Anyone built one of these CoreXZ variants?

Phaedrux

Might want to check out the Voron Switchwire. Probably the most modern and complete take on the coreXZ.

https://vorondesign.com/voron_switchwire

Luke'sLaboratory

@phaedrux Isn't that a deltesian?

coreXZ still has a "standard" gantry that isn't linkages like that.

@fcwilt https://twitter.com/bornity <- this guy loves em and i think designed his own.

fcwilt

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

Might want to check out the Voron Switchwire. Probably the most modern and complete take on the coreXZ.

https://vorondesign.com/voron_switchwire

Yes I've seen more than one of the that sort of design but I haven't seen an actual instance of the kind I posted.

I'm not sure what makes them both CoreXZ. The XZ part I understand but I don't know what Core implies about the design, if anything.

The person writing about the design I posted feels it has the all of the advantages of a Delta with none of the disadvantages.

I wonder if RRF3 can support this kind of printer...

Thanks.

Frederick

Phaedrux

Ah yes the photo does look more like a deltesian with the arms.

o_lampe

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

I don't know what Core implies about the design, if anything.

In my book it means both motors are stationary? But then a MarkForge would be a Core-printer, too?

o_lampe

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

it has the all of the advantages of a Delta with none of the disadvantages.

Hmm, if a Delta has any disadvantages, I see them here, too:

Tall towers for the extra Z-height a Delta needs
nonlinear kinematic

If I'd ever built a bedslinger, I'd go for a conveyor belt. But then the Delta arms would have disadvantages against wire-driven CoreXZ, because of the 45° tilt the gantry would need.

JoergS5

@fcwilt I saw this type in a book about parallel robots, offering better precision than a normal scara. But I cannot find the source any more...

Searching the book, I found an interesting article about precision here: https://ms.copernicus.org/articles/10/255/2019/ . The mentioned parallelogram is used in your type also (your type is something similar to cartesian parallel, tripteron family), giving higher precision. In my understanding, best for precision to hold something is to constrain it at both ends, second best is parallelogram, worst is cantilevered.

fcwilt

@joergs5 said in Anyone built one of these CoreXZ variants?:

@fcwilt I saw this type in a book about parallel robots, offering better precision than a normal scara. But I cannot find the source any more...

Thanks much. I will be reading that.

Frederick

o_lampe

@joergs5 said in Anyone built one of these CoreXZ variants?:

In my understanding, best for precision to hold something is to constrain it at both ends, second best is parallelogram, worst is cantilevered.

I'd really like to build a frame/gantry that is just right constrained. That would also include a cantilevered bed, but with anti-racking, self-leveling fishing line constraints.

fcwilt

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

I'd really like to build a frame/gantry that is just right constrained. That would also include a cantilevered bed, but with anti-racking, self-leveling fishing line constraints.

Is that a real thing - fishing line constraints?

Frederick

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...