existing support for segment-free delta motion. The rotary arrangement would need to use segmentation, and the step calculations would need to use trigonometric functions.

fcwilt

@dc42 said in Anyone built one of these CoreXZ variants?:

It isn't implemented in RRF and it would be more difficult to support than the linear tower arrangement. The linear tower arrangement (i.e. delta with just two towers) needs to do only basic maths and square roots to calculate the step times, and it could use the existing support for segment-free delta motion. The rotary arrangement would need to use segmentation, and the step calculations would need to use trigonometric functions.

So RRF could do the pictured type of printer?

If so, what would the M669 matrix look like?

Thanks.

Frederick

o_lampe

@dc42
I already deleted the reply, because a rotary stepper wouldn't solve the Z-motion. But good to know it's harder to implement.

o_lampe

Opposite to a wire driven CoreXZ, this version offers the possibility to tilt the effector in +/- X direction.
For a conveyor belt printer, would that be a useful feature?
Slicing for a belt printer is a big mystery for me anyway, so whynot add even more myth...

JoergS5

@o_lampe said in Anyone built one of these CoreXZ variants?:

possibility to tilt the effector in +/- X direction.

For tilting imho you need an additional actuator. The sample above makes sure by parallelogram and the stiff light blue construction that the effector is always horizontal. Two actuators for XZ. https://www.hindawi.com/journals/isrn/2013/593606/ is also funny and allows tilting.

I am surprised how much different kinematics exist, I discovered some new the last two days.