1P Z mod for Rat Rig V-Core 3

This mod allows you to implement the 1P Z motion system onto a Rat Rig V-Core 3 printer.

Please do not attempt this mod if you do not have the ability to machine the Dual Axis V-Pivot Crossaxle from stainless steel or aluminium. While this mod is currently working well on my printer, I do believe I can make further refinements to it.

While other mods, such as de-couplers in the bed arms greatly reduce lead screw artifacts in the prints, the 1P Z design makes it completely impossible to get lead screw induced artifacts in prints. As a bonus it also reduces other Z artifacts.

It has only been tested on the smaller V-Core 3 300.

I have the prototype up and running on my V-Core 3 and it works extremely well. It meets all of the design objectives, enabling Z tilt bed levelling with zero leadscrew artifacts.

The current version uses two linear rods for the rear bed arm mounted to a 3090 extrusion. Getting these linear rails perfectly aligned is not easy and you may need to mill the surface of the 3090 extrusion so that it is simple to mount the dual linear rails near perfectly true to each other. If the linear rails are not near perfectly aligned to each other, you will get binding.

In my case I was lucky enough not to need to do this and I have mine setup nicely and working well.

The Bed V-Block has been printed from ePAHT-CF and annealed post printing. This material should prove durable for long term use at 150C.

I will machine a Bed V-Block from alloy at a later date just to see if there are any advantages to it. However, testing over the last couple of months with one printed from ePAHT-CF filament makes me think the ePAHT-CF may be more than good enough. ePAHT also has the advantage that it provides some extra heat insulation, which stops heat conducting away from the bed to the Dual Axis V-Pivot crossaxle and rear bed arm.

The bed needs to have two 6mm diameter x 1 mm pitch, holes drilled and tapped into it to mount the Bed V-Pivot to the bed.

The Dual Axis V-Pivot Crossaxle can be machined from stainless steel or aluminium.

BOM for fitment to a Rat Rig V-Core 3
1 x 420 mm long 3090 extrusion.
1 x extra linear rail for the rear Z motion system (same length and spec as the one used on the original Rat Rig V-Core 3
1 x stainless steel or aluminium Dual Axis V-Pivot Crossaxle.
3 x VenterMech star drives (STL files for these are free)
2 x countersunk 6 mm screws to mount the Bed V-Block to the bed
2 x bed isolators to sit under the bed balls in the front arms. (I am currently testing two options for these. But cost will be no more than $5 each from Aliexpress or similar.

Printing recomendations
Rear arm and Bed V pivot must be printed from eSun's ePAHT-CF filament and then annealed in kitchen over at 120C for two hours to prevent pressure creep. These parts must be both rigid and able to withstand long term heat without deformation. ePAHT-CF meets these requirements very well. ePAHT-CF is easy to print and does not need to be printed in an enclosure. These two parts could also be printed from Polycarbontate-CF but I fear this is too prone to brittleness and cracking.

The rear bed arm is designed to be printed with the top face flat on the printer bed, I print this with supports uinside the V pivot section only. The two flaps on the sides of the V-Pivot are just there to assist with bed adhesion and are trimmed off after printing.

I did think of machining both these parts from alloy, but this would have caused to much heat 'leakage' from the bed.

Updates
V2 version of rear arm now has enlarged hole sizes for head of cap screws.

For a lot more detailed information and explanations of the 1P Z mtoion system please look here:

https://www.facebook.com/groups/3dprinterdesign/announcements

For information on the 1P Z motion system license please see:

https://www.thingiverse.com/thing:5442000

https://www.thingiverse.com/thing:5475498